Late leaf spot is one of the most aggressive and difficult to control peanut diseases. This fungal pathogen attacks any above-ground portion of the plant, leaving brown to black spots on the upper leaf surface. Leaf spots are the most conspicuous symptom, however. According to the University of Oklahoma Extension, be on the lookout for these symptoms:
- Brown to black, pinpoint-size dots on the upper leaf surface
- Black, circular spots with a less pronounced yellow halo
- Spots that reach about 1/4 in. in diameter
- Clearly defined spots on the lower leaf surface
- Pale green to yellow leaves that wither and fall off the plant
- Defoliation on lower leaves that progresses upward
- Dark brown to black, oval-shaped lesions on stems, petioles and pegs
Controlling leaf spot is critical to prevent heavy defoliation and yield loss. Experts recommend using an integrated management program that combines the following:
- Cultural practices. Rotation of peanuts with other crops and management of peanut residue by tillage can help delay the development of disease. Proper irrigation also helps reduce leaf spot.
- Genetic resistance. Peanut varieties differ in reaction to leaf spot, but levels of resistance in peanut varieties alone are not sufficient to provide adequate disease control.
- Fungicides. A fungicide program is normally required to prevent yield loss from leaf spot. Elatus® fungicide provides excellent control of foliar and soilborne diseases in peanuts. With two active ingredients, Solatenol® fungicide and azoxystrobin, Elatus provides improved control of Rhizoctonia (stem canker), early leaf spot, late leaf spot, Southern stem rot (white mold) and rust.
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