Alternate year bearing is often seen in longan trees. The main reason is that longan trees will be weaken after a large number of blossom, cannot draw robust autumn shoots, unable to form excellent mother branches, resulting in yield less fruit, even no flower and no fruit in the second year. If spread fertilizer before and after fruit picking in a timely manner, supply adequate nutrient, retard the potential recession, speed up the tree potential rejuvenation, robust autumn shoots will grow in time after piking up fruits, creating excellent-fruits mother branches and will be normal blossom in the second year, which can overcome the phenomenon of major or minor year bearing or alternate bearing and obtain good harvest.
Measures: Spreading preharvest fertilizer for 15 ~ 20 days before longan fruit picking should give priority to NPK complete fertilizer. Each living plant that more than 5-year-old or over 50kg should be fed with NPK (15-15-15) potassium nitrate or 0.75 ~ 1 kg of pure s-based compound fertilizer, spreading them on the topsoil under canopy after rain. Spreading postharvest fertilizer for 5 ~ 10 days after longan fruit picking should give preference to instant and available nitrogen fertilizer and potash fertilizer, each of them should be applied with 0.75 ~ 1.00 kg urea and 0.50 ~ 0.75 kg potassium sulphate, with uniform broadcast on the topsoil under the canopy after the rain. In addition, while fertilizing in the root, also needing top dressing. Before picking fruit, spraying a 0.2% ~ 0.3% potassium dihydrogen phosphate, 0.1% magnesium sulfate, 600 ~ 800 times amino acid active liquid mixture on foliar. After picking fruit, continuously spraying 2 ~ 3 times of 0.1% magnesium sulfate, 0.2% urea and 0.3% potassium dihydrogen phosphate, 800 ~ 1000 times activity humic acid liquid fertilizer mixture, spraying every 7 to 10 days, uniformly spraying all the branches and leaves inside and outside canopy. It is advised that to stop spraying when starting to drop down a drip. Adding a variety of nutrients start from leaves is conducive to the stability and rejuvenation of the tree.