project title: understanding the scale and …...harriet roberts horticultural consultant adas uk...

Agriculture and Horticulture Development Board 2015. All rights reserved

Project title: Understanding the scale and importance

of raspberry leaf blotch virus and its

association with raspberry leaf and bud

mite

Project number: SF 148

Project leader: Stuart MacFarlane, James Hutton Institute

Harriet Roberts, ADAS UK Ltd.

Report: Annual report, February 2015

Previous report: N/A

Key staff: Janet Allen, ADAS UK Ltd

Chris Dyer, ADAS UK Ltd

Location of project: ADAS Boxworth

Battlegate Road

Cambridge

CB23 4NN

Industry Representative: Seth Walpole, R W Walpole, Ivy Farm,

Terrington St Clement, Kings Lynn,

Norfolk, PE34 4PX

Date project commenced: 1 March 2014

Date project completed

(or expected completion date):

28 February 2017


DISCLAIMER

While the Agriculture and Horticulture Development Board seeks to ensure that the

information contained within this document is accurate at the time of printing, no warranty is

given in respect thereof and, to the maximum extent permitted by law the Agriculture and

Horticulture Development Board accepts no liability for loss, damage or injury howsoever

caused (including that caused by negligence) or suffered directly or indirectly in relation to

information and opinions contained in or omitted from this document.

© Agriculture and Horticulture Development Board 2015. No part of this publication may be

reproduced in any material form (including by photocopy or storage in any medium by

electronic mean) or any copy or adaptation stored, published or distributed (by physical,

electronic or other means) without prior permission in writing of the Agriculture and

Horticulture Development Board, other than by reproduction in an unmodified form for the

sole purpose of use as an information resource when the Agriculture and Horticulture

Development Board or AHDB Horticulture is clearly acknowledged as the source, or in

accordance with the provisions of the Copyright, Designs and Patents Act 1988. All rights

reserved.


AUTHENTICATION

We declare that this work was done under our supervision according to the procedures

described herein and that the report represents a true and accurate record of the results

obtained.

Stuart MacFarlane

Research Virologist

James Hutton Institute

Signature Date 20 February 2015

Harriet Roberts

Horticultural Consultant

ADAS UK Ltd.


Report authorised by:

Tim O’Neill

Horticultural Research manager

ADAS UK Ltd.



CONTENTS

Grower Summary…………………………………………………………………………………..1

Headline.................................................................................................................. 1

Background and expected deliverables .................................................................. 1

Summary of the project and main conclusions ....................................................... 2

UK wide sampling and assessment ............................................................................... 2

Virus transmission trials ................................................................................................. 6

Financial benefits .................................................................................................... 7

Action points for growers ........................................................................................ 7

Science Section……………………………………………………………………………8

Introduction ............................................................................................................. 8

The mite ........................................................................................................................ 9

The virus ..................................................................................................................... 10

Knowledge requirements ............................................................................................. 11

Aims and objectives..................................................................................................... 11

Materials and methods ......................................................................................... 12

UK wide raspberry sampling ........................................................................................ 12

Mite and virus assessment .......................................................................................... 12

Virus transmission trials ............................................................................................... 13

Results .................................................................................................................. 14

UK wide raspberry sampling and mite-virus assessment ............................................. 14


Discussion ............................................................................................................ 29

UK wide raspberry sampling and mite-virus assessment ............................................. 29



Conclusions .......................................................................................................... 31

Next steps ............................................................................................................. 31

Knowledge and Technology Transfer ................................................................... 32

References ........................................................................................................... 32

Appendices ........................................................................................................... 33

Appendix 1 – Cropping data collected for each sample ............................................... 33

Appendix 2 Results of the RLBV PCR test for each samples along with full cropping

details for each sample – Summer 2014 ...................................................................... 34

Agriculture and Horticulture Development Board 2015. All rights reserved 1

GROWER SUMMARY

Headline

There is a strong link between raspberry leaf blotch virus infection and the presence

of its vector raspberry leaf and bud mite.

Background and expected deliverables

Crop damage previously solely associated with the feeding of raspberry leaf and bud mite

(RLBM), is an increasing problem around the UK and it is now known that in some cases,

infection with Raspberry Leaf Blotch Virus (RLBV) is also involved. It affects Glen Ample in

particular but symptoms are increasingly being seen on other varieties (Figures 1 and 2).

There is also a suggestion (preliminary results: J. Allen/S. MacFarlane) that the recent

health decline in certain varieties such as Octavia (poor lateral development, die back,

blotchy leaves and malformed fruit - Figures 3 and 4) could be associated with this pest

and/or virus. The association between the mite and RLBV has been proven, but

increasingly, crop damage symptoms are being observed without the mite being seen in the

field.

This project aims to carry out a UK-wide sampling effort of plantations and conduct

experiments to try and elucidate the links between the mites, the virus, plantation age,

variety, yield loss and plant source, to inform strategies for control.

Symptoms

Figure 1. Minor leaf blotch symptom - primocane leaf

Figure 2. Moderate to severe infection to floricane lateral, blotches to primocane leaves


Figures 3 & 4. Severe infection - curled twisted chlorotic leaves and malformed fruit

Summary of the project and main conclusions

UK wide sampling and assessment

During the summer and early autumn of 2014, ADAS consultants contacted and visited 28

raspberry growers. In this first year of the project (to make sure positive samples were

collected) sampling was targeted to sites with a history of this pest, where potential

symptoms had been observed in 2013 or where there was a long history of raspberry

production. At each site the grower was interviewed and up to five plantations were

selected for sampling; both symptomatic and asymptomatic plantations and a wide range of

flori (summer) and primocane (autumn) fruiting varieties were sampled to differentiate why

some plantations are affected by the mite and/or virus and why others are not. Within each

plantation a single plant was selected and five of the newest fully emerged leaves from a

primocane were collected and sent to the James Hutton Institute for molecular analysis by

PCR (polymerase chain reaction). Detailed cropping information was collected for each site

to support and inform the results, including: variety, planting date, planting material, spawn

management, acaricide use, yield observed in 2013, presence of wild hosts and level of

symptoms at sampling.

Scale and severity of RLBM and RLBV

RLBV was confirmed in 30% of the 95 plantations sampled. Positive samples were found

on 40% of the holdings and 42% of the 24 different varieties sampled. Mites were detected

on 30% of the samples, 24% of which were also positive for RLBV. Both the mite and virus

were detected in all of the key fruit growing regions of the UK on both small and large

holdings utilising both protected and containerised production. This suggests the mites and

the virus are closely associated and widely distributed around the UK.


The presence or absence of RLBM strongly indicated whether or not the sample was likely

to be positive for the virus (Table 1). A total of 84 out of 91 samples (88.4%) gave results

consistent with the proven link that RLBM is a vector for RLBV.

Table 1. Association of Raspberry Leaf Blotch Virus (RLBV) with presence of raspberry leaf

and bud mite (RLBM) in UK Raspberry crops – 2014

Number of samples in each category

RLBM - RLBV -

RLBV + RLBM -

RLBV - RLBM +

RLBV + RLBM +

61 6 5 23

Mite-virus interaction and links with plantation decline

Several of the worst affected sites sampled in 2014 were grubbed at the end of the season

because of plantation decline as a result of this mite virus complex. It is clearly a damaging

condition and one that can build up over time. However it is still unclear whether the virus

can move systemically within a plant or whether overwintering populations of the mite

perpetuate the virus infection and plant damage. In this study the virus was rarely found in

the absence of the mite, which is promising as there is a much greater potential to control

the mite on farm than the virus. Overall there was good agreement between characteristic

symptoms of yellow leaf blotching and presence of the mite and or virus. However, in the

newer plantations a greater proportion of ambiguous symptoms did yield positive virus

results.

A summary of factors that appear to be associated with a high incidence of RLBV is

provided in Table 2.


