The main symptoms of drug damage:
(1) point type. This phytotoxicity is mainly manifested in the leaves of crops, and sometimes it also occurs in the stems or peels. Common drug spots are brown spots, yellow spots and reticular spots. If butachlor is not sprayed properly in the early stage of rice seedling field, irregular brown spots will appear on rice leaves; Spraying jinggangmycin on the leaves of watermelon seedlings will cause small macula; Bordeaux solution can produce brown reticular spots of cork tissue on the surface of apple.
(2) yellow type. This phytotoxicity is manifested in the stems and leaves of plants, especially the leaves turn yellow, mainly because pesticides hinder the normal photosynthesis of chlorophyll. According to the severity of phytotoxicity, it can be divided into two types: Gongxian leaf hair and whole plant yellowing. Yellow leaves can be divided into yellow heart leaves and yellow base leaves. For example, fenpropathrin has yellow buds on watermelon; When chlorotoluron slightly injured wheat, the basal leaves turned yellow; When wheat is harmed by simazine, it can turn yellow from the tip edge, and then spread to the whole leaf, resulting in yellowing and death of the leaf or the whole plant. Diuron can cause yellowing and chlorosis of cotton seedling leaves.
(3) Abnormal type. This phytotoxicity can show symptoms in the stems, leaves and roots of crops, and the common malformations include leaf curl, clumping, root swelling, deformed ears, deformed fruits and so on. For example, when wheat seed buds are damaged by dimethyl carbon tetrachloride, the base of bud sheath and young roots swell; When cotton seedlings are damaged by herbicide diethyl ether, the growing point will shrink and the cotton leaves will be deformed like pursed leaves. When tomato was damaged by 2,4-D, it showed typical hollow fruit and deformed fruit.
(4) withered type. This kind of phytotoxicity is often manifested as whole plant symptoms, mostly caused by improper use of herbicides. For example, the phytotoxicity of glyphosate in rice seedling stage can cause plants to wither and die; Watermelon seedlings were damaged by chlorotoluron, and the young leaves turned yellow, the leaves withered and the plants shrank, causing the seedlings to die.
(5) Growth stagnation type. This phytotoxicity inhibits the normal growth of crops and slows down the growth of plants. For example, the improper use of chlorotoluron in rapeseed shows slow growth and reduced branches, which has a certain impact on yield; Paclobutrazol (PP333) was used in late rice fields. If not transplanted, it will slow down the growth of rice seedlings and affect the normal heading.
(6) Infertility type. This phytotoxicity is caused by improper use of drugs during the reproductive growth period of crops. For example, before and after meiosis of rice pollen mother cells, the use of rice foot green can cause male sterility, resulting in empty green panicles and reduced production.
(7) shedding type. This kind of phytotoxicity is mostly manifested in fruit trees and some dicotyledonous plants. Fruit drop and other symptoms. If the peach tree is damaged by copper preparation, it will cause deciduous leaves; The use of methamidophos during the flowering of pear trees will lead to flowering; Improper use of ethephon in hawthorn will cause fruit drop and defoliation; Bordeaux mixture will cause apples to fall out of flowers and fruits; Sulfur mixture can also cause apples to fall off.
(8) poor fruit type. This phytotoxicity is mainly manifested in the fruits of plants, which makes the fruits smaller in size, abnormal in surface, poor in quality, and affects the edible value. For example, watermelon is harmed by ethephon, and the pulp of watermelon is dark red and has an odor; Tomato is harmed by copper preparation, which can make the cells on the surface of fruit die and form brown fruit phenomenon. Grapes are hurt by the panacea for increasing production, which is characterized by loose ears and shrinking fruits.
What's the difference between drug damage and disease?
The difference between spot phytotoxicity and physiological diseases lies in that the distribution of the former on plants is often irregular, and the whole field also shows the difference between light and heavy; The latter usually occurs universally, and the plant parts with symptoms are consistent. Spotted phytotoxicity is also different from fungal diseases, the former has great changes in the size and shape of spots; The latter has the lesion center and the spot shape is consistent.
