May. 25, 2021
Since the 1960s, the public hazards of pesticides have gradually attracted great attention from all over the world, and they have begun to pay attention to the research and application of low-toxicity and low-residue pesticides, especially the research and application of biological control and biological pesticides. Biological control is a method that directly uses the interaction between biological substances and organisms in nature to control diseases, pests and weeds or improve the ecology. It includes the use of parasitic or predatory animals and germs to prevent and control pests and weeds. In addition to using microorganisms to prevent diseases, insects, and weeds, biological pesticides also include the direct extraction of various disease-preventing, insecticidal, and weed-killing active substances, microorganisms and their metabolites from animals and plants to prevent pests and weeds and regulate plant growth.
Biological pesticides mainly include three categories: plant-derived pesticides, animal-derived pesticides and microbial-derived pesticides. Since these active substances are substances that exist in nature, they are easily decomposed by sunlight, plants or soil microorganisms, and rarely accumulate in agricultural products and the environment. Therefore, it is recognized internationally as the most promising pesticide. It has the following 3 significant advantages:
(1) Strong selectivity. It only has an effect on target harmful organisms. It is safer for humans, livestock, beneficial organisms and crops, and will not cause public hazards after application.
(2) Compared with organic chemical pesticides, harmful organisms are less likely to develop resistance to them.
(3) There are wide sources of raw materials for production. However, biological pesticides also have their limitations. For example, some plant-derived pesticides have low activity, large amounts of pesticides, and some have weak knock-down power, slower effect, and some insect hormone pesticides have strict application time limits, and missed control. During the period, the control effect was very poor. The following will briefly introduce the plant-derived pesticides commonly used on fruit trees.
Plant-derived pesticides are pesticides made directly from the active substances in plants that can prevent diseases and kill insects. It includes the following types of active substances:
(1) Phytotoxins, such as nicotine, etc.;
(2) Plant-derived insect hormones, such as the insect precoction found in the Ageratum plant, have the function of anti-insect juvenile hormone;
(3) Antifeedant, such as azadirachtin can prevent insects from feeding;
(4) Attractants, such as clove oil can attract Bactrocera dorsalis;
(5) Repellent, such as citronella oil can repel mosquitoes;
(6) Sterilization agent;
(7) Synergists, such as sesame oil (vegetable), etc.;
(8) Phytodefensins, which are antibacterial substances of susceptible plants themselves;
(9) Different plants can degrade biomass, and certain secondary biomass produced by plants can inhibit the growth of nearby plants of the same or different species;
(10) Plant endogenous hormones, such as gibberellin, cytokinin, brassinolide and triacontanol. The most important ones are the following products.
1. 0.5% fruit holy lotion: a broad-spectrum, high-efficiency insecticide and acaricide compounded with a variety of alkaloids based on matrine and nicotine. It is moderately toxic and is the only plant-derived pesticide that can kill Scale insects can kill mites. The insecticidal mechanism is mainly contact killing, but also has a certain stomach toxicity and fumigation effect. Its mechanism of action is similar to matrine and nicotine. It has a very good control effect on shield scales, rust ticks and aphids such as blue spot scales, black spot scales and mulberry shield scales, and the effective period of rust ticks can reach more than 30 days. It can also control red wax scale, tortoise scale, horned wax scale, puffing scale, citrus mealybug, black spine whitefly, citrus red spider, lateral polyphagous tarsus mites, citrus leaf miner, small green leafhopper And cabbage worms and so on. It is safe to many beneficial organisms such as Lacewing, Japanese square head beetle, Coccinella septempunctata, Ladybug red spotted, Amblyseius nissi, Bombyx mori and other beneficial organisms. It is safer to more than 30 crops such as oranges, peaches, pears, tea, peppers and corn, and has slight phytotoxicity to plums, grapes and walnuts. Do not mix with other pesticides when using it.
2. Nicotine: the insecticidal active ingredient extracted from tobacco, also known as nicotine. Nicotine preparations are moderately toxic to humans and animals, have contact killing, stomach poisoning and fumigation effects, and have a certain oviogenous effect. Its insecticidal mechanism is to paralyze the nerves. The vapour of nicotine can invade the body from any part of the insect body and exert a poisonous effect. Because nicotine is volatile, its duration is shorter, but the salt of nicotine is more stable and its duration is longer. It can control aphids, thrips, leaf rollers, heartworms, leaf miners, cabbage caterpillars, planthoppers and leafhoppers in fruit trees, vegetables, tea and cotton. Its dosage forms include 40% nicotine sulfate and 10% nicotine emulsifiable concentrate, as well as tobacco powder and homemade tobacco lime liquor. 800-1 000 times of 40% nicotine sulfate can control aphids in citrus, peaches, pears and apples, pear worms, citrus leaf rollers, peach leaf rollers, citrus psyllids, citrus leaf miners, and oranges. Vicious leaf beetles, stink bugs, leafhoppers and thrips. Mixing in 0.3% soap or washing powder can increase the insecticidal effect. The preparation method of the tobacco lime liquor is: 0.5 kg of tobacco, 0.25 kg of quicklime, 30 kg of water, first soak the tobacco with 5 kg of boiling water (with a cover), rub the tobacco with your hands when the boiling water is not hot, and then remove the tobacco and put it in 5 Knead repeatedly in kilograms of water until there is no muddy water, remove the tobacco leaves, filter the water soaking the tobacco leaves, and then dissolve the quicklime with 5 kilograms of water to form a lime milk filter, and finally mix the tobacco water and lime milk together and add 15 kilograms of water spray. However, the tobacco water and lime milk should be applied immediately after being mixed, and cannot be mixed with other pesticides. Tobacco lime water 30 times liquid can prevent and control malignant leaf beetles.
3. Matrine: also known as oxymatrine, is a highly effective, low-toxic insecticide and acaricide. Its insecticidal spectrum is wider. It is an insecticidal active substance extracted from the plant Sophora flavescens. Its main insecticidal active substances are a variety of alkaloids such as matrine, oxymatrine, nitinoidine and sophocarpine. It has contact killing and stomach poisoning effects. The insecticidal mechanism is a nerve agent. After the insect (mites) comes into contact with the agent, the nerve is paralyzed, and the protein coagulates and blocks the air valve and suffocates to death. Its preparations are: 0.6% Qingyuanbao, 0.36% Baicao No. 1, 0.2% and 1% Aphid Mites Water Agent. 800-l 000 times of 0.6% Qingyuanbao liquid can prevent and control peach worm, pear psyllium and looper, etc.; 500-800 times of liquid can control citrus red spider, apple red spider and hawthorn red spider, etc.; 600 -800 times the liquid can control the tarsal mites; 1000-1 200 times the liquid can control citrus, peach, pear, apple and vegetable aphids. It can also control cabbage caterpillars, diamondback moths, armyworms, loopers, leafhoppers, whiteflies and planthoppers. It is safer to crops and ladybirds, Japanese square head beetles and large lacewings. Can not be mixed with alkaline pesticides.
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