Table 2. Summary of some factors that appear to be associated with RLBV symptoms from

examination of 95 raspberry plantations in 2014

Factor Comment High(er) Incidence*

Low(er) Incidence*

Variety 10 out of 24 cv’s positive Glen Ample Octavia

Tulameen

Plantation age Trend for greater in older plantations - -

Region Present in all regions West Mids East Anglia South East

Planting material

Present in plantations grown from all types of planting material

Bare root short cane

Root Modules

Spawn management

Present whatever system used; worse where mechanical

Mow or Strim Hand or Shark

Wild raspberry Greater chance or infected crop if wild raspberry is adjacent

- -

Mite control Less RLBV if a mite control strategy is in place (be it for RLBM or two spotted spider mite)

No mite control

Acaricide or predators used

Cropping system

Present in plantations grown in all types of system

Outdoor Soil

Tunnelled containerised

*Only reported where sample size is greater than or equal to 10

Varietal susceptibility

Glen Ample and some of the older floricane varieties, as expected, were the varieties most

commonly affected by the condition, but more modern varieties including CV-C and some

primocane varieties (previously considered less susceptible) were also found to be affected.

This suggests a wide cohort of varieties could be infested with both the mite and virus. In

this first year the sampling effort was deliberately targeted to sites with a history of this pest,

where potential symptoms had been observed in 2013 or where there was a long history of

raspberry production. Wherever possible both symptomatic and asymptomatic plantations

and varieties were sampled at each site. To gain a more representative indication of the

level of RLBM and RLBV in the UK raspberry industry, further sampling is proposed in 2015

to collect information from a larger number of plantations including those with no history of

the pest or virus and located on sites in areas of the UK which until recently have not been

used for raspberry production and have been planted with modern primocane fruiting

raspberry varieties.

Trends in cropping situations where RLBV occurs

This initial survey also suggests that the way in which crops are managed may affect the

condition. Spawn management appears to have some effect on levels of the mite and virus

with physical methods of unwanted primocane removal (as opposed to chemical) seemingly

showing greater levels of the mite and virus. Potentially this could be related to seasonal


carry-over of mites as the presence and proximity of young primocane foliage to infested

floricane leaves allows mites to migrate onto next year’s canes. Earlier removal of the first

or second flush of primocane could hinder this migration and or systemic movement of the

virus. In this first year the question posed to growers was to describe their spawn

management approach, from which we received some basic responses; in 2015 information

will also be sought on timing of management.

Sites which used the acaricide abamectin and/or releases of the predatory mites, appeared

to have a lower level of RLBV and RLBM suggesting use of these agents could be providing

incidental control of the mite, thereby reducing levels of the virus. One site where leaf

blotching was observed early in the season on floricane leaves, was specifically treated with

abamectin for RLBM. Samples of both floricane and primocane leaves were collected. No

blotching or virus was detected on the primocane despite the floricane showing severe

symptoms and testing positive for RLBV. Specific sampling of identified locations in 2015

will collect further information on this topic. Presence of wild raspberry in close proximity to

raspberry plantations seemed to increase the proportion of plantations affected. As both

RLBM and RLBV can be found on wild raspberry hosts, proximity of infested wild raspberry

to commercial raspberry plantations could be responsible for infection into new plantations.

All sources of planting material (bare root short and long cane, modules and root cuttings)

used to establish the plantations examined in this study, showed examples of RLBV and

RLBM infection. However, bare root short cane planting material showed a greater

incidence or RLBV infection compared with other types. This might be explained by the

fruiting plantation age and/or growing system whereby the more traditionally managed and

older plantations which tended to show more RLBV, would more commonly have used

standard bare rooted plants for establishment.

A higher proportion of the more recently planted fruiting plantations were established using

root cuttings, or small soft module raised plants. Within this study only a small number of

samples were collected from plantations using these materials. In general however, these

showed a lower proportion of RLBV infection. It cannot be assumed however that this type

of planting material is less likely to be affected by RLBV, as the risk would be expected to

depend on the age, health status and the method of production used to grow the mother

plant. At present we do not know whether or not different plant material provides a lower

risk as regards the virus originating from propagation, but neither the mite nor the virus are

currently covered by the PHPS inspector scheme.

Tunnelled and containerised production gave mixed results and will be further investigated

in the wider survey in 2015.


Virus transmission trials

It is not clear whether the disease symptoms seen in plants infected by RLBV are caused

by the virus alone, moving within the plant systemically, or results from movement of mite

carrying the virus to different parts of the affected plant. It has been shown that the bright

yellow sectors of symptomatic raspberry leaves do carry higher levels of virus than the

adjacent green sectors of the same leaves, but presence of virus in root samples suggest

there can be movement of the virus without mite feeding. One method, in principle, to

separate the virus from the mite vector, is to transfer the virus from an infected plant to

another healthy plant by grafting, which should bypass the need to have mites to carry out

the virus transmission. Grafting is a long-established method for virus-testing and is known

to achieve the transfer of the great majority of viruses from plant to plant. Grafting

experiments were initiated in 2014 to investigate whether the virus is moving systemically

within raspberry in the absence of the mite. To do this, a section of an infected raspberry

plant is grafted to a growing healthy raspberry plant using the bottle graft method.

In Year 1 grafts have been set-up to healthy Glen Ample, and to several other older

cultivars that are maintained in collections at the James Hutton Institute known to be

infected with other raspberry viruses. These latter graft experiments will test the hypothesis

that infection of plants with multiple viruses results in increased disease symptoms and

might also increase the level of virus in the plant and, thereby, increase the chance of

successful transmission of RLBV through the graft. Grafted plants will be monitored in 2015

for visual symptoms and presence of the virus by PCR.

Main conclusions

30% of 95 samples taken in 2014 from 28 holdings throughout the UK tested

positive for Raspberry leaf blotch virus (RLBV).

There was a strong link between RLBV infection and presence of its vector

raspberry Leaf and Bud mite (RLBM).

66% with characteristic RLBV symptoms were positive for the virus, with just 4% of

samples showing no symptoms being positive.

It has not been possible in this first year to determine if RLBV is moving systemically

within raspberry plants.

Several factors appear to be associated with a high incidence of RLBV including:

variety, plantation age, type of planting material, spawn management, occurrence of

wild raspberry and measures used for mite control which will be further investigated

in 2015.


Financial benefits

Increased knowledge of the scale, severity and main causes of this disorder which is

becoming an increasing problem for many commercially grown varieties.

Potential to reduce crop damage through development of a rational control strategy

based on this better understanding of the mite-virus interaction.

Action points for growers

Careful monitoring and virus testing of young plantations is important to identify the

issue early and attempt to control the mite to avoid build-up of the mite over time.

Highly susceptible varieties could be used as indicator plants in new plantations.


SCIENCE SECTION

Introduction

Raspberry leaf and bud mite (RLBM), Phyllocoptes gracilis (Nalepa 1981) poses a serious

threat to the UK raspberry industry causing severe foliar damage, malformation of fruit and

associated yield loss to the main UK raspberry cultivars (Alford 1984, Mitchell, 2010).

Considerable work has already been done to investigate chemical and biological control of

the mite, but increasingly the leaf blotch and other symptoms are being observed in

plantations in the absence of the mites (personal observation J. Allen/S. MacFarlane).

Symptoms associated with RLBM feeding alone are similar to those seen in virus-type

infections, however work done in the 1980s concluded that there was not a virus component

to RLBM problem.

Using new techniques researchers at The James Hutton Institute demonstrated in 2012 that

diseased plants do carry a newly described virus (named raspberry leaf blotch virus; RLBV)

(McGavin, MacFarlane et al. 2012). Virus testing has since been carried out in response to

requests from individual growers and ADAS advisors on samples showing symptoms and

all have been found to carry this virus.

