1. Schisandra Sunburn mainly harms the fruit. Sunburn sites often show a herpes-like, sunken spot, leathery, hardened lesions, or plaques in the flesh tissue. The surface of the damaged fruit surface initially turned white (yellow or pink) and then changed to black-yellow-brown. When the scorching occurs severely, there is a pitted necrotic spot in the flesh tissue, and there is a necrotic tissue in the local flesh. The victim is vulnerable to other fruit rot pathogens and causes fruit rot.
2. Incidence The direct cause of Sunburn is thermal injury and UV radiation damage. Among them, thermal injury refers to sunburn caused by high temperature on the surface of the fruit and has nothing to do with light. Ultraviolet radiation damage is caused by sunburn caused by ultraviolet rays, which can lead to The cells collapsed. The occurrence of sunburn is related to many factors such as temperature, light, relative humidity, wind speed, variety, fruit development period and tree vigor. Among them, temperature and light are the main influence factors. 1Temperature and temperature are important factors affecting the sunburn of schisandra fruit. In sunny summer days, the surface temperature of schisandra fruit can reach 40-50°C, which is much higher than the maximum temperature of the day. Some scholars believe that the critical temperature that causes sunburn is between 30-32°C, and as the ambient temperature rises, sunburn time shortens and the degree of sunburn damage increases. 2 Illumination, light intensity, and ultraviolet light are important factors in the occurrence of sunburn in the fruits of Schisandra. Under natural conditions, the fruit that receives the light converts part of the light energy into heat energy, thereby increasing the surface temperature of the fruit, and the effect of high temperature on the temperature of the fruit, together causing the fruit surface to reach the critical temperature of sunburn, thus inducing the fruit day. Occurrence of burning.
The disease occurs from June to September, and the high-temperature, intense light summer peaks from July to August. It is often found in production that the annual peak of fruit scorch always coincides with the highest temperature in one year. Under the premise of relatively high temperature, if it is sunny, it can easily lead to sunburn, and the incidence of low temperature sunny days is low. The lower the relative humidity, the higher the incidence of sunburn; the wind speed can be adjusted by transpiration to change the fruit temperature, breeze can reduce the surface temperature of the fruit and reduce the incidence; different varieties of sensitivity to sunburn are different; fruit in different development The resistance to sunburn is different during the period. With the maturity of the fruit, the sensitivity to sunburn is reduced. In the same orchard, the incidence of sunburn is low in strong tree vigor and the incidence of weakness in weak tree vigor is heavy.
3. Prevention and control techniques 1 Strengthen cultivation and management, enhance tree vigor; pay attention to prevent excessive application of nitrogen fertilizer, apply more organic fertilizer, improve soil water retention and fertility, promote plant root development to depth, and improve plant early resistance. 2 When the pruning leaves more leaves, in order to avoid the fruit exposed to direct sunlight; through the sparse flowers and thinning, adjust and determine a reasonable percentage of fruit and fruit, fruit and fruit ratio. 3 Before the advent of high-temperature weather, the temperature of the fruit surface can be lowered by cold sprinkling, which can effectively prevent sunburn. 4 The fruit bagging method can reduce the sunshine intensity and the surface temperature of the fruit.
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