Control of Diseases and insect pests of persistent herbaceous Chrysanthemum

(1) symptoms of major diseases and their control

There are many diseases to chrysanthemum, the main symptom of which is ① powdery mildew (downy mildew), which damages the leaves, petioles and shoots of chrysanthemum. The disease is sprinkled with a layer of white powder, that is, conidia and hyphae. Diseased leaves are often distorted, the buds of seriously diseased plants can not open normally, growth stops, and even the whole plant dies; ② brown spot (leaf blight), mainly harmful leaves, round or oval spot purple-brown to dark brown, severe multiple disease spots connected throughout the whole leaf, the diseased leaves withered and blackened, and did not fall off. The diseased plant began to die upward from the lower leaves to the whole plant, and ③ sclerotial rot (white silk disease) mainly damaged the stem. Generally, it first occurs at the base of the soil surface stem, the disease spot is soft rot, and white hyphae appear when it is wet. When the disease spot around the stem for one week, the leaf yellow flower drooped and withered, and finally the whole plant withered, and there were mouse fecal sclerotia in the diseased stem.

Comprehensive disease control measures: ① thoroughly remove dead branches and leaves after autumn, remove diseased plants and diseased leaves in time, and burn them centrally; ② strengthen soil, fertilizer and water management, topping and pruning, pay attention to the selection of strong seedlings, reasonable close planting, should not be too dense, and maintain good ventilation and light transmission conditions in chrysanthemum garden Chemical control was used for ③. During the period from April to October, effective agents were alternately selected, such as 1 ∶ 1 ∶ 200 times Bordeaux solution, 20% trimethoprim 3000 times solution, 70% ethyl phosphorus lead manganese zinc solution, 58% metalaxyl manganese zinc solution 1000 times, 70% carbendazim manganese zinc 1000 times solution, 40% sclerotia net 1000 times solution, as well as chlorothalonil, carbendazim, carbendazim, mancozeb, methyl thiophanate, etc., to determine the spraying times according to the condition.

(2) main insect pests and their control

① grub, a beetle larva, can damage the young roots and buds of chrysanthemum in the ground and can be controlled by 1000 times of phoxim. ② chrysanthemum aphids, leafhoppers and bugs are mainly harmful to leaves and twigs. It can be rotated to choose imidacloprid (imidacloprid), good year winter, aphid Qingling, fast killing spirit, great hero, dimethoate and other medicament control. ③ leaf roll moth, leaf roll is harmful to leaves, it can be controlled by Uranus, cypermethrin, kung fu, enemy killing and other insecticides.

In order to prevent and control chrysanthemum diseases and insect pests, we should pay attention to the selection of high efficiency, low toxicity and low residual pesticides. Pesticide use is prohibited from 20 days before chrysanthemum harvest to the period of chrysanthemum harvest, so as to prevent chemical pollution of chrysanthemum.