What are the symptoms of phytotoxicity from commonly used pesticides?
Fungicides, acaricides, herbicides
●Mancozeb (non-complexed mancozeb)
Not suitable for use on edamame, lychee, or grapes during the young fruit stage, tobacco, cucurbit crops; use with caution on certain pear varieties - applying mancozeb when pears are small easily causes spots on the fruit surface. When the concentration used is too high, it easily causes phytotoxicity on jujube trees.
●Propiconazole
Using it at the seedling stage easily reduces the seedling rate, causes seedling stunting, inhibits growth, and burns young fruit; use it as much as possible in the middle and late stages of crop growth; crops such as cucurbits, grapes, strawberries, and tobacco are sensitive to it, so strictly control the dosage and use it after fruit set.
●Quintozene
When used in excess, quintozene easily causes phytotoxicity when it comes into contact with the young buds of crops.
●Chlorothalonil
At high concentrations, it easily causes phytotoxicity on pear, persimmon, peach, and plum trees. It also cannot be used within 20 days after apple petals fall.
●Hymexazol
It cannot be mixed with strongly acidic pesticides. A 100-fold solution may cause slight phytotoxicity on wheat, so attention should be paid when using it.
●Kasugamycin
It causes slight phytotoxicity on soybean and lotus root, so attention should be paid when using it near soybean and lotus root fields.
●Sulfur
Crops such as cucumber, beans, potato, peach, plum, pear, and grape are sensitive to this pesticide and prone to phytotoxicity. When using it, the concentration should be appropriately reduced or the number of applications reduced; in hot seasons, apply it in the morning and evening and avoid applying it at noon.
●Mineral oil emulsion
Spraying mineral oil emulsion at 150-fold plus 40% isocarbophos at 1200-1500-fold during the bud break stage and flowering stage causes phytotoxicity. After spraying mineral oil emulsion, wait 10-15 days before spraying lime sulfur mixture or Bordeaux mixture; within 1 week after spraying resin soap mixture, organophosphorus pesticides must not be used, and within 20 days lime sulfur mixture must not be sprayed.
●Kasugamycin-copper oxychloride
The young leaves of crops such as apple, grape, soybean, and lotus root are sensitive to this pesticide and will show slight curling and brown spots. When using it, pay attention to the concentration, and it is best to spray after 4 p.m.
●Bordeaux mixture
Chinese cabbage, peach, plum, and nai are sensitive to it during the growing period, and phytotoxicity easily occurs regardless of the formula; it can be used on apple, pear, and grape. When preventing and controlling citrus scab in spring, if the temperature exceeds 30°C and the buds have grown longer than "25px", spraying 0.8% equal-amount Bordeaux mixture will cause severe bud burn, so it should be changed to 0.5% double-amount Bordeaux mixture, which is safer; pear is sensitive to copper ions, so double-amount Bordeaux mixture should be used; grape is sensitive to lime, so half-lime Bordeaux mixture should be used. For example, spraying during the high-temperature period around noon in summer, on rainy days, in the morning when dew has not dried, and in strong wind can all easily cause phytotoxicity.
●Lime sulfur mixture
It easily causes phytotoxicity to the young and tender tissues of fruit trees such as grape, peach, pear, plum, mei, and apricot, so it should be used with caution, preferably sprayed during the leaf-fall season, and must never be used during the growing season or the flowering and fruiting period. It also has certain phytotoxicity to kiwifruit, grape, cucumber, and leguminous flowers.
●2,4-D butyl ester
It should not be used on dicotyledonous plants such as cotton, beans, vegetables, and rapeseed, or on large and wheat, rice seedlings before the 4-leaf stage and after jointing.
●Amitraz
Short-fruit-branch Golden Delicious apple is sensitive to this pesticide and has leaf-burn phytotoxicity.
