The most effective pesticide of late blight, how it is caused, and the difference between late blight and early blight

The pesticides that can effectively control late blight include ethyl phosphorus manganese zinc wettable powder pyrimidine nucleoside antibiotics and chlorothalonil. Late blight disease can occur when the field temperature is 10 ℃-24 ℃ and the relative humidity is more than 75%, or when the humidity is too high, the dew is too heavy, and it is foggy in the morning and evening. Late blight and early blight have different properties, characteristics and colors.

I. the most effective pesticide for the prevention and control of late blight

1. Generally, in the early stage of the disease, diseased leaves, diseased fruits and seriously diseased branches need to be removed in time, and then according to the situation of crop diseases at this stage, 40% ethyl phosphorus, manganese zinc wettable powder 300 times, pyrimidine nucleoside antibiotics 500 times, and azoxystrobin 800 times are sprayed every 5-7 days for 2-3 times.

2. When the disease is more serious, it is necessary to remove the central diseased plants and diseased leaves in time, and at the same time adopt the prevention and control method of integrated traditional Chinese and western medicine in time, according to the growth period and fruiting habits of different varieties, adopt different dense planting methods, such as double-stalk pruning, suitable for planting about 2000 plants per mu, single-culm pruning, suitable for planting 2500-3500 plants per mu, reasonable close planting, which can effectively improve the ventilation and light transmission conditions in the field. Reduce the humidity in the field and reduce the occurrence of diseases.

How is the late blight caused

The main results are as follows: 1. The suitable temperature for the occurrence of late blight pathogen is 18 ℃-22 ℃. A large number of sporangia are formed, which requires more than 95% relative humidity. When the field temperature is 10 ℃-24 ℃, and the relative humidity is above 75%, the disease can occur.

2. At the same time, under the condition of high humidity, heavy dew, foggy morning and night, planting in protected field is easier than that in open field, and the planting density is too high, such as more than 3500 mid-and late-maturing varieties per mu of tomatoes, more than 4000 early-maturing varieties per mu, and poor ventilation will lead to the occurrence of late blight.

3. The difference between late blight and early blight

1. Different nature

Early blight is a fungal disease, which can occur in both seedling stage and adult stage, while late blight pathogen mainly uses mycelium to winter in diseased potato tubers, and can also harm and winter on greenhouse tomatoes.

2. Different characteristics

The early blight is mainly harmful to the leaves, stems and fruits of crops, which is easy to occur in the leaves and branches of stems and leaves, while the late blight is mainly caused by stems, leaves and fruits at the same time.

3. Different colors

The stem of late blight will turn dark brown and rot at the same time, there are water-immersed irregular disease spots on the leaves, there are many white mildew at the junction of the disease and health on the back of the leaves, and there are slightly sunken spots on the fruit, especially on the green fruit. the disease spot of early blight has concentric rims in the middle, and when it is wet, the disease will grow black mildew layer, which is one of the typical symptoms of the disease.