tomato yellow leaf curl disease control with uv-blocking plastic

7/30/2019 Tomato Yellow Leaf Curl Disease Control With UV-Blocking Plastic

1/6

537

Tomato Yellow Leaf Curl Disease Control with UV-Blocking PlasticCovers in Commercial Plastichouses of Southern Spain

F. Monci, S. Garca-Andrs, F. Snchez, E. Moriones E. Esp, A. Salmern

La Mayora Experimental Station (CSIC) Repsol-YPF

29750 Algarrobo-Costa, Mlaga, Spain Embajadores 18328045 Madrid, Spain

Keywords:Bemisia tabaci, whitefly,Frankliniella occidentalis, thrips, pest management,ultraviolet light.

AbstractThe yellow leaf curl disease of tomato (TYLCD) is the main limiting factor to

production of tomato in the south of Spain. The causing agents of this disease are acomplex of virus species of the genus Begomovirus (family Geminiviridae) that innature are transmitted by the whitefly Bemisia tabaci. Two species have beenreported in Spain, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leafcurl Sardinia virus (TYLCSV). Control of TYLCD in protected crops of southern

Spain is difficult during the warm season (June to November) because of the highdisease pressure present under the low technology plastic houses normally used.After more than 50 years of research, only tomato cultivars partially resistant toTYLCD are commercially available which do not completely satisfy marketdemands in Spain. In addition, the low effectiveness of the insecticides used tocontrol the insect vector to levels in which TYLCD incidence is reduced, makesnecessary the search for alternative strategies for the control of this disease. The useof photo-selective plastic covers blocking ultraviolet light (UV) has been proposed asa good method for TYLCD control due to the interference with B. tabacivision thatresults in reductions of TYLCD incidence higher than 50%. However, no data areavailable on the effectiveness of this control strategy in the low technology plastichouses typical of southern Spain ("parral" type) in which large lateral windows are

completely open most of the time. Several field trials were performed during the1999/2000 and 2001/2002 agricultural seasons in commercial plastic houses ofMlaga (southern Spain). In each trial, tomato crops grown under plastic housescovered with standard UV-transparent film or with a photo-selective UV-blockingplastic film developed by Repsol YPF were monitored. Our results showed a clearreduction of the levels ofB. tabacipopulation numbers as well as of the incidence ofTYLCD under the cover that filtered UV light. This resulted in a significant yieldincrease of tomato crops under photo-selective UV-blocking plastic film cover.

INTRODUCTIONPlastic materials have contributed notably to the development of Integrated Pest

and Disease Management (IPM) and therefore to the introduction of alternative methodsfor reduction in the use of chemicals. Some examples are the use of physical barriers suchas the so called "antivirus" nets (Neal 1992; Bell and Baker 2000), the use of reflectivemulches (Greenough et al. 1990; Kring and Schuster 1992) or the development ofultraviolet light (UV)-blocking covers. Field studies carried out in the 90s in Israelreported significant reductions in whitefly, aphid, and thrips infestations in vegetablecrops grown under closed tunnels covered with UV-blocking plastic films whencompared with UV-non-absorbing plastics (Antignus et al. 1996, 1998, 2000 and 2001).The effect of different UV-absorbing plastics on whitefly and thrips populations in small

plastic houses open on the sides was also studied for ornamental crops in California(Costa and Robb 1999; Costa et al. 2002) and for vegetable crops in Spain (Gonzlez etal. 2001).

