California Leafy Greens Pest Update

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California leafy green growers have some good news: No critical diseases are on the radar for the current growing season, and according to Surendra Dara, strawberry and vegetable crop advisor and affiliated IPM advisor for the University of California (UC)-Cooperative Extension, there wasn’t much pressure outside of the usual suspects — thrips, Western flower thrips, leaf-miners, and aphids — this season, either.

lettuce field 14_WR

Dara mentions however, the presence of garden symphylans in leafy greens. The symphlan is a soil arthropod that resembles a tiny centipede, and has been seen in areas including Davis, Sacramento, and Ventura.

The symphylan, he explains, is an irregular pest as far as when and where it appears, making it difficult to monitor and evaluate management options. Enough research has been done, though, to identify a few basic traits.

The pest attacks the plants roots, which leads to retarded growth and plant death. According to UC-Davis IPM research, the symphylan is only a problem in fields that were not fumigated, or fields where fumigation
was ineffective.

As far as symptoms for growers to look out for, Dara explains that they might vary from crop to crop.

“It also depends on the stage [of plant development]. With the younger plants, the plant just dies; and if it is an older one, it shows as a weakening of the plant.”

Treating Garden Symphylan
According to Dara, crop protectants may be applied to the soil preventively, but if the infestation occurs too late in the season growers cannot apply certain controls as it will be too close to harvest.

“For example, chlorpyrifos is one of those chemicals that is applied only at the time of planting, or very early in the season,” he says.

The Usual Suspects
Aside from the garden symphlan, the typical leafy greens pests as mentioned previously, need to be monitored.

“They could be a major issue if you don’t monitor and control them in time, but usually the leafy greens growers take care of them with regular monitoring and chemical applications,” he explains.

Dara recommends sustainable ways of controlling these pests, such as crop rotation, implementing GAPs, and following IPM recommendations.

“For example, if growers are spraying chemicals, they should rotate those with different modes of action instead of using the same ones again and again to reduce resistance,” Dara says. Additionally, they should consider incorporating non-chemical alternatives in their IPM program.

Keeping up with fundamental strategies like GAPs and IPM will help make the plants stronger, and better able to withstand pest or disease damage, he adds.

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Alexander is the Associate Editor for American Vegetable Grower magazine and Productores de Hortalizas, both Meister Media Worldwide publications.
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