What are the main diseases of navel oranges? A detailed explanation
What are the main diseases of navel oranges? How should these diseases be prevented and controlled? Please introduce them. Fruit cracking, sunburn and navel yellow are the three major physiological diseases of navel oranges, and many first-time growers lack experience in preventing and controlling them. After years of trials, the author has accumulated rich experience in preventing and controlling navel orange fruit cracking, sunburn and navel yellow, and has effectively controlled...
What are the main diseases of navel oranges? How should these diseases be prevented and controlled? Please introduce them
Fruit cracking, sunburn and navel yellow are the three major physiological diseases of navel oranges, and many first-time growers lack experience in preventing and controlling them. After years of trials, the author has accumulated rich experience in preventing and controlling navel orange fruit cracking, sunburn and navel yellow, and has effectively controlled the occurrence of these diseases. They are introduced below for reference in various regions:
1. Fruit cracking disease. First, choose varieties (lines) with relatively strong cracking resistance. Generally, varieties (lines) with oval fruit shape and a small or closed navel have better cracking resistance, such as Newhall, etc.; second, strengthen scientific management to enhance tree vigor, especially during the dry period from after the plum rain to before the autumn rains, pay special attention to water management, irrigate or water (spray) in time, and keep the soil moist regularly to promote normal growth and development of the fruit. Third, during the rapid fruit expansion period, spray foliar potassium fertilizer 2-3 times consecutively. For foliar potassium fertilizer, 0.2% monopotassium phosphate or 0.3% potassium sulfate compound fertilizer can be used, and in early to mid-July, use a mixture of "920" at a concentration of 200 mg/L plus 800-fold thiophanate-methyl and an appropriate amount of fragrant paste, which can heal the cracks and prevent fruit cracking from occurring again.
2. Sunburn disease. Strengthening scientific management and covering the orchard with straw and other materials to preserve moisture are the foundation for preventing sunburn disease; planting forage grass or interplanting green manure in the orchard can reduce sunburn disease; in high-temperature seasons, do not spray pesticides such as mineral oil emulsion and lime sulfur mixture, so as not to aggravate the occurrence of sunburn disease. In the early stage of sunburn disease, paste white paper on the surface of sunburned fruit, and pull branches and leaves to shade the fruit to reduce direct sunlight exposure. Irrigating or spraying water regularly in the high-temperature seasons of summer and autumn can prevent and reduce the occurrence of sunburn disease.
3. Navel yellow disease. First, start with cultivating vigorous tree vigor and appropriately increase nitrogen fertilizer to raise the tree's nutrient level; second, before flowering, pull strong autumn shoots into a drooping or horizontal state so that most flowers face downward when opening, reducing sun-facing fruit and preventing the occurrence of navel yellow; third, from early to mid-June to mid-to-late July, in combination with fruit preservation, spray 30-40 mg/L "920" solution twice consecutively, and from late July to late August, apply 600-fold "yellow inhibitor ester" solution to coat and spray the navel part of the fruit to inhibit the occurrence and spread of navel yellow disease.
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