First, powdery mildew
1. Symptoms. The main damage to the leaves began in early May. The damage was severe from June to July, and the damage was reduced after August. At the beginning of the disease, small round spots of round or oval yellow-brown were formed on the back of the leaves, gradually forming large spots with a diameter of 2 to 2.5 mm; the leaves of the leaves were spotted brown and gradually grew out of white powder, and formed black particles in July and August. The disease develops from the old leaves to the new leaves. The white powder covers the entire leaf, causing the leaves to scorch and die, and the lower stems and roots to rot. The lighter ones can have new leaves the next year, and the most serious ones die. Low altitude, well shaded plots, continuous cropping, and other serious diseases, high altitude, poor shading, and uncultivated land are less prevalent.
2. Control methods. 1 Select broad-leaved forest belt, low-lying, sunny, loose and fertile soil, implement rotation; 2 sprayed with Qingfengmycin 80 units 2 or 3 times, or 70% thiophanate-methyl wettable powder 1000-1500 times The liquid is sprayed 3 times, or sprayed with Baume 0.3 degree lime sulfur for 3 to 4 times. Generally, it is administered once at the early stage of the disease, and the onset period is 2 to 3 times.
Second, anthrax
1. Symptoms. The initial onset of May, from mid-May to early June is the onset. The disease started from the margin of the leaf and showed an oval-shaped water-soaked spot. The lesion was purple-brown at the edge and gray in the middle, protruding toward the surface of the leaf. The lesions were detached and perforated at the middle of the lesion. The lesion size was 3-20 mm. There are also fusiform purple spots on the petiole, and the lesions merge with each other, causing the entire leaf to die. The occurrence of the disease is related to climate, cultivation system, growth period and forest belt.
2. Control methods. 1 selection of broad-leaved forest planting, rotation; 2 with 1:1: 100 Bordeaux mixture or 65% zein WP WP 300 to 400 times plus 0.2% detergent, in the early onset and the peak period, control 3 ~ 4 times.
Third, white spot disease
1. Symptoms. White Pelican disease, also known as erythrorrhea, and ground fire, occurs at an altitude of 1000m. The onset of the disease begins in early June. Heavier incidence occurs from late June to mid-July and the disease ends in late August. The pathogenic bacteria invaded the rhizomes of the Coptis chinensis plant, so that the leaf veins of the leaves first appeared purple-brown, gradually to the whole leaf, and afterwards it was brownish, like boiling water burned. After the damage to the whole plant leaves, the roots and stem base were rotted and the whole plant died. In general, the incidence of disease is heavy in continuous cropping, and the occurrence of wasteland is light.
2. Control methods. (1) More than 5 years of rotation with corn; (2) After the occurrence of the disease, first remove the diseased plants and diseased soil, and then use lime powder to disinfect the diseased plants and the surrounding soil, or use 50% Carbendazim WP 800 times .
Fourth, toxin disease
1. Symptoms. The onset began in early April and was severe in June. After injury, leaves showed yellowing on the sides of the veins and striping. The leaves of the narrow-leaf type showed yellowing, browning and scorching after yellowing, causing the death of the whole plant. Red spiders and big leafhoppers may be the source of transmission of poisonous insects.
2. Control methods. 1 Select wide-leafed disease-resistant varieties; at the beginning of 24 months, spray 40% Dimethoate 1000-1500 times to kill spider mites and leafhoppers.
Author: Shazi Town Government, Shizhu County, Chongqing
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