Schisandra leaf blight

Schisandra chinensis leaf blight is a common disease, which is widely distributed in Liaoning, Jilin, Heilongjiang and other provinces, which can cause serious consequences, such as early defoliation, fruit drop, shoot death, tree weakness, fruit quality decline, yield reduction and so on.

1. Disease symptom leaf blight is mainly harmful to leaves. It can be divided into two types according to the different initial sites and the size of disease spots on leaves. ① starts from the leaf tip or edge, then spreads to both leaf edges, and then spreads to the center to form large brown patches; with the further aggravation of the disease, the symptoms gradually occur from the lower leaves to the upper leaves, and the color of the diseased part changes from brown to yellowish brown; when the disease develops to a certain extent, the diseased leaves dry up and fall off, and the fruit wilts and wrinkles. There are many small round or irregular brown spots on the surface of ② leaves. In the later stage of the disease, the small spots fuse with each other into irregular large spots, and their symptom characteristics often vary with different varieties of Schisandra chinensis.

two。 According to the preliminary study, the etiology of Schisandra chinensis leaf blight is complicated, which may be related to pathogen infection (Septoriasp.), excessive results, stagnant water in the field, sudden change of temperature, improper fertilization and application of herbicides. The investigation found that there was no obvious onset center of the disease, but the closer to the sprinkler irrigation in the park, the more serious the disease was. In addition, the change of temperature is also a factor leading to leaf blight, which can easily be caused by the sudden invasion of cold air or sudden sunny weather after continuous high temperature.

Most of the disease began to occur in late May, and the peak period was from late June to late July. High temperature and humidity is the main factor for the occurrence of the disease. as a result, the disease is more serious in too many plants and rainy areas or years in summer and autumn, low-lying stagnant water and sprinkler irrigation in the same park, and more serious when nitrogen fertilizer is applied in the orchard and the shelf surface is closed. There are differences in the degree of susceptibility of different varieties, some varieties are extremely susceptible and the disease is serious, and some varieties have strong disease resistance and mild disease.

3. Control technology ① should strengthen cultivation management, pay attention to rational distribution of branches and vines, avoid canopy closure, and enhance ventilation and light transmission. Properly increase the proportion of phosphorus and potassium fertilizer to improve the disease resistance of the plant. In general, 1 ∶ 1 ∶ Bordeaux solution was sprayed in late May to prevent the disease. During the onset of the disease, 50% mancozeb wettable powder 500 times 600 times liquid spray can be used, once every 7 to 10 days, 2 times continuously for 3 times; or 2% agricultural antibiotic 120 water agent 200 times liquid, or 10% multi-antimycin wettable powder 1000 times 1500 times liquid spray, or 50% isocarbamide wettable powder 1000 times 1500 times liquid spray, once every 7 days, twice in a row.