Why do farmers prevent wheat from being sprayed with three preventions?

One spray and three preventions of wheat have been carried out for many years.
Especially in April this year, there was a lot of rain and wheat stripe rust was seriously harmful.
From top to bottom, an atmosphere of co-management was formed.
After hearing this, farmers were ecstatic and actively reported.
The affected area and the timely receipt of medicines have made exciting news
.
Up to now, the first spray and three prevention of wheat in Shangluo City have basically ended, the incidence of wheat stripe rust has been effectively controlled, and the wheat is growing well and a bumper harvest is expected
.
However, some small episodes occurred during the same spraying of pesticides, and some farmers stood by the ground not allowing pesticides to be sprayed
.
The main reason is that the wheat is in the flowering period and spraying pesticides will affect the pollination rate.
Is this true? According to the opinions of relevant experts, the application of pesticides during the flowering period of wheat will indeed affect the normal pollination of wheat, which may seriously affect the yield, but it is not impossible to spray
.
First, the flowering time of wheat is in the morning every day, so it is not possible to spray in the morning
.
Because you can't spray when there is dew, you can only spray in the afternoon
.
Second, the flowering period of wheat is very short.
Generally, the middle part of the wheat ear begins to flower on the first day, the upper part of the second day, and the lower part of the third day.
During the flowering period, yellow pollen can be seen.
If the whole ear becomes The white flower means that the flower has already bloomed, and the medicine can be sprayed in the morning
.
Wheat flowering period (with yellow flowers) Third, the application time of the three-prevention wheat spray is generally from the heading stage to the filling stage.
After the milk maturity stage, the effect is greatly reduced.
At the same time, the safety period of pesticide use is restricted.
If the spraying is too late, Will increase the risk of pesticide residues
.
Generally, pesticide residues should be reduced to a minimum level more than 15 days before wheat harvest
.
Wheat flowering period (the blooming period basically ends, there is no yellow flowers) Fourth, spraying can be used from the wheat heading period to the stage before flowering
.
The specific application time is determined according to the control base of local wheat stripe rust, powdery mildew, aphids and other pests.
Once the control indicators are reached, they should be prevented in advance to avoid greater harm
.
Under normal circumstances, from wheat heading to flowering period, once there is rainfall or after watering, the field humidity increases, and the probability of occurrence of wheat powdery mildew and wheat stripe rust is greatly increased.
Therefore, prevention and control of wheat powdery mildew and wheat stripe rust are required
.
The specifics are based on the results of on-site surveys by agricultural technicians
.
During the application period, a Chinese bee farmer stopped the wheat one-spray three-prevention team, claiming: spraying pesticides will cause the death of bees.
What is going on? As far as I know, the medicines used in Shangluo City include cyhalothrin, hexaconazole and potassium dihydrogen phosphate
.
Potassium dihydrogen phosphate mainly supplements the symptoms of lack of phosphorus and potassium fertilizer in the middle and late stages of wheat.
It can promote thick stalks, increase the number of flowering and pollination, increase the rate of seed setting, prevent wheat white ears, prevent lodging, prevent dry and hot wind, and mature early for 2 to 3 days.
, And the yellowing is good, reducing the chance of uneven blue and yellow
.
Fungicides such as wheat white ear hexaconazole and triadimefon are mainly used to prevent, treat and control diseases such as wheat powdery mildew and wheat stripe rust to avoid the increase of leaf disease spots and affect photosynthetic efficiency
.
In particular, the upper three leaves are functional leaves, which are also the main leaves that affect wheat yield.
If there are diseased spots, problems such as lower seed setting rate and lower thousand-grain weight will occur
.
Cyfluthrin and cypermethrin are pyrethroid insecticides, which have low toxicity and high efficiency.
They can have significant effects on wheat aphids, wheat midge, armyworm, etc.
, but are highly toxic to bees and fish.
If the bees come into contact with these pesticides during the honey collection period, all the bees in the hive will die, which will cause a big problem
.
Bees can fly to an altitude of 1000 meters, or they can fly straight for 2 to 3 kilometers at one time, and the farthest can fly to 14 kilometers away.
The normal distance for collecting honey is 1 kilometers
.
During the flowering period of wheat, it happens to be the flowering season of nectar plants such as Sophora japonica.
There are more food sources and the activity of bees is unusually frequent, but they usually move within one kilometer
.
Therefore, before the first spraying of the three preventions of wheat, it is necessary to be aware of the local bee breeding situation.
Do not use pyrethroid pesticides on wheat plots within 1 km away, but spray fungicides and micro-fertilizers.
And other pesticides and fertilizers
.
After patiently communicating with the farmers, the farmers knew that the three-prevention spray was for the sake of the farmers, it was for food safety, not for a show.
They knew the relevant formulations and methods of use of the pesticides, and they also knew that the pesticides and pesticides were sprayed this time.
The chemical fertilizers were carried out in full accordance with the relevant instructions and practical experience.
They all understood what we did, and effectively ensured that the coverage rate of the second application reached 100%, the total effective rate reached more than 95%, and the yield could be increased by 10%.
Above
.