What symptoms does apple blight rot have? What are the prevention and control methods? What kind of medicine do you use?

Apple blight rot, also known as neck rot and solid rot, is one of the important diseases of apple. High temperature and humidity climate is very easy to cause apple blight rot. What are the symptoms of apple blight? What are the prevention and control methods? What kind of medicine do you use?

Apple blight rot is one of the few diseases caused by lower fungi in apple trees, which is different from common rust, powdery mildew, brown spot, early deciduous leaf disease, scab, etc., and the control techniques (especially the selection of pesticides) are quite different. I'll tell you about it today.

I. harmful symptoms

Phytophthora rot is mainly harmful to fruit, root neck and leaves. After the damage to the fruit, the fruit surface produces irregular, uneven dark red disease spots, the edge is not clear like waterlogging. Sometimes the disease spot is separated from the pulp and the surface is white wax. After the flesh turns brown and rotten, the shape of the fruit remains spherical and elastic. The diseased fruit is very easy to fall off, and finally loses water and shrinks into a stiff fruit. White woolly mycelium can be seen in the dehiscence or wound of the diseased fruit. Marshal apple fruit disease, generally from the five edges of the first appearance of disease spots, brown dry spots between the two edges, surrounded by red halo, and then developed to two or three edges, and gradually spread to the whole fruit. When the disease is serious, the fruit detaches and loses its edible value. When the seedling and the root neck of the tree were damaged, the cortex showed brown rot, and after the disease spot was cut, the aboveground branches germinated slowly, the leaves were small and yellow, and finally the whole plant wilted and the branches withered. Leaf damage produces irregular grayish brown or dark brown disease spots, water stains, mostly from the edge or middle of the leaves, when wet, the disease spots rapidly expand to make the whole leaves rot.

Second, the law of the disease.

1. Period:

The fruit could be infected during the whole growth period, and there was a peak of infection and incidence after each rainfall.

two。 Variety:

The disease of Red Fuji is common, and dwarfing rootstocks are more prone to neck rot than Qiaohua rootstocks.

3. Climate:

The disease occurs rapidly and spreads quickly under the condition of high temperature and humidity.

4. Cultivation factors:

The disease is more serious in orchards with closed trees, weeds, weak trees, low-lying terrain and wounds in the root neck of apple trees, especially in orchards irrigated by heavy water before rain.

III. Prevention and control measures

1. Disease-resistant varieties were selected. Red Star and Golden Crown are susceptible to disease, while Fuji, Guoguang and Jonagin are more resistant.

two。 Strengthen cultivation management, timely fruit thinning, removal of diseased fruit and diseased leaves, concentrated deep burial or burning. Timely thinning of overdense branches and drooping branches to improve ventilation and light transmission conditions. Mulching plastic film or grass under the canopy can prevent germs in the soil from spattering on the fruit. Apple orchards with serious disease should not be intercropped with vegetables to reduce the disease conditions.

3. Clean up the fallen fruit in time and remove the diseased fruit and leaves from the tree for centralized treatment; be careful not to hurt the root neck when ploughing and weeding.

4. The infection site of Phytophthora rot is mainly on the fruit of the main branch less than one meter, especially the fruit near the ground is easy to be infected with Phytophthora rot. Therefore, when pulling branches, especially when pulling down layer branches, orchards with epidemic rot must be careful not to pull branches too much. Now that the disease has been found, the main branch should be hoisted up more than 60 centimeters in time, so that there is no chance of infection with Phytophthora.

Reference for control agents:

47% enoyl azosine suspension (low toxicity) using 50-60 ml / mu spray

40% enoyl fluridine suspension (low toxicity) using 33-40 ml / mu spray

687.5 g / L fluorobacterium aldicarb suspension (low toxicity) using 60-75 ml / mu spray

46% copper hydroxide water dispersible granules (low toxicity) use 25-30 g / mu spray

52.5% oxone cream urea cyanide water dispersible granules (low toxicity) use 20-40 g / mu spray

72% Urea ·Manganese Zinc wettable Powder (low toxicity) uses 133-180 g / mu spray

100 billion spores / g Bacillus subtilis wettable powder (low toxicity) use 10-14 g / mu spray