Pests & Disease Outlook

 

The 2025 winter weather has been colder than most years. Temperatures in the teens and single digits have caused the soil to freeze deep. While this may reduce some insects and pests, it can also harm wheat and hay crops. How deep the soil freezes depends on the amount of snowfall received. Snow acts as a natural insulator, blanketing the soil and preventing deeper freezing.

This year, the northern part of Ohio received less snow than some areas to the south. Reports from Toledo indicate significantly less snowfall than counties further south. Snow prevents wind from desiccating crops like wheat, barley, hay (alfalfa, red clover, etc.), and cover crops. Several northern farmers are already reporting wheat and barley damage. Cover crops may also suffer, and as thawing begins, expect damage to the crowns of hay crops, especially alfalfa roots, which tend to heave—just like fence posts.

Slugs and voles tend to decrease in cold winters, with cycles occurring every 2-5 years. During deep freezes, slugs must burrow deeper to survive. If the frost line reaches subsoil water or a high-water table, many perish. Voles, or field mice, remain active in winter, seeking food and shelter under the snow. Without snow cover, their populations often decline, much like slugs.

However, slug and vole populations can vary significantly even within short distances, depending on food and shelter. Areas with 3-6 inches of snow report high slug and vole activity, while regions with little snow see minimal signs. Vole runs are easy to spot this time of year, and populations above 10-15 per acre can pose serious threats to spring-planted crops. Reports of high vole numbers are increasing, with red clover and alfalfa particularly vulnerable as voles feed on the roots, causing plant crowns to dry out and die.

Without snow, expect more wind desiccation and crop damage; with more snow, expect higher slug and vole populations. Sometimes, you just can’t win!

Ohio soybean producers should watch for two new diseases this year: target spot and red crown rot. While not yet confirmed in Ohio, both are present in surrounding states. Red crown rot mimics sudden death syndrome, impacting roots and significantly reducing yields. However, it has a distinct red discoloration at the stem base, with small red fungal masses appearing as the plant matures. Identified by Purdue researchers in Decatur and Adams County, Indiana, this soil-borne pathogen spreads slowly. However, researchers believe it may have been overlooked for years and could be more widespread. Seed treatments and genetic resistance are being explored as control measures.

Target spot is spreading northward and resembles frog eye leaf spot or Septoria brown spot. It produces fungal spores that travel on weather fronts. Soybean leaf lesions appear reddish-brown with yellow halos, ranging from 3/8 to 5/8 of an inch. Pod lesions are circular, purple or black, with brown margins. This disease thrives in temperatures above 75°F with frequent rain and high humidity, starting on lower leaves and progressing through the canopy, leading to defoliation. Once considered a minor disease, target spot is becoming more frequent and damaging.

To manage these diseases, planting in wider rows and reducing soybean populations may help. Crop rotation, especially to corn, is an effective strategy for controlling both red crown rot and target spot.