Symptoms and control methods of walnut anthracnose

   1. Distribution and occurrence characteristics of walnut anthracnose generally occurred from June to August, slightly different from place to place. From late June to early July in Jiangsu, Henan and Shandong, and August in Hebei and Liaoning. The pathogen overwintered with hyphae and conidia in diseased fruits, diseased leaves or bud scales. in the following year, conidia were transmitted by wind, rain or insects and invaded from the wound or natural orifice. After the onset of the disease, the spore clusters were spread by Rain Water and re-infected many times. The onset of the disease sooner or later is closely related to the severity and Rain Water of that year. In general, there are many rainy days, high humidity, poor ventilation and light transmission. If the rainy season is early and Rain Water is more, then the onset is early and severe, on the contrary, the disease is mild or mild. The disease resistance of different varieties is different: Aksu and Kuqa in Xinjiang are easy to infect the disease, and the disease of mature species is light.

   2, pathogens and symptoms are fungal infection diseases, which are called small clumps and belong to ascomycetes. The non-sexual state is Colletotrichum gloeosporioides, which belongs to semi-unknown fungi.

   is mainly harmful to walnut fruit, and it also occurs on leaves, buds and shoots. The general disease rate is 20% to 40%. In severe cases, it can be as high as 90%, which makes the walnut kernel dry and the yield and quality greatly reduced. The damage is serious on walnuts all over the country.

The disease spot on    fruit was brown at first, then black, nearly round and sunken in the center. There are many brown to black dots on the plaque, sometimes arranged in a concentric pattern. When the humidity is high, the small black spot on the disease spot shows a small pink protuberance, that is, the pathogen conidium disk. A diseased fruit has one to more than a dozen disease spots, which are enlarged or connected, which can cause the whole fruit to blacken and rot.

The disease spot on    leaf is rare, and the disease spot is nearly round or irregular. Some disease spots spread along the leaf margin, and some extend along both sides of the main lateral vein. When the disease is serious, the whole leaf is withered and yellow. When the humidity is high, the black spots on the disease spot show small pink protuberances, which are conidia disks and conidia of bacteria.

   3. Prevention and control methods

The diseased fruits and leaves were removed by   ① in winter, and the diseased fruits were removed in time from June to July.

When planting   ②, the row spacing should not be too close, so that the ventilation and light transmission is good.

  ③ chemical control. Use 3-5 Baumedo stone-sulfur mixture before germination; 1: 1: 200 Bordeaux solution or 50% acetaminophen 600-1000 times before anthesis, and the young fruit stage is the prevention and treatment period. During the onset period, you can also use Dofu mn-Zn 1000 times + leather glue 0.03%, 2% Nongkang 120 water agent 200 times, 50% methyl topiramate 800 times 1 000 times, 50% carbendazim wettable powder 800 times 1 000 times.