Disease Management & Control

Seedling Diseases: All peanut seed should be treated with a fungicide (Vitavax PC, Dynasty PD, or Trilex) to reduce the incidence of seed-transmitted and soilborne seedling diseases such as Cylindrocladium, Aspergillus crown rot, Pythium, and Rhizoctonia. Vitavax PC (Captan + PCNB + Carboxin), Dynasty PD (mefenoxam + fludioxonil + azoxystrobin), Trilex Star (Captan + trifloxystrobin + metalaxyl + thiophanate-methyl), and Trilex Optimum (Captan + trifloxystrobin + metalaxyl) seed treatments are all effective in reducing seedling disease and protecting stand counts. Higher stand counts reduce the risk of tomato spotted wilt virus.

Tomato spotted wilt virus (TSWV): This virus is transmitted to peanuts by thrips, primarily tobacco thrips. TSWV reduces yield and causes shriveled, misshapen pods. All peanut fields in S.C. are vulnerable to significant yield loss from TSWV regardless of whether the farm has any history of peanut production.

White mold, Limbrot, Leaf Spot, and Web Blotch: The key to peanut disease control is preventing diseases from getting started. This is true for soil diseases such as white mold and Rhizoctonia limbrot, as well as leaf spot on the foliage. Alternating different fungicide chemistries reduces the potential for developing resistant strains of leaf spot and soil diseases. Alternating fungicides also gives some insurance against the failure of one product alone.

Cylindrocladium Black Rot (CBR) Control: CBR is caused by a soil fungus which occurs in the same fields from year to year, often in low spots. Rotation (at least 2 years out of peanuts and elimination of soybean from the rotation) is the best defense against severe CBR. Once established, CBR must be minimized with varietal resistance (Perry, Ga 03L, Ga 02C, Ga 01-R) and in severe cases, fumigation (Vapam 10 gal/ac). Vapam must be shanked into a bed at an 8” depth 2 weeks prior to planting. Avoid fumigating when there is a high risk of heavy rain (> 1.0”) within 2 days. Folicur, Abound, and Headline may provide some CBR suppression, but not control. Provost is a new fungicide which can provide improved suppression, but not control of CBR.

For more details, guidelines, and fungicide programs, see the Production Guide or contact Jay Chapin, 803-284-3343, jchapin@clemson.edu