Agronomic Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

 

Hay/Pasture Grasses

A report of armyworm activity was received earlier this week in orchardgrass. Armyworm thresholds are around 2-3/square foot. Armyworms generally can be controlled by pyrethroid application. In taller grass, increase water rates. Apply insecticides in the evening. Armyworm are most active at night. Read your insecticide labels carefully, not all pyrethroids are labeled on pasture grass, and not all active ingredient formulations are labeled. For example, Brigade (bifenthrin) is labeled for pasture grasses but Sniper (bifenthrin) is not. Some have short PHIs, and others have longer PHIs.

Sorghum

Continue scouting for corn earworm and fall armyworm in sorghum heads. Sorghum webworm is also present in low numbers. Texas A&M’s headworm threshold calculator can be found here: https://extensionentomology.tamu.edu/sorghum-headworm-calculator/. Webworms are considerably smaller than the other species and thresholds are approximately twice that of earworm/armyworm. We have not yet observed sugarcane aphid activity in fields we are monitoring. Late planted sorghum that has not yet headed should be scouted carefully when it heads for earworm and aphids, as it will be susceptible to aphids longer in the season.

Soybean

Adult earworm moth activity has been observed in flowering double crop soybean. While this does not necessarily mean a given field will be above earworm threshold, it is an indicator to be monitoring the field carefully.

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