However, as far as we know, data are not available on the performance of theseUV-blocking films for virus disease control in the low technology plastic houses typical

Proc. XXVI IHC Protected Cultivation 2002

Ed. A.D. Papadopoulos

Acta Hort. 633, ISHS 2004

Publication supported by Can. Int. Dev. Agency (CIDA)


2/6

538

of southern Spain ("parral" type) in which large lateral windows are completely openmost of the time. This paper deals with the work carried out on the use of UV-blocking

plastic house covers for the cultivation of tomatoes in these kinds of plastic houses. Wehave evaluated their effect on the populations of the sweet-potato whiteflyBemisia tabaciand the Western flower thrips (Frankliniella occidentalis, WFT) and on the incidence of

the yellow leaf curl disease of tomato (TYLCD), a viral disease caused by a complex ofvirus species (genus Begomovirus, family Geminiviridae) transmitted by B. tabaci(Moriones and Navas-Castillo, 2000).

MATERIALS AND METHODS

Field trials experimental designTrials were conducted in commercial-like parral type plastic houses at the La

Mayora Experimental Station (Mlaga, Southern Spain).Two trials were carried out. In the first trial, during the 1999/2000 agricultural

season, 784 tomato plants (cv. Rambo,) were transplanted in two plastic houses (32 mwide, 50 m long, 2.5-4 m high) during late September 1999.In the second trial, during the2001/2002 agricultural season, 500 tomato plants (cv. Rambo,) were transplanted in two

plastic houses (16 m wide, 50 m long, 2.5-3 m high) during late September 2001. In bothtrials, tomato crops were monitored from September through February (fall to winter).

In each trial, one plastic house was covered with standard UV-transparent film,and the other with a photo-selective UV-blocking plastic film (see below). These plastichouses have large open lateral windows along their longest sides (approximately 1 mhigh) to allow air circulation following the typical production practices of that area.

Natural B. tabaci and WFT infestation and TYLCD infection were monitoredweekly in these plasti houses. Plants were treated weekly forB. tabaci control usingspecific insecticides and were also subjected to preventive applications of insecticides,miticides and fungicides at various stages during the trial following normal practices ofthe area. At the end of February the tomato plants were pinched out above the youngestflower cluster for fruit ripening. Fruit set was ensured by weekly treatment with hormonal

growth regulators (4-CPA, ETISA, Nufarm) during flowering.

Plastics testedThe UV-absorbing film (UV-blocking film) tested was CA-2131P (Repsol YPF)

and the UV-non-asorbing film (reference film) was 2704FM (Repsol YPF), both 200micrometers thick. Light transmittance spectrum of these films was analyzed using a UV-VIS spectrophotometer model UV-3101PC (Shimadzu, Japan) in the laboratory and aUV-VIS portable spectroradiometer model LI-1800 (Li-Cor, USA) in the field.

Insect populationsIn each plastic house, insect populations were monitored on 6 yellow (forB.

tabaci) and 6 blue (for WFT, only during 1999-2000) sticky traps (10x10 cm) regularlydistributed within each plastic house avoiding border effect. Similarly, insect populationswere also monitored in 5 yellow and 5 blue sticky traps located close to windows.Additionally, B. tabaci adults were also monitored weekly on plants by counting thenumber of adults present in 9 leaflets per plant in 10 randomly selected plants avoiding

borders and in 3 plants close to the windows. The number ofB. tabaci adults per leafletwas calculated in each sampled plant.

TYLCD incidenceThe incidence of TYLCD was monitored weekly in the plants of each plastic

house (excluding the two border rows) by visual inspection.

Plant characteristics and yieldBefore pinching out plants, the following data were recorded from all the plants


3/6

539

in each plastic house: plant height from ground level to the top, number of flowers,number of set fruits. The commercial and non-commercial tomatoes were collected andweighted.

Statistical analysis

Statistical analysis was done using analysis of variance (ANOVA; SAS Institute1990).

RESULTS AND DISCUSSION

Plastics testedBoth CA-2131P and 2704FM are mono-layer LDPE films with mineral infrared

absorbers. 2704FM is transparent in the UV range of the solar spectrum, while CA-2131Pefficiently absorbs all radiation between 300 and 370 nm (Fig. 1). Due to migration oforganic UV absorbers, the UV transmission rises with time along the agricultural season,

but the radiation between 300 and 350 nm measured under the UV-blocking film wasnever higher than 1% of the radiation measured outdoors. Therefore, a significant UV-

blocking effect was caused by CA-2131P.

