One strategy, and probably the last one, for load regulation is early fruit thinning, which is a very good alternative to improve the size and condition of the cherry. It is recommended to thin out the fruit when the stone begins its hardening stage, thus having the advantage that the fruit setting is already defined, approximately 20 to 25 days after full blossom (DDPF).
For fruit thinning to be effective, it must end at most 30 to 35 days after full bloom, which is where the fruit cell division process physiologically ends.
“It is a somewhat subjective task, there is no calculation that can be estimated to eliminate or to make the decision to eliminate a % of fruit from the plant. There is a super limited time to do it and although it can be done up to 30 days after full flower, the first 15 days after full flower there is not such a clear expression of what the setting is, therefore, about 15 or 20 days after full flower the setting can only be evaluated and technically the time for this task is 10 days later, so there is also the time pressure that does not allow for so much flexibility.” said Carlos Tapia, Director of Avium SpA.
Both flower thinning and fruit thinning are very labor-intensive tasks. It is estimated that, depending on the type of orchard, some 70 days per hectare could be considered for this task versus 40 or 50 days per hectare for bud thinning and depending on these three types of load adjustment.
In the case of fruit thinning, the later the task is carried out, the less effect there is on the final characteristics of the fruit and the less effect there is on the vegetative characteristics of the plant. However, studies in Chile recognize that any of these treatments carried out properly and based on a technique are effective compared to a control treatment without load regulation.
A work carried out by María Dolores Raffo and Tadeo Ballivian, published by the Fruticultura & Diversificación Magazine Nº 48. EEA Alto Valle in Argentina, based on a research carried out in 2005 on the results of an early thinning test of fruit in the Lapins and Sweetheart varieties, revealed that when evaluating the distribution of sizes within each treatment and variety it was observed that thinning managed to increase the percentage of fruit in the Jumbo (26.1 to 28 mm) and Premium (greater than 28.1 mm) categories. In the thinned trees, 74% of the fruit was obtained within the Jumbo and Premium categories, while in the control only 36% of the fruit fell into these categories. The Lapins variety was the one that had better results than Sweetheart, which could be because it has a smaller size than Lapins.
The research concluded that the 94% of the thinned fruit of the Lapins variety presented exportable sizes (greater than 24 mm), while in the control the proportion of exportable fruit was 76%. As for the Sweetheart variety, the proportions were 91% for the thinning treatment and 84% for the control.
For its part, among the multiple studies carried out in Chile, it has been recognized that although earlier thinning in the case of buds and flowers is more effective for improving size, thinning of fruits ending before 35 DDPF always has a positive effect compared to the control without load regulation.
However, in the event of a deficiency in load regulation management, it is always advisable to intervene in the plant by removing excess fruit, even if it is a decision that may be made late in the season.
“The size and final condition of the fruit is mainly determined by seeking an optimal leaf/fruit ratio, recognized in the international scientific world as 3-4 leaves per fruit (200 cm2/fruit). If the decision to remove fruit from the plant is late, there is always an advantage in doing so, since the only way to improve this leaf/fruit ratio is by eliminating the excess fruit.
Perhaps this operation will not have a great impact on the final size of the fruit, but it will be positive in the distribution of sugars and nutrients, improving some nutritional indicators and °Brix and internal dry matter content. the expert added.
Bibliographic references.
- Carlos Tapia-Personal communication.
- Importance of regulating fruit load - Agronomy and Forestry UC-Marlenne Araya-Paula Wedeles.
- Regulation of fruit load in cherry trees: a practice that allows increasing export volumes - Fruiting and diversification - Dolores Raffo-Tadeo Ballivian.
