Sclerotinia sclerotiorum is one of the main diseases of rapeseed. The harmful symptoms of Sclerotinia sclerotiorum and the prevention and treatment of seedling stage lesions occur at the junction of ground rhizomes, forming reddish-brown spots, and then expanding to dry white, tissue wet rot, above White flocculent hyphae grow. After the diseased class is wrapped around the stem, the stem rot is caused, the seedlings die, and many black sclerotia are formed outside the diseased tissue. In the stage of adult planting, the initial round or irregular water-stained lesions, the center of the lesion is gray-brown or yellow-brown, the edge is dark blue, slightly rounded, the edge of the lesion is chlorotic, and the outer edge is yellow. When dry, the lesions rupture and perforate, and in the case of moisture, they spread rapidly, and the whole leaves rot, and white hyphae grow on them. The stem of the stem first appeared a fusiform light brown water-stained lesion, slightly concave, white in the middle, and brown on the edge. In humid conditions, the lesions develop very rapidly, and white hyphae grow on them. In the late stage of the disease, the stems are damaged, the vascular bundles are filamentous, the pith is hollow, and it is easy to fall. Many squid-like sclerotia are formed in the stem. . In severe cases, the whole plant is dead, and the lightly diseased plants are partially dead or early, and the seeds are not full. The petals were pale yellow after the disease, and then turned white. After the pods are infected, irregular white spots are formed, and small and round small sclerotia can be formed inside and outside the pods. After the seed is ill, the surface is rough, grayish white, dull or irregular.
Prevention and control of rapeseed sclerotinia:
1. Agricultural control. Cultivate and select varieties with strong disease resistance. First, the implementation of water and drought rotation. The sclerotia remaining in the soil is soaked and rotted by irrigation to reduce the source of infection; the second is to treat the residual strain. After threshing of rapeseed, the stems, branches, and cuticles are treated separately or placed in paddy fields to make fertilizer; the third is deep sterilizing. Deep ploughing in autumn, cultivating soil for 1-2 times in spring, can break and submerge the sac disk; fourth is seed treatment. Eliminate the sclerotia and kill the seed epidermis by screening, wind selection, pesticide dressing, etc., sowing disease-free seeds.
2. Chemical control. At the same time of implementing agricultural control, timely use of chemical and chemical control is a key technical measure to control and reduce the risk of Sclerotium disease. According to years of experience, in order to ensure the effectiveness of disease prevention, it is necessary to take the drug use period, select the drug, and adopt the correct Medication method. At present, the main pesticides commonly used are carbendazim, bacteriocin, sclerotium net, thiophanate and various fungicides . Since rapeseed is the most susceptible to flowering, it is very important to use the first drug in the initial flowering period. After 7-10 days, use the second drug. If it is continuous rainy day after 2 times, you should try to use it. Good 3rd medicine. In order to ensure the effect of disease prevention, one must adhere to the amount of water 50-60 kg when using the medicine; the second is to adhere to the spray of coarse fog, from the flower to the base stem should be sprayed everywhere, so that the plant surface forms a protective layer of chemicals.
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