Summary of Experience in Renovating Low-Yielding Bayberry Trees
Low-yielding bayberry trees mainly include: stunted young trees, excessively vigorous trees, aging trees, low-yielding trees in mixed forests, and trees of poor-quality varieties. Their causes of low yield differ, so renovation should be carried out according to specific circumstances.
1. Stunted young trees:
Because the amount of base fertilizer applied at planting of the seedlings was small, or even nonexistent, and the planting holes were small, the root system grew poorly; or because of damage from pests and diseases and the climatic effects of natural disasters, tree growth became weak, the canopy was short and small, and the branching ability was extremely poor, so the number of flowers and fruits was low. Trees showing this phenomenon are called stunted young trees.
Specific renovation measures:
(1) Deeply plow and widen the planting holes, add borrowed soil for renovation, and increase the application of organic fertilizer to promote the formation of soil aggregates, thereby improving the soil's ability to retain fertilizer and water, promoting the development of roots and shoots, and forming a canopy as early as possible. (2) Moderately increase heading-back pruning of the scaffold branches to promote the sprouting of latent buds on the bayberry tree, improve the canopy structure, and at the same time apply an appropriate amount of quick-acting nitrogen fertilizer and potassium fertilizer to strengthen tree vigor so that it bears fruit as early as possible.
2. Excessively vigorous trees:
Because the soil is deep and fertile, or because nitrogen fertilizer was applied in a one-sided way, and the trees were then allowed to grow naturally, vegetative growth became excessive. A large amount of tree nutrition was consumed in the growth of branches and leaves, flower buds were difficult to form or formed very few, and the trees entered the fruiting stage late or had very low yields.
Specific renovation measures: (1) Control fertilizer and water, especially apply little or no nitrogen fertilizer, and appropriately increase the application of phosphorus and potassium fertilizers; (2) From October to November, apply paclobutrazol to the soil at 0.2-0.4 grams of active ingredient per square meter of canopy projection area; or from March to April, spray the canopy with 700 mg/kg paclobutrazol; (3) In autumn, dig trenches about 30 cm deep near the canopy drip line and carry out an appropriate amount of root pruning; also carry out spiral girdling or bark inversion on some large branches to promote flower bud formation and improve yield and quality.
3. Aging trees:
Generally, the economic life of bayberry is 70-80 years, but due to improper management, or the effects of pests, diseases, and natural disasters, trees show many dead branches, sparse leaves, bare inner canopy, and very little fruiting. Trees showing these phenomena are called aging trees.
Specific renovation measures: (1) According to the specific condition of the aging tree's vigor, carry out partial renewal. Cut back the trunk and main branches in batches over 2-3 years, retain strong shoots sprouting from the middle and lower parts, and remove excessive suckers to facilitate renewal and rejuvenation. (2) While renewing, combine with increased application of organic fertilizer, loosen the surface soil, and mound with new soil to promote the sprouting of new shoots and root growth, and restore the canopy and yield again. (3) Note that the wounds from sawing off large branches should be smoothed flat, and grafting wax or water-based asphalt paint should be applied to protect the wounds and promote their early healing.
4. Low-yielding trees in mixed forests: Because the mixed trees around the bayberry trees are tall and too dense, they affect ventilation and light penetration in the canopy, resulting in low bayberry yield.
Specific renovation measures: (1) Mixed forest trees should be appropriately thinned to improve ventilation and light conditions for the bayberry trees. (2) If mixed with moso bamboo, because bamboo rhizomes have extremely strong branching ability, they must all be cleared away.
5. Trees of poor-quality varieties: Because fruit quality is poor, even if yield is high, they have little value and must be renovated through top grafting to change varieties.