Symptoms of virus disease in Brassica napus

(agricultural Wealth net) the symptom of Brassica napus virus disease is systematic withered spot, the early symptom of the old leaf is obvious, and then spread to the new leaf. At the beginning of the attack, there are needle-sized transparent spots, and then expand into a near-round surface 2 to 4 mm macula, the center is dark brown dead spots, necrotic spots around the oily stains. Purple-black fusiform to long strip disease spot appeared on the stem, and spread from the middle and lower part to the branches and fruit pedicels. In the later stage, the disease spot on the stem was mostly longitudinally or horizontally cracked, and the flowers and pods were easy to wilt or die. Pods produce black dead spots and are deformed.