Practicing Mechanical Thinning on Apple Trees
Mechanical thinning is a complementary technique to other thinning strategies allowing the reduction of chemical thinners on apple tree. The tools used, of the pre-floral type, allow total or partial destruction of flowers using wires to control fruit load.
Conditions for effectiveness :
For better effectiveness, it is recommended to intervene at most up to stage F (central flower open), otherwise there is a risk of removing rosette leaves or damage to fruits. The later the intervention, the greater the risk of injury to young fruits.
Moreover, the orchard must be managed in a "hedge fruit-growing" system, with low thickness and limited height (decreasing efficiency gradient from outside to inside).
However, for orchards with volume shapes, it is necessary to adapt pruning to have sufficient porosity and avoid branches that are too large, which are an obstacle to good intervention.
Furthermore, plots must be slightly uneven and relatively flat, alleys must be long and turning spaces spacious. Plots must also have high and homogeneous flowering.
Implementation means :
There are two wire-drawn tools :
- A tool adapted to the fruit wall or central axis of low thickness. Tool adjustment is crucial to increase the effectiveness of the technique : forward speed 7 km/h, rotation speed 350 rpm, number 270, wire density and length, as well as attack angle.
- A tool under experimentation adapted to volume shapes.
This technique requires monitoring by observations of the load after intervention and the damage caused to the foliage.
The removed leaf surface plays an important role in load regulation (intensity of physiological fruit drop at fruit set).
Details on the technique :
The effectiveness of thinning is closely linked to tool settings and tree architecture. The forward speed must remain constant, as well as the tree-tool distance.
Beware of using the Darwin® in rainy conditions due to increased depressive effect on wet foliage.
Beware of "over-thinning" when the mechanical tool is used with a chemical thinning program.
It is advised to avoid using the tool on young trees to avoid removing the apex of young shoots.
Application of the technique to...
All crops : Sometimes difficult to generalize
In the case of apple trees, the technique is applied to most commercial varieties.
All climatic contexts : Easily generalizable
Easily generalizable
Interventions independent of climate (except on wet foliage for Darwin®)
Effects on the sustainability of the cropping system
Environmental criteria
Effect on air quality : Increasing
phytosanitary emissions : DECREASE
Effect on water quality : Increasing
pesticides : DECREASE
Other : No effect (neutral)
Comments :
Reduction of chemical thinners (reduced doses or even suppression of applications). Possibility to eliminate all pre-floral chemical thinners
Agronomic criteria
Productivity : Variable
Variable
Risk linked to early intervention in case of spring frosts
Risk of too strong vigor rebound
Heterogeneity (except if fruit wall) in fruit distribution (less with handheld tools because the intensity of work can be visually adapted)
Production quality : Variable
Variable
No effect on roughness.
Mechanical thinning can cause fruit damage if performed late compared to recommended stages.
Damaged fruits can only be destined for the processing market.
Depending on the year's climatic conditions, risk of reduced fruit coloration linked to increased vegetative growth of shoots.
Functional Biodiversity : Variable
Variable
Important to protect bees. For this, it is advised to favor tool use in the morning and avoid too late use (full bloom) on sunny days.
Economic criteria
Mechanization costs : Variable
Reasonable investment cost and low maintenance cost Darwin® ~ €9000 (usable on about 30 ha)
Social criteria
Working time : Decreasing
Decreasing
Working time with the Darwin® tool is between 1 to 3 h/ha. Note that in some situations manual fruit thinning can reach 250 to 300 h/ha in the absence of a thinning technique on flowers or very young fruits.
This technique reduces the use of manual and chemical thinning. However, wire tools alone are insufficient and thus require one or more additional manual, mechanical, chemical passes.
Favored or disadvantaged organisms
Bioagressors favored
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Fire blight | pathogen (bioagressor) | Potential risk of transmission of fire blight through wounds caused by the tool. Avoid using the tool in case of fire blight present or declared in previous years. |
For more information
- Apple tree management. Mechanical thinning to reduce the use of chemical substances - Roche L., Codarin S., Mathieu V., Saffray C. - Ctifl, Technical brochure, 2010 - Infos-Ctifl, 261, 45-49 - http://www.ctifl.fr/ecophytopic/infos_ctifl/infos%20261/261p45-49.pdf
- Apple tree thinning - Mathieu V., Lavoisier C., Ferré G. Ctifl editions, Technical brochure, 2011 - Paris, Hortipratic collection, 221-233.
- Mechanical thinning on apple and peach - Vittone G. 2010 - Experimentation 2009-2010. Presentation on 06/11/2010 at La Pugère.
- Pre-floral mechanical thinning of apple. Physiological and agronomic points - Roche L., Codarin S. - Ctifl, Technical brochure, 2014 - Infos-Ctifl, 300, 30-36.
- Mechanical thinning using the Darwin® machine - Fruit Tec, Technical brochure http://www.arbo-viti.com/catal-darwin.pdf
Sources
- Information initially from the Guide for the design of fruit production systems economical in phytopharmaceutical products (2014) / Technical sheet n°10 - For more information https://www.gis-fruits.org/Actions-du-GIS/Guide-Ecophyto
Appendices
S'applique aux cultures suivantes
Favorise les bioagresseurs suivants
