Symptomatic control of lettuce pests

At present, some vegetable farmers in the suburbs of Beijing suffer from lack of measures to improve the quality of their products, affecting the appearance of lettuce and reducing the sales price. Here are the relevant plant protection technology for autumn lettuce, introduced to a large number of vegetable farmers.

(1) Lettuce split stems: This is due to excessive use of excessive fertilizer or watering at the time of the group planting period. Therefore, do not use a single overdose when fertilizing or watering the plants.

(2) Lettuce Downy Mildew: It is a fungal disease infested by Aspergillus saccharomycetes. The leaves of adult plants develop from top to bottom. When wet, there is a layer of white frosty mildew. Wind and rain insects, high temperature and low temperature, planting too dense can induce the disease.

Control methods: (1) 72.2% Prec 600 to 800 times liquid. (2) 64% Antitoxicant WP 500 times. (3) A 500 mg methacrylate Zn wettable powder.

The above three drugs are used interchangeably and sprayed once a week.

(3) Lettuce soft rot: It is a bacterial disease, which usually occurs in the middle and late stages. It can be used to irrigate the roots with 3000-4,000 times of streptomycin-soluble powder for 72 hours, and once a week.

(D) Botrytis cinerea: This disease is caused by Botrytis cinerea and it is also a common disease in protected cultivation of lettuce. The conidia of pathogenic bacteria spread with the air flow and the sclerotia were left in the soil and mixed into flowing water to spread to the petiole leaves. When the disease occurred, the surface had gray moldy layer, poor drainage, and low temperature and humidity were easy to cause.

Control methods:

(1) 50% Nong Liling 1000 times. (2) 50% carbendazim 600 times. (3) 50% speed Skeleton 1000 times.

The above three agents are used once a week, alternately, and they can be sprayed three times.

(5) Lettuce Sclerotinia: This disease is caused by the infection of S. sclerotiorum and is an important disease of lettuce. It is often caused by stalks and causes tissue decay. The surface has white flocculent hyphae with black murine sclerotia inside. The upper part of the diseased plant will soon shrink and die. Low temperature, humidity, rain or water in the field and high density can promote disease.

Control methods: (1) 40% of sclerotia net 1000 to 1500 times liquid. (2) 70% thiophanate-methyl 800 times. (3) 50% carbendazim 500 times.

The above three drugs were alternately sprayed, and the control effect was very obvious.

(6) Lettuce aphid: 50% of evasive powder from 1500 to 2000 times. 10% imidacloprid 1500 times spray.

The above two drugs were alternately sprayed and the control effect was good. (Shunyi Plant Protection Station)