Compared with the yellowing caused by lack of nutrition, the former often develops from yellow leaves to dead leaves, and yellowing occurs quickly in sunny days. There are many rainy days due to lack of nutrients, and yellowing is slow. Yellowing is often related to soil fertility and fertilization level, which is consistent throughout the field. Compared with the yellowing caused by virus, the yellow leaves of the latter are often broken green, and the diseased strain shows systemic symptoms, and the diseased strain is mixed with the healthy strain.
The difference between the deformity caused by drug damage and that caused by virus disease is that the former is universal and shows local symptoms in plants; The latter is often sporadic, showing systemic symptoms, often mixed with symptoms such as broken green, bright pulse and wrinkled leaves.
Compared with the symptoms of Fusarium wilt caused by infectious diseases, the former has no heart disease, and most of them occur slowly, first yellowing, then dead plants, and no rootstock transportation tissue browning; The latter is mostly caused by root canal blockage. When the sunshine is sufficient and the evaporation is large, it wilts first, then loses its green color and dies. The root canal is often brown.
Compared with physiological diseases and element deficiency, the slow growth caused by phytotoxicity is often accompanied by drug spots or other phytotoxicity symptoms, the latter is characterized by poor root growth, while the element deficiency is characterized by yellow or dark green leaves.
The main difference between drug-induced bad fruit and disease-induced bad fruit is that the former has only symptoms and no symptoms, and besides bad fruit, it also shows other drug-induced symptoms; The latter has symptoms, most of which have symptoms, while some asymptomatic viral diseases often show systemic symptoms or no other symptoms.
(1) Insist on testing before applying. Before the large-scale popularization of pesticide varieties, it is necessary to carry out experiments in a small area to screen the scope of application, prevention targets, prevention period, dosage and application methods of drugs, so as to be aware of them.
(2) Strictly master the use technology of pesticides. First of all, we should choose the right medicine and prescribe the right medicine; Secondly, it is necessary to register the dosage or density of pesticides, master the appropriate application period, adopt appropriate application methods, and pay attention to the application quality.
(3) Pay special attention to the measures to avoid injury after taking the medicine. First of all, it is necessary to thoroughly clean the sprayer, especially the sprayer that has been applied with herbicides. If other chemicals are sprayed, they must be thoroughly cleaned; For example, if the equipment spraying 2,4-butyl herbicide is not thoroughly cleaned, it will cause phytotoxicity to dicotyledonous crops. The correct cleaning method is: for the plastic bucket sprayer, soak it in 5% alkali solution for several hours and rinse it repeatedly with clear water; The iron drum sprayer was soaked in 1% ferrous sulfate solution 10 kg for 2 hours, and then washed with clear water for more than 2 times. In addition, the spray nozzle, spray blade and switch of spray equipment should also be carefully cleaned.
Secondly, it is necessary to properly handle the remaining liquid medicine in the sprayer, that is, after the application is completed, the remaining liquid medicine should not be dumped anywhere to avoid phytotoxicity.
Remedial measures to be taken after drug injury;
Check the growth and development of crops regularly within one week after application, especially in fields with herbicides and plant growth regulators, and do a good job of field head inspection.
First aid measures to reduce drug injuries are as follows:
Fertilization remediation. Increasing fertilizer can reduce the degree of phytotoxicity caused by symptoms such as leaf drug spot, leaf edge scorching and plant yellowing. If wheat seedlings are damaged by chlorotoluron, human feces can be used for topdressing, and urea and potassium dihydrogen phosphate can be used for topdressing outside the roots.
(2) Drainage and irrigation remedy. Proper irrigation and drainage can also reduce the damage degree of some herbicides.
(3) hormone remedy. For herbicides and plant growth regulators, such as 2,4-butyl ester, alachlor, herbicides, herbicides, ethephon and plastics, spraying gibberellin after phytotoxicity can reduce phytotoxicity. If dimethyl carbon tetrachloride is misused in watermelon mu, spraying gibberellin 20-30PPm can reduce the degree of phytotoxicity. (Reporter anonymous)