Brown spot disease: mainly damages leaves. In the early stage, the lesion was a round or oval purplish brown lesion with different sizes, and in the later stage, it was black to dark black. The boundary between the diseased part and the healthy part was obvious, and the center of the lesion turned light gray with black spots. In severe cases, most lesions are connected, and the diseased leaves are black, dry and fall off. Pathogens overwinter in dead leaves or soil with hyphae and conidia, which can be spread by wind and rain, irrigation and man-made. High temperature, high humidity, too dense plants and rainy seasons are beneficial to the occurrence and serious disease. Prevention and control methods: remove diseased branches and leaves in time, burn them centrally or bury them deeply to reduce the source of germs; Spraying 65% zineb 500 times solution, 75% chlorothalonil 500 times solution, or 80% mancozeb 400 times solution at the initial stage of the disease; Spray every 7 ~ 1 0 days1time, and spray continuously for 3 ~ 4 times.
Anthracnose: mainly damages leaves, young stems and branches. In the early stage of the disease, round and oval reddish-brown spots appeared on the leaves, and in the later stage, they expanded into dark brown spots, and the center turned from grayish brown to grayish white, while the edges were purplish brown or dark green, sometimes with yellow halo at the edges, and finally the spots turned dark brown, resulting in small black spots arranged in a wheel pattern, that is, the acervulus of the pathogen. This disease often occurs at the edge and tip of leaves, and in severe cases, most leaves wither and die. A round or nearly round lesion is produced on the stem, which is light brown and has black dots arranged in a wheel pattern. The pathogen overwinters in the host residue or soil with mycelium. It is spread by farming operations such as wind and rain or watering, and it is mostly infected from the wound. Prevention and treatment: Cut off the diseased leaves at the early stage of the disease and burn them in time to prevent expansion, and spray them with 800 times of 50% carbendazim wettable powder, 500 times of 50% anthrax thiram wettable powder or 500 times of 75% chlorothalonil.
Rust: After damage, yellow-brown powder is produced on the surface of leaves, causing leaf surface to lose water and die of scorch. Prevention and treatment methods: spray 400 times of 20% triamcinolone acetonide emulsifiable concentrate, 800 times of 50% triamcinolone acetonide wettable powder, or1:1:200 bordeaux solution at the initial stage of onset.