What to Do If Pear Trees Bloom Out of Season? Causes and Control Methods Explained

In the sand pear (Pyrus pyrifolia) production areas south of the Huai River and in the Yangtze River basin, every autumn a number of pear orchards show the phenomenon of out-of-season blooming. Any pear tree that has bloomed out of season will inevitably have a reduced yield the following year. Pear growers keep asking: why do pear trees bloom out of season? How can it be effectively controlled? Based on many years of practice, the author offers answers for fellow farmers, for their reference in production.

Causes of out-of-season blooming in pear trees

Compared with other fruit trees, pear trees are the most prone to out-of-season blooming, which is caused by the different physiological characteristics of their flower bud differentiation. The flower bud differentiation period of pear trees begins relatively early; generally, after petal fall in early May, when the young fruit begins to grow rapidly, the flower buds begin to differentiate. By mid-to-late June, when the young fruit swells rapidly, the flower buds also enter a period of massive differentiation. Generally, the calyx begins to form in mid-July, and most have formed by early-to-mid August. The stamens begin to form in mid-August, and the pistils begin to form from late August to early September. By the time the fruit is harvested, most of the flower buds have already formed, fully prepared for blooming. In this way, whether the bearing pear tree is in an off year or an on year, if it encounters adverse environmental conditions after harvest that cause all the leaves to drop, it will inevitably be forced into dormancy, thereby completing the physiological dormancy stage necessary before sprouting and blooming. When it lasts until the “little Indian summer of October” (generally October to November), with climatic conditions like those of warm spring days, and with sufficient soil nitrogen and water supply and relatively high carbohydrate production, the flower buds are very likely to sprout a second time and bloom out of season. After the out-of-season flowers develop into young fruit, they die when a cold wave hits and bring no benefit, and they consume a large amount of nutrients, making it even harder to form flower buds a second time, which inevitably affects the blooming and fruit yield of the following year.

There are three main factors that cause all the leaves of a pear tree to drop and the tree to enter a forced dormancy period: first, severe drought; second, severe damage by leaf-eating pests; third, excessive pesticides and hormone stimulation (this generally does not occur). Severe damage by leaf-eating pests is the most important factor among them. The main pests are the pear lace bug (also known as the pear tingid) and the pear psylla. Both pests use piercing-sucking mouthparts to suck the sap of the leaves; after the leaves are severely damaged, they gradually turn brown, dry up and drop, until the whole tree is bare. From July to early September, these two pests have the largest populations and cause the most severe damage among all their generations of the year. During this period, high temperatures and sustained drought weather are most likely to occur; if the three disasters strike together, the pear tree is very easily driven into a forced dormancy period.

Methods to control out-of-season blooming

The methods are simple and easy to carry out. This requires farmers to change the past one-sided approach of “once the fruit ripens, all is done; just wait to harvest the fruit and reap a bumper crop”, and to continue strengthening pear orchard management before and after fruit harvest, doing a good job of drought relief and pest elimination, and strictly preventing massive leaf drop. Before harvest, pay attention to irrigation of the pear orchard; in case of drought, a thorough watering must be given every 10 days, which effectively controls leaf drop and is even more beneficial for improving fruit yield and quality. After harvest, generally a thorough watering once in the middle of a drought is enough to preserve the leaves; the key is to strengthen the control of leaf-eating pests such as the pear lace bug and the pear psylla. Observation should be strengthened, and when pests are found, pesticides should be applied promptly to wipe them out. But note: within half a month before fruit harvest, pesticide application is prohibited in the pear orchard.