During this time of the season, (50 to 70 days into season) we are at a critical point in our disease management program. We should continue to maintain our leafspot control programs and implement a good program for prevention of white mold. We have ideal conditions for disease development and activity. Both leafspot and white mold are active in our area and weather patterns are very conducive for disease formation and spread. I wanted to share pictures of the most common diseases detrimental to peanuts and peanut yields. Please refer to the list below for Peanut RX Fungicide schedules and spray program recommendations.
1. Leafspot – As most of you know, we monitor and spray for two different types of leafspot.
Early Leafspot – Brown lesions, commonly surrounded by yellow halo. Located on top of leaf.
Late Leafspot – Color ranges from chocolate brown to dark black. Located on underside of leaf.
2. White Mold – Located in crown of plant. We can look for white mycelium or white fungal growth.
Also, please be aware that Subterranean white mold can be a problem and it is difficult to control. However, there has been no reports of subterranean white mold this season. Subterranean white mold can only be seen when plants are dug, no above ground symptoms are noticeable.
3. Peanut Rust – Appears as leafspots or flecks that are visible from both sides of the leaf. The leaves become a “rusty” yellow color as infection increases. Infections can develop on stems and leaf petioles.
4. Cylindrocladium Black Rot (CBR) – There has been no outbreak of CBR in approximately 3 years. But, we should be aware of plant symptoms. Typical signs of CBR include the plant turning light green to yellow, wilting, and ultimately death of the plant. Often, brick red, pinhead-size fungal structures called perithecia can be seen on the stems and crowns of the plants.