Neonicotinoid Seed Treatment on Cucurbits

In recent years, many seed companies have begun using the neonicotinoid insecticide thiamethoxam (FarMore) as a seed treatment on cucurbit and other vegetable seeds. Thiamethoxam is a systemic insecticide that moves from the seed coat into the seedling and then moves throughout the plant. Research has shown that these seed treatments provide about 3 weeks of excellent control of cucumber beetles, aphids and other pests. Unfortunately, the systemic nature of the insecticide also results in residues being present in the pollen that could potentially be harmful to honey bees and other pollinators. Although these seed treatments are a good pest management tool, growers should be cautious in how they use them to avoid possible harm to pollinators. Our research has shown that cucurbits that are grown in the greenhouse for 4-5 weeks before being transplanted into the field, do not have enough of the insecticide left in the stem and leaves to provide any protection from striped cucumber beetles, although there is sufficient residue in the pollen to harm pollinators. Therefore, I don’t recommend the use of insecticide treated seed for crops grown as transplants. For direct seeded crops, the seed treatment will provide about 3 weeks of control so growers should weight the benefit of the seed treatment vs. the potential harm to pollinators. If you choose to direct seed untreated seeds, you still have the option of using foliar insecticides for control of cucumber beetles, with less risk to pollinators.

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