After weeks of dry conditions across much of Montana, rainfall has finally returned—especially in central parts of the state, where totals ranged from half an inch to two or more inches in some places last week. While this moisture is welcome news for many crops, Montana’s pulse producers should also be on alert.
Excess soil moisture at this stage of the growing season can increase the likelihood of root rot diseases in lentils and peas. Among the most damaging is aphanomyces root rot, a soil-borne disease that thrives in saturated conditions and can devastate yield potential.
Understanding Aphanomyces Root Rot
Aphanomyces euteiches is particularly dangerous because it survives in soil for years and can infect plants even in the absence of obvious symptoms early on. The disease causes root browning, reduced nodulation, and plant stunting—often leading to poor canopy development and low yields. Once established in a field, it’s difficult to eliminate.
What Farmers Can Do
According to Dr. Uta McKelvy, Montana State University Assistant Professor Extension Plant Pathology, root rot disease can not be cured in the current crop. “The key with root rot diseases is prevention. However, scouting and identifying areas of root rot disease now can help farmers make informed management decisions for future crops.”
That said, Montana pulse growers are encouraged to:
- Monitor fields carefully for signs of poor root development or uneven stands, especially in areas with heavier soils or poor drainage. “Stunted plants and yellowing starting at the lower leaves and progressing up the plant is often the first visible symptom of root rot in the field,” said McKelvy.
- Avoid driving or spraying in wet fields, which can spread soil-borne pathogens from one field to another.
- Collect soil samples and test for aphanomyces if you have any suspicions. Early detection can inform future crop decisions. McKelvy said soil tests are available to detect Aphanomyces and other common root rot pathogens. “Farmers could also consider submitting a suspected root rot sample to their local Extension office or directly to the Schutter Diagnostic Lab for diagnosis and identification of root rot pathogens,” said McKelvy.
- Extend crop rotations to at least 4 to 5 years between peas and lentils to slow pathogen buildup in the soil where Aphanomyces root rot is detected.
- Improve drainage in low-lying areas that stay wet longer than surrounding ground.
Research and Resources
MPCC continues to invest checkoff dollars into research focused on soil health and disease resistance. Scientists at Montana State University and other research partners are studying better management practices and developing pulse varieties that show increased resistance to Aphanomyces and other pathogens.
This is also a good time to revisit past disease data and consult with your local Extension agent or crop consultant to ensure your rotation and management practices are optimized for the current season.
The rain is a double-edged sword—but with the right knowledge and response, Montana pulse growers can protect their investment and prepare for a successful harvest.
The Bottom Line
While the recent moisture brings hope for better yields, it also calls for vigilance. Monitoring, testing, and planning will be key to navigating the risk of root rot and making the most of this year’s growing season.
▶ Do you think you have seen signs of root rot in your fields this week? Share your observations or ask a question on our Facebook page.
