Agronomy eUpdate June 29th, 2023

Issue 963

Tar spot of corn has arrived in Kansas this season

Tar spot of corn, a disease caused by the fungus Phyllachora maydis, was confirmed in several fields in Doniphan County, Kansas on June 26, 2023. Corn growers should intensify scouting efforts. This article discusses several frequently asked questions about this new disease in Kansas. Early detection and timely fungicide treatment are critical to maximizing control of tar spot.

corn fungicide foliar fungicides foliar diseases tar spot 

Update: Pre-harvest weed control in wheat

This year’s short, thin wheat crop, coupled with late-season rains has resulted in a lot of questions about the best approach to managing large weeds in mature wheat. This article was originally published earlier this season and now has some updated information regarding herbicides labeled for use as harvest aids.

wheat weed control pre-harvest 

Controlling weeds after wheat harvest

When thinking about weed control in wheat stubble, there are two priorities – controlling already emerged weeds and preventing later flushes. Weeds that have been suppressed by the canopy will grow rapidly once crop competition is removed. Delaying control can result in lost soil moisture that could be used for crop production, as well as weed seed production.

weed control wheat post-harvest 

Wheat harvest: Identifying disease problems and setting harvest priorities

As wheat harvest progresses in Kansas, this article provides some reminders about diseases that may affect either grain quality or the viability of grain that is destined to be saved for seed. While most disease management decisions have been made, there are some strategies for mitigating losses on heavily infected fields.

wheat disease harvest loose smut fusarium head blight common bunt black point sooty mold 

Plant analysis for testing nutrient levels in corn

Plant analysis for nutrients is an excellent in-season “quality control” tool. It can be especially valuable for managing secondary and micronutrients that do not have high-quality, reliable soil tests available. Plant analysis can be used for diagnostic purposes and to monitor nutrient levels at a certain growth stage. Learn more in this article about using this test for corn.

corn Soil Testing Lab nutrient deficiency tissue testing nutrient anaylsis 

Identifying nutrient deficiency symptoms in soybeans

As the soybean-growing season progresses, the plants may begin showing signs of chlorosis or other leaf discoloration in all or parts of the field. While there may be many causes of this discoloration, nutrient deficiency is one possibility. There are a few causes that lead to nutrient deficiencies in soybeans.

soybeans nutrient deficiency chlorosis 

Diagnosing wheat production problems - Updated publication for 2023

The K-State Research and Extension publication “Diagnosing Wheat Production Problems” has been updated. This comprehensive resource was a collaborative effort between three K-State departments: Plant Pathology, Agronomy, and Entomology. The 66-page full-color publication will help growers diagnose likely causes of slow growth, distorted appearance, off-colors, injury, and death of wheat plants from planting to harvest. Check it out!

publication wheat KSRE 

Soybean gall midge detected in Kansas - Be on the lookout

This past week, soybean gall midge was found infesting soybean and sweet clover in Marshall and Nemaha counties. This pest should be actively scouted for during the growing season, especially in counties along the Nebraska border. Losses from soybean gall midge infestation are due to plant death and lodging.

soybeans insects soybean gall midge 

Soybean insect activity - Dectes stem borers

In the last week, many soybean fields have been scouted around north central Kansas and found no significant infestations of early-season defoliators. However, a large number of adult Dectes stem borers were sampled. The numbers revealed in sampling this past week were higher than usual. Fields that have high infestations later in the summer need to be harvested at a high priority to prevent lodging.

soybeans insects dectes stem borer 

Registration is open for the 2023 K-State/KARA Summer Field School

Kansas State University and the Kansas Agribusiness Retailers Association (KARA) will be hosting two, 2-day field schools on July 11-12 and July 13-14 at the K-State Agronomy North Farm. This year’s program will focus on soybean production and fertility. Other topics on the agenda include herbicide symptomatology, weed ID, summer annual forages, crop diseases, soil management, and more! Get registered today!

KARA Field Day