The interaction between pesticide and fertilizer
Mix insecticide and miticide with fertilizer
Numerous production practices prove that many chlorinated hydrocarbons, organophosphates and carbamates pesticides can influence the plant growth and mineral nutrition. By using disulfoton on crop, it can reduce the absorption of manganese and increase the absorption of zinc; phorate can reduce the nitrogen content in the cotton plant body; after chlordimeform is sprayed on cotton, the concentration of calcium, magnesium, phosphorus and potassium in the cotton stalk will increase. By studying the migmatization of different nitrogenous fertilizer and nematicide on cotton, it can be seen that nematicide can obviously promote the growth of cotton, increase the output and improve the content of nitrogen and potassium in cotton leaves; the effect of aldicarb is higher than oxamyl; compared with the single use of nematicide and single use of nitrogenous fertilizer, by mixing nematicide with nitrogenous fertilizer (nitramine, ammonium sulfate and urea), the plant height, total cotton bolls in single plant, plant dry weight as well as the nitrogen and phosphorous content in the leaves will obviously increase. Experiments that carried out on rice show that carbofuran and phorate can increase the absorption of nitrogen, besides, carbofuran has stronger auxo-action on the absorption of nitrogen than phorate. The mixture of nitrogenous fertilizer and insecticide will have synergistic effect. By studying the interaction between superphosphate and moncrotophos on the sorghum absorption of phosphorus, it can be seen that when the insecticide concentration is low, superphosphate and moncrotophos will have antagonism on the absorption of phosphorus; when the moncrotophos concentration is high, they will have synergistic effect.
The influence of fertilizer on insecticide
By mixing nitrogenous fertilizer, phosphatic fertilizer and potash fertilizer with insecticide (such as abamectin insecticide), it may improve the surface activity of some pesticides, increase the permeability and adhesive force as well as improve the insecticidal activity. Some microelements may react with different insecticides, thus it may increase or reduce the insecticidal activity. Some fertilizers can be used as the insecticide and fungicide, for example, Russians use ammonium nitrate as the nematicide, which can not only control the soil nematodes, but also can reduce the environment pollution caused by the use of insecticides. The improvement of plant nutrition will also enhace its resistance to insect attack, while young organizations or the mature meristem or the plant parts that grow slowly will also be easy to attack by pests, therefore, the use of nitrogenous fertilizer will have positive effect on the controlling of insect attack. However, by largely using the potash fertilizer, it can reduce the insect attack. Sugar, amino acid and amide that exist in the plant body are the forage stimulants of most of the piercing-sucking insects, but the change of mineral nutrition in the plant body will also influence the change of these substances. By applying fertilizer, it can influence the insect resistance of plant by adjusting the accumulation of these low molecular organic compounds. The deposition of silicon in the plant epidermal cells is also a kind of mechanical obstacle for the mouthparts of piercing-sucking insects and especially for the mandibles of chewing insects. In some districts that are lack of silicon, by mixing the silicon with insecticide, the effects of insecticide will be improved. By reasonably mixing the insecticide with fertilizer, it can improve the penetration, absorption and conduction of insecticide pesticide in the plant body and insect body, improve insect resistance of plants, enhance the control efficiency as well as reduce the dosage of insecticide.
Mix fungicide with fertilizer
Fungicide will also have certain influence on the mineral nutrition of plant. By using Captan, thiram, quintozene, dexon and mancozeb on corn, they can reduce the absorption of manganese and increase the absorption of zinc. Besides, the plant fresh weight will also increase. By spraying carbendazim, thiophanate methyl, zineb and thiram on the peanut leaf surface, the nitrogen content in the blade will increase, among which thiophanate methyl and carbendazim will have biggest influence on the increasing of nitrogen content; besides, by using thiophanate methyl, carbendazim, high concentration of zineb and thiram, the phosphorus and potassium content in the blade will also increase.
The influence of fertilizer and plant nutrition on fungicide
By applying fertilizer, the plant disease resistance will either increase or reduce, thus it will influence the disease prevention effect of fungicide. In 1988, Jam-riska and other people mixed fungicide with nitrogenous fertilizer and found that the mixture has certain synergistic effect. Some German patents reported that by spraying 80 percents of mancozeb (4.50kg/hm2) and metalaxyl zineb (4.50kg/hm2) on tomatoes and mixing them with urea ammonium nitrate solution, the control effect on phytophthora can reach 80.3 percents and the infect will be only 15 percents if it rains 10mm 5 days later; however, if the pesticide is not mixed with urea ammonium nitrate solution, the control effect will only be 58.5 percents and the infection rate can reach up to 31.7 percents. It can be seen that fertilizer has obvious synergism on the pesticide and it is also considered that this kind of synergism is generated as urea ammonium nitrate solution reduces the leaching loss of fungicide on the plant surface. By improving the nutritional status with fertilizer (such as applying urea), it can also promote the crop absorption of systemic fungicide. For example, in the wheat production, by spraying the mixture of propiconazole and urea on wheat, the absorption of propiconazole can be improved as urea can improve the activity of blade as well as the photosynthetic rate can improve after using propiconazole and urea. By applying nitrogen, the susceptibility of plant will increase. Mascagn studied the effects of nitrogenous fertilizer and fungicide (mancozeb and triadimefon) on winter wheat and reported that by increasing the nitrogenous fertilizer, the wheat leaf rust will become more serious as the nitrogen application can reduce the disease prevention effect of fungicide. At this time, the dosage of fungicide should be increased so as to reduce the plant disease. The increasing of potassium nutrition will improve the disease resistance of host plant. Researchers have proved that potash fertilizer is a supplement in the application of fungicide on preventing rice disease. Calcium and other microelements, such as copper, have been used as the fungicide for a long time. For example, the effective constituents of Bordeaux mixture are calcium and copper.