What are the key points of pear tree bloom-period management? Explained clearly in one article

The quality of pear tree bloom-period management directly affects pear fruit yield and quality, so refined bloom-period management lays a solid foundation for the whole year's management. So what are the key points of pear tree bloom-period management?

1. Pre-bloom topdressing

Pre-bloom topdressing can improve flower bud quality, meet the nutrients consumed by blooming, and increase the fruit-setting rate. Half a month before blooming, apply quick-acting fertilizer mainly composed of compound fertilizer, generally 0.5-1 kg per mature tree; for weak trees, add 1-2 kg of urea. The fertilization amount should account for 10-15% of the whole year.

2. Pre-bloom supplementary pruning

For pear trees that were pruned too lightly and retain too many flowers, supplementary pruning should be carried out, mainly to thin out slender weak branches, diseased and dead branches, and overly dense branches, and to regulate the tree's load. Determine the number of flowers to retain according to the number of fruits to retain; generally the number of flowers retained should be 1-2 times more than the reserved fruit quantity. Keep only 1 flower bud per fruit spur and thin out excess flower buds. For varieties that are insensitive to pruning response and not easy to form flowers, a string of flower buds formed by leaving growing branches unpruned should be appropriately shortened, which can bring fruiting branches closer to the trunk and also promote the growth of new branches, preparing for future fruiting.

3. Flower thinning and artificial pollination

Pear tree flower buds are compound buds, with as many as 5-18 flowers per inflorescence, and blooming consumes a large amount of tree nutrients. Thinning out excess flowers can concentrate the tree's nutrient supply and increase the fruit-setting rate. Flower thinning can be done when the inflorescences separate, keeping 1-2 side flowers per inflorescence. For varieties with a low self-fruit-setting rate, pollinizer trees should be properly arranged. If pollinating varieties have not been properly arranged, artificial pollination should be used. For artificial pollination, 2-3 days before pollination, collect fully swollen flower buds or just-opened flowers from mature trees of suitable pollinating varieties, take the anthers, dry them to release pollen, and concentrate manpower on artificial point pollination at the beginning of full bloom.

4. Boron spraying at bloom period

Boron can promote pollen tube germination and elongation and promote the transport of sugars within the tree. Boron spraying at bloom period can increase the fruit-setting rate of pear trees. When 25% and 75% of flowers have opened, spray once each time with a 0.3-0.5% borax (boric acid) solution, adding 0.3-0.5% urea. Blooming requires large amounts of phosphorus and potassium, so adding or separately spraying a 0.3% potassium dihydrogen phosphate solution can also increase the fruit-setting rate.

5. Frost prevention at bloom period

Pear trees bloom early, and the bloom period is mostly before late frost, making them highly susceptible to late frost damage. After pear flowers are frozen, the female pistils turn brown and shrink, and although they bloom, they cannot set fruit. There are several methods of frost prevention:

1. Pre-bloom irrigation can lower soil temperature, delay root activity, postpone the bloom period, and reduce or avoid the harm of late frost.

2. Whitewashing the trunk: whitewashing the trunk before blooming can make the tree temperature rise slowly and delay the bloom period by 3-5 days, avoiding or reducing frost damage.

3. Smoke frost prevention: smoke can reduce the radiation and loss of soil heat and has a moisture-retaining effect. At the same time, smoke particles can absorb moisture, causing water vapor to condense into liquid and release heat, raising soil temperature and reducing or avoiding frost damage. During the bloom period, local weather forecasts should be listened to.

When the temperature may drop to -2°C, frost prevention is needed. Commonly used smoke materials include sawdust, straw, firewood and grass, tree leaves, etc. Pile them in layers and alternately, with kindling inserted in the middle to help ignite and produce smoke. Before smoking, organize manpower into sections with dedicated personnel on duty, hang a thermometer 1 m above the ground, and record the temperature at fixed times. If the temperature suddenly drops to 0°C in the early morning, ignite the smoke. When igniting, follow unified orders and proceed simultaneously. After igniting, be careful to prevent open flames, make it emit thick smoke as much as possible, and be careful not to scorch the tree trunk and branches.

Frost-prevention smoke agents can also be used for frost prevention. The commonly used formula is ammonium nitrate 20-30%, sawdust 50-60%, waste diesel oil 10%, and fine coal powder 10%. The finer the ammonium nitrate, sawdust, and coal powder, the better. After mixing in proportion, put it into an iron cylinder and ignite it when used. The dosage is 2-2.5 kg per mu. Note that it should be placed on the upwind side.