No systematic survey however has yet been done to reveal how widespread this newly

described virus is, whether it is always associated with mite feeding and whether it is also

associated with chronic decline of raspberries. In addition, no experiments have yet been

done to discover whether RLBM causes crop damage greater than normal feeding damage

in the absence of the virus, or whether it is the virus that causes the majority of the disease

symptoms. Figures 1 and 2 detail the sort of damage observed from this mite-virus

interaction.


Figure 5. RLBV/RLBM symptoms on raspberry. A) Symptoms on floricane leaves, B) leaf

rolling, C) mottled leaf blotch symptom, D) Symptoms on primocane leaves Source: JHI

Figure 6. Severe symptoms observed on Glen Ample in 2013, causing lateral die back and

malformed fruit - confirmed RLBV, no mites observed.

The mite

Raspberry leaf and bud mite (Phyllocoptes gracilis Nalepa; RLBM) is a microscopic mite of

the family Eriophyidae (gall and rust mites) that colonises red raspberry and closely related

Rubus species and hybrids. They have a very large geographical range, being found in

most countries where raspberry is grown, particularly Europe and North America where they

are known by the common name ‘dry berry mites’ (Ellis, Convers et al. 1991). In the UK

A

B

C

D


they readily colonise raspberry in the wild and are frequently found on commercial stocks.

The damage caused by these mites can range in severity depending on various factors.

The two main factors appear to be 1) environment and 2) cultivar. The change in raspberry

production in the UK from open-field production to semi-protected, tunnel grown crops that

that are well sheltered, warm and prone to dense humid canopies, along with the reliance of

the industry on one or two highly susceptible cultivars (Glen Ample and Octavia), has led to

a rapid increase in reports of damage attributed to these mites (Mitchell, 2010). Like many

other eriophyid mites, RLBM rely on wind movement to travel long distances and it is

impossible to completely isolate plants to prevent spread. There is also the possibility that

the mites may be transported and distributed to new plants on the hands or clothes of

personnel, machinery or flying insects. Once infected, the population of mites within

modern fruiting plantations can rapidly increase, resulting in damage to fruiting cane leaves,

primocane leaves and ultimately the ripe fruit, where quality is reduced due to misshapen

and poorly formed drupelets. Little is known about when the virus is transmitted by the mites

and to what plant tissues (buds or leaves) and whether the virus can move systemically

through the plant.

The virus

JHI studies have shown that the virus is present in the mite, can be transmitted by the mite

and, importantly, has been detected in almost every sample of symptomatic raspberry that

has been tested to date (samples obtained from Southern England, Scotland and mainland

Europe). The virus belongs to a group of similar viruses that are each transmitted by an

eriophyid mite. In at least one example, a virus of legumes, it appears that the mite cannot

multiply efficiently unless it carries the virus, and plants that are resistant to the virus are

very poor hosts for the mite. These studies have not been done for RLBM and RLBV.

In an earlier study (1970s), different raspberry cultivars were examined for their ability to

support mite populations, with the finding that Malling Promise was a much poorer host for

the mite than was Malling Jewel. A previous HDC project (SF 81) reported that Glen Ample

and Malling Landmark were highly susceptible and supported high numbers of mites,

whereas Glen Magna was found to have significantly fewer mites and this was linked to leaf

hair density. During 2011, virus-infected samples that were collected from England and

Scotland have primarily been of Glen Ample, but also include Malling Jewel and Glen Rosa,

often in close proximity to other varieties not showing symptoms. These results suggest that

there are differences in cultivar reaction to this disease, although it is not known whether

these cultivars resist the mite, the newly identified virus or both.


It is also not clear whether the disease symptoms seen in plants infected by RLBV are

caused by the virus alone or result from a combination of virus effects and mite effects,

although we have shown that the bright yellow sectors of symptomatic raspberry leaves do

carry higher levels of virus than the adjacent green sectors of the same leaves (S.

MacFarlane, unpublished results). One method, in principle, to separate the virus from the

mite vector is to transfer the virus from an infected plant to another, healthy plant by

grafting, which should bypass the need to have mites to carry out the virus transmission.

Knowledge requirements

Attempts to control the problem by spraying plants with acaricides to kill the mites have not

been particularly successful, with the development of strong symptoms even in plantations

where few mites can be detected. If it can be shown that the virus is the major cause of the

observable symptoms then a strategy to identify and incorporate virus-resistance into new

cultivars might be appropriate. Currently, however, our knowledge of the interaction

between mite, virus and raspberry plant is very poor. For example, we do not know:

Whether the virus can be present in the plant in the complete absence of mites;

Whether spread of the virus in the plant requires movement of the mite from leaf to

leaf (i.e. is the virus systemic or localised in the absence of the mite?);

Whether the virus can cause disease symptoms in the absence of mites;

Whether the mites cause the symptoms in the absence of the virus;

Whether the virus causes stronger symptoms when it is in combination with other,

commonly occurring viruses.

Aims and objectives

The project aim is to understand how widespread raspberry leaf blotch virus (RLBV) is in

the UK and to better understand the association between the virus and mite infestations.

The specific objectives in the first year were:

To determine how widespread RLBV is in UK floricane and primocane raspberry

plantations;

To confirm preliminary observations that RLBV is associated with plantation decline

(failure of buds to break in situations where obvious symptoms of mite feeding or

the virus are not displayed);

To identify the cropping situations where RLBV occurs i.e. in propagation and/or in

fruiting plantations) or where plants are being grown in close proximity to wild

carriers (Rubus ideae);


To monitor varietal susceptibility to mite and RLBV so as to identify any varietal

traits which might be utilised by plant breeders to provide tolerance or resistance to

the mite feeding and/or infection by the virus.

Materials and methods

UK-wide raspberry sampling

ADAS carried out a UK-wide survey and sampling of raspberry plantations. Plantations

were selected based on history of RLBM infection, but also to represent:

The key fruit growing regions of the UK;

The range of varieties grown;

The different cropping systems used;

Different ages of plantations.

Samples were taken between June and September 2014 aiming to sample plantations

during flowering or harvest. At each site up to five plantations were identified for sampling,

again based on this criterion. Within each plantation the crop was carefully assessed for

symptoms of the mite and/or virus, and cropping details were recorded. These are detailed

in Appendix 1 and include a zero to five score of symptoms observed in the field: 0 = no

disease, 1 = <5% plants affected, 3 = ~50% plants affected, 5 = all plants showing

symptoms; plus description of symptoms including leaf blotches, mite feeding, crumbly fruit

and leaf tip curling. Within identified plantations leaf samples were taken from a single stool

where symptoms were observed and the location marked so that the exact stool could be

returned to for future assessments. If no symptoms were observed a representative sample

was taken in the same manner. Samples consisted of five of the newest fully expanded

leaves from the top of the primocane from each identified stool. Leaf petioles were carefully

wrapped in moist tissue paper and these were individually bagged labelled and sent to JHI

within 48 hours of sampling. At JHI they were assessed for mite infestation and the

presence of virus.

Alongside the sampling ADAS collected detailed cropping information to inform

understanding of the pest, its control and links to virus; this information is shown in

Appendix 1.

Mite and virus assessment

For each set of leaves a digital photo was taken to show symptoms, after this five

microcentrifuge tube lid-sized disks were taken from the different leaves in the sample and


combined into one tube constituting one tissue sample. For all leaf samples two tubes of

leaf discs were prepared, one for RNA extraction and the second for storage. Leaf samples

were stored at -80 °C prior to extraction. Virus detection in raspberry plant samples

involved processing the leaf to isolate total plant RNA. To amplify RLBV sequences present

in the RNA sample, 2 µl of RNA was mixed with 46 µl RNAse-free water, 1 µl each of RLBV

primers 1095 and 1087 (derived from RLBV RNA3 encoding the capsid protein) and

combined with an Illustra Ready-To-Go RT-PCR bead (GE Healthcare).

The database and results from virus analysis and mite infestation examination was then

analysed by ADAS statistician Chris Dyer to correlate the field observations with levels of

the mite/virus.


