Curly Top Virus Research in Tomatoes 2008
Two trials were conducted at the Western Colorado Research Center at Orchard Mesa to investigate methods of managing curly top virus in tomatoes. One trial evaluated reflective plastic mulch on drip irrigated tomatoes. The second trial looked at chemical control options that are available to commercial tomato growers.
Mulch Color Trial


This replicated trial compared reflective plastic mulch to red plastic in drip irrigated 'Shady Lady' tomatoes.

Plastic mulches are widely used with drip irrigation to help reduce water use, warm soils and control weeds. Mulches come in many colors, and a lot of research has been done on the impact of mulch color on plant growth and crop yields. Reflective mulch is silver in color and mirror-like. It has been marketed as an insect repellent mulch.

We planted a simple replicated comparison of red and reflective mulch with four replications. Mulches were laid with a commercial mulch layer as illustrated in the top picture/video. Each plot consisted of 30 plants at 34" spacing on either red or reflective mulch. There were four replications.

'Shady Lady' plants were grown from seed in a greenhouse and transplanted on May 14. No insecticides were applied to the plants at any time during the growing season.

The plants were irrigated with drip tape laid on the soil surface below the plastic mulch. The drip tape shows up in the pictures as the line down the center of the plastic. The pictures at right show the plastic just after holes were punched for transplanting.

The tomato plants were evaluated on an approximate two week interval throughout the growing season for symptoms of curly top virus. Curly top was rated strictly on visual symptoms. Whole plant leaf roll and color change along with purple veins were symptoms used for curly top diagnosis.

 

Graph Curly top infection rate was analyzed with a paired t-test and the difference between red and reflective mulch was statistically significant (P=0.033). Fewer plants on the silver mulch showed symptoms of CTV. Plants grown on red mulch had 12.4% curly top, while those on reflective mulch had 2.4% virus infestation.
Yellow sticky traps were placed in the center of each plot on May 23 to monitor leafhopper activity. We changed traps and counted all leafhoppers three times (every two weeks), then pulled the traps from the field in early July.

66% fewer leafhoppers were captured on the traps on the reflective mulch. There were fewer leafhoppers on the reflective mulch on all traps on all sample dates.


Actigard/Admire Trial

insecticide trial was conducted at the same Western Colorado Research site in 2008 to evaluate curly top virus control options available to commercial tomato growers. 'Mountain Fresh' tomatoes were transplanted on May 13 after being grown from seed in a greenhouse. The plants were grown on red plastic mulch laid over drip irrigation tape.

The Insecticide treatments were:

Actigard, 3/4 oz/A, applied three times at 2 week interval
Admire Pro, 10.5 oz/A as drench in transplant hole
Admire Pro + Actigard, combined as above

Actigard was applied to appropriate plots on 5/22, 6/3, and 6/13. 3/4 oz per acre of surfactant was used in the second and third spray. The Admire Pro was applied with a hand held CO2 pressured backpack sprayer calibrated to apply 10.5 fl oz/A to a plant population of 3846 plants/A (34" x 4 ft spacing).

Plots were 33' long. They were arranged in a randomized complete design with three replications. Initially there were 10 plants per plot at 34" spacing (some plants died due to other factors).

The graph at right shows the percentage of curly top infected plants for each treatment. There was an apparent impact of treatments on curly top incidence, but differences were not statistically significant at P=0.05. The lack of statistical significance among treatments was due to extreme variability in the data.

Graph

This page was updated on April 26, 2014