How to prevent and cure the three major diseases of navel orange

Fruit cracking, sunburn and navel yellow of navel orange are three major physiological diseases, and many new growers lack experience in prevention and control. Chen Tangjun is one of the earliest professional households to cultivate navel orange in Jinhua City, and now there are more than 200 mu of navel orange. after 15 years of observation and experiment, he has accumulated rich experience in preventing and curing navel orange cracking, sunburn and navel yellow, and effectively controlled the occurrence of diseases. Now introduced as follows, for local reference: first, the prevention and control of fruit cracking disease: first of all, the varieties (lines) with strong cracking resistance should be selected. generally, the varieties (lines) with oval fruit shape, small or closed navel have better crack resistance, such as Newhall and so on. Secondly, it is necessary to strengthen scientific management and strengthen the tree potential, especially during the dry period from the plum rain to the autumn rain, so as to irrigate or spray water in time, keep the soil moist and promote the normal growth and development of fruits. Thirdly, foliar potash fertilizer was sprayed continuously for 2 times during the period of rapid expansion of fruit. Foliar potash fertilizer can choose 0.2% potassium dihydrogen phosphate or 0.3% potassium sulfate compound fertilizer, and in the first and middle of July, the mixture of "920" with a concentration of 200mg/L (liter) plus methyl topiramate and an appropriate amount of incense paste can heal the cracks and prevent fruit cracking from happening again. Second, the prevention and control of sunburn: strengthen scientific management, orchard covering straw and other soil moisture conservation is the basis for the prevention of sunburn; planting forage or interplanting green manure in orchards can reduce sunburn; in high temperature season, do not spray pesticides such as oil emulsion and stone sulfur mixture, so as not to aggravate the occurrence of sunburn. In the early stage of sunburn, stick white paper on the sunburn fruit surface, and pull branches and leaves to block the fruit to reduce direct sunlight exposure. Regular irrigation or spraying in high temperature seasons in summer and autumn can prevent and reduce the occurrence of sunburn. Third, the prevention and control of umbilical yellow disease: first, start with the cultivation of healthy trees, appropriately increase the application of nitrogen fertilizer to improve the tree nutrition level and nitrogen metabolism function; secondly, pull the strong autumn shoots into a drooping or horizontal state before flowering, so that the vast majority of flowers are facing down when they bloom, reduce Xiangyang fruit and prevent the production of navel yellow. From the first ten days of June to the last ten days of July, the "920" solution of 30~40mg/L (liter) was sprayed twice, and from late July to late August, the navel of the fruit was sprayed with 600x "xanthate" solution to restrain the occurrence and spread of umbilical yellow disease.