Grafting is a long-established method for virus-testing and is known to achieve the transfer

of the great majority of viruses from plant to plant. In 2014 virus transmission trials were set

up using a section of an infected raspberry plant grafted to a growing healthy raspberry

plant using the bottle graft method. A soft tissue stem of approximately 15 -20 cm (scion)

was cut from the infected plant (NB older, harder stems cannot be used and so these

experiments can only be done during part of the growing year). All the leaves apart from

those at the tip were removed. A 1 cm upward incision was made a quarter of the way from

the top of the stem. The incision should cut into the vascular tissue. A complementary

incision was made into the stem of the healthy (recipient) plant. The two stems were joined

together using a tongue and groove connection. The join was held together with a strip of

soft, air-tight (Nesco) film. To provide a water supply until the graft union successfully forms,

the base of the scion section was placed into a small bottle or tube of water.

A functional graft junction usually forms within one month and at this time the bottle was

removed (the scion often continues to grow on as an integral part of the recipient plant). The

top two or three nodes of the recipient plant stem (above the graft junction) were removed

and, after a further six weeks or so, the new leaves that emerge from this resected stem

were tested for the presence of virus. After this, the grafted plants were managed in the

normal way with the removal of older stems over the winter period, and new growth

occurring in the next year is also tested for the presence of virus.

Working with RLBV and its mite vector it is very important that live mites are not present on

the graft scion, as these will migrate onto the recipient plant giving false results for virus

transmission via the plant vasculature. So, in our experiments, prior to grafting, the RLBV-

infected plants providing the scions were treated with Dynamec (abamectin) to try to kill any

mites. Plants were also carefully inspected to confirm they were visibly free of mites.


Results

UK-wide raspberry sampling and mite-virus assessment

A total of 95 raspberry plantations were sampled from 28 grower holdings in 2014. Table 3

details the sites sampled, their geographic region, the variety sampled, planting year and

RLBV and RLMB results.

The majority (50%) of samples came from the South East, 10-15% from each of East

Anglia, West Midlands and northern regions and 3-5% from both Scotland and the South

West.

A total of 24 different varieties were assessed, including primocane and floricane varieties.

Of these, Glen Ample made up 25% of samples, Octavia 14%, Tulameen 10% and coded

varieties CV-A and CV-B 6% each. Other varieties consisted of just one or two samples.

Glen Ample is widely regarded as currently the most susceptible variety to RLBM. Other

varieties were chosen to gain further information on varietal susceptibility particularly where

these varieties are grown in close proximity to infected plantations.

Plantation age was recorded: 62 % of plantations were planted in the past five years, 28%

in the last 10 years with the remaining being plantations of older varieties, sampled due to

level of infection.

Of the 95 samples, 29 (30%) were positive for RLBV, this accounted for samples taken on

40% of the holdings tested. Ten of the 24 varieties sampled were positive for the virus, and

the virus was detected in all of the key fruit growing regions of the UK.

Mites were detected on 29 samples, 23 of which were positive for RLBV. Full details of all

sites, along with the detailed responses to the cropping questions, are shown in Appendix 2.


Table 3. Sample details from plantations assessed, including results of the RLBV PCR test for each sample along with a score of disease

severity observed in the field (0-5 scale), observations of visual symptoms in the laboratory and mite presence in the laboratory – Summer

2014

Sample Number

Site number Region Variety: Planting year:

Field level of disease: 0 (no symptoms) to 5

(severe symptoms scale

Symptoms on

laboratory sample

RLBV PCR test

result

RLBM presence absence

1 Site 1 South East Tulameen 2007 1 - - -

2 Site 1 South East Glen Fyne 2012 1 + - -

3 Site 2 North Tadmor * 0 - - +

4 Site 2 North Octavia * 3 + + -

5 Site 2 North Glen Ample * 0 - - -

6 Site 3 North Octavia 2013 0 - - -

7 Site 3 North Glen Ample 2012 3 + + -

8 Site 3 North Glen Ample 2012 0 - - -

9 Site 3 North Octavia 2014 0 - - -

10 Site 2 North Tulameen 2011 0 - - -

11 Site 4 East Anglia Glen Ample 2008 1 + + +

12 Site 4 East Anglia Glen Ample 2008 1 - - -

13 Site 4 East Anglia Chemainus 2014 0 - - -

14 Site 4 East Anglia Tadmor 2014 0 - - -

15 Site 5 South East Glen Ample 2013 5 + + +

16 Site 5 South East Polka 2011 3 + + +


Sample Number




Symptoms on

laboratory sample

RLBV PCR test

result


17 Site 5 South East Tulameen 2005 0 - + +

18 Site 5 South East Octavia 2008 0 - - -

19 Site 6 South East CV-B 2011 0 - - -

20 Site 6 South East Glen Ample 2011 0 - - -

21 Site 6 South East CV-C 2010 0 - - -

22 Site 6 South East Glen Ample 2012 1 + - -

23 Site 7 South East CV-C 2013 2 + + -


25 Site 7 South East CV-C 2013 0 + - -


27 Site 8 South East CV-B 2011 1 - - -



30 Site 8 South East CV-C 2012 0 - - -

31 Site 9 West Mids Glen Moy 1980 3 + + +

32 Site 9 West Mids Polka 2012 0 - - +

33 Site 9 West Mids Glen Ample 2012 1 + + +

34 Site 9 West Mids Octavia 2012 1 + + +

35 Site 10 West Mids Himbo Top 2013 0 - - +


Sample Number




Symptoms on

laboratory sample

RLBV PCR test

result




38 Site 11 Scotland Glen Ample 2012 3 + + +

39 Site 12 Scotland Glen Ericht 2012 2 + + +


41 Site 12 Scotland Glen Ericht 2012 5 + + +


43 Site 13 West Mids Autumn Bliss 1999 0 + - -

44 Site 13 West Mids Glen Magna 1999 1 + + +

45 Site 13 West Mids Glen Clova 1979 1 + + +


47 Site 14 East Anglia CV-A 2010 1 + - -

48 Site 14 East Anglia Glen Ample 2004 0 - - -


50 Site 15 South East Tadmor 2010 1 - - -

51 Site 15 South East Glen Ample 2012 1 - + -

52 Site 15 South East Himbo Top 2012 0 - - -

53 Site 16 South East Autumn Bliss 2006 0 - - -

54 Site 16 South East Glen Clova 2007 1 + - -


Sample Number




Symptoms on

laboratory sample

RLBV PCR test

result





58 Site 1 South East Glen Doll 2009 1 - - -

59 Site 1 South East Tulameen 2008 1 + - -

60 Site 1 South East Himbo Top 2008 1 - - -

61 Site 1 South East Tadmor 2011 1 + + -

62 Site 17 South East Glen Ample 2011 3 + - -

63 Site 18 South East Autumn Treasure 2012 0 - - -

64 Site 18 South East Glen Magna 2007 0 - - -

65 Site 18 South East Polka 2012 0 - - -



68 Site 19 East Anglia CV-A 2012 2 - - -




72 Site 20 East Anglia Polka 2010 3 - - -

73 Site 20 East Anglia Glen Lyon 2005 0 - - -


Sample Number




Symptoms on

laboratory sample

RLBV PCR test

result


74 Site 20 East Anglia T Plus 2007 0 - - -

75 Site 20 East Anglia CV-B 2013 0 + - -

76 Site 20 East Anglia Octavia 2010 3 + - -

77 Site 21 South West Octavia 2011 0 - - -

78 Site 21 South West Tulameen 2011 3 + - +

79 Site 21 South West Glen Ample 2011 3 + + +

80 Site 22 South East Kwanza 2013 0 - - -

81 Site 22 South East CV-D 2014 0 - - -

82 Site 22 South East CV-E 2013 0 - - -

83 Site 22 South East CV-F 2014 0 - - -

84 Site 16 South East Glen Clova * 0 + + -

85 Site 23 South East CV-A 2013 0 + - -

86 Site 23 South East CV-G 2010 1 + - -


88 Site 24 East Anglia Octavia 2008 1 + - -


90 Site 25 South East Octavia 2008 3 + + +

91 Site 1 South East Glen Fyne 2012 0 - - -

92 Site 26 North Glen Ample 2011 5 + + +


Sample Number




Symptoms on

laboratory sample

RLBV PCR test

result


93 Site 26 North Autumn Treasure 2011 0 - - +



Varieties CV-A to CV-G are proprietary varieties the identity of which has been coded

(*) Data not available


In order to try to better understand the links between the mite and the virus and the

additional data collected for each plantation, the data has been manipulated into the

following series of summary tables. Due to the breadth of the survey in 2014 and the

targeted nature of the sampling (directed to plantations with a history of the pest) after

statistical consultation it was not deemed sensible to carry out statistical analysis at this

stage but rather to use this initial survey to guide further sampling which can be subject to

statistical assessment. Where relevant the data set has been further subdivided to show

the results just for Glen Ample and just for plantations planted in the past five years in order

to simplify the data set.

