SOD Disease ManagementRevised 10/20/2016

SOD Management Topics

There are five sudden oak death management topics covered in

this presentation:

1. SOD monitoring and management overview

2. Selective removal of California Bay Laurel

3. Phosphonate applications and gypsum soil amendments

4. Bark scribing to remove SOD cankers

5. Drought and oaks

1. Disease Management - 1st step

• Do I live in an area at risk for SOD?

• Are there California Bay Laurels and/or tanoaks where I live?

• Are my oak species:

– California Coast Live Oak

– California Black oak

– Shreve’s oak (Santa Cruz to Santa Barbara)

– Canyon Live Oak

– Tanoak

Use SODmap Mobile app for disease assessment

Available free for Apple iOS and Android

2. Selective removal of Bay

Oaks are infected by spores produced on leaves

of California Bay laurels

– Selectively remove bay laurels around high value

oaks

– Reduce overall bay density on property

Choose line depending on size of your oak. Risk should be no more than 0.2. Draw horizontal line from

0.2 until it intersects the line you picked based on size of oak. Draw vertical line at intersection point.

On x axis is the minimum buffer zone where you should remove bay laurels

Oak Diameter

My oak has a diameter of 70 cm (yellow curve)

To reduce risk at 0.2 level need to remove bays

for a buffer of 6 m around trunk (gray lines)

If I want to reach risk of 0.15, then I have to remove

Bays for 10 m (red lines)

Oak Diameter

Reducing overall bay density beneficial (red line infection rate when it

rains a lot; black line infection levels when dry)

3. Preventive applications with phosphonate

(phosphite) injections and gypsum amendments

Phosphite Treatments

• One injection treatment every two years between

Halloween and Christmas

• One topical treatment in the fall each year, but with

gypsum amendment one topical treatment every two

years may be reasonable

• Soil amendment with gypsum highly recommended but

only if treating with phosphites. Gypsum amendments are

not effective by themselves

Phosphite injection dosages

Treatment once every two years

Phosphite Use Guidelines

and Application Protocol

This protocol is designed to give the applicator practical

information for successfully applying phosphonate (aka phosphite)

(ex. Reliant®, Agri-Fos® systemic fungicides) to Oak and Tanoak

trees for the treatment of sudden oak death (SOD). Two application

methods are currently available; injection under the bark directly

into the sapwood, and topical application of the product, mixed with

a spreader/sticker surfactant (ex. Pentra-Bark™ penetrating

surfactant), onto the trunk of the tree. Both methods have been

found to be effective at controlling the growth of Phytophthora

ramorum, the causal agent of the disease, in oaks and tanoaks.

Application Protocol Pt. 2

Injection treatments require additional equipment in the form of

spring-loaded, hydraulic, or air pressure injectors that maintain a

positive pressure required for introducing the diluted product into

the tree. The injections are made through holes drilled into the trunk

and use relatively small amount of chemical usually about 50-

200ml (1.5 – 7oz), to treat a tree.

The topical application, on the other hand, uses commonly available

liquid spray equipment and does not leave holes in the tree. The

topical method however requires considerably more product (2-

15L, 0.5-4gal) and overspray may damage surrounding vegetation,

including moss and lichens.

Phosphite Application Materials and Supplies

Disinfectant

MeasuringInjectorsGloves

Pentra-bark

Surfactant

Water

Phosphonate

Mixing Bucket

Face Shield

Spray Rig

Drill

Drill Bit

Application Protocol Pt. 3

Applications should be made when the tree is actively transpiring.

Avoid treating trees during very hot or very cold weather, or when

new leaves are emerging.

Currently in Northern California one injection application every

two years is recommended or apply a spray application every year,

preferably in the Fall or late winter. Subsequent injection treatments

should be made once every two years, preferably in the Fall, you

can alternate between injection and topical application methods.

Preventative treatment, before infection has occurred, has been

found to be more effective than curative treatments. At least 4

weeks are necessary for the applied chemical to take full effect.

List of Application Materials and Supplies

Checklist for injection treatments:

- Phosphonate (Reliant®, Agri-fos®,

etc.)

- Water

- Disinfectant

- Liquid measuring devices, pipettes,

conical tubes, or beakers

- Plastic mixing containers, beakers, etc.

- 5 gal bucket for carrying syringes,

washing, and disinfecting

- Rechargeable cordless drill and bit

- Syringe-type tree injectors Chemjet®,

Arborjet®, Sidewinder®, etc.

- Examination gloves

- Safety glasses or face shield

Checklist for topical application:

- Phosphonate (Reliant®, Agri-fos®,

etc.)

- Pentra-Bark surfactant

- Water

- Liquid measuring devices, pipettes,

conical tubes, or beakers

- Plastic mixing containers, beakers, etc.

- Spray equipment, hydraulic, pump-up

type, or backpack mounted.

- Examination gloves

- Safety glasses or face shield

Mention of commercial products does not constitute endorsement by the

University of California or the UC Cooperative Extension Service.

Always follow the manufacturer’s directions, restrictions, and

precautions on the product label.

Topical (spray) Application

Prepare the treatment solution as per the label:

1.9 L phosphonate + 1.9 L water + 95 ml Pentra-Bark surfactant

which in English measurements equals

62.4 oz phosphonate + 62.4 oz water + 3.2 oz Pentra-Bark surfactant

Adult trees may require between 2 and 15 L (0.5 - 4gal) of mix per tree

depending on their size.

Measure phosphonate

and water and mix in

tank.

Measure Pentra-Bark

surfactant and add to

tank just prior to

application.

