How to correctly select and apply pesticides for flowers
How to correctly select pesticides for application to flowers.
When using pesticides on flowers, we must follow the principle of matching the remedy to the disease, so as to avoid phytotoxicity.
Dimethoate and omethoate can cause obvious phytotoxicity to ornamental plants of the Rosaceae family such as Japanese apricot, cherry blossom, flowering peach, elm-leaved spirea, and Chaenomeles speciosa. When dimethoate is sprayed from June to October, it often causes petals to wither and curl and leaves, inflorescences, and small branches to drop off.
Dichlorvos causes obvious phytotoxicity to Japanese apricot, elm-leaved spirea, and others, so under normal circumstances other insecticides should be used instead. Dichlorvos also causes varying degrees of phytotoxicity to rhododendrons, Japanese pagoda trees, and others.
Trichlorfon causes phytotoxicity to cherry blossom, Japanese apricot, and others.
When fenitrothion is used to kill insects in the high-temperature season, it causes serious phytotoxicity to pomegranate and also fairly severe phytotoxicity to cruciferous flowers. When using chlordimeform, avoid using it on rose of Sharon and dahlia.
To prevent pesticides from causing phytotoxicity, first, switch to other highly effective and harmless pesticides; second, reduce the concentration used as much as possible; third, do not spray under conditions of high temperature and high humidity.
1. Follow the rules for the safe use of pesticides
In flower cultivation, the prohibited pesticides include: methamidophos, methyl parathion, parathion, monocrotophos, phosphamidon, benzene hexachloride (BHC), DDT, toxaphene, dibromochloropropane, chlordimeform, ethylene dibromide, nitrofen, aldrin, dieldrin, mercury preparations, arsenic, lead, dithianon, fluoroacetamide, glucoflur, tetramine, sodium fluoroacetate, silatrane, and others.
2. Adopt safety protection measures
Applicators must carry out the prescribed safety protection measures to prevent poisoning. Leftover pesticide liquid and the rinse water from application equipment should be collected and safely disposed of, and must not be poured out at will. Empty containers must not be reused; they should be properly collected and disposed of, marked and stored safely, or centrally disposed of.
Discarded and expired pesticides must be handled in accordance with relevant national regulations and must not be casually thrown away, so as to avoid causing phytotoxicity to flowers or poisoning people and livestock.
3. Scientific cultivation to reduce pesticide use
Through cultivation measures, some pests and diseases can be eliminated and conditions unfavorable to the occurrence of pests and diseases can be created. At the same time, the ability of flowers to resist pests and diseases should be improved, such as by cleaning the garden and field, disposing of diseased plant residues, reducing the sources of pests and diseases, rational close planting, increasing ventilation and light transmission in greenhouses or plastic tunnels, promptly draining waterlogged areas, lowering field humidity, and scientifically formulated fertilization, so that flowers grow robustly and their ability to resist pests and diseases is improved.
4. Strengthen physical control
To avoid the development of pesticide resistance in pests and diseases, physical control should be chosen as much as possible. For example, yellow sticky insect boards can be hung up to trap and kill aphids and leafminers, and silver-gray film can be laid or hung in the field to repel aphids while also increasing light intensity. Taking advantage of the phototaxis of many insects active at night, methods such as light traps and bait traps can be used to eliminate pests, and insect-proof nets can also be used to reduce the probability of pest occurrence.
5. Carry out biological control
Biological control is also a measure for reducing pesticide use and avoiding the development of pesticide resistance in flowers.
First, use bacteria, fungi, viruses, or their metabolites that can cause disease and death in pests to control insect pests. Usually, disease-causing microorganisms of pests are artificially cultured and then made into powders for spraying, so as to kill the pests. For example, among bacterial preparations, Bacillus thuringiensis is extremely toxic to the larvae of Lepidoptera insects and has an excellent killing effect. Test results show that using fungi to kill insects is also very effective. For example, Beauveria bassiana parasitizing in the bodies of insects of Lepidoptera, Coleoptera, and others as well as mites can very effectively kill pests. The fungus Aschersonia causes extremely high pathogenicity in whiteflies. Research and application of using viruses to control insects have likewise made great progress, and the one used more often is nuclear polyhedrosis virus. Insect viruses have very strong specificity and strong pathogenicity, and their effects are lasting. In practical application, virus preparations are often made into aqueous agents, platinum agents, wettable powders, and others, and sprayed or applied into the soil to control insect pests.
Second, use the antagonistic effects among microorganisms and the metabolites of certain microorganisms to inhibit the growth and development of flower-pathogenic microorganisms, or even cause their death. Such substances are antibiotics. For example, the flower bacterial fertilizer code-named "5406" can control certain fungal diseases, bacterial diseases, and mosaic virus diseases of flowers.
Third, use the biological chain, food chain relationships, or parasitic relationships in nature to control pests. For example, use Encarsia formosa to control cotton aphids; use dragonflies, mantises, and others to prey on pests, and so on.
Plant immunity and the effective components in plant juices can also be used to control pests and diseases. For example, a dilute aqueous solution of garlic juice can control quite a few kinds of pathogenic fungi. Using plant physiologically active substances to control pests and diseases is currently a key research focus at home and abroad and is one of the methods with very good prospects. In addition, using bioengineering methods to control pests and diseases is also a new development trend, such as transgenic technology and others.
6. Match the remedy to the disease
For the control of flower pests and diseases, one must first understand the causes of occurrence, infection cycle, and ecological environment of the pests and diseases, and grasp the patterns of time, location, and scope of damage, before one can match the remedy to the disease.
Medication for non-infectious diseases (1) Sunscald damage: the middle part of the upper leaves of the plant looks as if burned by fire and appears light red, but the damaged parts show no moldy growth after rain. (2) Waterlogging damage can cause root rot and easy lodging. Frost damage: the leaf margins of seedlings first dry and scorch and curl, the damaged parts show no moldy growth after rain, and the stem bark splits. (3) Drought damage: the middle and upper leaves become wrinkled and droop. (4) Pollution damage: the leaves are dirty and easy to wipe clean. Fertilizer damage: young buds wilt and growth stagnates. (5) Nutrient deficiency damage: the plant grows slowly, the leaves are deformed and lusterless, and the leaves fall off from the bottom upward along the stem.
The above diseases belong to physiological diseases, and pesticides are of no use against them; they can only be solved by changing the ecological conditions, while at the same time supplementing with foliar fertilization.
2. Medication for infectious diseases (1) Fungal diseases: the leaves often have white powder, rust powder, sooty mold, mold layers, and blotches, and after rain the backs of the diseased spots often have moldy growth of fungal spores. For this disease, zineb and shuangyiling can be selected for routine control. At the peak of the disease, kecun powders, amobam, Tuzet, carbendazim, and kewenling can be used alternately, with dilution concentrations as follows: 500 to 800 times liquid for powders, and 800 to 1000 times liquid for emulsifiable concentrates or aqueous agents. (2) Bacterial diseases mainly harm rhizomes, corms, bulbs, tubers, and others. The damaged parts become powdery under dry conditions and water-soaked under high-temperature conditions. For this disease, 30 grams of agricultural streptomycin of 200,000 units can be added to 50 kg of water for spraying or watering. (3) Viral diseases appear as mosaic, necrotic spots, ring spots, leaf yellowing, deformity, cluster branching, upper leaf drop, and others. You can select 20 tablets each of oxytetracycline and virazole, dissolve them in 12 kg of water for spraying or watering, or use 2.5 kg of banlangen (Isatis root) boiled and then sprayed or watered.