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Purple-brown caterpillar with orange head on a green corn leaf.

Common Stalk Borer Activity Estimate: May 20, 2021

Warmer weather is finally here. Although we have accumulated quite a few degree days for common stalk borers, nowhere in the state has reached accumulation levels for common stalk borer caterpillar movement into corn fields.

Purple-brown caterpillar with orange head on a green corn leaf.

Common Stalk Borer Activity Estimate: May 6, 2021

We are beginning to accumulate degree days a little faster for common stalk borers. Eggs will be hatching through much of the state, and we will continue to monitor activity as the season progresses.

Green corn leaf with common stalk borer caterpillar within.

Common Stalk Borer Activity Update: June 6, 2019

It finally warmed up and the insects have definitely become more active. However, our calculations indicate that not enough degree days have been accumulated for common stalk borer activity to warrant any scouting, but spraying field edges should be avoided through most of South Dakota in the next week.

Purple-brown caterpillar with orange head on a green corn leaf.

Common Stalk Borer Activity Update: May 30, 2019

Another cool, wet week has led to a limited accumulation of degree days. Based on our calculations, common stalk borer activity still doesn’t warrant any scouting, but spraying field edges should be avoided around Hot Springs, Winner and Vermillion.

Green corn leaf with common stalk borer caterpillar within.

Common Stalk Borer Activity Update: May 23, 2019

Not too much is new regarding common stalk borer activity when compared to last week. Another cool, wet week has led to a limited accumulation of degree days. Based on our calculations, common stalk borer activity still doesn’t warrant any scouting. We will continue to monitor the degree days and provide updates.

Green corn leaf with common stalk borer caterpillar within.

Common Stalk Borer Activity Update: May 16, 2019

The hatching and movement of common stalk borer caterpillars can be estimated by using degree days with a developmental threshold of 41 degrees Fahrenheit. Common stalk borer eggs typically begin to hatch at 575 degree days.

White butterfly with black markings on wings, resting on a green leaf.

Cabbage White Butterflies Are Here!

Keep an eye out for cabbage white butterflies in your garden. These butterflies lay eggs on the underside of the vegetable leaves. Once the eggs hatch, their caterpillars feed on cabbage, broccoli, Brussel sprouts, cauliflower, kale, turnips and radishes.

Young corn seedlings emerging from a spring field.

Watch Closely for Weed Emergence

Cool, dry conditions have slowed weed emergence and growth, but dry conditions also have limited the activation of preemergent chemicals. Given this scenario, fields need to be scouted closely to ensure that weeds do not get away.

Two, dark green aphids on a bright green leaf.

Small Aphid Populations Observed in Wheat

This week we received the first report of aphids in wheat for the 2021 season. The populations won’t be increasing rapidly until the daily temperatures warm up, but it is still a good idea to scout fields and determine if aphids are present.

Two photos of alfalfa weevils during different lifecycle stages. The left is the larva stage and has a longate, green larvae that looks like a caterpillar with white stripe running down the body and brown h

Alfalfa Weevils Are Active, and It’s Time to Scout

Scouting and managing alfalfa weevils when they reach the determined thresholds can prevent yield loss and encourage healthy regrowth of infested alfalfa stands.