CATDOLL : CATDOLL: Biological control methods for red spider pests

1. Biological control methods of red spider pests

(1) Artificial control: scrape the bark and burn it in batches before the overwintering eggs hatch. After scraping the bark, apply whitewash (lime water) on the tree trunks to kill most of the overwintering eggs.

(2) Agricultural control: Based on the hatching pattern of red spider eggs and their habit of feeding on weeds after hatching, the soil should be turned over in early spring to remove ground weeds and keep the field free of weeds during the hatching period of the overwintering eggs, so that the red spiders will die because they cannot find food.

(3) Physical control can be achieved by applying a closed adhesive ring of about 1 cm wide on the trunk of the tree before the tree sprouts and the red spider mites are about to climb up the tree to cause damage (around late April). Apply non-toxic, non-drying insect glue and repeat the process every two months to prevent the red spider mites from moving up the tree to cause damage. The effectiveness can reach over 95%.

(4) Biological control There are many types of red spider mites in the field. According to investigations, the main types are Chinese lacewings, mite-eating ladybugs and predatory mites. Among them, the Chinese lacewings have a larger population and prey on the red spider mites. Protecting and increasing the number of natural enemies can enhance their control over the red spider population.

2. What are the characteristics of red spiders harming peach trees?

The red spider mites that are currently prevalent in various places are mainly the hawthorn spider mite (also known as: hawthorn red spider).

(1) Damage characteristics: The main damage is to the leaves. In the early stage of the damage, the leaves show many small chlorotic spots, which gradually expand into patches. When the damage is serious, the insects gather on the leaves to spin silk webs and lay eggs. The affected leaves first develop gray-yellow spots on both sides of the main vein near the petiole. In severe cases, the leaves wither and fall off.

(2) Occurrence pattern: 6 to 7 generations occur in a year. The fertilized female adults overwinter in the cracks of the bark and the soil at the base of the trunk. They can also overwinter in fallen leaves and dead grass. In spring, when the buds swell, they come out of hibernation and climb onto the tree. When the buds turn green, they move to the buds to cause damage. After the leaves unfold, they move to the leaves to feed. After more than ten days, they begin to eat on the leaves.

After the nymphs hatch, they gather on the underside of the leaves and suck the leaves.

Most of them die, and the new female insects have not yet laid eggs. This is the best time to use pesticides for prevention and control. Later, the occurrence becomes more and more serious, and the damage lasts until mid-to-late September.

(1) Prevention and control methods ① Combined with orchards in winter

manage

, clean up fallen leaves, scrape off bark, turn over the tree tray, and eliminate some overwintering female insects. ② Before germination, spray with 50-100 times of Solibar or 3-5 degrees of lime sulfur mixture. ③ During the growth period, when the overwintering female insects are in the peak period of hibernation or the first generation of eggs have finished hatching, spray 1500 times of 5% Nisolan emulsifiable concentrate. Later, you can choose 1500-2000 times of 20% suosijing water suspension, 2000 times of 20% saoejing wettable powder. If the insect population density is too high, you can spray 2500 times of 34% shamitiliguo.

3. I have an azalea plant, and the leaves are spotty, dry, and falling off. What's going on?

There are many reasons for the yellow leaves of azalea. Let's see which one is causing yours:

(1) Excessive watering and long-term over-humidification of the soil in the pot will cause lack of oxygen in the soil, causing some fibrous roots to rot, hindering normal breathing and absorption of water and nutrients, and causing the leaves to turn yellow and fall off. After being affected, the young leaves will first turn light yellow, and then the old leaves will gradually turn yellow. You should immediately control watering, stop fertilizing, and loosen the soil frequently to ensure good soil ventilation.

(2) Drought and dehydration. If you forget to water your flowers or water them only halfway (wet on top and dry on the bottom) for a long time, it will affect nutrient absorption and easily cause the leaves to become dull and lusterless, and the leaves to wilt and droop. First, the old leaves at the bottom will age, and then gradually turn yellow and fall off from the bottom to the top. At this time, you need to water them in small amounts and spray them with water to allow them to gradually recover before switching to normal watering.

