What if there is a layer of black ash on Wei Zi's leaves?

Lagerstroemia indica, also known as pomegranate tapetum, has two generations at 1 and overwinters as eggs or nymphs. Female adults and nymphs suck juice on bud axils, leaves and branches, causing black branches and leaves to fall off, which seriously affects the growth and development of trees. Their excreta can induce sooty blotch, which is one of the main pests that harm Lagerstroemia indica.

Prevention and control methods:

1. Strengthen quarantine, prevent the inflow of germs, apply fertilizer rationally, enhance the insect resistance of plants, keep ventilation and light transmission, avoid excessive plant density, and combine pruning in winter and early spring to burn insect branches. When the quantity is small, it should be scraped off manually.

2. Chemical control. (1) Spray 10- 15 times of turpentine mixture or 40-50 times of engine oil emulsion 1-3 times in winter to eliminate overwintering females. (2) Before germination, spraying 3-5% sulfur mixture or 3-5% diesel oil emulsion to kill the overwintering nymph. (3) Nymphs are the key to control. First, the newly hatched nymphs unearthed should be sprayed with 500 times solution of 50% carbaryl wettable powder or 5% phoxim EC 1000 times solution on the soil surface around the roots in early spring. During the incubation period, when the shell is not thickened and the pesticide is easy to penetrate, spray it every 7 7- 10/time for 2-3 times continuously, and choose 40% omethoate emulsion, 80% dichlorvos emulsion, 50% phoxim emulsion and 25% iminophosphate emulsion 1 00.

Spraying 25% triadimefon wettable powder 3000 times solution, 70% thiophanate methyl wettable powder 1000 times solution, or 80% zineb wettable powder 500 times solution, Baijunling, several drugs have better effects. Combined with pesticides such as cyanopolyester, it is used to control aphids, leaf curl moths, small white moths and so on.