Prophylaxis by Managing Leaf Litter in Orchards
1. Presentation
Characterization of the technique
Description of the technique:
Information originally from the Guide for designing fruit production systems that are economical in phytosanitary products (2014) / Technical sheet no. 11. To learn more See link
Principle:
This technique consists of removing leaf litter or accelerating its degradation to reduce the inoculum of certain bio-aggressors. It is a prophylactic method particularly interesting in orchards with high inoculum.
Removal, shredding, and burying are the means used to manage leaf litter. The two modalities removal/burying and shredding/burying are effective against scab. However, removal shows better effectiveness than shredding.
Example of implementation:
Practical applications of the technique: three possible modalities
- Removal or shredding of leaves on the inter-row
Removal
– A brush sweeper or a rotor blade vacuum collector (attached to the rear of the tractor) removes leaves from the inter-row; it can also be combined with a satellite (rotary brush) that brings leaves from the edge of the grassed area back onto the inter-row to allow the sweeper to vacuum them. One round trip per inter-row is necessary.
Shredding
– A shredder with knives (better than hammers) allows fine shredding of leaves on the inter-row. Useful on frost days because of better shredding.
- Management of leaves on the row
Moving leaves from the row to the inter-row
– A blower or a brush allows moving leaves onto the inter-row to then shred or remove them
Burying leaves on the row
– A disc subsoiler allows burying leaves on the row (hilling)
- Application of urea
– Spraying urea (5%) on the row and inter-row accelerates leaf degradation (by stimulating microbial activity) and also has an inhibitory effect on fungal development (scab)
- In autumn, at the beginning of leaf fall (early to mid-November), targeting the foliage, and/or,
- In spring (March), with a sprayer, jets directed downward (top jets closed), ventilation off to target the litter or with a weeding boom.
NB: In orchards with significant autumn inoculum, combining these modalities is recommended.
Details on the technique:
To ensure maximum effectiveness, certain conditions must be considered:
Removal/shredding/burying should be done after leaf fall is complete, avoiding wet periods (difficulty removing leaves).
For burying, the irrigation system must be compatible (suspended or buried).
Urea application (not usable in organic farming) should be done during the first third of leaf fall or in spring just before bud break.
Implementation period
Spatial scale of implementation Plot
Application of the technique to...
All crops: Easily generalizable
Easily generalizable
Technique can be adapted to various fruit species
Regulation
2. Services provided by the technique
3. Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on air quality: Increasing
Phytosanitary emissions: DECREASE
Effect on water quality: Increasing
N.P.: NEUTRAL
Pesticides: DECREASE
Effect on fossil resource consumption: Increasing
Fossil energy consumption: INCREASE
Other: No effect (neutral)
Comments
Nitrates: The risk of nitrate leaching linked to urea application is negligible because the quantities applied are very low (20 U), the nitrogen is partly immobilized by the leaves and the urea form transforms rather slowly into nitrates in winter.
"Agronomic" criteria
Productivity: Variable
Variable
Burying is interesting in orchards with mechanical weeding. Otherwise, superficial roots risk being damaged by the soil working tool once a year.
Soil fertility: Variable
Variable
If leaves are exported, the soil organic matter balance will be penalized. To compensate for this negative effect, it is possible to make compost outside the orchard and then spread the compost in the orchard.
Regarding urea application, if done in autumn/winter on waterlogged soil, there is a risk of compaction.
Urea input in autumn (20 U) or spring (3-5 U) has a low impact on the nitrogen balance.
Functional Biodiversity: Variable
Variable
If combined with soil work, burying leaves causing repeated passes especially under poor conditions related to burying leaves can disturb soil macrofauna (earthworms, ground beetles).
"Economic" criteria
Operational costs: Increasing
Increasing
Cost of passes for the different leaf litter management modalities
Mechanization costs: Variable
Variable
For leaf litter removal, need to purchase suitable equipment
– Rotor blade vacuum sweeper €15,000–20,000 excl. tax
– Brush sweeper: half the price
NB: purchasing in a Cuma (farmers' cooperative) can help amortize the equipment.
For shredding, no specific tool purchase except equipping the shredder with a set of knives (€350 with wear on stony ground after 15 ha)
"Social" criteria
Working time: Increasing
Increasing
Working time:
Removal 1-2 h/ha
Fine shredding 1 h/ha per pass with one to three passes depending on shredder width, shredding fineness, and period
Burying/hilling 4 h/ha
Urea application 45 min/ha
Peak period: Variable
Variable
Burying:
Potential of about 30 ha per machine (difficult to do more, as the suitable periods for its use are limited, between the end of leaf fall and before rain or snow which limits agricultural machinery passage and/or sweeping efficiency…).
It is necessary to be in a "bud break" situation before leaf fall begins to facilitate leaf accumulation on the row throughout their fall before burying by hilling.
- Issue: winter pruning may have started before tool passage (at 100% leaf fall), making leaf removal or shredding difficult (reduces effectiveness) due to the presence of pruning debris.
4. Organisms favored or disadvantaged
Favored Bioagressors
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged bioagressors
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Pear scab | pathogen (bioaggressor) | ||
| Apple scab | pathogen (bioaggressor) | ||
| Weeds | weeds | Burying the litter helps destroy weeds |
Favored Auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged Auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Predatory and granivorous ground beetles | Natural enemies of bioaggressors | Burying combined with soil work can disturb ground beetles | |
| Earthworms | Soil functional organisms | Burying combined with soil work can disturb earthworms |
Favored climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
Disadvantaged climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
5. For further information
- Effect of four non-chemical sanitation treatments on leaf infection by Venturia inaequalis in organic apple orchards.
- -Holb I.J.
Peer-reviewed journal article, 2007
Europ. J. Hort. Sci., 72 (2) S, 60-65.
- Scab in apple orchards - Autumn cleaning is better with it.
- -Gomez C., Brun L., Chauffour D., De Le Vallée D.
L’arboperformance, Technical brochure, 2005
L’arboperformance, 592, 23-26.
- Integrated fruit production guide, 2014
- -Regional Chamber of Agriculture Paca, La Pugère Station.
Book, 2014
Objectifs Info Arbo, 24-25.
- Integrating scab control methods with partial effects in apple orchards: the association of cultivar resistance, sanitation and reduced fungicide schedules
- -Didelot F., Caffier V., Baudin M., Orain G., Lemarquand A., Parisi L.
Conference proceedings, 2008
7th International Conference on Integrated Fruit Production, 27-30/10/2008, Avignon. IOBC/WPRS Bulletin, 54. 2010. 525-528.
- Benefits of reducing primary scab inoculum in apple orchards
- -Brun L., Gomez C., Dumont E.
Phytoma, Peer-reviewed journal article, 2005
Phytoma – Plant protection, 581, 16-18
- Return to prophylaxis against scab
- -Crété X.
2005
Réussir fruits et légumes, 243, 46-47.
- Innovative protection strategies against apple scab: design, evaluation and integration in orchards
- -Brun L., Didelot F., Parisi L.
Innovations Agronomiques, Peer-reviewed journal article, 2007
Innovations Agronomiques, 1, 33-45
6. Keywords
Bioaggressor control method: Physical control
Mode of action: Avoidance Action on initial stock
Type of strategy regarding pesticide use: Substitution
Annexes
S'applique aux cultures suivantes
Défavorise les bioagresseurs suivants
Défavorise les auxiliaires
