What are the main diseases of navel orange?

What are the main diseases of navel orange? How should these diseases be prevented? The cracking, sunburn and navel yellow of navel orange are the three major physiological diseases, and many beginners lack experience in prevention and control. After years of experiments, the author has accumulated rich experience in the prevention and control of navel orange fruit cracking, sunburn and navel yellow, and effectively control the occurrence of diseases. Now introduced as follows, for local reference: first, fruit cracking disease, first of all, it is necessary to select varieties (lines) with strong cracking resistance, generally with fruit oval, small or closed navel varieties (lines) have better cracking 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 for 3 times in the period of rapid fruit expansion. 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 200 mg / L and 800 times of methyl topiramate and an appropriate amount of fragrant paste can heal the cracks and prevent fruit cracking from happening again. Second, strengthen scientific management of sunburn, orchard covering straw and other soil moisture conservation is the basis for preventing sunburn; planting forage grasses 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, umbilical yellow disease begins with the cultivation of healthy trees, the appropriate application of nitrogen fertilizer to improve the nutrition level of the tree, and then pull the strong autumn shoots into a drooping or horizontal state before flowering, so that most of the flowers bloom downward and reduce the sunny fruit to prevent the production of navel yellow. Once again, from the first ten days of June to the last ten days of July, combined with fruit protection, the "920" solution of 40 mg / L was sprayed twice, and from late July to late August, 600 times of "xanthate" solution was sprayed on the navel of the fruit to restrain the occurrence and spread of umbilical yellow disease. Click to get more navel orange planting techniques click to get more fruit planting techniques