Armyworms Found in Small Grain Fields

By Scout Nelson

Early-season scouting of small grain fields shows very few disease or pest concerns across many growing areas. Field scouts report no major issues in the wheat fields they visited during the first week of monitoring. Research plots near Rochester and Rosemount also show minimal problems, with only a few aphids and a single case of halo blight found in an oat variety trial.

The latest Small Grains Disease and Pest Update reported that true armyworms have been found in several rye cover crop fields in southeastern and southwestern areas. These findings suggest that armyworms have moved north and may be present in numbers high enough to require treatment in some locations.

Farmers are encouraged to scout fields carefully for armyworms. A good method is to separate crop plants and look for fecal pellets on the soil surface. If pellets are present, growers should check beneath soil clumps and crop residue for larvae. Scouting should begin along field edges and in areas where grain has lodged. Treatment is recommended when four or more worms are found per square foot.

Weather conditions remain favorable for crop growth, with daytime temperatures mainly in the 70s and low 80s and cooler nighttime temperatures. However, recent rainfall has increased leaf wetness periods, creating conditions that support disease development.

As a result, the risk of tan spot, Septoria, rust diseases, and Fusarium head blight (FHB) is gradually increasing in some locations. Disease risk has reached moderate levels for highly susceptible spring wheat varieties at several weather monitoring sites.

Crop specialists recommend fungicide applications based on crop type and growth stage. Oat growers who did not spray earlier for crown rust should consider treatment when heads are fully emerged. Barley growers may apply fungicides at heading to help manage FHB and net blotch, especially on susceptible varieties.

Winter wheat and spring wheat growers are advised to apply fungicides at the beginning of flowering if tan spot or Septoria is present in the lower canopy or if varieties are highly susceptible to FHB.

Researchers note that premium fungicides may provide limited additional value under current disease conditions, as overall FHB risk remains relatively low in many areas.