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Content by Philip Rozeboom

A white and purple seedhead of a Canada thistle with a blurry, bright green background.

Perennial Weed Management in the Fall

Most herbicide applications to manage perennial weeds have already occurred. However, now is the time to consider fall applications for weeds that were not treated or escaped the spring application.

Tractor applying residual herbicide to a bare field.

Fall-Applied Residual Herbicides

Many parts of South Dakota can experience dry conditions when residual herbicides are applied, resulting in inadequate weed control. In these areas, residual herbicides can be applied in the fall and take advantage of a longer period to receive activating precipitation.

A green sunflower head with brown frass throughout.

Sunflower Moths Causing Problems

While scouting late-planted sunflowers two weeks ago, there were increased observations of sunflower moth caterpillars in the heads that were later than the rest of the field. Sunflower moths are best managed as moths or early instar larvae.

Tall, green grass surrounding a small, green yellow toadflax plant that hasn’t quite flowered yet.

Yellow Toadflax Has Not Flowered in Some Parts of South Dakota

Yellow toadflax is a difficult-to-manage weed that infests pastures and rangeland. In contrast with other weeds, yellow toadflax should be sprayed when flowers are present for more-effective management.

Soybean field with abundant grass and weeds between rows.

Cheap and Simple Soybean Herbicide Programs Do Not Pencil Out

While simple, one-herbicide programs are initially easy on the budget, it is important to consider indirect costs of surviving resistant weeds that reduce soybean yield and produce seed that will have to be managed later.

Bottom side of a soybean leaf revealing a sever soybean aphid infestation.

Management Recommendations for Soybean Aphids

In many fields across eastern South Dakota soybean aphid populations have reached economic thresholds, and there have been a lot of questions regarding the best approach to managing the 2024 outbreak.

Light colored moth on a yellow sunflower head.

Sunflower Moths Observed in South Dakota

Sunflower moths have been observed in South Dakota sunflower fields this week. Sunflower heads are most susceptible to damage caused by the sunflower moth caterpillars from the onset of flowering to when the ray petals begin drying.

Small, green grass plant amongst brown soil.

Woolly Cupgrass Management

Compared to other grassy weeds, woolly cupgrass is difficult to manage due to the large seed and tolerance to select herbicides. Proper identification will ensure proper selection of management tactics.

Small, green teardrop shaped insects on a green, soybean stem with pink flower.

It’s Time to Scout for Soybean Aphids

Small populations of soybean aphids were observed this week while scouting. Early scouting will ensure that populations do not rapidly increase and exceed the recommended economic threshold.

Weeds growing abundantly between rows of soybean in a research plot.

Weeds Are Starting to Flower: Management tactics to minimize seed production in soybean

Flowering weeds are an indication that seed production is about to occur, and viable seeds can soon be produced. Learn a variety of strategies to manage these weeds before they become a problem in your soybean fields.