Lemon tree leaves with a lot of black patches on the back?

Lemon tree. The black patches on the dorsal surface of the leaves may be caused by the fungus for lemon resin disease. Scrape off the diseased part of the trunk, apply 100 times of king copper, and 300-400 times of 70% tobuzin. It is recommended to apply fertilizer reasonably, strengthen management, and improve the disease resistance of fruit trees.

Lemon resin disease: lemon resin disease is also called gum disease, the disease harms the trunk, leaves, fruits, the main trunk of the victim, the bark is reddish-brown, sagging, the tissue is soft, secreting mucus with a foul smell, the leaves, young shoots and young fruits are damaged, the surface produces black-brown protruding dots, dense into a piece of sand, commonly known as "sand skin."

Disease, black spot disease, which occurs on the fruit is called pedicle rot, which is caused by fungi, and the plants of weak trees, dead trees and diseased and insect trees are seriously affected.

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Cultivation method of lemon tree:

Water is similar to the cultivation method of oranges, and lemon trees need more water when growing, so it is necessary to replenish water in time.

2.Light and temperature: lemon trees need more sunlight to grow, but they can not be exposed to strong light for a long time, the suitable temperature for their growth is 23 to 29, the temperature is too high to pay attention to shading, the temperature is lower than 0 degrees will cause lemon trees to be frosted.

3.Fertilization: It needs enough fertilizer to grow, apply more thin fertilizer during the growth period, apply less diligently, and apply it several times if the plant is not growing well.

Lemon trees love fertilizer, especially when flowering and fruiting, but also top dressing. During the growing season, the well-decomposed organic liquid fertilizer is fertilized once every month or so, and the potassium dihydrogen phosphate is fertilized once every 40 days or so.

In the spring, fertilization should be mainly farmhouse fertilizer, and at this time, it should be applied with organic fertilizer, which can promote the growth of flowers and leaves, and spray thin urea on the leaves after flowering.

solution, fertilizer in autumn is mainly based on fast-acting fertilizer.

4.Pruning and control: The main pests and diseases of lemon trees are spider mites.

Scale insects, aphids.

etc., for these you can use 80% dichlorvos.

Emulsifiable concentrate 1500 times liquid spray control. The pruning of lemon trees requires the pruning of dead branches, stubbed weak branches, and long branches that have no initial void effect.

Because lemon is fruitful, try not to use medicine If only the old leaves at the bottom are yellow, this is normal aging metabolism, and there is no need to do any treatment; If the young leaves are also yellow, or even fall off, consider that the water is rotten roots; If it is only a lack of green and yellow, it may be a lack of fertilizer, and it is best to use organic fertilizer.

Aphids. Whitefly:

Harm and occurrence: after the new shoots and new leaves of lemon are extracted, the aphids concentrate on the back of the leaves to suck juice, causing the new leaves to roll up and not grow normally, the common color of aphids is dark green and black, when the aphids are harmed, there are often ants and soot disease, the occurrence of whiteflies is also after the new shoots and new leaves are extracted, they like to suck juice on the back of the young leaves, and they are easy to fly, which will cause stunted development of leaves, and cause the outbreak of soot disease when a large number of occurrences.

The inner young leaves lay eggs, and the eggs are small white grains.

Prevention and control methods: Reasonable pruning, keep fruit trees ventilated and breathable, reasonable budding and retaining shoots, to avoid the occurrence of whiteflies and aphids. Reasonable selection of pesticides, in the occurrence of aphids, whiteflies can choose the following pesticides spraying: good winter 1000 times, 70% imidacloprid.

2000-2500 times, 2000 times for all souls, acetamida.

1000-1500 times, avermectin.

2000 times.

Leaf miner: Harm and occurrence: Leaf miner moth is an important pest of lemon seedlings, young trees and adult tree shoots, with larvae as the pest of new shoots and young leaves, diving into the young leaf epidermis to feed on mesophyll, forming a silvery-white curved tunnel, forming a black line in **, due to the meandering insect road, resulting in new leaf curling, hardening, leaf shedding, spring, summer, autumn shoots occur seriously, leaf damage will cause the occurrence of canker disease, the insect is also called a drawing worm, ghost painting.

Prevention and control methods: Reasonable control of shoot budding, unified shoot release, cut off the pest food chain.

When the new shoots out of 1-2cm, spray once every 7 days until the tips stop, the pesticides used are: cyfluthrin 3000-3500 times, Wanling 2000-2500 times, avermectin 2500-3000 times, 2000-2500 times of moth, control adults should be sprayed in the evening, and the larvae that dived into the leaves should be sprayed in the afternoon.

This is supposed to be a scale worm, a sap-sucking pest. Insecticides should be applied in a timely manner. Light and temperature Lemons are light-loving plants, but if the sun is too strong, they will have poor growth.

Generally, at noon, the plants need to be replaced with an annual average temperature of more than 15, the best growth temperature is 23 to 29, more than 35 stop growing, -2 is frost damage. Lemons generally do not need to be cooled down in summer, and they can enter the room before the frost falls and exit the room after Qingming, so they can safely overwinter. Watering and fertilizing Lemons need more water to grow and develop, but too much water is not easy to rot the roots.

There should still be ants. The small white dots should be budworms, and the other worms should be ladybugs. Budworms and ants have a symbiotic relationship, ladybugs eat buds is a food chain relationship, you pay attention to observe, ants will move buds, will protect buds from ladybug attacks.

It's a small ecological chain, and it's fun.

Are you sick or sick? The small white dots should be buds, and other small insects should be ladybugs. Bugs and ants are symbiotic.

Ladybugs eat buds in the food chain. Pay attention. Ants move the buds, protecting the buds from ladybugs.

It's a small organic chain and it's a lot of fun.

Hello Can you eat the situation that the lemon is black on the outside may be contaminated with dirt, dust and other substances, if these substances make the lemon black, then after washing the lemon and removing the blackening substance, it can be continued to eat. If the lemon is blackened, soft, juice and other deterioration due to microbial contamination, then such a lemon should not be eaten to avoid symptoms of physical discomfort after eating. 