pesticide damage refers to the phenomenon that the normal growth and physiological function of protected plants are destroyed due to incorrect use of pesticides, thus reducing the yield or quality. sometimes the tree can repair itself, but most of the damage is irreversible, and even can directly take the life of the orange tree.
in the summer of citrus management, anthrax, canker, lipid spot macula, red spider, rust tick and other diseases and insect pests are high. in order to cope with the first enemy of citrus growth, fruit growers should also pay attention to avoiding the occurrence of pesticide damage while using medicines.
generally speaking, citrus pesticide damage can be divided into acute pesticide damage and chronic pesticide damage.
1. acute pesticide damage: symptoms of pesticide damage appear within hours to days of spraying, such as spots, deformities, yellowing and wilting of leaves or fruits, rolled leaves, deciduous fruits and so on.
2. chronic pesticide damage: it takes a long time for symptoms to show, such as photosynthesis weakened, flower bud formation and fruit ripening delayed, small, malformed, flavor and color deterioration, etc.
according to the causes, citrus pesticide damage can be divided into inferior pesticide pesticide damage, drift pesticide damage, over-concentration pesticide damage, mixed pesticide damage, ignoring phenophase pesticide damage and so on.
1. pesticide damage
there are 3,800 formally registered pesticide production enterprises in china, and some ineligible workshops are also involved. the pesticides with low quality and low safety factor are easy to cause problems.
when purchasing pesticides, we should listen to the opinions of professionals, purchase regular pesticides from regular channels, clarify their use characteristics, select different pesticides for different prevention and control objects, and avoid misuse or reuse.
2. pesticide damage caused by drift
herbicides are easily sprayed, fumigated, leached and other reasons that lead to unexpected tree acceptance, which is very easy to lead to citrus damage.
3. pesticide damage in excess concentration
pesticides have strict application concentration. pesticide hazards caused by excessive use of pesticides are common. the main causes are wrong calculation and unknown rational multiple.
pesticide damage of emulsifiable oil
novice need to pay attention to the superposition of dosage forms: too many emulsifiers and microemulsions are compounded at one time, and too much solvent concentration in them may dissolve the fruit cortex and lead to pesticide damage. not only the main ingredients of pesticides can lead to pesticide damage, but also the additives in pesticides can lead to pesticide damage.
4. mixed pesticide harm
some pesticides can produce synergistic effect, reduce the number of medication, and achieve the goal of both disease and pest treatment. but if they are not familiar with the characteristics of pesticides, they will often be harmful if they are mixed randomly.
in order to pursue windfall profits, some businessmen spread "prescriptions" to fruit growers indiscriminately, with 2-3 kinds at a minimum and 4-5 kinds of pesticides mixed, together with their own lack of understanding of their pharmacological properties, which often resulted in pesticide harm.
therefore, when mixing pesticides, we should be familiar with the characteristics of pesticides and pay attention to the formulation and mixing sequence.
5. ignoring phenological phenological damage
in high temperature and drought weather, the water evaporates quickly, the medicinal liquid dries instantly, the medicinal concentration increases, and the fruit tree absorbs the medicinal liquid quickly, the physiological function metabolism is strong, but the resistance is relatively low, therefore, the medicinal damage is easy to occur.
spraying pesticides immediately after continuous heavy rains and sunny days, when the temperature is too high, and spraying pesticides at flowering stage, young leaves and young fruit stage are also easy to cause pesticide damage.
therefore, try to avoid wind, rain or hot sun and other climatic conditions, medication at high temperature should pay attention to appropriate concentration reduction. spraying should try to avoid the flowering and young fruit stages of crops, even at this time medication should also be appropriate to reduce the concentration of medication.
the occurrence of pesticide damage is mostly due to poor technology. with high technical level, strong awareness of prevention and careful organization, the possibility of pesticide damage is small.
1. sprinkler rinse
if spraying causes pesticide damage, the plant should be washed with clean water immediately to reduce the absorption of pesticides, repeated washing 3-4 times, as far as possible to wash out the plant surface of the pesticide.
2. topdressing of quick-acting fertilizer
spraying 0.3% urea and 0.2% potassium dihydrogen phosphate solution on the leaves every 5-7 days for 2-3 times can promote plant growth, improve their resistance to pesticide damage, and significantly reduce the losses caused by pesticide damage. if the leaf surface has produced the symptom of pesticide spot, leaf edge blight or plant coking, it can be topdressed and cultivated, and urea 5-6 kg per mu, to promote plant growth and reduce the degree of pesticide damage.
3. strengthening management
cut the damaged fruit trees to remove the dead branches and leaves. at the same time, the middle tillage should be strengthened to loosen the soil at a depth of 10-15 cm, so as to improve the permeability of the soil, promote the development of root system and enhance the ability of root system to absorb water and fertilizer.
4. neutralization and mitigation
under the guidance of pharmacological technicians, heterosexual neutralization was performed after washing.
(1) acidic pesticides can be neutralized by alkaline pesticides, or sprayed with some quicklime or plant ash, or sprayed with 1% bleaching powder liquid on the leaves.
(2) injuries caused by misuse or excessive use of organophosphorus, pyrethroid and carbamate pesticides can be sprayed with 0.5-1% lime aqueous solution or laundry powder or soap water of the same concentration, especially ammonium bicarbonate alkaline fertilizer solution.
(3) for the pesticide damage caused by regulators and herbicides that inhibit and interfere with crop growth, it can be sprayed with 2 000 times of brassinolide and 1 500 times of aminosulfonate.