Peanut leaf spot the onset of symptoms and prevention measures

Date:2014/6/19 16:20:05 Hits:92

  Recently, many farmers to reflect the occurrence of relatively severe peanut leaf spot, for this situation, Henan dragon plant protection staff to share knowledge about the incidence of peanut leaf spot and prevention measures:

  Peanut leaf spot there?

  Peanut leaf spot and Alternaria leaf spot, including two kinds. Brown spot called “early leaf spot disease”; melasma, also known as “black gangrene disease.” Both diseases throughout China's major flower production areas. Multi-mixing occurs on the same plant the same blade. Rotation in the incidence of light, even as to the incidence of weight. The longer cropping life, the incidence of the more severe, often less than the harvest season, the leaves fall off in advance, this phenomenon is often mistaken for premature peanuts mature symbol. Peanut victims generally cut 10% to 20%, even more than 30%.

  What are the symptoms of peanut leaf spot?

  Peanut leaf spot is a leaf black spot, leaf spot and net blotch collectively, the disease can occur in the same plant or even mix the same blade. Leaf spot occurs earlier, began to appear in the field about the early flowering stage; black spot and net blotch occurs later, began to appear in most flowering in the field. Black spot and net blotch incidence of heavy, causing severe defoliation.

  The above three kinds of lesions occurred mainly in the leaves, petioles, stipules, stems also suffer. Compared to the first onset of old leaves in the lower part, the upper leaves gradually spread in the incidence of severe stem, petiole, fruit and other parts of the needle can form lesions. Leaf spots around the front of the blade has a clear yellow Hui wheel; leaves yellowish brown to dark brown.

  1 leaf spot. Occurred in front of the leaf lesion is brown or dark brown, round or irregular in shape, about 4 to 10 mm in diameter. Around the lesion has a clear yellow halo, like frog eyes, dorsal color lighter, no yellow halo. Sometimes produce gray mold shaped in the lesion. Formed on the stems, petioles and fruit needle oval spots, dark brown, slightly sunken.

  2 black spot. Occurred later than leaf spot lesion is small and round, dark brown or dark brown, 1 to 6 mm in diameter. Leaf spot lesions compared with neat edges, no yellow halo or obvious. Many black particles carrying raw leaf spot, arranged in concentric ring lines, on which the generation of spores and conidia plexus.

  Control measures:

  1. Agricultural control.

  (1) Clear sick deformed: When closing peanuts, as the plant debris or leaves collected for livestock fodder. Before sowing the timely processing of peanut vine stacked pile, the initial source of infection to eliminate the disease.

  (2) rotation Huancha: peanut leaf spot a single host, only infect peanuts, so the sweet potato, wheat crops across the ring or with rice as floods, droughts and crop rotation carried out, there is a good preventive effect.

  2. Chemical control.

  Use the same spot off the stand Net 1 +1 WP throughout peanut growing season, according to the disease since the beginning flower spray every 10 to 15 days a second drug, continuous spray 3-5 times per acre spray box, can achieve the effect of prevention and control of disease development and. Other original pesticides such as carbendazim, thiophanate, chlorothalonil, such as Bordeaux mixture is cheap but has been unable to suppress the disease. Try to use some high-end special effects products.