First, the concept and function of topping
Topping is an important grape management technique that involves removing the tips of new shoots that are growing along with a few young leaves. Through topping, the distribution and transportation of nutrients in the plant can be reasonably adjusted, and the contradiction between nutrient growth and reproductive growth can be coordinated, which is helpful to concentrate the nutrient supply to the needs of effective fruits and reduce the waste of nutrients. Topping plays an important role in preventing grape greed, promoting early ripening, increasing yield and improving quality.
Second, the topping method and technical essentials
The topping covers the topping of fruiting branches, the topping of vegetative branches and the topping of long-growing branches spreading on the main side.
(1) Topping of fruiting branches
1. Purpose and function:
The main purpose of fruiting branch topping is to adjust the nutrient distribution in the tree to improve the fruit setting rate. The new shoots grow rapidly before flowering, and if they are not topped in time, they will consume too much nutrients, which will affect the differentiation of flower buds and the growth of flower buds, and reduce the fruit setting rate. By topping, nutrients can be concentrated in the inflorescence, thereby increasing the fruit setting rate.
2. Topping time:
Fruiting shoot topping can usually be done from a week before flowering to during flowering, but the best time is 3-5 days before flowering. To determine the flowering period of grapes, you can observe the characteristics of the flower buds, such as the color of the flower buds changing from green to dark green or greenish-brown, the flower buds are full of size, and the small flower stalks are erect. These characteristics indicate that the grapes have entered the optimal period before flowering.
3. Degree of topping:
The degree of topping needs to be determined on a case-by-case basis.
At the optimal time for topping, young leaves or shoots smaller than 1/3 of the normal leaf size should be removed. The most suitable time for topping is to remove young leaves that are less than 1/3 the size of normal leaves 3-5 days before flowering or at the beginning of flowering.
For varieties that are prone to flower and fruit drop, 2-3 leaves can be left for topping 7 days before flowering.
For varieties with a high fruit setting rate, 6-7 leaves can be left for topping 2-3 days before flowering.
Varieties with a particularly high fruit setting rate can be plucked more than a week after flowering, leaving 8-9 leaves for topping to maintain the supply of nutrients.
(2) Topping of vegetative branches
Vegetative shoots are winter shoots that form in the previous year and form branches without inflorescences after germination. For the topping of vegetative branches, it is usually more appropriate to leave 7-12 leaves for topping. For the branches with moderate growth potential, 12 leaves can be left for topping, and for the branches with weak growth potential, 7-8 leaves can be left for topping, so as to promote the thickening of new shoots and the enrichment of winter buds at the base. For shoots that are too strong, 10 leaves can be left at the time of the first topping, and a second topping can be carried out when the secondary shoots formed have grown to 7-8 leaves.
(3) Topping of long branches spreading on the main and side sides
The main and lateral spreading branches are mainly used to extend the extensions on the main side vines that expand the canopy. The timing and method of topping are as follows:
For the weaker growth of the extended shoots, the new shoots with stronger lower parts can be selected to replace the original extension shoots, and the topping is carried out when the growth reaches 10 leaves to promote the thickening growth of the branches.
For the mediocre and robust elongated shoots, topping should be done in mid to late September to facilitate the maturation and aging of the elongated shoots.
For the extended shoots with too strong growth potential, topping can be carried out in advance to promote the development of secondary shoots, disperse nutrients, and avoid excessive growth.
Through the above topping methods and technical essentials, it is possible to better manage the vines, increase the fruit setting rate, promote early ripening, increase the yield and improve the quality of the grapes.
summary
Topping is a key management technique in viticulture, which can effectively regulate nutrient distribution, increase fruit set, promote early ripening, increase yield and improve grape quality through different methods of topping. Proper topping is essential for healthy growth and a good harvest.