How to Control Grape Aphids and Green Leafhoppers, Methods for Fresh-keeping and Storage, and Timing of Base Fertilizer Application

Grapes are one of the fruits currently sold in relatively large quantities, and it is now the season for eating grapes, with all kinds of grape varieties available on the market. For farmers, grapes with good flavor bring greater returns, so in terms of cultivation, how do you control grape aphids and green leafhoppers? How do you keep grapes fresh for storage? When should base fertilizer be applied to grapes?

I. How do you control grape aphids and green leafhoppers?

Aphids and green leafhoppers both belong to the piercing-sucking pest category, use the same pesticides, and their control methods differ slightly. Aphid control only requires even spraying. For green leafhopper control, however, you need to spray the outer perimeter of the orchard first, then spray inside the orchard. The reason is that green leafhoppers have strong migratory ability; if you apply pesticide starting from inside the orchard, they will fly to the outside of the orchard, so by spraying the outer perimeter of the orchard first, you block off their escape route, achieving the effect of encircling and annihilating them throughout the entire orchard.

II. How do you keep grapes fresh for storage?

Modern storage mostly uses controlled atmosphere and refrigeration, with relatively complex equipment, while rural areas currently mainly adopt simple storage methods, such as cellar storage, vat storage, as well as sulfur dioxide fumigation storage and mini cold storage, among other types of storage.

1. Cellar storage. People in northern China have experience in storing grapes in cellars, generally building the cellar on a hillside or on the edge of a plateau, with 4-6 tiers of wooden racks set up inside the cellar, and one layer of grape clusters placed gently on each tier. The specific methods of cellar storage management are:

① After harvesting, pre-cool the grapes in a shady place for 2 days. The pre-cooling temperature must be controlled below 10°C, so that the field heat is fully released. Then carefully place the grapes on the racks inside the cellar.

② Control the temperature and humidity inside the cellar. Generally, in the early stage of cellaring, since the outside air temperature is relatively high, ventilation measures can be used to keep the temperature below 10°C. After winter begins, the air temperature drops, and the method of ventilating by day and closing at night can be used to keep the cellar temperature at 0-1°C. A relative humidity of 80%-90% is preferable; when humidity is insufficient, water can be sprayed on the ground to maintain moisture. When the outside temperature drops below 10°C, attention should be paid to sealing the cellar door.

③ Strengthen inspection and promptly remove diseased clusters and rotten berries.

2. When the quantity of grapes to be stored is relatively small or when storing courtyard grapes, the vat storage method can be used; in the North China area, household vats or jars are commonly used for storage. Before storage, wash the vat clean, let it dry, then load the grape clusters. The methods of loading the clusters are:

① Direct loading method: gently place the grapes into the vat, laying them flat layer by layer, filling to 2/3 of the vat, and covering the top layer with a layer of disease-free, undamaged cabbage leaves. In the early storage period, turn and inspect the vat once every 10-15 days. When the temperature is high, pay attention to ventilation (opening the lid), and when the temperature drops to -5°C, pay attention to covering the vat opening well and keeping it warm, so that the temperature inside the vat remains at 1-2°C. In some places, people sprinkle dry powder of chili branches and leaves at the bottom of the vat, which also has a clear bactericidal and fresh-keeping effect.

② Partitioned loading method inside the vat: after washing the vat clean and letting it dry, make wooden rack frames of different sizes in a “#” shape according to the slant of the vat wall, with the bottommost tier 10 cm from the vat bottom, placing one layer of grapes on each tier, with 5-6 layers per vat, then seal the vat opening tightly with newspaper pasted over it, and generally no further turning of the vat is needed. This method generally allows grapes to be stored until around the Spring Festival.

III. When should base fertilizer be applied to grapes?

The timing of base fertilizer application differs somewhat by region. Generally, for greenhouse grapes and early-maturing varieties, it is best to apply around the Autumn Equinox; for late-maturing varieties, apply fertilizer immediately after harvest.

Applying too early: the aboveground part of the grape is still growing, and deep digging during base fertilizer application damages the root system, which causes excessive leaf transpiration and leads to leaf drying.

Applying too late: the ground temperature drops, root activity tends to stop, leaf function ceases, so fertilizer utilization rate is greatly reduced, fertilizer efficiency takes effect slowly, and its effect on spring flowering and fruit setting and new shoot growth of the fruit tree is relatively small. If delayed until spring, it cannot meet the energy needed for spring grape budding, but instead begins to take effect in summer, which easily causes excessive vegetative growth of grapes, leading to unstable fruit setting, uneven berry sizes, and so on.