What to do when persimmon trees have a low fruit set rate? Two methods to teach you

Persimmon is the fruit produced by an important, widely cultivated fruit tree, grown mainly in the mountainous areas of Henan, Shanxi, Shaanxi, Hebei and other places. Persimmons were introduced to France and the Mediterranean countries in the 19th century, and later to the United States. The fruit of the persimmon tree is about 5 to 8 cm in diameter, yellow to red. Persimmons contain vitamin A and a small amount of vitamin C.

Improper cultivation and management of persimmon trees easily leads to flower and fruit drop. The main causes of flower and fruit drop in persimmon trees are, first, physiological fruit drop, which is caused by a physiological imbalance in the tree itself, mainly due to insufficient nutrition and poor pollination. Excessive vegetative vigor consumes too much nutrition, and insufficient light inside the canopy will aggravate physiological fruit drop. The first physiological fruit drop occurs 3—5 days after petal fall, and the second 25—30 days after full bloom. Second, pests and diseases, pesticide damage, and tree injury cause flower and fruit drop. The following measures can be taken to reduce flower and fruit drop in persimmon trees and improve the fruit set rate.

1. Control the persimmon fruit borer. 7 to 8 days after the persimmon tree begins to bloom (based on 1 flower opening in the persimmon orchard), you can choose 2.5% fenpropathrin 2500-fold solution, 21% methomyl 2500-fold solution, 10% duolaibao suspension concentrate 1000 to 2000-fold solution, 5% leifuling emulsifiable concentrate 2000-fold solution, 25% chlorbenzuron No. 3 2000-fold solution, etc. for spray control. Rotating the pesticides gives a better control effect.

2. Improve the fruit set rate. (1) Plant Zenjimaru, which has male flowers, as a pollinizer tree; pollinizer trees should account for 10% to 20% of the total number of trees. (2) Topdress and water before flowering. During the flowering period, spray 0.1% borax solution with 300 ppm gibberellin solution, or 0.1% borax solution, 0.3% urea solution and 0.5% potassium dihydrogen phosphate solution.

(3) Slow down new shoot growth. When 50% of the flowers have opened, girdle the trunk or main branches.

Configuring pollinizer trees      

Most persimmon varieties have strong parthenocarpic ability, but some varieties, especially most Japanese sweet persimmon varieties such as Fuyu and Izu, have weak parthenocarpic ability and must be provided with pollinizer trees. It is appropriate for pollinizer varieties to account for 10% to 20% of the main cultivated varieties; varieties that flower earlier and have male flowers can be chosen, such as Zenjimaru and Akagaki.      

Raising the tree's nutritional level      

Lack of fertilizer and water in persimmon trees is the main cause of low yield and severe alternate bearing. For high and stable yields, rational fertilization and irrigation are essential. In mature persimmon orchards, the suitable nitrogen:phosphorus:potassium ratio is 10:3:9. In the course of a year, nitrogen fertilizer should dominate in the early stage of fertilization, with phosphorus and potassium fertilizers increased later.    Base fertilizer should be applied around harvest time in combination with autumn plowing. It should be mainly organic fertilizer, and the amount applied can account for half of the annual fertilization amount. Generally, for large trees in full fruit period, apply about 100 kg of barnyard manure and about 10 kg of superphosphate per tree.  

Topdressing is usually carried out 2—3 times in May during the shoot tip dormancy period (before flowering), after the first physiological fruit drop peak, and before the fruit rapidly expands and colors. It can significantly promote fruit set, and can also promote the formation and differentiation of flower buds for the next year and improve flower bud quality.