According to the investigation and analysis, in the case of frequent combination of cold wave and drought, the improper use of herbicides in wheat fields is prone to freezing phytotoxicity.

cause

Reasons for drug selection In many areas, wheat fields have been used with high-osmolality isoproturon, phenylsulfonate, isoprolong, bensulfuron-isopropion, chlorosulfonate, isoproturon and other herbicides containing isoproturon. After applying these herbicides, it is easy to cause freezing damage in case of cold wave.

Frequent cold waves According to statistics, there have been 5 cold waves during the period from November 20, 2008 to January 20, 2009. Such frequent cold weather can easily lead to freezing damage in wheat fields using the above herbicides.

The large amount of drug used and the high concentration of drug solution were found in the townships (towns) such as Shujia, Hanliu, Gaoyou, Longjing, etc., and all the fields with serious freeze damage increased the dosage, and some fields were 50% isoproturon. The amount of mu is increased to more than 230 grams, and some are mixed with fenoxapropan. When the cold wave is frequent, the occurrence of frozen phytotoxicity in the increased amount of wheat field is unavoidable. According to another investigation, insufficient water supply and excessive concentration of liquid medicine are also one of the causes of freezing phytotoxicity.

Drought Winter drought in 2008 is also an important cause of freezing phytotoxicity. According to the survey, all the phytotoxics in the wheat field with small soil moisture and dry white surface are serious. In the same field, the frozen phytotoxicity occurred in the damp place, the upper part of the wheat seedlings did not freeze to death, and the tops of the wheat seedlings were all frozen to death. It shows that the humidity in the field has a cold-resisting effect on the wheat seedlings, which can prevent the occurrence of freezing phytotoxicity.

Tillage is extensively cultivated and relatively coarse, no-tillage wheat field, wheat seedlings are shallow, and there is no soil layer protection in the tillering section, and the freezing damage is serious.

The cold resistance of wheat with large seedlings and weak seedling age is relatively strong, and vice versa. The phytotoxicity of strong seedlings is lighter, and the weak phytotoxicity of weak seedlings and diseased seedlings is relatively heavy.

Soil factors are mainly found in sandy soils, and clay soils do not occur.

Precaution

First, determine the duration of medication based on weather forecasts. The current weather forecast has been relatively accurate, especially the application of satellite cloud maps, which can accurately predict the weather conditions in the next week. Just pay attention to the weather forecast to avoid bad weather medication.

Secondly, strictly control the dosage of isoproturon, do not arbitrarily increase the dosage, and use sufficient water.

Again, pay attention to the soil moisture when using the medicine to prevent the occurrence of freezing phytotoxicity. Do not use the drug in the case of soil drought. Soil drought also has an effect on the efficacy of isoproturon. If the wheat field is dry, you can moisturize it before using it.

Remedy

The wheat fields where frozen phytotoxicity occurs should be remedied according to the specific conditions. For the plots with a survival rate of 70% to 80%, the management of fertilizer and water should be strengthened to promote the growth of wheat seedlings. Fields with a survival rate of 30% to 40% in the tillering section, especially wheat with extensive land preparation and sandy land, are exposed to the soil surface, and the wheat seedlings cannot recover and can be considered for other crops.

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