General Grape Bagging Time, Price, Pre-Bagging Spraying and Key Technical Points
Bagging grape berries can improve the smoothness and finish of the fruit surface and enhance coloring. As an important technical measure for pollution-free fruit, it has already been widely used in production. So when should grapes be bagged? How much does it cost per bag? What should be sprayed before bagging? What are the key technical points? According to the Changsha grape planting base, the appropriate type of fruit bag should be selected according to the variety and the different climatic conditions of each region. Prices differ for bags of different specifications, generally a few cents per bag.
When should grapes be bagged?
The bagging period for grapes generally begins immediately after the fruit set is stable and the clusters have been trimmed and the berries thinned, and ends before the rainy season arrives, to prevent early infection diseases and prevent sunburn. Bagging should avoid high-temperature weather after rain or weather that suddenly clears after continuous overcast and rainy days; generally 2-3 days should pass, and bagging should be done after the fruit has slightly adapted to the high-temperature environment.
What should be sprayed before bagging grapes?
1. Before bagging, the orchard should be thoroughly sprayed with a fungicide, with emphasis on spraying the fruit clusters, and bagging should be carried out after the spray liquid has dried. First soak 6-7cm of the bag opening end in water to make it moist and soft, so it is easy to shrink the bag opening. When bagging, first use your hands to open the paper bag and make it bulge, then put the entire fruit cluster into the bag from bottom to top. Then shrink the bag opening onto the cluster stalk and tie it tightly with the sealing wire on one side. Above the wire, leave 1—1.5cm of the paper bag; when bagging, it is strictly forbidden to rub the fruit cluster with your hands.
2. After spraying the grapes, bag them promptly once the spray liquid has dried, preferably finishing the same day. If there is no rain and no dew at night, finish bagging within two days at the latest. For large vineyards, work can be done block by block; according to labor and bagging speed, calculate the number of bags that can be done in one day, and spray only as much as can be bagged. Never bag before the spray liquid has dried, as this can also easily cause fruit rot. Also note that when bagging, try to avoid touching the berries with your hands, and be sure to tie the upper opening tightly to prevent rainwater leakage.
3. Do not spray when there is dew, strong sun, or strong wind; it is best to spray from 7 to 10 a.m.; spraying should be even, not excessive, and especially not missed. For trellis grapes, both sides should be sprayed, and for overhead trellises, both sides of the fruit clusters should also be sprayed; use effective pesticides such as mancozeb, thiophanate-methyl, DuPont Fuxing, etc., and by all means do not spray fake pesticides. When spraying, choose a fine swirl disc for the sprayer nozzle, which helps make the spray fine and even.
What are the key technical points for grape bagging?
1. Do a good job of management before bagging. 1. Fertilize according to soil fertility; 2. Before bagging, the orchard must be watered thoroughly once, and bagging begins after the ground dries; 3. Spray the grapes to be bagged once with a fungicide, using 70% thiophanate-methyl at 800 times plus 40% Wenjianjun at 800 times; 4. Thin out small berries, diseased berries, deformed berries, etc. from the fruit clusters to improve grape quality.
2. Choose suitable paper bags. According to the micro-environment of grape growth and the shape and size of the clusters, choose paper bags with strong wind and rain resistance, good air permeability, high light transmittance, high hydrophobicity, and antibacterial properties.
3. Bag at the right time. Choose the bagging time around mid-June, before 10 a.m. or after 4 p.m. When bagging, use your right hand to open the bag opening, and your left hand to support the bottom of the bag, so that the ventilation and drainage openings on both sides of the bag bottom open; pull the bag upward from below, place the fruit stalk at the slit above the bag, position the fruit cluster in the center of the bag, and tie the bag opening tightly with wire.
4. After bagging, it is no longer necessary to spray pesticides targeting fruit diseases and pests; the focus is on preventing and controlling diseases and pests of grape leaves such as leafhoppers and downy mildew. Closely observe pests that easily enter the bag and cause damage, such as maize weevil, pasture bugs, citrus mealybug, and tea yellow thrips; when the damage is severe, the bags can be opened and pesticides applied. Pesticides can include 50% fenpropathrin-cypermethrin EC at 2000-3000 times, 48% Lorsban at 1200-1500 times, etc.
5. After bagging, grapes can be harvested with the bags on, or the bags can be removed about 10 days before harvest. Red varieties can have their bags removed about 10 days before harvest to increase light exposure to the fruit and promote good coloring. Varieties such as Kyoho generally do not need bag removal, and the goal of harvesting in stages can also be achieved by removing bags in batches. In addition, if the paper bag used has high light transmittance and can meet the coloring requirements, the bags may also be left on to produce clean and pollution-free fruit. When removing grape bags, do not remove the fruit bags all at once; first open the bag bottom and let the fruit bag remain over the upper part of the cluster to prevent bird damage and sunburn. Bag removal should be done before 10 a.m. or after 4 p.m. on sunny days, and can be done all day on cloudy days.
6. After removing grape bags, generally there is no need to spray again, but the progress of fruit coloring must be closely observed. After bag removal, some aged leaves near the fruit clusters and overly dense branches and vines on the trellis can be pruned to improve ventilation and light conditions on the trellis surface, reduce disease and pest damage, and promote fruit coloring, but note that leaf removal must not be excessive or too early. It is worth pointing out that leaf removal should not be done at the same time as bag removal, but should be done in stages and batches to prevent sunburn.