1, downy mildew symptoms:
The disease can occur in both seedling and adult stages, especially in adult stage. The disease spread from the lower part to the upper part, and pale yellow, nearly round or polygonal lesions were formed in the early stage on the leaves. When the humidity was high, a white mold layer grew on the diseased spots on the back of the leaves, which would cause the whole leaves to dry up seriously. Make the oil wheat vegetable lose its commodity value.
Prevention and control methods:
(1) Rational close planting for agricultural control, with plant row spacing15cm and 20cm. Control the temperature of the shed, spread the air in time, and cultivate in time after watering. Flood irrigation is strictly prohibited in the late growth stage.
(2) For chemical control, 5% chlorothalonil dust powder can be sprayed conditionally, with the dosage per mu 1 kg, and 66.8% mequat wettable powder, 200-250 times of 40% ethyl phosphate wettable powder or 800 times of 72.2% Pulik water solution can also be sprayed, 7-/kg.
2, gray mold symptoms:
Infected at seedling stage, the damaged stems and leaves were soaked and rotted; Infected at the adult stage, it started from the leaves near the surface, which were initially soaked in water, then expanded rapidly, the stem base rotted, and a gray-brown or gray-green mold layer was produced on the surface in wet environment.
Prevention and control methods:
(1) Agricultural prevention and control: increase temperature and heat preservation, control humidity, prevent water film from forming on the surface of plants, appropriately reduce the temperature difference between day and night, and avoid cold air invasion.
(2) 5% chlorothalonil dust agent can be used to spray powder, mu dosage 1 kg, or 6.5% metoclopramide ultra-fine dust, mu dosage 1 kg. Use 600-800 times of Tektronix or 600-700 times of 50% Sukeling wettable powder, or 65% Wanmeiling 1000 times of liquid, and spray it at the initial stage of onset.
3, brown spot symptoms:
It is mainly harmful to leaves, which is initially soaked in water, and then gradually expands into round to irregular, brown to dark gray lesions.
Prevention and control methods:
(1) Avoid partial application of nitrogen fertilizer in agricultural control, and timely spray leaf fertilizer to promote the robust growth of plants and enhance disease resistance.
(2) 75% chlorothalonil wettable powder 1000 times solution is added with 70% thiophanate-methyl wettable powder 1000 times solution, or 50% chlorphenamine wettable powder 1500 times solution is sprayed for control,10 ~/kloc-0.
4. Symptoms of Liriomyza sativae:
It belongs to Diptera and Diptera. Both adults and larvae can do harm. Female adults fly and stab the leaves of plants to feed and lay eggs. Larvae dive into the leaves to feed on mesophyll, resulting in irregular snake-shaped wormways, and chlorophyll is destroyed, which affects photosynthesis and seriously causes leaf dryness.
Prevention and control methods:
(1) Agricultural control: Clean the fields, and concentrate the residues of crops harmed by liriomyza sativae to be buried deeply, fertilized or burned.
(2) Chemical control: 3000 ~ 4000 times of1.8% Everdeen EC or 48% Lesburn EC 1000 times of EC spray control.
5, Bemisia tabaci symptoms:
It is a pest of Homoptera, whitefly family, which sucks plant leaf liquid with adults and nymphs, causing the damaged leaves to fade, wilt or die, and can spread viral diseases.
Prevention and control methods:
(1) Agricultural control: ① Disinfect the shed to reduce the source of insects. Thoroughly clean the shed before seedling raising, mix sawdust with 2 kg ~ 3 kg/mu of sulfur and 0.25 kg of 80% dichlorvos oil, light it in piles, seal it for a day and night, and let it air out without smell before use. To eliminate the source of insects. ② When the shed is buckled in autumn and winter, a 60-80 mesh insect net is set to prevent Bemisia tabaci from entering the shed. (3) Using the yellow tropism of Bemisia tabaci, hanging a yellow trap board in the shed and above the crops, painting the board with 10 oil and then painting it every few days, which has a certain trapping and killing effect.
(2) Chemical control: fumigation with heavy lice. Or choose high-efficiency, low-toxicity, safe and low-residue pesticide spray for continuous prevention for three times, such as spraying 5% Chlorpyrifos or10% imidacloprid or 5% Dagong wettable powder with 2000 times solution.