In order to improve the yield and quality of fruit, reduce the number of spraying of pesticides , and increase the growth period of trees, the following key periods are mastered in the prevention and control of pests and diseases .

First, the buds are obviously inflated, that is, the light rod medicine. In this period, a high concentration of fungicide and insecticide should be sprayed on the tree and under the tree. Mainly control a variety of wintering bacteria and pests.

The second is to spray a higher concentration of fungicides and insecticides during the bud period, mainly to control flower rot.

The third is to spray fungicides and insecticides one week after falling flowers, mainly to prevent a variety of diseases and aphids, red spiders, pear hibiscus and so on.

Fourth, after picking the fruit, spray a higher concentration of fungicides and insecticides before the leaves, mainly to eliminate the wintering pests and diseases, and reduce the damage in the second year.

Remedy in case of phytotoxicity in fruit trees

First, the cause of phytotoxicity

At present, there are many varieties of pesticides used in production, and their properties are different. The main causes of phytotoxicity are pharmacy, fruit trees, application methods and environmental conditions.

1. Formulation and characteristics of the drug : The physical and chemical properties of the drug have the greatest relationship with the fruit tree. Under normal circumstances, inorganic agents with strong water solubility and small molecular weight are most likely to cause phytotoxicity, such as copper and sulfur preparations. The water-soluble agent is safer, and the microbial agent is safe for fruit trees. The degree of phytotoxicity caused by different dosage forms of pesticides is also different. Oil agents and emulsifiers are more likely to cause phytotoxicity, followed by wettable powders, and milk powder and granules are relatively safe.

2. Sensitivity of fruit trees to pesticides: stone fruit trees such as peach, apricot and plum are sensitive to Bordeaux mixture during the growing season, and it is easy to produce phytotoxicity regardless of the ratio. When the amount of Bordeaux liquid heavy lime is lower than the multiple amount, pears, apples (especially golden crown varieties), hawthorn, persimmon trees, etc. are susceptible to phytotoxicity. When the amount of Bordeaux liquid heavy lime is higher than the equivalent amount, the grape is susceptible to phytotoxicity. When 45% dasenium is used, pears and apple trees are highly susceptible to phytotoxicity when the dilution ratio of the liquid is less than 1000 times. Among them, pear varieties are more harmful to pears, and snow pears are second; apples are heavier with Jinguan and Jonagold, and Fuji, Qinguan and US 8 are lighter.

3. Method of administration of the drug : the concentration of the drug is too high, the dissolution of the drug is not good, the mixing is unreasonable, the spraying period is improper, etc., and the phytotoxicity is easy to occur. Due to the resistance of pests and diseases, the concentration of the drug used is getting higher and higher, or the mismatch concentration is too high, which may also cause phytotoxicity. If the spray is too large, it will cause local phytotoxicity when the powder is not evenly distributed. Some pesticides cannot be mixed, and not only will they fail after mixing, but some will also cause phytotoxicity.

4. Environmental conditions: The environmental conditions have the greatest impact on temperature, humidity and light. High temperature and strong light are prone to phytotoxicity, because high temperature can enhance the chemical activity and metabolism of the drug, which is beneficial to the infiltration of the drug into the plant tissue and easily cause phytotoxicity. When the humidity is too high, some of the agents are also likely to cause phytotoxicity. Spraying herbicides in windy weather is prone to “fluctuation”.

Second, the symptoms of phytotoxicity

According to the speed of the occurrence of phytotoxicity and the obvious degree of symptoms, it is generally three kinds of acute phytotoxicity, chronic phytotoxicity and residual phytotoxicity.

1. Acute phytotoxicity: refers to the symptoms of phytotoxicity soon after application (hours or days). It is characterized by rapid onset, obvious symptoms and visible to the naked eye. Generally, there are symptoms such as spot burning, perforation or chlorosis, yellowing, deformity, thickening, curling or even withering and falling off on the leaves; symptoms such as spots, deformities, smallness, and fruit drop appear on the fruit; Symptoms such as falling flowers, discoloration, decay, and falling buds; plant growth retardation, dwarfing, or even death of the whole plant.

2. Chronic phytotoxicity: refers to the phytotoxicity that does not appear symptoms quickly after administration. It is characterized by slowness, some symptoms are not obvious, and it is difficult to judge in a short time. More often, the growth is slow, dysplasia, delayed flowering, increased fruit drop, reduced yield, and poor quality.

3. Residual phytotoxicity: When the fruit tree is sprayed, more than half of the pesticides fall on the ground, and the pharmacy is basically left in the soil when the toxic soil or soil is applied. Some of these pesticides decompose slowly, and accumulate to a certain extent in the soil, which will affect the growth of fruit trees. Its symptoms are similar to chronic phytotoxicity.

Third, remedial measures

Due to the phytotoxicity caused by improper use of pesticides, remedial measures should be taken actively according to the specific causes of the phytotoxicity and the degree of damage, so as to minimize the degree of phytotoxicity.

1. Irrigation and water spraying: If it is found early, the infected plants should be sprayed with water immediately to dilute and wash off the pesticides adhering to the foliage and branches to reduce the pesticide content in the tree. The earlier and more timely this measure is, the better the effect will be.

2. Spray neutralization: If the leaves are whitened by phytotoxicity, the granular spray of 50% sodium humate can be used to form 3000 times solution; or 50% humate can be formulated into 5000 times solution for irrigation. After 3 to 5 days, the leaves will gradually turn green. If the pesticide is caused by misuse or excessive use of pesticides such as organophosphorus, pyrethroids, and aminomethyl esters, spray 0.5% to 1% of lime water, washing powder, soapy water, etc., especially spraying alkali such as ammonium bicarbonate. The chemical fertilizer solution is better, not only has detoxification effect, but also can play the role of root dressing and promote growth and development.

3. Timely topdressing: After the fruit tree suffers from phytotoxicity, growth is blocked, the growth is weak, and it is necessary to topdress in time to promote the recovery of the affected fruit trees as soon as possible.

4. Cultivated loose soil: After the fruit trees are damaged, it is necessary to timely cultivate the loose soil on the garden, and artificially cultivate the roots, and appropriately increase the application of phosphorus and potassium fertilizer to improve soil permeability, promote root development and enhance the recovery of the fruit itself. ability.

5. Appropriate amount of pruning: After the fruit tree is harmed by the medicinal plant, it should be trimmed in time and in a proper amount, the dead branches should be cut off, and the dead leaves should be removed to prevent the spread of the dead part or the infection of the pathogen and cause disease.

More pesticide knowledge , please pay attention to China Pesticide Network

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