- Author: Michelle Leinfelder-Miles
I sent plant samples to the UC Davis Plant Pathology Diagnostics lab for confirmation on disease. Rather than Rhizoctonia, the lab identified Fusarium oxysporum on all of the plant tissue submitted. While Fusarium oxysporum is the causal agent of Fusarium wilt (a.k.a. Fusarium yellows), the symptoms on these plants indicated root and crown rot, and NOT yellows. Fusarium root rot is common on other beans; however, it has not been a common problem in California limas. For this particular field, its cropping history has been various vegetables for the last couple years, including tomatoes with a severe Fusarium problem in 2016. Rotating out of beans or vegetables to grains would be a good management strategy for future years because Fusarium can live in the soil for several years. Fungicide seed treatments may also help. In this particular case, we talked about managing water well to try to avoid moisture stress (too much or too little) of the current crop to optimize the crop that is there. The grower and PCA assured me that they can manage the moisture well with the drip irrigation on this soil type. For future bean planting, waiting until soil temperature is warmer and not planting as deep would also be important strategies.
- Author: Rachael Freeman Long
The Diseases and Abiotic Disorders section of the UC IPM Pest Management Guidelines for Dry Beans have been recently revised and updated and are now available online at UC IPM Dry Beans Pest Management Guidelines.
Authors include Farm Advisors Carol Frate (emeritus) and Rachael Long and UC Davis Professor Paul Gepts. Two new diseases were added, including pythium in established plants and chocolate blotch on limas. The Fusarium wilt sections were also consolidated and new photos were added throughout the guidelines. This includes an updated photo page to compare common diseases and abiotic symptoms to help identify them (Photo Identification).
With the upcoming planting season for dry beans, these guidelines can help with managing diseases in your fields. Worried about southern blight? Yes, beans are susceptible and you'll need to rotate to a non-host crop, including corn or grains for at least 2-years to reduce the inoculum. How about alfalfa mosaic virus? This disease is transmitted by aphids from alfalfa fields, so avoid planting beans adjacent to alfalfa. This information and much more are available through the revised UC IPM Dry Bean guidelines!
The remaining pest management sections, including insect pest and weed management, are in the process of being revised and will be published soon!