Variety

Table 4. Percent of samples by variety found to be positive for RLBV in 2014

Variety % of samples positive

for RLBV Number of plantations

sampled

Autumn Bliss 0 2

Autumn Treasure 0 2

Chemainus 0 1

Glen Ample 58 24

Glen Clova 67 3

Glen Doll 0 1

Glen Ericht 100 2

Glen Fyne 0 2

Glen Lyon 0 1

Glen Magna 50 2

Glen Moy 100 1

Himbo Top 0 3

Kwanza 0 1

Octavia 36 14

Polka 25 4

T Plus 0 1

Tadmor 25 4

Tulameen 10 10

CV-A 0 6

CV-B 0 3

CV-C 25 4

CV-D 0 1

CV-E 0 1

CV-F 0 1

All varieties 31 95

Of the 24 varieties tested 14 tested negative for the virus. Sampling was skewed to sites

with a history of this pest, where potential symptoms had been observed in 2013 or where


there was a long history of raspberry production. Although these 14 were generally

varieties with only a few samples, the fact that they were often growing in close proximity to

infested plantations could support the theory of differential varietal susceptibility. Glen

Ample was the variety with the most samples, 58 % of these samples tested positive for the

virus, compared with 36 % of Octavia and 10 % of Tulameen the next most sampled

varieties.

Plantation age

Table 5. Percent of samples by plantation age found to be positive for RLBV in 2014

Plantation age (years since planting)

% of samples positive for RLBV

Number of plantations sampled

< 5 years 25 59

5 to 10 years 29 27

>10 years old 80 5

The majority of plantations sampled were planted in the past five years, of these 25 % were

positive for RLBV. Older plantations showed a greater level of RLBV but again these

plantations were often targeted within this survey in order to capture some highly infested

sites.

Region

Table 6. Percent of samples by region found to be positive for RLBV in 2014

Region % of samples positive

for RLBV Number of plantations

sampled

East Anglia 6 16

North 30 10

Scotland 100 5

South East 20 49

South West 33 3

West Midlands 75 12

All regions number of plantations 31 95

Samples were taken from the key fruit growing regions of the UK, RLBV was found in all

regions. Remembering that sampling was skewed to sites with a history of this pest, where

potential symptoms had been observed in 2013 or where there was a long history of

raspberry production, these figures are not an impartial representation of the geographical


spread of this disease, however what they do show is that the virus is present throughout

the country.

Laboratory symptoms and virus presence

Table 7. Interaction between RLBV PCR results and characteristic symptom presentation,

for all varieties, just Glen Ample and just plantations planted in the past five years –

Summer 2014

Sample set Symptom observation

% RLBV PCR results Total number of samples

- ve samples

+ve samples

All samples

No symptoms 96 4 54

Symptoms 34 66 41

Glen Ample

No symptoms 89 11 9

Symptoms 13 87 15

<5 years old

No symptoms 97 3 37

Symptoms 40 60 25

Overall few asymptomatic plants carried the RLBV infection. Looking at Glen Ample alone

however, there did appear to be a greater proportion (11% compared with 3-4%) of RLBV

infection on asymptomatic plants. In general however there was good agreement between

characteristic symptoms and presence of the virus in Glen Ample. False positives i.e.

where symptoms were seen but no virus was detected were more common in other

varieties and newer plantations.

Field symptom severity

With severity of symptoms scored in the field, ambiguity of symptoms appears worse with

no clear trend in increasing % positive virus results with field severity of symptoms. All

samples were also tested for black raspberry necrosis virus (BRNV) as it is generally

accepted that the presence of more than one virus can worsen plant decline. Just 17% of

samples had BRNV. Although more commonly present where symptoms were seen,

symptom severity did not seem to be linked necessarily to the presence of both viruses with

just nine samples positive for both viruses, range of severity in these was: three no

symptoms, four showed severity index one and two were severity index 5. Thus there was

little evidence to suggest that severe symptoms as recorded in this survey were associated

with infection by both viruses. However the current method does not accurately measure

overall decline.


Table 8. Interaction between severity of symptoms observed in the field and presence of

RLBV and possible associated black raspberry necrosis virus (BRNV)

Severity of disease in the field (0-5 scale) % + RLBV % + BRNV Total number in category

0 – No symptoms 7 13 39

1 - <5% plants affected 37 50 31

2 – 5-50% plants affected 7 0 7

3 - ~50% plants affected, 30 19 13

5 - All plants showing symptoms 17 13 5

Total number in category 30 16 95

Virus presence and yield

Overall no clear trends were demonstrated in the data between presence of the virus and

reported yield in 2013 however this was a poorly answered question within the survey. The

severely affected sites which were sampled were showing clear declines in fruit quality and

yield.

Table 9. Interaction between 2013 yield and presence of RLBV

RLBV result

2013 yield

Poor Average Good

%RLBV positive 35 22 67


Association of mite and virus

The presence of RLBV in association with RLBM was strongly supported with 84 of 95

samples (88.4 %) agreeing with this link. The occurrence of six samples with confirmed

RLBV and no evidence of mites and/or damage may be due to 1) transient mite infestation

which has been controlled or declined naturally 2) mite occurrence was at a very low

incidence which was not possible to detect or 3) systemic virus infection was present

following a historic mite infestation. The presence of five samples where RLBV was not

confirmed but the mite was maybe due to 1) the presence of mite populations which do not

transmit the virus or 2) that mite feeding was not extensive enough to have transmitted the

virus. The latter seems more likely as four of the five in this category were primocane

varieties showing no symptoms and were sampled earlier in the year.


Table 10. Association of RLBV with presence of RLBM in UK raspberry crops – 2014

Number of samples in each category

RLBM -

RLBV -

RLBV +

RLBM -

RLBV -

RLBM +

RLBV +

RLBM +

61 6 5 23

Overall just 9% of samples testing positive for RLBV were found without mites. Within the

Glen Ample subset the proportion was higher at 17%. The results showed that 82% of all

varieties and 100% of Glen Ample samples where mites were found were positive for the

virus, suggesting that a very high proportion of the mite population carry the virus.

Interestingly, within the newer plantations a much higher proportion (25%) were found to

have mites but no virus, suggesting perhaps that it may take time for the virus to develop in

canes or may relate to the fact that there were more primocane varieties in this sub set.

Table 11. Interaction between RLBV PCR results and RLBM presence, for all varieties, just

Glen Ample and just plantations planted in the past five years – Summer 2014

Sample set Raspberry leaf and bud mites observed

% RLBV PCR results Total number in category

- ve samples

+ve samples

All samples

No mites 91 9 67

Mites 18 82 28

Glen Ample

No mites 83 17 12

Mites 0 100 12

<5 years old

No mites 91 9 46

Mites 25 75 16

Crop management and virus

The following tables look at some of the other parameters recorded relating to how the crop

is grown and managed.


