Introduction to the Technical Methods of Bagging Pear Fruit

1. Bagging effect: it can improve fruit quality, control fruit diseases and pests, reduce pesticide residues, and increase fruit storability.

2. Selection of paper bag types: suitable paper bag types should be chosen according to different cultivars, different climatic conditions, different bagging purposes and economic conditions. For green-skinned pear cultivars, single-layer bags are preferable; for cultivars with large and dense fruit dots, paper bags with strong shading properties should be used. Among Japanese pear cultivars, Housui pear is best suited to a single-layer kraft paper bag coated with paraffin, Kosui is best suited to a bag with a green inner layer and an outer layer that is white outside and black inside, and Xinxing, Niitaka, Okusankichi, Xinsue and others are best suited to double-layer bags with a red inner layer.

3. Bagging period: the time of stomatal and lenticel formation generally begins 10-15 days after flowering, and can last as long as 80-100 days after flowering, with the young fruit stage 10-15 days after flowering being the most concentrated. Therefore, to inhibit the development of fruit dots and obtain fruit with a beautiful appearance, bagging should be done earlier, generally starting 10-20 days after petal fall and completed within about 10 days. If the fruit is bagged and protected only 25-30 days after petal fall, most of the stomata have by then become suberized and brown, forming fruit dots, and the expected effect of bagging cannot be achieved.

4. Bagging method: bagging can be carried out after strict flower and fruit thinning and spraying. When bagging, hold one end of the bag opening between the right thumb and index finger, take a fruit bag off sideways, twist the bag opening open, support the bottom of the bag with one hand, insert the other hand into the bag to open the bag body, pinch the two corners of the bag bottom to open the ventilation and drainage openings at the two bottom corners, and make the whole bag body puff out. Hold the fruit stalk with one hand and the fruit bag with the other, and put the fruit into the bag from bottom to top, placing the fruit stalk at the cut in the middle of the bag opening so that the fruit sits in the middle of the bag body. Squeeze and fold longitudinally from the fruit stalk at the middle of the bag opening toward both sides, fold the bag opening up to the fruit stalk, tear open above the wire notch, turn the tying wire 90 degrees in reverse, rotate it once around the bag opening, and tie the bag opening tightly at 2/3 above the fruit stalk. Then tap the middle of the bag bottom so that the two ventilation and drainage openings at the bag bottom open, and the fruit bag hangs upright.

For pear fruit bagging, it is best to bag the whole orchard and the whole tree, to facilitate centralized and unified management after bagging. If only partial bagging is to be done, choose moderately vigorous or slightly above moderately vigorous trees in the early full-bearing stage; do not choose old and weak trees, falsely vigorous trees, diseased trees or trees in windy openings, and especially do not choose stunted old trees for bagging. For a single tree, bag fewer pears on the due south and southwest sides to reduce the rate of sunburned fruit. Choose fruit on branches in the middle or front-middle part of the tree; do not bag fruit on the inner canopy or the outer tips of shoots; bag fruit on strong branches and strong spurs, and do not bag fruit on weak branches and weak spurs.

5. Bagging precautions: ensure the young fruit sits in the middle-upper part of the bag body and does not touch the bag wall, to prevent stink bug stinging, abrasion, sunburn, and contamination of the fruit surface by pesticide solution, pathogens and insect secretions through the bag wall. Be very careful during bagging; do not touch the young fruit, which would cause artificial "tiger-skin fruit", and do not use too much force, to prevent breaking the fruit stalk, tearing the base of the fruit stalk, or tying the wire so tightly that it affects fruit growth or so loosely that the fruit bag is blown off by the wind. Do not tie the bag opening into a trumpet shape, to prevent accumulation of rainwater; tie it firmly and tightly, to the extent that the fruit stalk is not damaged, to prevent rainwater and pesticide liquid from flowing into the bag or diseases and insects from entering the bag. Be careful not to bag leaves inside the bag. When bagging, do the upper part of the tree first and then the lower part, and the inner canopy first and then the outer part, to prevent knocking off fruit after the paper bags are put on. For a single tree or a single orchard, it is best to bag the whole tree or whole orchard, to facilitate centralized and unified management after bagging. When bagging, try to distribute the fruit evenly within the tree canopy; do not bag too many fruits on one branch, so that the fruit bags are adjacent to one another. It is best to leave a single fruit per inflorescence, and one fruit bag can only hold one fruit.

6. Bag removal: the sugar content of pear fruit decreases somewhat after bagging, and removing the bags before harvest can increase the sugar content of the fruit to a certain extent, but the effect is not obvious, while it has a clear effect on fruit dots and fruit color, that is, removing the bags before harvest reduces the effect of bagging in improving the appearance quality of the fruit. Therefore, for pear cultivars that do not need coloring at the fruit ripening stage, the fruit should be harvested with the bags on, and the bags removed later at grading time, because the skin of bagged pear fruit is relatively tender, and harvesting with the bags on can prevent the fruit from losing water, having its skin bruised, or having its surface contaminated.

7. Supporting techniques for bagging: bagged orchards should strengthen soil, fertilizer and water management, deep-plow to mature the soil and expand the active soil layer, enhance root function, increase the amount of fertilizer applied, and develop a healthy, slightly vigorous tree vigor; note that weak trees should not be bagged. In terms of training and pruning, the amount of branches and leaves should be appropriately reduced, with a reasonable distribution of branches, uniform light, and three-dimensional fruiting. Pay special attention to flower and fruit thinning, with a reasonable crop load, to prevent the tree vigor from becoming too weak and to increase the marketable fruit rate of bagged fruit. In addition, pay special attention to the control of special diseases and pests that appear after bagging, such as yellow mealybug, Kamisongo mealybug (Pseudococcus comstocki), pear psylla, stink bugs, sunburn, water rust and so on.