Control methods of Peanut Brown spot

Peanut brown spot is a fungal disease, which is caused by Cercospora infestans, which harms peanut leaves. At first, it is a chlorotic spot, then it expands into a near round or irregular spot, the disease spot is larger and lighter than black spot, the leaf front is dark brown or tea brown, the back is brown or yellow brown, and there is a bright yellow halo around the disease spot. Let's take a look at the prevention and control methods of peanut brown spot.

Symptoms of peanut brown spot

Peanut brown spot is mainly harmful to peanut leaves, which is chlorotic at first, and then expands into near-round or irregular spots, which is larger and lighter than black spot, dark brown or brown on the front, brown or yellow on the back, and a bright yellow halo around the spot. The grayish brown powdery mildew layer can be seen on the disease spot with high humidity, that is, the conidiophores and conidia. The petiole and stem are infected with long oval, dark brown spots.

Incidence conditions of Brown spot in Peanut

The pathogen overwintered on the diseased body with ascomycetes, mycelia or ascomycetes. The following year, the conidia were produced under suitable conditions, and the initial infection and re-infection were carried out by means of wind and rain transmission. The hyphae extended directly into the intercellular space and cells to absorb nutrients, and generally did not produce haustorium. The growth temperature of the pathogen ranges from 10 to 33 ℃, and the optimum temperature is 25 to 28 ℃. The climate is rainy and humid, and the disease is serious. The disease occurred earlier, and the disease of young leaves was more serious than that of old leaves.

Control methods of Peanut Brown spot

1. Some resistant varieties were selected, such as Hua 39, 68-4, 8130, Luhua 11, Luhua 13, Luhua 9, Qunyu 101, P12, Hua 17 and so on.

2. At the initial stage of the disease, 25% manganese zinc wettable powder 375 g / ha and 70% methyl thiophanate wettable powder 263 g / ha can be sprayed, once every 7 days, twice in a row, and used alternately.