Analysis of the Causes of Leaf Curling in Sugar Mandarin and Its Prevention and Control Methods
Leaf curling in sugar mandarin is a fairly common phenomenon in winter and spring, and many fruit growers encounter this situation. Some farmers, not knowing where to start, miss the best period for prevention and control, resulting in undesirable losses. Below, the editor brings you the causes of leaf curling in sugar mandarin and the corresponding prevention and control measures. Come and learn about them with the editor.
1. Environmental factors
Spring is rainy, and if the orchard is located in low-lying terrain, there is relatively much standing water on the ground. Excessive water content in the soil causes poor root respiration in sugar mandarin, which in turn affects the roots' absorption of water. Over time, the leaves curl and turn yellow due to water loss.
Prevention and control methods: Dig drainage ditches deep, keeping the drainage ditches more than 80 cm from the surface, to reduce soil water content; then loosen the soil to increase oxygen content. At the same time, cover the surface around the tree roots with rice straw or stalks to reduce the scouring of the soil surface at the roots by rainwater and lower damage to the roots. Finally, spray the leaves with brassinolide to improve stress resistance.
2. Pests
Aphids damage new shoots, causing an insufficient supply of nutrients, which in turn affects the leaves, making them turn yellow and curl. In addition, summer and autumn are the peak period for red spider mites, which harm leaves, new shoots and fruit, causing leaves to turn yellow and fall off.
Prevention and control methods: For aphid damage, acetamiprid or other products can be sprayed to protect new shoots. For red spider mites, saomanjing or kelmante can be sprayed to control red spider mites.
3. Nutrient deficiency
The biggest reason sugar mandarin leaves turn yellow, become thin and curl is nitrogen deficiency. Nitrogen deficiency mainly occurs on old leaves, while new leaves are better; the leaves as a whole turn yellow. In the early stage of nitrogen deficiency, the leaves become light green, then turn yellow. In addition, insufficient nitrogen fertilizer also further causes iron deficiency in sugar mandarin.
Prevention and control methods: Strengthen management and increase the application of organic fertilizer. If the deficiency is severe, root-outside fertilization can be combined with it, spraying a low-concentration urea and monopotassium phosphate fertilizer solution once every 10 days, and borax can be added to the fertilizer water. If there are symptoms of iron deficiency, add other elements to it. If the nutrient deficiency is caused by root damage, while supplementing fertilizer through the leaves, pay attention to caring for the roots of the sugar mandarin.
4. Improper management
When forcing flowering in the previous year, spraying the leaves with excessively high concentrations of foliar fertilizer, plant growth regulators, insecticides, etc. causes certain damage to the leaves, which can also cause leaf curling the following year.
Prevention and control methods: Rice straw can be used to cover the roots to prevent damage to the root system from sunlight. Suspend root fertilization, and after the new shoots mature, adopt the principle of frequent light fertilization to promote root growth. After the new leaves unfold but before they turn dark green, spray foliar fertilizer so that both the roots and leaves absorb nutrients together and promote the recovery of tree vigor.
The above is an introduction to the causes of leaf curling in sugar mandarin and the prevention and control methods. We hope it can help you. If you want to learn more related knowledge, please stay tuned to us.