Causes and Control Methods of Alternate Bearing in Pear Trees

Pear trees are grown throughout China, and pears are popular with many people. For pear growers, however, the alternate bearing phenomenon in pear trees is a real headache. Alternate bearing in pear trees can seriously affect pear yields and reduce growers' economic returns. So what causes alternate bearing in pear trees? And how should it be controlled? Below, the editor brings you the causes and control methods of alternate bearing in pear trees. Let's take a look!

I. Causes

1. Tree-related causes

In years when pear trees bear relatively abundant fruit, nutrients are continuously transported to the fruit. This causes a large reduction in the nutrient reserves of the pear tree, so the tree does not have sufficient nutrients that year to form flower buds. Therefore, after passing through an "on" year, an "off" year occurs because the tree's nutrient reserves are too low. Then in the "off" year, because the fruit load is small, nutrient reserves increase, and there are sufficient nutrients to promote flower bud differentiation. Thus the following year becomes an "on" year for the pear tree, and this cycle repeats, resulting in alternate bearing.

2. Environmental causes

Environment is a major cause of alternate bearing in pear trees. Under harsh environmental conditions, such as low temperatures, frost and drought, the growth of pear trees is greatly harmed. For example, a pear tree that would normally bear fruit may suffer flower or young fruit damage from late frost, leading to flower and fruit drop. This causes excessive nutrient accumulation in the tree, producing a large number of flower buds, and the following year becomes an "on" year. In addition, pests and diseases can also easily cause alternate bearing; pests and diseases readily cause defoliation and flower drop in pear trees. They affect flower bud differentiation in pear trees, and if not controlled in time, the following year is likely to become an "off" year.

II. Control Methods

1. Reasonable pruning

We should control the amount of flowers on pear trees through reasonable pruning to ensure a suitable leaf-to-fruit ratio. This avoids an imbalance between nutrient accumulation and consumption in the tree and alleviates alternate bearing. In an "on" year, heavy pruning should be carried out, while in an "off" year, light pruning should be done. When pruning in an "on" year, we should, on the premise of ensuring that year's yield, control the number of flower buds and shorten more of the medium and long fruiting branches. Handle overly dense and overly long branches to improve the light environment. In an "off" year, fewer thinning cuts and fewer heading cuts should be made, and no major restructuring or renewal of the pear tree should be carried out. Then attention should be paid to summer pruning to promote the development of secondary shoots in an "off" year and increase the number of flower buds the following year.

2. Strengthen management

During the flowering and fruiting period of pear trees, we should appropriately thin flowers and fruit to avoid an excessive load on the pear tree, adjust the leaf-to-fruit ratio, and increase nutrient accumulation. Special attention should be paid to flower thinning; appropriate early flower thinning can effectively reduce nutrient consumption. Then attention should also be paid to fertilizer and water management to enhance the absorption capacity of the pear tree roots and ensure nutrient uptake by the pear tree. Doing a good job of pest and disease control and avoiding natural disasters can also effectively prevent alternate bearing in pear trees. Finally, growth regulators should be applied reasonably to promote flower bud differentiation. In an "on" year, regulators such as ethephon are mainly used, while in an "off" year, gibberellin and similar substances are mainly used.

The above is a brief introduction to the causes and control methods of alternate bearing in pear trees. That's all for today's introduction. This article is for reference only, and we hope it can help you!