How to prevent alternate bearing in longan? A detailed guide to prevention and control methods

Longan is widely cultivated in warm regions such as Fujian, and growing longan can come with all sorts of problems, all of which affect growth and yield. Today we will mainly discuss what to do when longan shows alternate bearing, and how to keep yields balanced and stable. A brief introduction for everyone's reference.

I. Causes

1.There are many longan varieties; some have a strong ability to hold flowers and fruit, while others easily drop flowers and fruit, so it is best to choose a good variety.

2.The bearing mother branches are damaged by borers during the young leaf stage of the autumn shoots, resulting in poor growth and failure to flower and fruit well. Or downy mildew during the flowering period causes heavy flower drop and a small fruit set. Drought during autumn shoot flushing and the fruiting period affects bud sprouting and shoot flushing, and causes fruit drop. Rain during the flowering period leads to heavy flower drop and failure of pollination and fertilization. A warm winter prevents flower bud differentiation.

3.Blindly pursuing more fruit in years with abundant flowering, without thinning flowers or fruit, over-consumes nutrients without adequate replenishment. This causes growth imbalance, with no new buds sprouting and no shoot flushing. Extensive management means no care or attention at all.

II. Preventive measures

1.After harvest each winter, you should apply enough farmyard manure along with intertillage to keep the soil fertile and well structured, and give weak trees individual support. Dig good ditches in the field and do a good job of drainage and irrigation to prevent waterlogging and drought. During the growing period, mainly prevent downy mildew and the longan stem borer, prune off damaged and diseased branches, and use low-phytotoxicity, high-efficiency pesticides for control to keep pests and diseases in check.

2.If the canopy is too large, over about 5 m, nutrients have too far to travel and cannot reach their destination; it is best to prune the canopy back to about 3 m so nutrients are transported in time. In vigorous years, be sure to thin out some flower clusters and excess fruit, diseased fruit and weak fruit. This prevents nutrient consumption and, conversely, leads to poor fruit. In an off year, take care to remove some buds to avoid shoot flushing and concentrate nutrients. During flowering, hand pollination can be done to increase the fruit set rate. In addition, apply fertilizer several times, and be sure to maintain all the nutrients needed during the flowering and fruiting periods. Spray zinc sulfate as a foliar fertilizer to balance the relationship between vegetative growth and reproductive growth.

Once you grasp the phenomenon of alternate bearing in longan, you can match it against the causes and carry out good preventive measures. However, there are many causes of alternate bearing, so you can identify the causes yourself based on your actual situation and implement your own preventive measures.