Is it good to treat grapes during the berry enlargement stage? It needs to be judged case by case

A netizen asked: “Is it good to treat grapes during the berry enlargement stage?” In fact, the grape berry enlargement stage, that is, after the grape berries have set fruit and begin to grow rapidly, when the fruit is nearly the size of a soybean, is called the grape berry enlargement stage. This is the most vigorous period in the grapevine's entire annual growth cycle, and also a key period in the grape's entire annual production, so the treatment during the grape berry enlargement stage must be viewed case by case.

1. Which varieties are suitable for enlargement treatment?

Basically all grape varieties are suitable for enlargement. So whether enlargement can be done depends not on the variety but mainly on the level of management, the size of the cluster, and so on.

For example, in vineyards with extensive management, enlargement agents are not suitable. First, fertilizer and water cannot keep up, so the enlargement effect is not obvious; second, a deficiency of trace elements such as boron, calcium and magnesium makes splitting more likely.

There is another situation: varieties or grape clusters with clusters that are too tight, without prior treatment, are not suitable for enlargement, because after the berries enlarge, the squeezing between berries will worsen, and the squeezing can also easily cause splitting.

As shown in the picture, Kyoho with too many berries set and clusters too tight is not suitable for enlargement, otherwise squeezing is easily caused; after berry thinning, when the cluster tightness is moderate, enlargement can then be carried out. After cluster elongation and berry thinning, Treasure grape can still undergo enlargement treatment; after cluster elongation and berry thinning, Frey grape can likewise undergo enlargement treatment.

2. What are the benefits of enlargement treatment?

1. Berries become larger, especially for seedless varieties

For example, Crimson Seedless, through enlargement, can have its berries go from 4-5 g to ~8 g; Summer Black, through enlargement, can have its berries go from 5-6 g to 8-12 g; Frey, through enlargement, can have its berries go from 3-4 g to 5-6 g;

2. It can promote the seedlessness of seeded varieties

Through enlargement treatment, Muscat Hamburg, Jingya and Kyoho can be turned from seeded varieties into seedless varieties, improving the marketability of the fruit.

3. It makes up for defects in the fruit, giving good marketability and promoting sales

For example, Kyoho with poor fruit set, through enlargement, has its berries become tightly packed, improving marketability

3. Timing of enlargement treatment

If enlargement treatment is too early, the fruit stalk becomes thicker and more severely hardened, and it is also prone to forming tough fruit; if too late, its natural enlargement period is missed and the effect is not obvious. So the timing must be paid close attention to.

Golden Finger grapes treated for enlargement 7 days after flowering had severely thickened and hardened fruit stalks. Recommended enlargement timing:

One treatment after flowering: the treatment time is about 15 days after flower drop.

Two treatments after flowering: treat once 12 days after flower drop, then after an interval of about 7-10 days, treat a second time.

In addition, there is another issue to note with enlargement treatment: because of the many cell divisions, the large berries and the rapid growth of the flesh, the growth of the skin and the growth of the flesh are not coordinated, which will moderately increase the risk of splitting. Therefore, the amount of calcium fertilizer used must be increased. For different varieties, use enlargement agents in a targeted way, and be sure to increase fertilizer and water inputs. When fertilizer and water conditions are sufficient, the correct use of enlargement agents will not affect the internal quality and taste of the grapes.