Seedless grapes: generally treated at the end of flowering.

Triploid grapes: most of them bloom but do not bear fruit, and their fruit-bearing ability is very poor. It is suitable to treat with GA3 from full flowering stage to full flowering stage.

Grape with stone: Generally, it should be treated 1-3 days after flower withering, and the whole ear should be sprayed or dipped.

Suitable period for keeping flowers and fruits of seed grapes (physiological fruit drop period)

2. Cytokinin

Thibenuron and Pifilon: treated 1-3 days after anthesis, and the treatment period varies with varieties, such as Kyoho grape, which is usually treated at the final flowering stage.

PS: Pyridone and thiabendazole are rarely used alone in production practice, but most of them are mixed with GA3, which can improve fruit setting effect and reduce side effects.

3. Plant hormones

For example, spraying 4-CPA (PCPA) on the ear 3-7 days after flowering can improve the fruit setting rate of seedless grapes.

4. Growth inhibitors

Such as paclobutrazol, chlormequat chloride, mepiquat chloride, calcium cyclohexylsulfamate, etc. , can inhibit vegetative growth, promote reproductive growth, make more nutrients into fruit growth, thus improving fruit setting rate.