Striped Cucumber Beetles Already Active

Originally posted on the May 16, 2022 OSU VegNet Newsletter – posted By Jim Jasinski

My Extension colleague in Pickaway County sent me a quick note and picture over the weekend that the Striped Cucumber Beetle is actively searching and feeding on transplanted or emerged cucurbit crops. Given how cool the temperatures have been the past few weeks I thought it was a bit early but these past few days of 80+F have certainly activated them out of their overwintering locations and into nearby fields. Like the canary in the coal mine, this pest alert from southern growers should help growers in central and northern Ohio prepare to scout and manage transplants or emerged seedlings of cucumber, squash, zucchini, pumpkin or melon.

Striped cucumber beetle.

The active ingredient applied in the picture below is imidacloprid, a systemic insecticide which is very effective at controlling beetles, as evidenced by the pile of dead cucumber beetles on and near the treated plant. Because this product is systemic in the plant, there are also residues that will accumulate in the pollen and nectar. Foraging honey bees, bumble bees, squash bees and other pollinators that collect these food resources may not be outright killed but more subtle sub-lethal effects might be detected when brought back to the nest. So, decisions about pesticide selection, pest severity, timing and non-target impacts need to be considered before use.

dead cucumber beetles

Dead cucumber beetles, Champ Henson.

To prepare for the arrival of striped cucumber beetles, consider reviewing a short but detailed video of several management options (beetles/plant thresholds, systemic seed treatment, use of transplants and in-furrow application) posted to the OSU IPM YouTube channel (https://youtu.be/RSzTT_gbma4).

Foliar insecticide recommendations for all crops including cucurbits can be found in the Midwest Vegetable Production Guide (https://mwveguide.org/uploads/pdfs/27-Cucurbit-Crops.pdf).

Recall that while seedlings can survive and outgrow minor beetle damage, it is key to prevent bacterial wilt transmission while the plants are most susceptible prior to the 3-4 leaf stage. Bacterial wilt infected plants will become symptomatic once there is high demand to translocate water from the roots to the shoots, such as the time of fruit enlargement. No treatments are available to reduce bacterial wilt once a plant is infected.

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