How to manage grapes during the flowering period? Detailed explanation of 6 key points
The period from grape flowering to young fruit swelling is a very important stage in the grape growth cycle. Whether the management at this stage is in place directly affects the grape yield and quality of that year. Below is a detailed explanation of the 6 key points of grape flowering period management.
1. Topdressing
To ease the competition for nutrients between vegetative growth and reproductive growth during the flowering period, and to meet the needs of flowering and fruit setting, topdressing must be carried out before and after flowering, and a 0.2%-0.3% boric acid or borax solution should be sprayed before flowering to promote pollen tube elongation and increase the fruit-setting rate. At the same time, branch and vine management should be done well to improve ventilation and light conditions in the vineyard. During the grape flowering period, in order to save nutrient consumption, work such as tying vines, removing secondary shoots, pinching tips, pinching off ear tips, and removing secondary clusters should be carried out in time.
2. Strengthen temperature and humidity control
For grapes grown in greenhouses, attention must be paid to controlling the temperature and humidity inside the greenhouse. To increase the pollen germination rate and ensure smooth pollination and fertilization. Greenhouse temperature management targets: maintain around 28 degrees C during the day and 16-18 degrees C at night. Humidity control: upon entering the flowering period, stop irrigation, keep the air humidity inside the greenhouse at around 50%, and pay attention to frequent ventilation. For open-field grown grapes, temperature is difficult to control, but soil moisture should be managed through measures such as loosening the soil and reducing humidity, striving to make the vineyard humidity favorable for flowering and fruit setting.
3. Thinning inflorescences
Thinning inflorescences is carried out from 10 days before flowering to the beginning of flowering, according to the strength of the new shoots and the size of the plant load. When there are more than 2 inflorescences on 1 fruiting branch, remove the weak and small ones among them, and remove the inflorescences on weak fruiting branches, so that strong fruiting branches have 1-2 inflorescences, medium-strong branches have 1, and weak branches have none.
Leaving 1 inflorescence on extension branches can control excessive growth, and leaving no inflorescence on reserve branches keeps their growth robust. The number of inflorescences retained should be about 1/4 more than the planned number, and after fruit setting, remove those clusters with severe fruit drop
4. Cluster shaping
Reasonable inflorescence trimming can greatly reduce the workload of fruit thinning, standardize the fruit clusters, facilitate fruit packaging, and improve the uniformity of the commercial appearance.
(1) Tip-only shaping: the clusters are neat and attractive, fruit thinning is easy, the workload is small, bagging is easy, and cluster diseases are fewer. The suitable period for inflorescence shaping is from 1 week before flowering to the beginning of flowering. For Kyoho, Pione, Jingya, Cuifeng and other Kyoho-series varieties, leave 3.5-4.5 cm of the ear tip, 8-10 segments of spikelets, and 50-60 flower buds. For diploid and triploid varieties, such as Wink, Red Globe, White Rosario, Summer Black and other varieties, generally leave 5-6 cm of the ear tip.
(2) Cluster trimming method for seeded cultivation of Kyoho-series grape varieties: remove the secondary ear and the following 8-10 spikelets, retain 15-20 segments, and remove the ear tip.
(3) Cluster trimming method by cutting short overly long branches: the clusters are neat and attractive, cluster diseases are fewer, and the cluster size is moderate, but the operation is slightly more complicated than leaving only the ear tip. This method is commonly used for varieties such as Summer Black, Giant Rose, Shine Muscat, etc. From 2 days before flowering to the 3rd day of flowering, pinch off excess flower buds on the 3-4 longer branches at the shoulder of the inflorescence, leaving flower buds about 1-1.5 cm long, and shape the inflorescence into a cylindrical form. The length of the inflorescence does not need to be trimmed at this time. For inflorescences with secondary ears, remove the secondary ears promptly after the inflorescence unfolds.
(4) Branch thinning by removing one out of every two: simple and practical, the cluster size is moderate and loose, and ventilation and light penetration are good, but there are many wounds in the middle of the cluster, making it prone to disease.
(5) Palmate shaping: cutting off the middle and lower part of the cluster and leaving the branches in a palmate shape. In this way, the cluster is wider, bagging is inconvenient, the permeability in the middle of the cluster is poor, it is easy to squeeze and crack the fruit, and sour rot is severe in the later stage.
5. Artificial supplementary pollination for female-flower varieties
Most grape varieties are bisexual flowers and can be naturally fertilized. However, because the stamens of female-flower varieties degenerate, pollination is needed to obtain higher yields. Therefore, attention must be paid to artificial supplementary pollination.
6. Pest and disease control
The main grape diseases during the flowering period include downy mildew, gray mold, rachis blight, white rot, anthracnose, powdery mildew, black pox, etc. The main insect pests include thrips, green plant bugs, clearwing moths, red spiders, aphids, mealybugs, scarab beetles, etc. Preventive pesticides must be applied well 2-4 days before grape flowering.