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Green beetle larvae with a white stripe running down its body.

Alfalfa Weevil Activity Prediction Update: April 14, 2020

The alfalfa weevil is a major spring insect pest of South Dakota alfalfa. Before 2018, this insect was reported as having large populations throughout much of South Dakota. However, during 2018 and 2019, we received fewer reports of alfalfa weevils, which may have been a result of the cooler and wetter spring conditions that were observed.

Canada thistle growing in a pasture.

Fall Noxious Weed Control

Fall weed control can give the best weed control, but it also can be a poor time. If the noxious weeds were sprayed or clipped earlier this summer, and there is good weed growth now, this would be an excellent time to spray these weeds and get a good kill.

A pasture containing a mixture of grasses and alfalfa.

Scouting for Grasshoppers in Pasture and Alfalfa

For 2019, we have either received reports of very high grasshopper numbers or of very low or nearly absent populations. Most reports of high populations have originated from areas near rivers and other waterways. This suggests that the rich foliage along the banks of waterways has provided excellent habitat for grasshoppers and has boosted their populations in those areas.

a flooded alfalfa field

Managing Flooded Alfalfa

As floodwaters rise again in parts of South Dakota, spring planting seems to feel further and further away. One crop that is often overlooked in the hustle and bustle of the approaching planting season is alfalfa.

Three types of plant bugs. From left: Meadow plant bug, Lygus bug, and alfalfa plant bug.

Plant Bugs Showing Up in Alfalfa Fields

Plant bugs are now becoming active in alfalfa fields across the state. A common question we receive is why some of these bugs looks so different from others. There are actually three different types of plant bugs that commonly appear in alfalfa fields: meadow plant bugs, Lygus bugs (aka tarnished plant bugs), and alfalfa plant bugs.

Green beetle larvae with white stripe and brown head.

Alfalfa Weevil Activity: June 7, 2019

Quite a few degree days were accumulated over the course of the last week. Alfalfa fields should be closely monitored for alfalfa weevil activity for the next couple of weeks, even in areas where degree days indicate the alfalfa weevils are pupating.

Teardrop shaped green insect with long legs and antennae on a lighter green leaf.

Pea Aphid Populations Increasing in Alfalfa

While scouting alfalfa this week, we noticed pea aphid populations are starting to increase. The forecast is looking favorable for this pest, so it will be important to continue monitoring populations prior to and after the first cutting.

Green beetle larvae with a white stripe running down its body.

Alfalfa Weevil Activity Update: May 30, 2019

It was another cool week for most of South Dakota, with little degree day accumulation occurring. However, alfalfa fields should still be monitored for alfalfa weevil activity, although the cool, wet weather might have slowed the pest down.

Brown beetle with long snout.

2019 Alfalfa Weevil Activity

It was another cool week in South Dakota with not a lot of degree day accumulation occurring. Alfalfa fields should still be monitored for alfalfa weevil activity even though the cool wet weather might have slowed this pest down.

Green beetle larvae with a white stripe running down its body.

2019 Alfalfa Weevil Activity Prediction

One of the major insect pests of alfalfa in South Dakota is the alfalfa weevil. In 2018, we received fewer reports of alfalfa weevils, which may have been a result of the cooler and wetter spring conditions. It’s possible that populations may also be lower in 2019 due to the similar spring conditions that we are currently experiencing.