Sorghum black bundle disease

Symptomatic sorghum black bundle disease is a vascular bundle disease, also known as duct bundle blackening. When the leaf is obvious, brown stripes appear on the leaf vein, and there are large necrotic spots along one or both sides of the main vein, so that the leaf and leaf sheath become purple or brown, when the leaf is dry, the stem is a little thick, and there is branching in the upper part of the diseased plant. Transverse section of the diseased stem shows that the vascular bundles, especially the xylem ducts, turn brown and are blocked. In the longitudinal section, the vascular bundles turned reddish brown or dark brown from bottom to top, and the vascular bundles of the basal internodes blackened more obviously than those of the upper internodes. Seriously diseased plants withered early, did not heading or did not bear fruit, and the yield was reduced by 50%. China is distributed in three northeastern provinces. The pathogen Acremonium stictum W.Gams is called Alternaria oryzae, which belongs to semi-known subphylum fungi. Synonym Cephalosporium acremonium Corda. The colony is round, the aerial hyphae are dense, curly, initially white, and then light pink. Conidiophores without septum, size 40-60 × 3 (um). Conidia unicellular, nearly colorless, oval, 4 × 1 um in size. In addition to harming sorghum, it can also harm many kinds of monocotyledons and dicotyledons, such as corn, soybean, wheat, oat, cotton and so on. The route of transmission and incidence conditions of the disease are carried by seeds and soil. After invading from the root of the host, the bacteria entered the vascular bundle tissue. Under natural conditions, field pathogens can also infect leaves and leaf sheaths and cause the disease through vascular bundle expansion. The disease has been reported in Egypt, Argentina, Venezuela, Mexico, Sudan, Honduras and other countries. The incidence of Tx622A and rx623A is obvious in our country. Foreign Sc35-6, Sc630-11E and GPR-148 showed disease resistance. Control methods (1) breeding disease-resistant varieties. (2) to carry out quarantine to prevent the spread of the disease.