Cultivation techniques of Lagerstroemia indica in Yunnan

Select the field where lignified seedlings are transplanted, and apply sufficient base fertilizer in the hole before planting. Fertilize once a month during the growth period of young trees, and pay attention to picking buds to help dry. Fertilize twice a year after the plant grows, and apply phosphorus-based compound fertilizer at flowering stage to facilitate flowering. Prune the fallen leaves once after winter dormancy. Cutting off residual flower branches, fruit branches, over-dense branches, pests and diseases branches, and applying basic fertilizer (mainly organic fertilizer) around the base can promote vigorous growth and flowering in the next year. There are few pests and diseases. Insects such as scale insects harm branches, so don't kill them, and don't spray pesticides such as dimethoate as soon as possible.

1, ground planting: 1 1 After defoliation, planting in March of the following year. When planting, leave the trunk 100~ 120 cm high and cut off the upper part. After the new spring bamboo shoots grow, choose 3~4 main branches with suitable angles and let them blossom.

2. Potting: Using the seedlings of old branches in the past is a good way to quickly cultivate bonsai. Because the branches of Lagerstroemia indica are soft, potted Lagerstroemia indica can be properly climbed and bound. Generally, when the spring shoots stop growing and the branches tend to be semi-lignified, they are coiled and drawn with thin brown ropes to make bonsai in various postures. 1. Strengthen the light. Lagerstroemia indica likes sunshine, so it must be placed in a sunny place outdoors during the growing season.

2. Water it in time. Keep the soil moist in spring and winter, and water it once every morning and evening in summer and autumn. In case of drought and high temperature, the watering frequency can be appropriately increased every day, and it can be watered with river water, well water, rainwater and tap water stored for 2 ~ 3 days.

Trim. The flowers of Lagerstroemia indica grow at the top of the spring shoots that germinated that year, with strong germination and irregular crown, which needs pruning.

Winter pruning: In order to ensure normal flowering and form large inflorescences, winter pruning is very important. If planted in the ground, cut off the branches of the current year at the height of the main branches, so that the robust branches can blossom in the next year; First, cut off all sprouting branches, diseased branches and overlapping branches. In order to beautify the shape, the top of the full terminal bud of other branches is cut short at ` 1 cm, generally leaving only about 5 cm.

Pruning after flowering: After flowering in summer, some residual flowers should be pruned to prevent them from bearing seeds, so as to reduce nutrient loss and promote the germination and flowering of new branches. Pruning in the growing period is not suitable for pruning or shortening the new branches sprouting in spring, otherwise it will easily lead to only long branches without flowering.

4. Fertilize. Generally, crape myrtle management is relatively extensive. Spraying fertilizer in early March, combined application of nitrogen, phosphorus and potassium: applying phosphorus and potassium once from late May to early June to strengthen branches and promote flowers; Apply flowering fertilizer at the end of July and the beginning of September. The fertilizer is cake fertilizer and water. powdery mildew

Lagerstroemia indica is an important target of 1 powdery mildew. After the disease, the leaves of Lagerstroemia indica often turn yellow and fall off, which directly affects the tree vigor and ornamental effect.

Gardening has a strong ability to prevent crape myrtle from sprouting branches, so for plants with serious diseases, all the branches of that year can be cut off and burned in winter to completely eliminate the source of the disease. If Lagerstroemia indica planted at home is found to be infected with powdery mildew, the diseased leaves should be removed in time and the potted flowers should be placed in a ventilated and light-transmitting place. In field cultivation, it is necessary to control planting density, strengthen daily management, pay attention to increasing the application of phosphorus and potassium fertilizer, control the application amount of nitrogen fertilizer, and improve the disease resistance of plants; At the same time, we should also pay attention to the selection of disease-resistant varieties.

When the condition of chemical control is serious, Pomei 3-4 stone sulfur mixture can be sprayed before germination in spring; Spraying 80% zineb wettable powder 500 times, or 70% thiophanate-methyl 1000 times, or 20% triadimefon EC 1500 times, or 50% carbendazim wettable powder 800 times for prevention and control.

brown spot

Brown spot disease often occurs in Lagerstroemia indica growing season. The occurrence of brown spot disease often leads to a large number of dead leaves and fallen leaves of plants. Affect viewing and flowering.

Early detection of horticultural control, timely removal of diseased branches and leaves, centralized incineration or deep burial, and reduction of pathogen sources. Strengthen cultivation management, plastic pruning, so that plants are ventilated and transparent. It is best to change the soil for family potted plants every year.

At the initial stage of chemical control, 500 times of 50% carbendazim wettable powder, 65% zineb wettable powder 1000 times or 800 times of 75% chlorothalonil wettable powder can be sprayed for control.

Coal stain

Sooty blotch invaded Lagerstroemia speciosa mainly after being harmed by Lagerstroemia speciosa and Lagerstroemia speciosa, that is, using the mucus secreted by them as nutrition, and inducing a large number of bacteria polluted by 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.

Horticultural prevention and control ① make trees ventilated and transparent through measures such as thinning seedlings and pruning; (2) timely control aphids, scale insects, whiteflies, etc. Because the secretion of these insects is the basis of the existence of pathogens in sooty blotch.

Lime-sulfur mixture is commonly used in chemical control, with Pomei 3 lime-sulfur mixture in winter and 0.3 lime-sulfur mixture in summer and autumn. It can also be controlled by phosphorus trichloride and litsea cubeba leaf juice.

Yellow thorn moth

Yellow thorn moth, with medium size and caterpillar larvae, is one of the main omnivorous leaf-eating pests of garden flowers.

Horticultural control combined with winter pruning can remove overwintering cocoons from branches, thus eliminating or reducing insect sources.

Physical control of Lagerstroemia indica in family pots and artificial removal of overwintering cocoons after defoliation can completely eliminate the insect source. In field production, black light can be set to trap and kill adults in the emergence stage.

For chemical control, it is best to use chemicals before the larvae spread, spraying 80% dichlorvos EC 1000 times, 50% phoxim EC 1000 times, or 2.5% deltamethrin EC 4000 times.