Table 12. Percent of samples found to be positive for RLBV x planting material, for all

varieties, just Glen Ample and just plantations planted in the past five years – Summer 2014

Planting material

All Glen Ample <5 years

%RLBV positive

Total number in category

%RLBV positive


%RLBV positive


Bare root long cane

25 12 60 5 33 9

Bare root short cane

48 40 77 13 45 20

Modules 15 20 33 3 20 15

Potted long cane

33 3 0 1 0 2

Root 7 14 * * 7 14


31 90 64 22 27 60

*No data in this category

Bare root short cane was the most commonly planted material in this survey and in general

showed the highest proportion of positive RLBV results, particularly in the Glen Ample

subset (77 % of samples positive for RLBV). Root and module material showed a lower

proportion of positive RLBV results (7% and 15% respectively) however there was a greater

number of these sorts of plantings in the newer plantations which generally had a lower

level of infection, which may be a result of the age of the plantation and or variety rather

than planting material.

Table 13. Percent of samples found to be positive for RLBV x spawn management strategy,

for all varieties, just Glen Ample and just plantations planted in the past five years –

Summer 2014

Spawn management strategy


%RLBV positive


%RLBV positive


%RLBV positive


Hand 17 24 33 3 19 21

Mow 67 15 100 6 50 10

Mow + hand 33 3 50 2 0 1

None 0 1 * * * *

Shark 14 14 100 1 17 6

Shark + hand 19 21 38 8 12 17

Shark + Strimming

0 5 0 1 0 2

Strimming 88 8 100 2 100 4


31 91 61 23 26 61

*No data in this category


Overall it appears that the more physical methods of spawn removal (strimming and

mowing) show an increasing trend in positive RLBV infection results (Table 13), this may be

an artefact of some other parameter e.g. overall production system, or perhaps timing of

removal. This requires greater investigation to discover if it is relevant to infestation.

Wild raspberry and RLBV

Both RLBM and RLBV can be found on wild raspberry hosts, so proximity of wild raspberry

to commercial raspberry plantations could be one factor involved in infection of new

plantations. Table 14 shows the percent of sites which were positive for the virus at

locations where wild raspberry was and was not present. Overall 30 plantations had wild

raspberry and 57% of the samples from these plantations were positive for RLBV. In

comparison just 18% of plantations where wild raspberry was not present were positive for

RLBV. For the newer plantations (planted in the past 5 years) this trend continued.

Table 14. Percent of samples found to be positive for RLBV x presence of wild raspberry on

site, for all varieties, just Glen Ample and just plantations planted in the past five years –

Summer 2014

Wild raspberry


%RLBV positive


%RLBV positive


%RLBV positive


Absent 18 61 43 14 16 43

Present 57 30 89 9 50 18


31 91 61 23 26 61

Mite control and RLBV

Where acaricides, such as abamectin (Dynamec), were used in 2014 a smaller proportion

(26% compared with 42% of samples) were found to be positive for RLBV. This was

mirrored in the presence of RLBM in these samples as well (Table 15). Where predatory

mites were released into the crop (i.e. suggesting an IPM approach is being adopted and

therefore native predators should be present (Table 16)), fewer positive virus results (19%)

and fewer plantations with RLB mites were found. This suggests that both control

strategies, although more commonly applied for two spotted spider mite control, do show

some incidental benefit against this pest/virus interaction.


Table 15. Percent of samples found to be positive for RLBV and presence of raspberry leaf

and bud mites x acaricide use – Summer 2014

Acaricide used in 2014? %RLBV positive % with RL&B Mite Total number in

category

No 42 46 26

Yes 26 23 65


Table 16. Percent of samples found to be positive for RLBV and presence of raspberry leaf

and bud mites x predatory mite release (Phytoseilus persimilis) - Summer 2014

Predator release in 2014? %RLBV positive % with RL&B Mite Total number in

category

No 35 34 65

Yes 19 19 26


Cropping system

Of the remaining questions asked, the growing system used suggested a greater proportion

of positive results from the un-tunnelled systems and those grown in the soil. Remembering

that sampling was skewed to sites with a history of this pest, where potential symptoms had

been observed in 2013 or where there was a long history of raspberry production, these

findings need treating with caution.

Table 17. Percent of samples found to be positive for RLBV x growing system - Summer

2014

RLBV results

Tunnelled Growing system

No Yes Trough Soil

%RLBV positive 44 11 16 38

Total number in category 52 37 30 61


In Year 1 grafts were set up with healthy Glen Ample (which is known to be very susceptible

to RLBV), and with several other older cultivars that are maintained in the collections at JHI

and which are known to be infected with other raspberry viruses. These later graft

experiments will test the hypothesis that infection of plants with multiple viruses results in

increased disease symptoms and might also increase the level of virus in the plant and,

thereby, increase the chance of successful transmission of RLBV through the graft. No


transmission of virus into the graft was observed in 2014. These plants will be assessed in

2015 for symptom development and the presence of the virus

Discussion

UK-wide raspberry sampling and mite-virus assessment

Scale and severity of RLBM and RLBV

Of the 95 plantations sampled, 30% were positive for RLBV. This accounted for samples

taken on 40% of the holdings tested and 42% of the varieties sampled. Mites were

detected on 30% of samples, 24% of which were positive for RLBV. Both the mite and virus

were detected in all of the key fruit growing regions of the UK on both small and large

holdings utilising both protected and containerised production. This suggests that the mites

and the virus are closely associated and widely distributed around the UK.

Mite virus interaction and links with plantation decline

In terms of links with plantation decline, several of the worst affected sites sampled in 2014

were grubbed at the end of the season because of plantation decline as a result of this mite-

virus condition. It is clearly a very damaging condition and one that can build up over time.

What is not clear however is whether the virus can move systemically or whether

overwintering populations of the mite perpetuate the condition. In this study the virus was

rarely found in the absence of the mite, which is promising as there is a much greater

potential to control the mite on-farm than the virus. Overall there was good agreement

between characteristic symptoms of yellow leaf blotching and presence of the mite and or

virus. However, in the newer plantations a greater proportion of ambiguous symptoms did

yield positive virus results, therefore careful monitoring and virus testing of young

plantations is important to identify the issue early and avoid build-up of the mite over time.

Varietal susceptibility

As expected, Glen Ample and older floricane varieties were the most commonly affected by

the condition, but more modern varieties, including CV-C and primocane varieties

(previously considered less susceptible), were also found to be affected. These results

suggest a wide cohort of varieties could be infested with both the mite and virus. In this first

year the sampling effort was targeted to sites with a history of this pest, where potential

symptoms had been observed in 2013 or where there was a long history of raspberry

production. At these sites both symptomatic and asymptomatic plantations and varieties

were sampled. To gain a more representative indication of the level of RLBM and RLBV in

the UK raspberry industry, further sampling is proposed in 2015 to collect information from a


larger number of plantations, including those with no history of the pest or condition and in

relatively newer growing regions, and a larger sample of modern primocane varieties.

Trends in cropping situations where RLBV occurs

Some interesting observations have been made from this initial survey, which indicate that

how crops are managed may affect this condition. How spawn is managed appears to have

some effect on levels of the mite and virus, with physical methods (as opposed to chemical)

seemingly showing greater levels of the mite and virus. Potentially this could be related to

seasonal carryover of mites with the presence and proximity of young primocane foliage to

infested floricane leaves allowing mites to migrate onto next year’s canes. Earlier removal

of the first or second flush of primocane could hinder this migration and or systemic

movement of the virus. In this first year the question posed to growers was to describe their

spawn management approach, from which we received some basic responses. A better

question would have been to ask about timing of management, as well how cane is

managed and this will be posed to growers in 2015 to try to find out more about this

observation.

Sites which used an acaricide, such as abamectin, and/or releases of predatory mites

appeared to have a lower level of RLBV and RLBM, suggesting that the use of these agents

could be providing incidental control of the mite and therefore reducing levels of the virus.

