Common pests and diseases of Lagerstroemia indica and their solutions

Lagerstroemia indica is our common ornamental flowers and trees, which are widely planted. Lagerstroemia indica has good ornamental effect and remarkable air purification effect, but it is easy to be infected with pests and diseases. Let's learn about the common pests and diseases of Lagerstroemia indica and their solutions:

Common pests and diseases of Lagerstroemia indica and their control methods;

1, crape myrtle

Brown spot disease is a common disease in Lagerstroemia indica growing season. At the beginning of the disease, the spots are round or nearly round, with different sizes and some irregularities. The focus is purple-black to black with light edge color. Then the color of the lesion deepened, showing black or dark black, and the boundary with the healthy part was obvious. In the later stage, the color of the lesion center becomes pale and small gray-black mildew spots appear. When the condition is serious, the diseased spots become one piece, and the whole leaf turns yellow quickly and falls off early. When brown spot disease is serious, it often causes a large number of leaves to wither and fall off, which affects ornamental and flowering.

Solution: Strengthen daily management, and spray 500 times of 50% carbendazim wettable powder, 65% zineb wettable powder 1000 times of 65% carbendazim wettable powder or 800 times of 75% chlorothalonil wettable powder at the initial stage of treatment.

2. sooty blotch, Wei Zi

Sooty blotch, also known as coal smoke disease, is mainly caused by Lagerstroemia indica and its invasion, that is, it uses the mucus secreted by them as nutrition to induce a large number of bacteria polluting coal to multiply. After the disease, the leaves of diseased plants are covered with black mold layer, which not only affects the ornamental value of Lagerstroemia indica, but also affects the photosynthesis of leaves, resulting in the weak growth of plants and early defoliation.

Solution: We should prevent and control aphids, scale insects and whiteflies in time, because the secretion of these insects is the basis of the existence of pathogenic bacteria in sooty blotch. Commonly used chemicals include stone sulfur mixture, Bomei 3 stone sulfur mixture in winter and 0.3 stone sulfur mixture in summer and autumn. It can also be controlled by phosphorus trichloride and litsea cubeba leaf juice. Or spray 500-800 times of 50% carbendazim wettable powder and 500 times of 70% thiophanate methyl.

3. Lagerstroemia indica powdery mildew

Powdery mildew of Lagerstroemia indica is common in the provinces and cities where Lagerstroemia indica is planted in China. At the early stage of the disease, small white powder spots appeared on the leaves, which were round or irregular faded spots after expansion, covered with a layer of white powdery mildew, and the layer of powdery mildew turned gray in the later stage. After the flowers are infected, the surface is covered with white powder, and the flower spikes are deformed, losing ornamental value. The plants affected by powdery mildew will become shorter, the tender leaves will be twisted and withered, the leaves will become smaller without spreading, and the branches will be deformed. If it is serious, the whole plant will die. After the onset of Lagerstroemia indica, the leaves often turn yellow and fall off, which directly affects the tree potential and ornamental effect.

Solution: pay attention to the daily maintenance and management of Lagerstroemia indica, and spray Bomei 3 ~ 4 stone sulfur mixture before germination in spring; When the disease occurs in the growing season, it can be prevented by spraying 500 times 80% zineb wettable powder, 1000 times 70% thiophanate-methyl, 1500 times 20% triadimefon emulsifiable concentrate or 800 times 50% carbendazim wettable powder.

4. Aphids

In the north of China, 5 ~ 8 generations occur every year, and the eggs overwinter near the buds, with May as the initial stage and June as the peak stage. Nymphs and adults cluster to harm young leaves of Lagerstroemia indica and suck juice, which affects growth and development.

Solution: Strengthen cultivation management measures to reduce the source of disease. When aphids are abundant, cough 40% omethoate and 40% acephate 65,438+0,000 ~ 65,438+0,500 times or spray skin spring 65,438+0,000 ~ 2,000 times, but pay attention to avoid phytotoxicity.

5. Rong Jie

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.

Solution: spray 10 ~ 15 times turpentine mixture or 40 ~ 50 times engine oil emulsion 1 ~ 3 times in winter to eliminate overwintering female insects. Before germination, spray 3 ~ 5 degrees sulfur mixture or 3% ~ 5% diesel oil emulsion to kill overwintering nymphs.

6, big decline moth

The big decline moth is also one of the pests invading Lagerstroemia indica. Larvae bite the leaves, twigs or strip branches and fruit cortex in the protective bag, resulting in partial baldness of shrubs.

Solution: Take out the capsule and spray 90% trichlorfon 1000 times solution to kill the hatched larvae in early May-June. The effect is very good.

Lagerstroemia speciosa makes people like to watch flowers and trees, which can be planted in the courtyard at home, and small plants can also be planted in pots to decorate and beautify the home. Lagerstroemia speciosa can be watched and purify the air, which is a good helper for a beautiful home environment.