Exempting Organic Growers from State Spray Program Reduces California Tomato Production

Stunted Tomatoes

Stunted Tomatoes

Beet Curly Top Virus is a viral disease of tomatoes vectored by the sugarbeet leafhopper. In California, leafhoppers overwinter in the foothills and in the spring they migrate down into tomato fields. Since 1943 the California Department of Agriculture has conducted a spray program targeting the leafhopper in the foothills. This spray program has prevented massive losses in tomato fields. However, in recent years organic farming operations in the foothills have been exempt from the spray program. As a result, large populations of leafhoppers have migrated from the unsprayed organic fields into tomato fields with disastrous results.

“Had California’s 2013 tomato crop not been hit so hard by the Beet curly top virus (BCTV) it could have been a banner year for growers.

Bob Gilbertson, plant pathologist with the University of California, Davis, estimates last year’s tomato crop was reduced by about a million tons because of BCTV, which is vectored by the Beet leafhopper.

Tomato plants with BCTV become stunted and develop curled leaves. Upon closer inspection of the undersides of tomato leaves the veins appear swollen and they turn purple, Gilbertson said. Plants also turn a dull green-to-yellow and the fruit is small and tends to ripen prematurely.

Disease transmission begins early in the season as leafhoppers migrate from the foothills to the agricultural valleys, but can also happen during the growing season.

Adult leafhoppers tend to overwinter in the foothills. In the spring the females lay eggs on the green plants in the foothills and acquire the virus during feeding. As new leafhoppers become adults they then migrate to the valley.

The California Department of Food and Agriculture has a curly top spray program where the state sprays the foothills for the Beet leafhopper.

Tomatoes with curly top symptoms began showing up in late March of last year. Losses were the highest in Fresno, Kern and Kings Counties. Yield losses appeared far beyond the western foothills, and even into San Joaquin County.

Why was it so bad?

Gilbertson suspects a combination of favorable conditions for the leafhopper and hosts for the virus in the foothills.

There are limitations on the spray program, which could have helped leafhopper populations thrive.

“The spray program is being constrained now by certain farmers who want to do organic production in the foothills,” he said.”

Author: Fitchette, T.
Affiliation: Reporter.
Title: Virus slams 2013 California tomato yields.
Source: Western Farm Press. 2014-02-12. Available: http://westernfarmpress.com/vegetables/virus-slams-2013-california-tomato-yields?page=4

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The Dilemma of Insect Fragments in Processed Tomatoes

Tomato Fruitworm Damage

Tomato Fruitworm Damage

The tomato fruitworm is the most serious insect pest of tomatoes in the US, feeding on fruit and contaminating it with insect parts, excrement and decay-causing organisms. Interest in spraying insecticides to control the fruitworm was accelerated in the 1930s by the finding of insect fragments in canned products, which were seized and destroyed as adulterated foods by the FDA. Today, insecticides are used to prevent widespread insect damage to tomatoes and tomato shipments for processing are rejected if more than 2% damage is found. Therein is the dilemma. If the standard was relaxed (say to 4%), tomato growers could probably make one less insecticide spray. However, consumers may not want more insect fragments in canned tomatoes and may actually want a tighter standard which would result in more insecticide sprays.

“All loads of processing tomatoes in California are evaluated by inspectors from the Processing Tomato Advisory Board, a marketing order, under the direction of supervising inspectors from the California Department of Food and Agriculture. A load of processing tomatoes is rejected if 2% or more of the tomatoes by weight have a worm or excreta in the flesh of the tomato.

The damage tolerance acceptable to consumers and industry could be changed accordingly. Increasing the tolerance might be expected to result in a reduced number of insecticide applications when used in conjunction with a careful monitoring program.

A reduction in the tolerance might also be considered, arguing that consumers would not tolerate even the present level of insect fragments which, as our results indicate, is possible to have in the final product.”

Authors: Zalom, F. G., and A. Jones.
Affiliation: Department of Entomology, University of California, Davis
Title: insect fragments in processed tomatoes
Source: Journal of Economic Entomology. February, 1994. 87[1]:181-186.