What are the main causes of grape berry drop?
Grapevines always experience berry drop during the growing process, and this is a situation that has a relatively large impact on growers' economic returns. There are many reasons for berry drop; the natural environment and insufficient nutrients can both cause this phenomenon. Here we list several reasons for you.
1. Natural berry drop
The survival of the fittest in nature also applies to grapevines, so natural berry drop is a relatively common problem, and the amount of fruit dropped each time is not large, so its economic impact is relatively small. The reason is that during the growth process of the fruit tree, some grape berries do not receive enough nutrients to sustain their growth; the nutrients are taken up by the well-developed berries, and as time passes, these poorly developed berries fall off on their own. To some extent this is actually somewhat beneficial, as it allows the other grapes to obtain more nutrients. Choosing high-quality seedlings can alleviate this situation.
2. Insufficient nutrients
Grapevines generally bear a relatively large amount of fruit, and because of the planting area, growers cannot tend to every single vine in detail, so berry drop caused by insufficient nutrients naturally occurs. At each stage of growth, the types of fertilizer needed and the emphasis placed on them differ. If this situation occurs relatively frequently, growers should adjust the types of fertilizer they apply. Generally, berry drop is mostly related to nitrogen fertilizer, so everyone can pay attention to the use of nitrogen fertilizer. If some vines have clusters with many poorly developed berries, the growers should immediately change their fertilization in a targeted way.
3. Pests and diseases
Berry drop caused by pests and diseases is a relatively serious type; once the disease breaks out, it basically affects fruit in large batches, so extra attention must be paid to this aspect. Canker, water-bag disease, downy mildew, anthracnose and so on are all diseases that relatively easily lead to berry drop, and growers must clearly identify the type of disease and apply the right treatment. Berry drop caused by disease is relatively easy to identify: the surface of the fallen berries will be abnormal, such as rot or soft rot, which is basically disease-related berry drop. As for pests, attention should be paid to things like red spider mites, which are relatively easy to find on grapevines. Besides applying the right treatment, choosing varieties with good disease resistance is also a good preventive approach.
4. Excessive light
Excessive light is mostly caused by improper operation by growers during pruning, and is generally not very serious. When grapevines grow, the branches and leaves become relatively dense; if they are not pruned, a large amount of nutrients cannot be supplied to the berries. It is recommended that growers control the pruning time to after the berries have formed, as this makes targeted pruning convenient and less likely to result in mistaken cuts. Try not to prune the leaves on each fruit cluster; they can be slightly parted so that light can occasionally pass through, which can effectively prevent high temperatures while also meeting the grapes' light requirements.
Grape berry drop actually has some other causes as well; for example, a variety not matching the growing environment can also lead to this situation. Everyone should try to choose varieties suited to their own local area, and when yields are similar, focus on their own local actual conditions, such as cold-resistant, heat-resistant and disease-resistant varieties, according to their own needs.