(3) Long-term lack of fertilizer. If ammonia fertilizer is not applied or the pot and soil are not changed for a long time, the soil lacks nitrogen and other nutrients, resulting in weak branches and leaves, thin and yellow leaves. It is necessary to change the pot in time, replace it with new loose and fertile culture soil, and gradually apply thin and decomposed liquid fertilizer or compound flower fertilizer.

(4) Excessive fertilization. If too much fertilizer is applied, the new leaves will become thick and uneven, and the tips of old leaves will turn dry, brown and fall off. Stop fertilizing immediately, increase the amount of watering, so that the fertilizer flows out from the drainage holes at the bottom of the pot, or immediately turn the pot upside down, rinse the soil with water and then replant it.

(5) High temperatures. If flowers that prefer cool weather (such as cyclamen, fuchsia, and begonia) are placed in a hot place and exposed to strong sunlight in summer, it is very easy to cause the tips and edges of young leaves to dry out, or the leaves to turn yellow and fall off. They need to be moved to a well-ventilated, cool place in time.

(6) Excessive shading. If flowers that like sunlight are placed in the shade or in places with insufficient light for a long time, their branches and leaves will grow too long, their leaves will become thin and yellow, and they will not bloom or will bloom very rarely. Be sure to move the flower pot to a sunny place.

(7) The soil and water are alkaline. In most areas of the north, the soil and water contain a lot of salt and alkali. Planting flowers that prefer acidic soil, such as azalea, camellia, Michelia, gardenia, orchid, white orchid, osmanthus, etc., will cause the leaves to gradually turn yellow due to the lack of soluble iron and other elements that can be absorbed by them in the soil. When planting, acidic soil should be selected, and alum fertilizer should be applied frequently during the growth period.

(8) Tight and poor ventilation. If too much nitrogen fertilizer is applied, the branches and leaves will grow too luxuriantly, and if they are not pruned for a long time, the inner branches and leaves will not receive enough light, which can easily cause the leaves to turn yellow and fall off. Reasonable fertilization and increased pruning should be used to ensure ventilation and light transmission.

(9) Dry air. When the indoor air is too dry, some flowers that prefer a humid environment, such as spider plants and orchids, often have dry leaf tips or scorched leaf edges. You should take measures such as spraying water or covering with plastic film to increase the air humidity.

(10) Improper temperature. If the room temperature is too low in winter, flowers that prefer high temperatures are often susceptible to cold damage, which can cause the leaves to turn yellow, and in severe cases, the flowers may wither and die. If the room temperature is too high, the plant's transpiration is excessive, and the root water and nutrients are insufficient, which can also cause the leaves to turn yellow. Please pay attention to adjusting the room temperature in a timely manner.

(11) The soil is acidic. The red soil in the south is acidic, and magnesium and other elements are easily lost. Planting flowers and trees that are alkali-tolerant or prefer slightly volatile soil, such as oleander, boxwood, and winter jasmine, often causes the veins of old leaves to lose their green color and turn yellow. You can apply calcium magnesium phosphate fertilizer or spray magnesium sulfate solution.

(12) Pests and diseases. Leaf spot diseases caused by fungi and other pathogens can easily cause partial necrosis of leaves, with yellow spots or patches. In severe cases, the entire leaf turns yellow and falls off. When infected by mosaic virus, yellow-green patches appear on the leaves. When attacked by scale insects, red spiders, etc., the leaves can also turn partially yellow and wither, or even turn yellow and fall off. All of these should be sprayed with pesticides in a timely manner for prevention and control.

(13) Strong stimulation. When using pesticides with too high a concentration to control pests and diseases, or when being polluted by toxic gases in the atmosphere, or when watering with cold water suddenly when the temperature is high, it is easy to cause the tips or parts of the leaves to turn yellow and dry, or even the whole plant to die. Therefore, attention should be paid to the rational use of pesticides and efforts should be made to eliminate air pollution sources. Avoid watering flowers with cold water around noon in midsummer. Finally, it should be mentioned that the yellowing of potted flowers is sometimes caused by one reason, but it is often caused by multiple factors. A correct diagnosis should be made before the right medicine can be prescribed.

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