How to avoid pesticide damage to flowers? These prevention methods you need to master
Although using pesticides can prevent and control flower pests and diseases, improper use can very easily cause pesticide damage to flowers. Pesticide damage can generally be divided into acute pesticide damage and chronic pesticide damage. The main symptoms are uniform spots appearing on the leaf surface, leaf edges curling and scorching, slow plant growth, and in severe cases even death. Therefore, the concentration and dosage of pesticides must be strictly controlled. If it is found that using the standard dosage and concentration of pesticide cannot achieve the expected effect, the pesticide variety should be changed. Pesticides must not be mixed at will, so as to avoid causing pesticide damage.
1. Random mixing of pesticides: When flower diseases and insect pests occur at the same time, people usually mix insecticides and fungicides, using two or three agents, and some even add foliar fertilizer. If the properties of several pesticides are the same and their pH values are close, no chemical reaction will occur, and there will be little effect on pesticide efficacy; otherwise, it will affect the performance of the pesticide efficacy and also cause pesticide damage. For example, Bordeaux mixture is a suspension made from copper sulfate, quicklime and water. It can prevent and control many fungal diseases. Its liquid is alkaline and cannot be mixed with commonly used pesticides, nor with lime sulfur mixture or rosin agents, otherwise it will reduce pesticide efficacy and cause pesticide damage. Therefore, when mixing pesticides, you must first understand their pharmacological characteristics. Those that can be mixed should be mixed, and those that cannot be mixed must be used separately.
2. Inappropriate spraying time and method: The spraying cycle is too short. In different periods of pest and disease occurrence, the length of the pesticide spraying cycle differs. Generally, it is once every half month in the initial stage and once a week at the peak. In fact, many pests are difficult to kill and pathogens are difficult to eradicate, so some flower growers use pesticides frequently, some once every 3 days, and some even once a day. As a result, the pests were not killed and the diseases were not eradicated, but pesticide damage appeared in the flower seedlings. In this situation, the spraying cycle must be strictly controlled, otherwise pesticide damage is even harder to cure than pests and diseases. During prevention and control, attention should be paid to alternating the use of pesticides to prevent pests and pathogens from developing resistance, which causes frequent application and ultimately leads to pesticide damage. Some flower growers, when spraying pesticides, do not spray the pesticide onto the key parts, and sometimes linger too long on a certain part, causing a large amount of pesticide solution to remain on the leaf surface and resulting in pesticide damage to flowers. This phenomenon is especially obvious on old leaves and large leaves.
3. Non-standard pesticide preparation procedures: There are many dosage forms of chemical agents, including wettable powders, emulsions, tablets, granules, solutions, etc. Some of these dosage forms can dissolve directly, while others cannot dissolve completely. Undissolved particles suspended in the solution can easily clog the nozzle during spraying. Even if smaller particles are sprayed out from the nozzle, they remain on the leaf surface, causing localized pesticide damage to the plant. Therefore, when preparing pesticides, attention must be paid to strictly following the procedures: first dissolve pesticides of different dosage forms in a small container, then transfer them into a large container, and after they are completely dissolved or evenly melted, transfer them into the sprayer.
4. Sprayers are not cleaned and have other residues: In actual operation, flower growers often use certain sprayers as general-purpose pesticide tools. Sometimes, after using one type of pesticide, they fill another type of pesticide without cleaning it. As a result, the residue of the original pesticide causes pesticide damage to flowers. In particular, residues of pesticides such as herbicides are even more harmful to flowers.
5. Flower allergies. Practice has shown that some flowers are allergic to a specific pesticide. For example, cockscomb and Chinese rose are quite sensitive to dichlorvos, and chrysanthemum is sensitive to dimethoate emulsifiable concentrate diluted below 1500 times. Pesticide damage still occurs even when the concentration is not high and the operation is very standard. There are currently no rules to follow for flower allergies, and they can only be explored through practice. This requires that when applying pesticides that are not very familiar, pesticide damage tests should be done first, so as to reduce the occurrence of pesticide damage.