Stir to mix tank

contents.

The mixture will

foam if shaken or

agitated heavily.

Apply treatment solution

uniformly to the tree trunk

from 3-4m (9-12’) height, or as

high as you can reach without

spraying the foliage.

Soak the tree trunk thoroughly

until the application solution

just starts to run off at the base

of the tree.

Avoid overspray. Application

to foliage will cause damage to

the leaves of most plants

including oaks.

Injection Application

Formulations that you can use depending on the type of injection

equipment available.

1 part phosphonate + 29 parts water = 1:30 delivered in 20ml

doses (typical of the Chemjet type injector – 20psi).

1 part phosphonate + 59 parts water = 1:60 delivered in 40ml

doses (typical of the Arborjet type injector – 35psi).

1 injection per 6 inches of trunk

circumference measured at 4 feet above

the soil line.

or

1 injection per 1 yard of canopy diameter,

measured at the drip line.

Example: Trunk circumference = 48

inches (48/6=8) and the canopy diameter

= 24 feet (8 yards). Prepare 8 injections of

phosphonate.

Multiple trunks or an asymmetrical crown

may make it difficult to calculate the

number of injections. If in doubt take both

measurements and use the one that results

in the higher dose.

Calculate the number of

injection sites:

Measure volume of

phosphite and water.

Prepare injectors.

Place injections where there is a clear

translocation path up the tree. Avoid

drilling below limb stubs or near

shakes, cracks, depressions, or into

soft or punky wood.

Drill injection holes in bark.

Sharp bits and slower drill speeds

perform better as they cut rather than

tear the wood.

The drill depth is dependent upon the

type and age of the tree as well as the

thickness of the bark. There is a slight

“pop” as the drill enters the sapwood.

The hole should be drilled

perpendicular to the tree trunk or at a

very slight downward angle.

Run the bit in and out of the completed

hole to clear out wood chips that may

interfere with the injection.

Insert Injectors

Check for leaks around the

injection site. On actively

transpiring trees the treatment

solution will be absorbed in 5 to 15

minutes.

If the injection fails to be absorbed

by the tree try cleaning out the hole

with the drill bit or move to another

site and drill a new hole.

Injection holes may be left open,

covered with a sealant such as

grafting wax, or plugged with

specifically designed plastic pegs.

Sanitation

Use Lysol or diluted bleach to

disinfect equipment and prevent the

spread of SOD.

Clean and rinse injectors between

applications.

Disinfect boots, vehicles, and

equipment thoroughly.

Safety

Read and follow all label

instructions.

Follow safety guidelines.

Wear appropriate clothing

and equipment.

Mention of commercial products does not constitute

endorsement by the University of California or the UC

Cooperative Extension Service. Always follow the

manufacturer’s directions, restrictions, and precautions

on the product label.

Gypsum Amendments(Anhydrous Calcium Sulfate)

• 3 to 5 lbs of granular Gypsum per tree, depending on tree size

• Mix with top layer, in an area with radius of about 3 feet around trunk

• Apply possibly one or two weeks before phosphonate treatment, or at the latest at the same time as treatment

• Increases efficiency of both injections and bark treatments

• Bark treatments plus gypsum can be applied once every two years rather than yearly

About 3 feet around trunk

4. Canker Scribing for SOD infections

Can we excise cankers from oaks stems, if we catch them early on?

– Ran experiment during the dry 2012-2014 period at 3 sites in

Northern California

– Results show that, during drought, 75% of oaks are not easily

infected

– Using the remaining 25% we can say with strong statistical

support that:

P. ramorum was detected in an equal number of scribed vs. non

scribed trees

Canker Scribing for SOD infections

Based on our results we cannot recommend scribing

Positive control (infected but not scribed) lesion

≈ 1cm

Infected/scribed lesionNew lesions outside scribed area

Scribed Area

Initial

infection

site

≈ 1cm

5. Drought and oaks

• Water deficiency due to prolonged diminished

precipitation and increasing temperatures

• Physiological changes:

– Direct effects such as thinner canopy, leaf abscission,

stunted growth

– Indirect effects: secondary pathogens and pests

• Some effects reversible: direct physiological changes,

branch and foliage issues, stem decay

• Some effects irreversible: stem issues, some root rots

Stunted growth

Fungal twig dieback

Cryptocline Fungal branch dieback

Diplodia

Twig girdlers Agrilicus

Foliar insects, oak pit scale

Canker rots, HymenochaetalesRoot rots, Armillaria

Soilborne Phytophthoras

Trunk insects &

associated fungi

Stem cankers & terminal

secondary decay fungi

Managing drought (1 - short term)

• Ameliorate conditions to avoid onsite of irreversible symptoms, normally done during drought:

– Place ground cover around (not on) tree base to lower evaporation and increase absorption

– In case of prolonged drought and onsite of symptoms, water deeply (12 inches) once a month, November to June, only

– Within a tree species, there is variable resistance to drought among individuals this is both genetic and site dependent. Learn to speak “tree”, to understand which ones need help

– When irreversible symptoms are obvious; there is nothing you can do except for making sure windthrows will not cause damages or fatalities

Managing drought (2 - Long Term)

• South aspect, shallow sandy or rocky soils, midslope are most impacted by drought

• Maintain a density appropriate for the site: thin, thin, thin: but do so before or after drought

• Make sure canopy is pruned back, important when trees are isolated or in low density stands

• When landscaping, avoid planting under trees. Also when making compositions use species with comparable drought resistance

• Individual trees growing in drier sites are more drought tolerant: saplings growing in these sites may be more drought tolerant.

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