Prevention of common phytotoxicity of cotton herbicides
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1. Cotton suffers from the symptoms of different herbicides
1.12,4-D butyl ester phytotoxicity
Cotton is most sensitive to 2,4-D-butyl ester. After the damage, the cotton leaves become smaller and narrower, showing a "chicken claw" shape. When the damage is serious, the fruit branches cannot extend normally, and the growth and development of flowers and buds are affected.
1.2 Fluorine poison
Trifluralin mainly controls cotton weeds and some broad-leaved weeds in cotton fields. When used in excess, the root growth and development of cotton is affected. After the damage, the main root of the cotton grows to form a tumor, the xylem becomes brittle and easy to fold, and the secondary roots are sparse. When the damage is serious, the dead seedlings are caused in the cotton seedling stage.
L.3 Paraquat phytotoxicity
Paraquat is a herbicide herbicide. It will show signs of damage on the day after the cotton spray. At the beginning, the leaves appear to be burnt and watery, and white spots appear later. When severe, the stems and leaves are all scorched.
1.4 Glyphosate phytotoxicity
After the cotton is harmed by glyphosate, the symptoms develop slowly, and the symptoms are usually manifested after 7 days. The main performance is that the initial cotton leaves are mildly wilting from top to bottom, the growth is slow, and the plants become dwarf, similar to the symptoms of blight. In severe cases, the roots gradually rot and the whole plant of cotton dies.
2. Causes of cotton herbicide phytotoxicity
2.1 spray equipment mixed
When spraying in cotton fields, the equipment used was sprayed with a herbicide containing 2,4-D-butyl ester to cause phytotoxicity. Cotton is very sensitive to 2,4-D-butyl ester. The equipment sprayed with this herbicide is washed repeatedly with washing powder and alkaline water, or used in cotton fields after being placed for a long time, which will still cause phytotoxicity to cotton.
2.2 Drift when spraying
In the vicinity of cotton fields, especially the upper wind, spraying herbicides containing 2,4-D-butyl ester and metformin, often containing 2,4-D butyl ester and methyl tetrachloride. The herbicide is often caused by the drift of the liquid.
2.3 The dosage is too large
When the cotton field is closed with 48% trifluralin emulsifiable concentrate, the dosage per acre should not exceed l50 ml, and the dosage is too large to cause phytotoxicity. Or the spray is not uniform, causing the concentration of the local liquid to be too high, and phytotoxicity may also occur.
2.4 improper operation when spraying
When using herbicides such as paraquat and glyphosate to control weeds in cotton, there is no protective cover on the nozzle, or careless when spraying, spraying the liquid onto the cotton to cause phytotoxicity.
3. Prevention and remedial measures
3.1 preventive measures
3.1.1 cotton field spraying equipment should be dedicated
When spraying in cotton fields or in neighboring areas, use sprayers, measuring cups, etc. that have been sprayed with 2.4-D butyl ester.
3.1.2 Selection of suitable herbicide varieties
It is forbidden to use herbicides containing 2'4-D-butyl ester and metformin in the cotton field to prevent the liquid from drifting.
3.1.3 The dosage should be accurate
For the cotton field soil treated with trifluralin, the suitable dosage of 48% trifluralin emulsifiable concentrate per acre is 100-125 ml. Always spray evenly to prevent heavy or leaking spray.
3.1.4 pay attention to strengthen protection
When using herbicides such as paraquat and glyphosate to control weeds in cotton, choose a windless weather, and install a protective cover on the nozzle. When spraying, lower the nozzle to avoid spraying the liquid onto the cotton.