Effect of covers on B. tabaciand WFT populationsSimilar results were obtained in 1999-2000 and 2000-2001 for B. tabaci

populations. Lower populations of adult B. tabaci individuals were detected under theUV-blocking plastic films measured either on sticky yellow traps or on plants. Thus, asshown in Fig. 2 for the 1999-2000 season, higher levels ofB. tabaci were observed underthe normal plastic cover. This is especially notable for data obtained on plants at periodsof peak trap catch, in which there were about 50% more whiteflies present under thereference film than under the UV-blocking film. Therefore, a lower presence ofB. tabaciwas observed under the UV-blocking film. A similar trend was observed for measuresobtained in traps or plants present near the windows of the plastic houses (Fig. 3) whichmay indicate that the photo-selective UV-blocking films reduced the entrance ofB. tabaci

through the windows.The population ofF. occidentalis was very low during the period studied, but witha trend to rise in the final part of the experiment under the reference film (January 2000).

No such increase was observed under the UV-blocking films (Fig. 4) suggesting thatthese plastic films can also reduce efficiently the WFT populations present in this type of

plastic houses.

Effect of covers on TYLCDA significant lower incidence of TYLCD was detected in the tomato crops grown

under the UV-blocking plastic films. Thus, in both trials, at 18 weeks after planting, 70-80% of the plants grown under the reference film were affected by TYLCD, whereas,under the UV-blocking film, only 30-50% of the plants were infected. Therefore, UV-

blocking films in addition to reducing B. tabaci populations showed to be an effectivetool to reduce TYLCD incidence in this low technology plastic houses, characteristic ofSouthern Spain, that maintain large free open windows during most of the growing

period.

Effect of covers on plant characteristics and yieldDuring the 1999/2000 and the 2000/2001 trials similar yield trends were obtained

showing a better performance of plants under the UV-blocking films. Thus, asexemplified in Table 1 for 1999/2000, plants were higher, had more flower clusters per

plant and more set fruits. These resulted in a significant increase (37% increase) incommercial fruit yield per plant (Table 2). Since in previous trials with no TYLCDinfection, no differences were observed in the plant development under these two plasticcovers, these differences were attributed to the different TYLCD incidences observed.


4/6

540

Therefore, UV-blocking plastics appear as an effective tool to reduce yield losses causedby TYLCD in protected tomato crops.

Literature Cted

Antignus, Y., Mor, N., Joseph, R.B., Lapidot, M. and Cohen, S. 1996. Ultraviolet absorbing plastic sheets protect crops from insect pests and from virus diseasesvectored by insects. Environ. Entomol. 25:919-924.

Antignus, Y., Cohen, S., Mor, N., Masika, Y. and Lapidot, M. 1996. The effects of UV-blocking greenhouse covers on insects and insect-borne virus diseases. Plasticulture.112:15-20.

Antignus, Y., Lapidot, M., Hadar, D., Messika, Y. and Cohen, S. 1998. Ultraviolet-absorbing screens serve as optical barriers to protect crops from virus and insect pests.J. Econ. Entomol. 91: 1401-1405.

Antignus, Y. 2000. Manipulation of wavelength-dependent behavior of insects: an IPMtool to impede insects and restrict epidemics of insect-borne viruses. Virus Res. 71:213-220.

Antignus, Y., Nestel, D., Cohen, S., Lapidot, M. 2001. Ultraviolet-deficient greenhouse

environment affects whitefly attraction and flight-behavior. Environ. Entomol. 30(2):394-399.

Bell, M.L. and Baker, J.R. 2000. Comparison of greenhouse screening materials forexcluding whitefly (Homoptera: Aleyrodidae) and thrips (Thysanoptera: Thripidae). J.Econ. Entomol. 93: 800-804.