Specific sampling of identified locations in 2015 will collect further information on this topic.

Presence of wild raspberry in close proximity to raspberry plantations seemed to increase

the proportion of plantations affected. Both RLBM and RLBV can be found on wild

raspberry hosts and these results indicate that the proximity of infested wild raspberry to

commercial raspberry plantations is one pathway by which infection may be introduced to

new plantations.

Bare root short and long cane planting material showed a greater incidence of RLBV

infection but this could be an artefact of plantation age or growing system. Theoretically

however, risks of RLBM presence from propagation could be greater in bare root material

as these plants will be older at planting, having been grown at the propagator for up to three

years. During this time there is the possibility of mite infestation and therefore latent virus

infection. Although every effort will be made to avoid this by propagators neither the mite

nor the virus is currently included in PHPS certification inspections by Plant Health

inspectors. In the newer plantations there is a trend towards planting module and root

material and this showed a lower proportion of plants affected by RLBV. However it cannot

be assumed that this type of planting material is less likely to be affected by RLBV as risk


would be expected to depend on the age, health status and the method of production used

to grow the mother plant. Young High Health status plants grown with good isolation from

other Rubus plants versus older plants grown in traditional spawn beds in field alongside

other raspberries and Rubus crops would be at lower risk as the latter has greater potential

exposure to the mite and virus. At present we do not know whether or not different plant

material provides a lower risk as regards the virus originating from propagation.

Tunnelled and containerised production gave mixed results and will be further investigated

in the wider survey in 2015.


To date (when tested two months after grafting) no RLBV has been detected in recipient

plants that have been grafted with infected material. These plants will be monitored though

2015

Conclusions

The survey has confirmed that raspberry leaf and bud mite (RLBM) and the

associated raspberry leaf blotch virus (RLBV) is widely distributed across the UK

and across many varieties commercially grown, including primocane varieties;

RLBV was rarely found in the absence of RLBM and was closely associated with

characteristic leaf blotch symptoms in older plantations; however symptoms were

more ambiguous in younger plantations;

Presence of wild hosts for both the RLBV and the RLBM in the form of wild

raspberry appeared to increase levels of both the mite and virus;

Some interesting interactions between planting material, spawn management

strategies, acaricide use and predatory mite introductions have been highlighted and

require further investigation.

Next steps

In-depth sampling and agronomic investigation of identified positive sites to

determine:

o Levels of overwintering mites in buds;

o Movement of mites within the canopy i.e. when they move to primocane;


o Movement of virus – is it present in buds, when is it detected in floricane

leaves, is it present in the primocane prior to or after mite movement to the

primocane.

Additional UK sampling:

o Further 10 sites (c. 50 further samples) selected to capture additional

varieties and growing systems under represented from year one.

Continue to monitor virus transmission trial;

Propagate, inoculate and assess historical varieties from the JHI germplasm

collection with reported tolerance/resistance to leaf and bud mite disease.

Recording key traits (canopy architecture, leaf hairiness etc.) which may infer

tolerance and could be incorporated into breeding programmes.

Knowledge and technology transfer

No knowledge transfer activity has occurred at this stage, however and awareness article

updating growers on the 2014 findings could be produced for HDC News

References

Alford D. (1984) A colour atlas of fruit pests – Their recognition, biology and control. Wolfe

publishing pp. 228-229

Ellis M., Converse R., Williams R. and Williamson B. (1991) Compendium of Raspberry and

Blackberry Diseases and Insects. The American phytopathological society pp 70-71

Wendy J. McGavin, Carolyn Mitchell, Peter J.A. Cock, Kathryn M. Wright and Stuart A.

MacFarlane. 2012. Raspberry leaf blotch virus, a putative new member of the genus

Emaravirus, encodes a novel genomic RNA. Journal of General Virology, 93, 430 – 437.

Mitchell, C. (2010). Developing techniques to manage raspberry leaf and bud mite in tunnel

produced raspberry. Horticultural Development Company final report for project SF81.


Appendices

Appendix 1 – Cropping data collected for each sample

Reference number:

Grower contact:

Address:

Contact tel.:

Contact email:

Field ref:

Variety:

Planting date:

Plant source (propagator or country of origin):

Planting material (long cane/ bare root/root/modules:

Tunnelled (Y/N):

RLBM symptoms (Y/N):

Mite observed (Y/N):

RLBV symptoms (Y/N):

Level of disease observed at time of sampling: (0 = no disease, 1 = <5% plants affected, 2 = 5-50% plants affected 3 = ~50% plants affected, 4 = 50-75% plants affected 5 = 75%-100% plants showing symptoms) plus description – leaf blotches, mite feeding, crumbly fruit, leaf tip curling:

Describe surrounding vegetation (is wild raspberry present any symptoms obvious):

If RLBM/RLBV detected on site when was this and has the virus been confirmed before?

Brief site history

Any other observations (e.g. non characteristic symptoms – general decline, poor lateral development, crumbly malformed fruit etc.)

Average crop yield if available and any changes over time:

Sampled by:

Date sampled:

Date delivered to JHI:

Additional questions

Do you have any wild raspberry on site? Y/N

Has Tayberry ever been grown on this site? Y/N

Did you spray acaricides in 2014? Y/N

Did you release predatory mites (e.g. Phytoseiulus persimilis, Neoseiulus/Amblysieus cucumeris)

Y/N

Describe your spawn management approach e.g. First 2 flushes remove with Shark and or hand removal


Appendix 2 Results of the RLBV PCR test for each samples along with full cropping details for each sample – Summer 2014 S

am

ple

Nu

mb

er

Vari

ety

:

Pla

nti

ng

year:

So

il o

r

co

nta

iner

gro

wn

Level o

f

dis

eas

e

Sym

pto

ms

RL

BV

PC

R

test

resu

lt

Mit

es

Pla

nti

ng

mate

ria

l:

Tu

nn

elled

Cro

p y

ield

Wild

rasp

be

rry

Tayb

err

y

Acari

cid

es

Pre

dato

ry

mit

es

Sp

aw

n

man

ag

em

en

t

1 Tulameen 2007 soil 1 - - - Bare root

Y - No Yes Yes No Shark

2 Glen Fyne 2012 soil 1 + - - Modules Y - No No Yes No Hand

3 Tadmor 0 - - +

4 Octavia 3 + + -

5 Glen Ample

0 - - -

6 Octavia 2013 Soil 0 - - - Bare root long cane

N = No No Yes No Shark + hand

7 Glen Ample

2012 Soil 3 + + - Bare root long cane

N - No No Yes No Shark + hand

8 Glen Ample

2012 Soil 0 - - - Bare root long cane


9 Octavia 2014 Soil 0 - - - Bare root long cane

Y - No No Yes No Shark + hand

10 Tulameen 2011 0 - - -

11 Glen Ample

2008 Pots 1 + + + Bare root



Sam

ple

Nu

mb

er

Vari

ety

:

Pla

nti

ng

year:

So

il o

r

co

nta

iner

gro

wn

Level o

f

dis

eas

e

Sym

pto

ms

RL

BV

PC

R

test

resu

lt

Mit

es

Pla

nti

ng

mate

ria

l:

Tu

nn

elled

Cro

p y

ield

Wild

rasp

be

rry

Tayb

err

y

Acari

cid

es

Pre

dato

ry

mit

es

Sp

aw

n

man

ag

em

en

t

short cane

12 Glen Ample

2008 Pots 1 - - - Bare root short cane


13 Chemainus 2014 Pots 0 - - - Bare root long cane


14 Tadmor 2014 Pots 0 - - - Bare root long cane


15 Glen Ample

2013 Pots 5 + + + Bare root long cane

Y - No No Yes Yes Shark + hand

16 Polka 2011 Pots 3 + + + Bare root short cane

Y No No Yes Yes Hand

17 Tulameen 2005 Pots 0 - + (faint) + Potted long cane

Y = No No Yes Yes Shark + hand

18 Octavia 2008 Pots 0 - - - Bare root long cane

Y = No No Yes Yes Shark + hand

19 CV-B 2011 soil 0 - - - Root Y = No No Yes No Hand


Sam

ple

Nu

mb

er

Vari

ety

:

