Summer is the peak season of various pests and diseases, and the high temperature also causes inconvenience to application of the pesticides, and phytotoxicity is also prone to occur. So how can we not only avoid phytotoxicity, but also improve the efficacy of the application in summer?
1: Determine the application time according to the temperature and its trend
For plant, insect or pathogen, 20 to 30 degree, especially 25 degree, is the most suitable activity temperature. At this time, it is more effective to fight with them around this temparature and it’s also safer for the crops.
In the summer hot season, the time of application should be before 10:00 am and after 4:00 pm.
Spring and autumn cool season, should choose from 10:00 am to 2:00 pm.
In the greenhouse in winter and spring, it is better to apply in the morning of sunny days.
2: Determine the application time according to the humidity and its trend
After the liquid sprayed from the nozzle is deposited on the plants, it needs to form a uniform film to cover the surface of the target to the greatest extent and then it could work. This process can be affected by many factors, among which the influence of air humidity bigger.
If the air humidity is low, the moisture in the drops will quickly evaporate into the air, even before it can spread on the surface of the plant; if the air humidity is too high, the droplets deposited on the surface of the plant will easily condense into bigger droplets. It is deposited under the influence of gravity and is likely to cause phytotoxicity.
Therefore, the time of application needs to follow two principles:
A: The air humidity is slightly dry;
B: After the application, the liquid can form a dry film on the surface of the plants before sunset.
3: Three common illusions during the application
3.1 Determine the quantity of the pesticides only by the dilution rate
Most people are accustomed to calculating the quantity of the pesticides by this way. But it’s not very reliable. The reason why it is necessary to control and calculate the quantity of the pesticides applied is because it is necessary to calculate the dosage of the pesticides in unit area to ensure good efficacy and safety to the plants and environment.
Attention: After adding the pesticides in each barrel of water according to the dilution rate, it is necessary to calculate the details like how many barrels of water per acre will be needed and the speed of spraying.
At present, due to the shortage of labor force, many people tend to add pesticides into tank by higher rate and spray quickly. This is obviously wrong. The most reasonable measure is to choose a good spraying machine, adding exact quantity of the pesticides and spraying uniformly.
3.2 The closer the nozzle is to the target, the better the efficacy will be.
After the liquid is ejected from the nozzle, it collides with the air and breaks into smaller droplets. That is to say, the farther away from the nozzle, the smaller the droplet is within a certain distance. Small droplets are easier to deposit and spread on the plants. Therefore, letting the nozzle close to the plant will not bring better efficacy.
In general, the nozzle of the knapsack electric sprayer should be kept at a distance of 30 to 50 cm from the plants, and, for motorized sprayer, it should be kept at a distance of about 1m. According to the performance of the sprayer and its nozzle, swinging the nozzle allows the mist to fall on the plant to gain better efficiency.
3.3 The smaller the droplet, the better the efficacy
The best size of the droplets is related to its distribution, deposition and spreading on the surface of the crop. If the droplets are too small, they will float in the air and it will be difficult to deposit on the plants. This will definitely cause waste. If the droplets are too large, more liquid will drop on the ground, which is also a waste.
Therefore, it is necessary to select suitable spray equipment and nozzles according to the control targets and the environment. For example, fogger machine can be selected for controlling diseases and tiny pests such as whitefly and mites in greenhouse. While when you are in the open field, you have to choose a device can produce bigger droplets.