Costa, H. S. and Robb, K.L. 1999. Effects of ultraviolet-absorbing greenhouse plastic filmon flight behavior ofBemisia argentifolii (Homoptera: Aleyrodidae) andFrankliniellaoccidentalis (Thysanoptera: thripidae). J. Econ. Entomol. 92: 557-562.

Costa, H.S., Robb, K.L. and Wilen, C.A. 2002. Field trials measuring the effects ofultraviolet-absorbing greenhouse films on insect populations. J. Econ. Entomol. 95:113-120.

Gonzlez, A., Rodrguez, R., Ban, S., Franco, J.A. and Fernndez, J.A. 2001. The

influence of photoselective plastic films as greenhouse cover on sweet pepper yieldand on insect pest levels. Acta Hort. 559:233-238.Greenough, D.R., Black, L.L. and Bond, W.P. 1990. Aluminium-surfaced mulch: an

approach to the control of tomato spotted wilt virus in solanaceous crops. Plant Dis..74: 805-808.

Kring, J.B. and Schuster, D.J. 1992. Management of insects on pepper and tomato withUV reflective mulches. Fla. Entomol. 75: 119-129.

Moriones, E., and Navas-Castillo, J. (2000). Tomato yellow leaf curl virus, an emergingvirus complex causing epidemics worldwide. Virus Res. 71: 123-134.

Neal, K. 1992. Screen pest out, reduce chemical use. Greenhouse Manager. April 11: 54.SAS Institute 1990. Users guide, version 6. SAS Institute, Cary, NC.


5/6

541

Tables

Table 1. Plant characteristics in the 1999-2000 trial measured before the plants werepinched out above the uppest flower cluster at the end of February 2000.

Number of flowerclusters per plant

Number of setfruits per plant

Height(cm)

Reference film 6.32 a 3.85 a 114.1 a

UV-blocking film 7.42 b 5.25 b 137.2 b

Values with different letter in the same column are significantly different at p=0.05

Table 2. Fruit yield in the 1999-2000 trial

Commercial production Non-commercial production

Number offruits per plant

Fresh weight(g/plant)

Number offruits per plant

Fresh weight(g/plant)

Referencefilm

26.62 a 2569 a 0.68 a 44 a

UV-blockingfilm

30.03 b 3520 b 0.34 b 25 b

Values with different letter in the same column are significantly different at p=0.05

Figures

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

300 400 500 600 700 800 900 1000 1100

wavelength (nm)

spectralirradiance(W/m

2)Outdoors

Reference film

UV-blocking film

Fig. 1. UV-VIS spectrum of the plastics tested


6/6

542

Fig. 2. Mean number of adultBemisia tabaci individuals captured per yellow sticky trap

(left) and per leaflet (right) in the central zone of the plastichouse during 1999-

2000.

Fig. 3. Mean number of adultBemisia tabaci individuals captured per yellow sticky trap

(left) and per leaflet (right) in the border zone of the plastichouse during

1999/2000.

Fig. 4. Mean number ofFrankliniella occidentalis adults captured per blue sticky trap

during 1999/2000.

0

50

100

150

200

250

300

350

0 5 10 15 20

weeks after planting

meannumberofin

sectspertrap

Reference film

UV-blocking film

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

2

0 5 10 15 20


meannumberofinsectsperleaf

Reference film

UV-blocking film

On trap On plant

0

50

100

150

200

250

300

350

0 5 10 15 20


meannumberofinsectspertrap

Reference film

UV-blocking film

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

2

0 5 10 15 20


meannumberofinsectsperleaf

Reference film

UV-blocking film

On trap On plant

0

1

2

34

5

6

7

8

9

10

0 5 10 15 20


meannumbe

rofinsectspertrap

Reference film

UV-blocking film

On trap

tomato yellow leaf curl disease control with uv-blocking plastic

Documents