Sunburn is caused by burns caused by strong sunlight. It is usually caused when the temperature is high or the temperature changes drastically. The trunk and large branches are infected, and the sunburn surface is irregularly burnt and scorched, and it is easily infected by rotting bacteria. Cause rot disease.
The disease is a physiological disease. The number of stomata on leaves is several times less than that of field crops in the same area. When the light is too strong, the stomata are blocked and the transpiration is reduced. When the temperature on the chip is too high, it exceeds its own tolerance, and the chlorophyll is destroyed. Then the mesophyll tissue loses water and scorches. Direct sunlight is the direct cause of sunburn.
Peak of disease: At noon when the sun is very strong in summer, the transducing tissue and cambium cells at the root neck of the seedlings in contact with the soil surface are scalded to death by high temperature, forming a colorless ring with a width of several millimeters, and the transduction channel Was destroyed, causing the seedlings to fall.
When the seedlings are just unearthed, because their stems are extremely tender, if the surface temperature reaches 32, sunburn will begin to occur. With the growth and development of seedlings, it gradually develops from tender and watery fleshy tissues to lignification, and its temperature tolerance also tends to increase. In addition, the sunburn of seedlings is also closely related to its own genetic factors, soil conditions in the nursery, and technical management of seedlings.
Prevention and control measures for paulownia sunburn: spraying foliar fertilizer and supplementing nutrients to increase leaf thickness can effectively resist the occurrence of paulownia sunburn.
Timely spraying water and spraying to increase the water content and air humidity of the soil, improve the microclimate of the orchard, and ensure the adequate supply of water are the most fundamental measures to prevent sunburn.
Bagging, covering the fruits that grow on the top of the canopy and the outside of the canopy with a special sleeve for paulownia, this is the most effective and direct measure to prevent paulownia sunburn.
Deeply turning the garden soil, it can promote the robustness of the root system of the Fatong tree, increase the water absorption range and capacity of the root system, and maintain the balance between the growth of the ground and the underground.
Paste white paper, smear lime slurry on the sunburn prone to sunburn or paste a piece of white paper on the part of the fruit that has slight sunburn, or apply a layer of lime slurry to prevent the occurrence of sunburn or Reduce the symptoms of sunburn.
Cover with tree tray, moisturizing and cooling. In summer, around the tree trays and the dense roots along the crown of the tree, lay 10 cm to 13 cm thick fresh grass or straw and other mulch to facilitate moisturizing and cooling, promote root activity, regulate soil moisture and the orange orchard The microclimate promotes the normal development of fruits.
Scientifically spray pesticides to avoid spraying pesticides with high concentrations, and avoid spraying pesticides under the scorching sun. During the fruit-bearing period, use lime-sulfur mixture as little as possible. If it is necessary to use lime-sulfur mixture to control rust tick, the concentration should be 0.2 Baume, and try to avoid excessive aggregation of the liquid on the fruit surface.