●Propargite
Crop seedlings and young leaves of new shoots are sensitive to this pesticide under high temperature and high humidity conditions and are prone to phytotoxicity. To be safe for crops, for cucurbits and beans, cotton seedlings, etc. below 25 cm, the dilution factor of 73% emulsifiable concentrate should not be lower than 3000-fold, and for citrus new shoots and young leaves, etc., it should not be lower than 2000-fold.
●Azocyclotin
The suitable use concentration is 1500-2000-fold solution. When commonly used at low temperatures, it will cause relatively mild phytotoxicity to young leaves of spring shoots, and will also cause flower drop, leaf drop, fruit drop, etc. Using it on orange new shoots of 10-15 cm easily causes phytotoxicity.
Insecticides
●Malathion
Some varieties of tomato seedlings, cucurbits, cowpea, sorghum, cherry, pear, and apple are sensitive to this pesticide, so pay attention to the concentration when using it.
●Dimethoate, omethoate
Crops such as hops, Asteraceae plants, some varieties of sorghum, tobacco, jujube trees, peach, apricot, mei trees, fig, and citrus are sensitive to dimethoate emulsifiable concentrate diluted below 1500-fold. Excessive use on peanut will cause the leaves not to close at night, so pay attention to the use concentration before application.
●Fenitrothion
Cruciferous vegetables such as Chinese cabbage, radish, cauliflower, cabbage, green vegetables, and kale, as well as sorghum, are sensitive to it, so pay attention when using it.
●Phoxim
Cucumber, kidney bean, and watermelon are sensitive to this pesticide; spraying 50% emulsifiable concentrate at 500-fold causes phytotoxicity, and at 1000-fold it may also cause slight phytotoxicity; sugar beet is also relatively sensitive to phoxim, so when mixing and sealing seed, the dosage and sealing time should be appropriately reduced. Sorghum is sensitive and should not be sprayed; for corn, only granules can be used to control corn borer; at high temperatures, leafy vegetables are sensitive and easily suffer leaf burn.
●Triazophos
Crops such as sugarcane, water bamboo, and corn are prone to phytotoxicity.
●Chlorpyrifos
Chlorpyrifos is extremely sensitive to tobacco and lettuce and should be prohibited; it causes phytotoxicity to cucurbit seedlings, so it should be used after the cucurbit vines are longer than 1 m; in addition, some cherry varieties are also very sensitive to it.
●Methidathion
Spraying during the flowering stage should be avoided to prevent phytotoxicity. The appropriate time for use is before flowering, and the concentration should not be increased arbitrarily, otherwise it will cause brown leaf spots. In June-July, when the temperature exceeds 30°C, using 800-1000-fold makes young fruit extremely prone to phytotoxicity.
●Profenofos
At high concentrations, it has certain phytotoxicity to cotton and cucurbits and beans, and has phytotoxicity to alfalfa and sorghum; for cruciferous vegetables and walnut, avoid use during the crop flowering stage.
●Trichlorfon (dichlorvos)
Sorghum and beans are especially sensitive and should not be used; cucurbit seedlings, corn, and apple (varieties such as Shuguang and Marshal) are also prone to phytotoxicity from trichlorfon in the early stage.
●Fenobucarb
Within 10 days before and after applying pesticide in paddy fields, avoid using propanil to prevent phytotoxicity.
●Cartap
Do not apply pesticide during the flowering stage of rice or when crops are wet from rain or dew; seedlings of cruciferous vegetables are sensitive to this pesticide, so do not apply pesticide in summer when growth is weak under high temperatures.
●Diafenthiuron
Under high temperature and high humidity conditions, it easily causes phytotoxicity to seedlings. Under normal conditions, the dosage of 25% diafenthiuron emulsifiable concentrate should not exceed 50 ml/mu.
●Isoprocarb
Tuber crops are sensitive to this pesticide and should not be used. Within 10 days before and after application, propanil must not be used.
●Carbofuran (furadan)
When applying this pesticide in paddy fields, it cannot be used at the same time as herbicides such as propanil and chlorpropham, so as to prevent phytotoxicity (propanil should be applied 3-4 days before carbofuran application, or applied 1 month after this pesticide is applied).