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Whitefly transmitted viruses – Fall 2020

The outlook for problems with whitefly transmitted viruses does not look good for fall 2020 vegetable crops. Several viruses were reported at low levels at the end of the spring crops and have already been detected in early fall crops/experiments. This combined with rapidly increasing whitefly populations (and continued hot, dry weather) indicates we will likely see severe infestations of whitefly and viruses transmitted by whiteflies.

By far the best solution for whitefly vectored viruses is host plant resistance (to the virus). There are numerous varieties of tomato which are resistant to tomato yellow leaf curl and are standard fall varieties in most of southern Georgia. This are likely a necessity this fall throughout southern Georgia.

Cucurbit crops have two viruses which are transmitted by whitefly. Unfortunately there is not any host plant resistance to these viruses; however, cucurbit crops vary greatly in their response to infection. Yellow squash is extremely sensitive and complete crop loss can occur. Zucchini are a little less susceptible but still respond poorly. Cucumbers readily show symptoms but are not affected as much and generally still produce marketable fruit.

Snap bean is highly susceptible to a whitefly-transmitted virus complex (cucurbit leaf crumple virus and Sida golden mosaic virus) that can cause considerable economic loss. Based on 2017 disease loss assessment, we experienced 60-70% crop loss in fall grown snap beans in Georgia. The last two years we screened snap bean varieties for resistance against the virus complex and identified a handful that has moderate levels of resistance. However, their performance on yield and quality is yet to be evaluated. The following is the list of snap beans that have shown some resistance: 

Polaris

Barron

BMN-RMR-8

Hastings white

Yakima

Furano

Tema

Valentino

HMX5106

Affirmed