RESEARCH POSTER PRESENTATION DESIGN © 2015

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The Lower Rio Grande Valley in Texas was once a very productive

area for winter tomatoes. At it’s peak, the LRGV maintained over

40,000 acres of tomato production. Over the past several decades,

an invasion of devastating diseases most notably the Tomato

Yellow Leaf Curl Virus (TYLCV) has almost wiped out the tomato

industry and is still a limiting factor for farmers interested in this

high-value crop. The challenges of organic or transitioning farms

are even more formidable since these farmers lack the tool that can

defend against the virus (and its main vector the silver leaf whitefly

(Bemesia tabaci)).

In effort to resurrect the tomato industry in south Texas and assist

local farmers looking to capture the momentum of local organic

agriculture, we selected the tomato variety, Tycoon F1, which has

some resistance to TYLCV, to experiment with. In an effort to

deter the whitefly using UV light, we compared the use of silver

mulch and standard hay as mulch in terms of total marketable

yields and number of whiteflies.

Introduction

Research Questions

All research was conducted at UTRGV Agrecology Research

Garden that is certified organic by USDA. The tomatoes were

started in a greenhouse on Aug. 6th and transplanted on Aug. 29th,

2015 into a 36” wide raised bed with 2 ft staggered spacing and a 4

ft buffer between each mulch treatment. Each treatment block was

repeated three times.

Nine sticky traps were collected each week for four weeks and

counted for number of whiteflies. A total of four harvests were

collected and measured for average fruit weight and total

marketable fruit.

Methods

A one-way ANOVA showed a significant difference in the average

marketable fruit weight between the silver plastic mulch and hay,

however the silver plastic compared bare soil was not significant.

Whiteflies traps followed a similar trend as marketable fruit. Silver

plastic had the best overall performance but the difference was not

statistically significant.

Preliminary Results Discussion

Overall the reflective plastic had less whiteflies, produced fruit

earlier, and more consistently compared to tomatoes grown over

hay or bare soil. The low statistical values may be due to sample

size. To test this a larger experiment will be conducted at Terra

Preta farm, Edinburg, Tx.

Incorporating integrated pest management (IPM) would be

valuable in the South Texas tomato growing industry. In

September, massive amounts of whiteflies migrate due to the

harvest of cotton fields. Later transplanting dates may promote

better harvests for winter tomatoes. This combined with reflective

mulch should be relatively effective in deterring the whitefly. A 4’

x 2400’ roll of silver reflective plastic mulch costs around $224. To

reduce the cost of man-hours, using a plastic mulch layer

attachment is highly reccomended and would cost between $1900-

$4000. A plastic mulch planter costs roughly $115. One draw back

to this method of pest management is that the plastic is discarded

after a single use. In regions where this plastic is common, such as

in the California strawberry industry, recycling centers are

available for thes types of materials.

Refrences

1. Cznosnek H (ed) The Tomato yellow leaf curl virus disease:management

molecular biology and breeding for resistance. Springer, Dordrecht,

Neththerlands

2. C. Summers, J. Mitchell, J. Stapleton 59(2):90-94, Mulches reduce

aphid-borne viruses and whiteflies in cantaloupe, California, 2005.

ACKNOWLEGEMENTS

Special thanks to Subtropical Organic Agricultural Research

(SOAR) Partnership from USDA- NIFA-ORG award # 2013-

51106-20970, where funding this project was provided, the

Agroecology lab at UTRGV, and the advisement of Dr. Alexis

Racelis.

1) Will there be a difference in planting strategies/mulching in

terms of whitefly infestations?

2) Will there be a difference in marketable tomato yields among

the two mulching strategies?

Department of Biology, University of Texas- Rio Grande Valley

Lindsey Richards, Alexis Racelis

Mulch Treatment Methods for Whitefly Control in Tomato Plants

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Weekly Comparison of Whitefly Population on Sticky Traps

Reflective Bare Hay

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Reflective Bare Hay

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Week 1: Sept. 8th – 15th (6 weeks old)

Bare (Control) Hay Silver Reflective Plastic

Week 2: Sept. 22nd – 29th (8 weeks old)

Week 3: Sept. 29th – Oct. 6th ( 9 weeks old)

Week 4: Oct. 6th – 13th (10 weeks old)

Dec. 1st Harvest

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Silver Plastic Hay Bare

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Average Fruit Weight

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Silver Plastic Hay Bare

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Total Marketable Fruit Weight