How to prune persimmon? Analysis of the causes of leaf curling in persimmon seedlings
Persimmons contain very rich nutritional components; for example, persimmons actually contain pectin, vitamin C, carotene, iodine, and so on. Basically everyone can eat persimmons, especially people with constipation or high blood pressure, who are very suited to eating persimmons. Now more and more people are starting to grow persimmons, but many problems also appear during the persimmon growing period, such as: how should persimmons be pruned? What is going on with leaf curling in persimmon seedlings?
How to prune persimmon
1. Mainly, when the main trunk has almost reached the desired height, pinch off all the tender buds at its top, so it will no longer grow taller. Of course, for useless side branches and side branches that have already reached a suitable height, the top tender buds should also be pinched off.
2. Persimmons are pruned by single-head and double-head training methods. That is, keep 1-2 heads per plant, and when the remaining branches grow to 10 cm long, break them all off. For early-maturing varieties (except self-topping ones), keep 3-4 fruit trusses and then pinch off the top; for mid- and late-maturing varieties, keep 6-10 fruit trusses and then pinch off the top according to need. In this way they will no longer grow, and the nutrients will be retained for flowering and fruiting.
3. Pruning and pinching of persimmons should be determined according to variety, planting density, and whether they are grown on trellises or without trellises. If growing determinate varieties without trellises, when each plant grows to 30 cm tall, keep 2 to 3 branches; after the third flower cluster appears on the main branch, leave 2 leaves above and pinch off the tip; after 1 flower cluster on the side branch, leave 2 leaves above and pinch off the tip.
4. If growing indeterminate varieties with trellis support, generally two methods are used: single-stem training and double-stem training. Single-stem training means keeping only the main branch and removing all side branches; double-stem training means keeping one main branch and one side branch.
What is going on with leaf curling in persimmon seedlings
1. Viral disease. Viral disease causes leaf curling. There are commonly 6 types: mosaic type, fern-leaf type, streak type, giant-bud type, leaf-curling type, and yellow-top type. Infected plants are stunted, with curled, clustered leaves; in severe cases, only leaf veins remain and there is no leaf mesophyll. Viral disease spreads through virus-transmitting insects (such as aphids and whiteflies) and sap contact, and hot, dry weather favors its occurrence. Control measures: 1. Select virus-resistant varieties. 2. Implement crop rotation to reduce the initial infection source. 3. When disease occurs, spray a 1000-fold potassium permanganate aqueous solution, which can control diseases such as soft rot and also supplement manganese and potassium. To control virus-transmitting insects such as aphids, choose 10% imidacloprid 2000-fold solution or 20% solution or 20% Confidor 4000-fold solution.
2. Hormone-type phytotoxicity such as 2.4—D. The symptoms of 2.4—D phytotoxicity are bending of leaves or growing points, new leaves unable to unfold normally, distorted and deformed leaf margins, raised stems and vines, and lighter color. The phytotoxicity symptoms of other hormones such as chlormequat and 4-CPA are lighter than those of 2,4—D. Control measures: the hormone concentration used for mid-maturing varieties should be 20 PPM, and for early-maturing varieties 15 PPM; when the temperature is high, the concentration should be lower. When using it, be careful to prevent it from touching tender leaves or growing points, and it must never be sprayed. After phytotoxicity occurs, some growth-promoting medicinal fertilizers can be applied, such as Aopuer and natural brassinolide. This phytotoxicity occurs over a large area and has no disease center, which is different from other diseases.
3. Physiological leaf curling. Before and after tomato harvest, the leaves of the first fruit cluster curl slightly, or the leaves of the whole plant curl into a tube shape and become brittle. The cause is that due to high temperature and drought, tomato stomata close, causing leaf curling. Control measures: carry out drought-resistance training from planting until fruit set. After fruit set, water and fertilize in a timely manner, and use shade netting coverage. On sunny days cover during the day and uncover at night; on cloudy days do not cover.
4. Damage by the tea yellow mite. Its main symptoms are leaves becoming narrow, stiff and upright, shrunken or distorted and deformed, and finally bald tips. It is difficult to identify with the naked eye. Control agents can include 15% pyridaben 3000-fold solution, 1.8% abamectin 3000-fold solution, or 73% propargite 2000-fold solution, etc.
5. Wind and cold invasion. If ventilation in the greenhouse is too sudden, the exchange between cold outdoor air and warm indoor air is strong, and it is very easy to cause tomato leaves near the vents to curl. Under normal circumstances, as long as ventilation is increased gradually to harden the seedlings, this problem will not occur.
6. Nutrient deficiency. Phosphorus deficiency appears as purple-red leaf undersides, small brown spots on the leaves, upward curling of lower leaves, yellowing of old leaves, and black-brown death of leaf tips. Generally, low temperatures at the seedling stage affect phosphorus uptake, and soil that is too acidic or compacted is also prone to phosphorus deficiency; this can be solved by applying phosphate fertilizer to the soil or spraying 0.3% monopotassium phosphate on the leaves. Magnesium deficiency appears during the swelling stage of the first flower cluster, when the lower old leaves of the plant lose green, yellowing appears between the veins, and then spreads upward, forming yellow mottled leaves. In severe cases, the leaves become stiff or curl upward at the edges, and necrotic spots or brown bands appear between the veins. This can be solved by applying a complete-element fertilizer or spraying magnesium sulfate 50-100-fold solution on the leaves.
How do persimmons grow deformed
If fruits become deformed, they must have been affected by some stimulus that caused the deformation. Sometimes pest and disease damage can also cause fruit deformation, but deformation caused by pests and diseases is not as obvious as in the picture. These persimmons look so “deformed”, which is indeed uncommon. Under normal circumstances, multiple causes can lead to fruit variation. For example, there are now too many places applying pesticides; during pesticide application on melons and fruits, the influence of wind transmission or bird transmission may affect the flowering and fruiting of fruit trees, thus making them abnormal. In addition, during the process of treating fruit trees for pests and diseases, the diffusion and volatilization of pesticides can also lead to this phenomenon.
How to control pests and diseases on persimmons
1. Clean the orchard in winter to reduce the overwintering pest and disease base. Combined with winter pruning, thoroughly clean diseased fruit, diseased calyxes, dead branches, and fallen leaves to remove overwintering pest and disease sources.
2. Before sprouting in spring, spray once with 5-degree lime sulfur mixture or 95% petroleum oil emulsion 150-fold solution.
3. To control major pests such as persimmon mealybug, persimmon calyx borer, and giant mealybug, on the basis of the above control measures, scrape off old bark and apply 5-10-fold omethoate in a ring, with remarkable effect. In addition, try to use biological pesticides such as Bacillus thuringiensis or diflubenzuron to control leaf-eating pests.
In the article above, the editor also introduced for everyone some problems encountered during the persimmon growing period and their solutions. In fact, in rural areas the persimmon tree is also a relatively common tree, and the nutritional value of persimmons is very high, so people can also eat some persimmons in appropriate amounts.