How to prevent and control peanut brown spot? A full analysis of practical methods

Peanut brown spot is a fungal disease caused by infection with Cercospora arachidicola of the subphylum Deuteromycotina. It damages peanut leaves, initially appearing as small chlorotic spots, which later expand into nearly round or irregular small spots. The lesions are larger and lighter in color than those of black spot disease, appearing dark brown or tea-brown on the upper leaf surface and brown or yellowish-brown on the underside, with a bright yellow halo around the lesions. Let's take a look at the control methods for peanut brown spot below!

Symptoms of peanut brown spot

Peanut brown spot mainly damages peanut leaves, initially appearing as small chlorotic spots, which later expand into nearly round or irregular small spots. The lesions are larger and lighter in color than those of black spot disease, appearing dark brown or tea-brown on the upper leaf surface and brown or yellowish-brown on the underside, with a bright yellow halo around the lesions. When humidity is high, a grayish-brown powdery mold layer can be seen on the lesions, which consists of the pathogen's conidiophores and conidia. When petioles and stems are infected, the lesions are elongated-oval and dark brown.

Conditions for the occurrence of peanut brown spot

The pathogen overwinters on diseased plant residues as stromata, mycelial masses, or ascocarps. In the following year, when conditions are suitable, it produces conidia, which spread through wind and rain to cause primary infection and re-infection. The mycelium extends directly into intercellular spaces and cells to absorb nutrients, and generally does not produce haustoria. The temperature range for pathogen growth is 10-33°C, with the optimum at 25-28°C. In rainy and humid climates, the disease is severe. The disease occurs relatively early, and young leaves are more severely affected than old leaves.

Control methods for peanut brown spot

1. Choose relatively disease-resistant varieties such as Hua 39, 68-4, 8130, Luhua No. 11, Luhua No. 13, Luhua No. 9, Qunyu 101, P12, and Hua 17.

2. In the early stage of the disease, you can use 25% mancozeb · wettable powder 375-750 g/ha or 70% thiophanate-methyl wettable powder 263-350 g/ha for spraying, once every 7 days, 2 times in a row, used alternately.