What pesticide works well for protecting flowers and fruits of Wokan mandarin?
During this period, Wokan mandarin's demand for potassium increases, so a high-nitrogen and high-potassium water-soluble fertilizer can be used from before flowering to after flowering to ensure normal flower bud differentiation and achieve flower and fruit protection. After fruiting, Guomofang or a high-potassium fertilizer can be used to promote rapid fruit expansion while improving the toughness of the peel and avoiding fruit cracking.
How to protect flowers and fruits of Wokan mandarin
1. Spring topdressing. In spring, citrus is in the stage of sprouting, flowering, vigorous cell division of young fruit and alternation of new and old leaves, which consumes a large amount of stored nutrients. In addition, at this time the soil temperature is mostly low, and the root absorption capacity is weak. Applying quick-acting fertilizer, often decomposed human urine plus urea, potassium dihydrogen phosphate, potassium nitrate, etc., supplements the tree's insufficient nutrients. Studies have shown that quick-acting nitrogen fertilizer applied to the soil takes 12 days to reach the young fruit, while foliar spraying takes only 3 hours. After foliar spraying at the flowering stage, the nitrogen content in the flowers increases significantly, the dry matter of young fruit and the diameter of young fruit increase markedly, and the fruit-setting rate improves. To protect flowers and fruits with foliar fertilizer, a commonly used concentration is 0.3%-0.5% urea, or 0.3% urea plus 0.3% potassium dihydrogen phosphate sprayed at the flowering stage, and then sprayed once more 15-20 days after flower drop.
2. Girdling and scoring. Girdling at the flowering stage and young fruit stage is an effective method to reduce citrus fruit drop. It can block the transport of nutrients and improve the nutritional level of young fruit. Scoring is safer than girdling, simple and easy to carry out, but the phloem conducting tissue is easily reconnected, so a single scoring often cannot achieve the desired effect. For the trunk or main branches, girdling 1-2 mm wide in one ring can achieve good results in protecting flowers and fruits, and the girdling heals in about 1 month. The stronger the tree vigor, the faster it heals. In addition, wiping out spring shoot vegetative branches in spring to save nutrient consumption can also effectively increase the fruit-setting rate.