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Relatively speaking, the grass weeds such as A. sinensis have higher tolerance to low temperature than wheat, and can grow slowly at low temperature. Before the winter, there was no field using herbicides or poorly used. The grasses in the field were often older when they were removed in the spring of February and the beginning of March, which would affect the elimination effect. In the early spring, for grasses with grasses that are about 4 years old, it is advisable to use some herbicides that can be used at low temperatures.
In the large-scale production of our province, the common herbicides used to control grass weeds in wheat field stems and leaves are isoproturon, thiazoloxacillin, acetylene ester and its compounding agent with oxazolin. Sulfachlor, methyl disulfuron and the like. Among them, isoproturon will reduce the anti-freezing ability of wheat seedlings. In the case of severe frosty weather (the minimum temperature is lower than 2 °C) about 1 week after application, the wheat seedlings are susceptible to freezing, causing "frozen phytotoxicity". Generally, do not use this medicine in low temperature season. . When the wheat seedlings are poorly grown due to stains, freezing, etc., they are on the oxazocilin and methyl disulfuron. The tolerance of herbicides such as acesulfame is decreased, and the growth of wheat seedlings is likely to be severely inhibited after application, which can cause serious death, and these herbicides should be avoided in the low temperature season. It is relatively safe to apply clodinafop and its compounding agent with oxazolin at low temperature, but it should also avoid application when the temperature is too low, otherwise it will not only affect the herbicidal effect, but also may cause phytotoxicity. In some places in our province last year, there was a large area of ​​wheat seedlings in the early spring after the application of domestic acetylene ester preparations encountered low temperature, yellowing of the leaves and so on.
Common herbicides for controlling broadleaf weeds in wheat field stems and leaves are bensulfuron-methyl, bensulfuron-methyl, flufenoxyacetic acid, bentazone, oxadiazon, and 2, 4-chloro. These herbicides have relatively good safety to wheat seedlings, but other drugs such as oxadiazon and other drugs use slow killing speed in low temperature period, and the herbicidal effect will be affected to varying degrees. Herbicide such as 2 methyl 4 chlorine is low temperature. It is also prone to phytotoxicity during use.
Tip: In our province, there are two grassy peaks in the wheat field weeds under normal conditions. The first weed peak appears after wheat sowing and before wintering. The grass weeds in the field mainly emerge during this period, and some Broad-leaved weeds emerged; the second peak of weeding appeared after the temperature rose in the spring, mainly broad-leaved weeds, and some grasses weeds. For these fields, production advocates the use of drugs to control grass weeds before winter (before mid-December), and to remove grass weeds. Relatively speaking, there are many suitable pesticides for controlling broad-leaved weeds in wheat fields, and weeding is relatively simple. The requirements for grass age are not strict, and broad-leaved weeds also have grass peaks in spring. Therefore, it is not suitable for production at low temperatures. During the period, the stem and leaf treatment agent is used to control the broadleaf weeds. It is best to use the herbs in the spring field after the broadleaf weeds are basically out, and the grass and grass are removed together.
Late weeds in wheat field occurred later, and the amount of weeds was higher after the temperature rose in spring. The weeds and broadleaf weeds in grasses were larger, and grass weeds and broadleaf weeds occurred. Due to the small grass age, it is usually used in the spring to control the grass damage.
Due to the long-term use of a few herbicides such as benzooxacillin, isoproturon, and bensulfuron-methyl, in recent years, the province has a small miscellaneous miscellaneous miscellaneous such as sedge, hard grass, bluegrass, Japanese maiden, and pork mites. The population of grass increased, and the herbicidal effect of herbicides such as fenoxapropion, isoproturon and bensulfuron was decreased. Especially when these weeds were older, the resistance was stronger and the herbicidal effect was worse. Fields with more occurrence of these weeds should be removed by treatment when the grass age is small. In the early spring, the wheat field of grasses with weeds reaching the four-leaf stage is suitable for cold-warming heads, early application of acetylene ester and its compounding agent with oxazolin.
How to choose herbicides in low temperature wheat fields
In production, the herbicide should be used as much as possible at a daily average temperature of 10 ° C or higher and a minimum temperature of 5 ° C or higher to avoid application of the herbicide in the low temperature season. Usually, in Jiangsu and other places, January is the coldest month of the year. During this period, weeds and wheat all enter the wintering period, and the growth is extremely slow. It is not suitable to apply herbicides. When the herbicide is applied at a low temperature, the herbicidal effect is often affected, and the phytotoxicity is more likely to occur.
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