How to use fungicides to improve their effectiveness
How can fungicides be used to improve their effectiveness? Please explain the methods. To improve the effectiveness of fungicides, you can refer to the following methods: (1) Reasonably prepare the concentration: when spraying fungicides (including liquid formulations and wettable powders), the agent must be mixed with water or diluted to an appropriate concentration. Different fungicides have different use concentrations...
How can fungicides be used to improve their effectiveness? Please explain the methods
To improve the effectiveness of fungicides, you can refer to the following methods:
(1) Reasonably prepare the concentration: when spraying fungicides (including liquid formulations and wettable powders), the agent must be mixed with water or diluted to an appropriate concentration. Different fungicides have their own special requirements for use concentration, and when preparing the concentration, you must strictly follow the "instructions for use" and must not increase or decrease it at will. If the concentration is too high, it can very easily cause phytotoxicity, while if the concentration is too low, it will not achieve the effect of controlling the disease.
(2) Master the number of applications: the number of sprays of fungicides is mainly determined by the length of the residual effect period of the agent and meteorological conditions. Generally, spray once every 10-15 days, for a total of 2-3 sprays. In special circumstances, such as rain after application, a supplementary spray should be applied promptly.
(3) Improve application quality: the application quality of fungicides includes the amount applied and the quality of spraying. The amount applied should be appropriate; applying too much will, on the one hand, increase costs, and on the other hand, can very easily cause phytotoxicity. But applying too little will fail to achieve the purpose of application. The quality of application must be careful; when spraying, the droplets should be fine and dense and the spraying should be even, covering the stems and both sides of the leaves of the plants, and striving not to miss any area.
(4) Strictly prevent phytotoxicity: fungicides can cause phytotoxicity for many reasons. First, agents with generally stronger water solubility are prone to causing phytotoxicity. Second, different crops also have different sensitivities to agents. For example, Bordeaux mixture generally does not cause phytotoxicity, but it can also cause phytotoxicity in copper-sensitive crops. Legumes, potatoes, and cotton are sensitive to lime sulfur mixture, and the probability of phytotoxicity is relatively high. Furthermore, different growth and development stages of crops also react differently to agents; generally, the seedling stage and the booting and flowering stages are prone to phytotoxicity. In addition, phytotoxicity also has a certain relationship with meteorological conditions such as temperature and sunlight. Generally, applying the agent under conditions of high temperature and drought, strong sunlight, heavy fog, or high humidity can easily cause crop phytotoxicity.
(5) Choose the correct timing of spraying: generally speaking, spraying fungicides too late or too early will affect the control effect. Spraying too early not only causes waste, but also reduces the control effect. If spraying is too late, because a large amount of pathogens have already invaded the host or caused damage, then even if a systemic therapeutic agent is sprayed, the result will be "too little, too late" and "half the effort for twice the result." Therefore, when using fungicides, you should apply them in a timely manner according to the occurrence patterns of different crop diseases, forecast and prediction, and the specific situation of disease occurrence. Usually, the application time of fungicides should be before disease onset (protective application) or at the early stage of disease onset (preventive measures), which is best.
(6) Be cautious with mixing agents: many fungicides are alkaline pesticides, so they cannot be mixed with insecticides that easily decompose and lose effectiveness when encountering alkaline substances. For example, Bordeaux mixture and lime sulfur mixture are alkaline and cannot be mixed with 1605, dimethoate, dichlorvos, and others, otherwise it will cause "mutual ruin." There are also some fungicides such as carbendazim and Beauveria bassiana that cannot be mixed with fungicides such as Bordeaux mixture, lime sulfur mixture, and thiophanate, and likewise will cause the insecticidal (fungicidal) microorganisms to lose physiological activity and insecticidal (fungicidal) ability, thus becoming ineffective. In addition, some mixtures that produce chemical reactions and cause phytotoxicity also cannot be "randomly matched." Of course, not all fungicides cannot be mixed with other pesticides; a small number of fungicides can also have a synergistic effect after being mixed with pesticides. For example, when dimethoate is mixed with acidic fungicides such as zineb or wettable sulfur or colloidal sulfur, it will not only not affect the exertion of the pesticide effect, but will instead also improve the pesticide effect.
(7) Pay attention to avoiding resistance: the use of fungicides also involves the problem of crop disease resistance. Long-term use of a single agent (mainly systemic fungicides) will cause pathogens to develop resistance, and even repeated application will be of no help, or may even make matters worse. To avoid disease resistance, on the basis of scientifically selecting pesticides, effectively carry out alternating (rotational) use of different types of agents, and strictly prohibit the long-term single use of one pesticide.
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