Pla

nti

ng

year:

So

il o

r

co

nta

iner

gro

wn

Level o

f

dis

eas

e

Sym

pto

ms

RL

BV

PC

R

test

resu

lt

Mit

es

Pla

nti

ng

mate

ria

l:

Tu

nn

elled

Cro

p y

ield

Wild

rasp

be

rry

Tayb

err

y

Acari

cid

es

Pre

dato

ry

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Sp

aw

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ag

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20 Glen Ample

2011 Container 0 - - - Modules Y = No No Yes No Shark + hand

21 CV-C 2010 soil 0 - - - Root Y = No No Yes No Hand

22 Glen Ample

2012 Container 1 + - - Y = No No Yes No Shark + hand

23 CV-C 2013 Container 2 + + floricane -ve primocane

- Root N - No No Yes No Hand

24 Glen Ample

2013 Container 0 - - - Potted long cane

Y = No No Yes No Hand

25 CV-C 2013 Container 0 + - - Root N = No No Yes No Hand

26 Glen Ample

2012 Container 2 - - - Bare root long cane

Y = No No Yes No Hand

27 CV-B 2011 soil 1 - - - Root Y = No Yes Yes Yes Hand

28 Tulameen 2005 soil 1 - - - Bare root long cane

Y = No Yes Yes Yes Hand

29 Tulameen 2006 soil 1 - - - Bare root long cane

Y = No Yes Yes Yes Shark

30 CV-C 2012 soil 0 - - - Root Y = No Yes Yes Yes Shark


Sam

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31 Glen Moy 1980 soil 3 + + + NK N = Yes Yes Yes No Mow

32 Polka 2012 soil 0 - - + Bare root short cane

N = Yes Yes Yes No Mow

33 Glen Ample

2012 soil 1 + + + Bare root short cane


34 Octavia 2012 soil 1 + + + Bare root short cane


35 Himbo Top 2013 soil 0 - - + Bare root short cane

N - Yes Yes No No Mow



37 Glen Ample



38 Glen Ample

2012 soil 3 + + + Bare root long cane

Y - Yes No Yes No Shark

39 Glen Ericht 2012 soil 2 + + + Modules N Yes No No No Strimming


Sam

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Nu

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Vari

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nta

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Level o

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Sym

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Pre

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Sp

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40 Glen Ample


N Yes No No No Strimming

41 Glen Ericht 2012 soil 5 + + + Bare root short cane


42 Glen Ample



43 Autumn Bliss

1999 soil 0 + - - Bare root short cane

N = Yes No Yes No Strimming

44 Glen Magna



45 Glen Clova 1979 soil 1 + + + Bare root short cane



N + Yes No Yes No Strimming

47 CV-A 2010 soil 1 + - - Root Y = No No Yes Yes Mow + hand


Sam

ple

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Vari

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year:

So

il o

r

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nta

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gro

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Level o

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dis

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PC

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Cro

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Pre

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Sp

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48 Glen Ample

2004 soil 0 - - - Bare root short cane

N No No No No Mow + hand

49 Octavia 2010 soil 1 - - - Modules N No No No Yes Hand

50 Tadmor 2010 soil 1 - - - Modules N No No No Yes Hand

51 Glen Ample

2012 soil 1 - + - Modules N No No No Yes Hand

52 Himbo Top 2012 soil 0 - - - Modules N No No No Yes Hand

53 Autumn Bliss

2006 soil 0 - - - Modules N - No No Yes Yes Shark

54 Glen Clova 2007 soil 1 + - - Bare root short cane

N = No No Yes No Shark

55 Tulameen 2012 soil 1 - - - Modules N = No No Yes No Shark

56 Octavia 2009 soil 1 - - - Bare root short cane

N = No No Yes No Shark

57 Tulameen 2005 soil 1 - - - Modules N - No No No No Shark

58 Glen Doll 2009 soil 1 - - - Modules = No No Yes No Shark

59 Tulameen 2008 soil 1 + - - Modules N - No No Yes No Shark

60 Himbo Top 2008 soil 1 - - - Modules N = No No Yes No Hand

61 Tadmor 2011 soil 1 + + (very - Modules = No No No No Hand


Sam

ple

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Vari

ety

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year:

So

il o

r

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Sym

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faint)

62 Glen Ample

2011 soil 3 + - - Modules N = No No Yes Yes Shark + hand

63 Autumn Treasure


N = Yes Yes No No Shark + Strim

64 Glen Magna



65 Polka 2012 soil 0 - - - Bare root short cane


66 Glen Ample



67 Tulameen 2007 soil 1 - - - Bare root short cane

N - Yes Yes No No Shark + Strim

68 CV-A 2012 Container 2 - - - Root Y = No No Yes Yes Hand



71 CV-A 2011 Container 2 - - - Root Y - No No Yes Yes Hand


Sam

ple

Nu

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Vari

ety

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year:

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il o

r

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gro

wn

Level o

f

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Sym

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72 Polka 2010 Container 3 - - - Bare root short cane

Y = No Yes Yes No Hand

73 Glen Lyon 2005 Container 0 - - - Bare root short cane

Y - No Yes Yes No Hand

74 T Plus 2007 Container 0 - - - Modules Y = No Yes Yes No None

75 CV-B 2013 Container 0 + - - Root Y + No Yes Yes No Hand

76 Octavia 2010 Container 3 + - - Bare root short cane

Y - No Yes Yes No Shark

77 Octavia 2011 Soil 0 - - - Bare root short cane

N = No No No No Mow

78 Tulameen 2011 Soil 3 + - + Bare root short cane

N = No No No No Mow

79 Glen Ample

2011 Soil 3 + + + Bare root short cane

N = No No No No Mow

80 Kwanza 2013 Container 0 - - - Modules Y Yes No Yes Yes Shark + hand

81 CV-D 2014 Container 0 - - - Modules Y Yes No Yes Yes Shark + hand


Sam

ple

Nu

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Vari

ety

:

Pla

nti

ng

year:

So

il o

r

co

nta

iner

gro

wn

Level o

f

dis

eas

e

Sym

pto

ms

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PC

R

test

resu

lt

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es

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nti

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l:

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Cro

p y

ield

Wild

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be

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Tayb

err

y

Acari

cid

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Pre

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mit

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Sp

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82 CV-E 2013 Container 0 - - - Modules Y Yes No Yes Yes Shark + hand

83 CV-F 2014 Container 0 - - - Potted long cane

Y = Yes No Yes No Shark + hand

84 Glen Clova Soil 0 + + - Bare root short cane

N + No No Yes No Shark

85 CV-A 2013 Container 0 + - - Root Y No No Yes Yes Shark + hand

86 CV-G 2010 Container 1 + - - Root Y No No Yes Yes Shark + hand

87 Octavia 2010 Container 0 - - - Bare root short cane

Y No No Yes No Shark + hand

88 Octavia 2008 soil 1 + - - Bare root short cane

Y - No No No No Shark

89 Glen Ample





91 Glen Fyne 2012 soil 0 - - - Modules Y = No No Yes No Hand


Sam

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Vari

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Pla

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year:

So

il o

r

co

nta

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gro

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Level o

f

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Sym

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PC

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Sp

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92 Glen Ample


N = Yes No No Yes Mow

93 Autumn Treasure

2011 soil 0 - - + Bare root short cane

N = Yes No No Yes Mow

94 Glen Ample


N Yes Yes Yes No Mow + hand

95 Glen Ample


N No Yes No No Mow

project title: understanding the scale and …...harriet roberts horticultural consultant adas uk...

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