Installing Rain Covers in Orchards
1. Presentation
Characterization of the technique
Description of the technique:
Information originally from the Guide for the design of fruit production systems economical in phytosanitary products (2014) / Technical sheet no. 23. For more information: see link
Principle:
This technique, currently under study, consists of installing a plastic tarp "rainproof" above the trees so that the foliage is not wetted during rainy episodes.
The expected effects against various diseases (scab on apple and pear, moniliosis on cherry and mirabelle plum, gloeosporium on apple) have been under experimentation for several years but are not yet validated.
Example of implementation:
Example of application
On apple trees:
It is important that the orchard infrastructure is adequate. That is, the posts must be driven 1 m deep and ridge cables and transverse cables are needed. Also needed are tarp fastening materials (carabiners, bungee cords), clips or tensioners for hail net, plastic tarp 1.40 m wide (depending on the distance between rows).
Two modalities are possible for installation:
– tarp fixed under the hail net
– tarp combined (welded) with the hail net (prototype tested in 2014)
On cherry trees:
The same materials and instructions applied on apple trees should be considered for cherry trees.
Two installation modalities exist for this fruit species:
– tarp in tunnel system (raised hoops and posts) in single row
– tarp-net in experimental single row system (trellising, posts)
Details on the technique:
To achieve maximum effectiveness of rainproof tarps, certain conditions must be considered:
– In the case of apple scab, deploy the tarps early March before the start of primary infections and fold the tarps after harvest or even at the end of primary infections (if no scab spots in the orchard) to limit the impact on tree water needs and fruit quality
– On cherry trees, deploy the tarps at veraison (start of cracking risk) and fold them immediately after harvest to ensure sufficient light on the foliage
– Do not leave gaps at tarp joints (apple case)
– Provide sufficient width to cover the entire row
– Orientation of tree rows (and tarps) in the direction of prevailing winds to avoid lateral entries during rain with wind
– Check that joints are well sealed and that tarp slope and tension allow good runoff of rainwater
– Check system integrity (no tears) after each climatic event
– Need to adjust water and fertilizer inputs
Implementation period On established crops
Spatial scale of implementation Plot
Application of the technique to...
All crops: Sometimes difficult to generalize
Sometimes difficult to generalize
Several fruit species may be concerned to manage different pests. The best-known experiments to date concern apple (against scab) and cherry (against moniliosis and other storage diseases).
Experiments on plum, mirabelle plum, kiwi and table grape have been under study for a few years but expected effects are not yet validated.
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
Pesticides: DECREASE
Other: No effect (neutral)
Comments:
On apple: reduction, even total suppression of fungicides under the tarps. This results in improved air and water quality regarding reduced use of phytosanitary products.
However, the tarps are not biodegradable and have the same landscape impact as a hail net.
"Agronomic" criteria
Productivity: Variable
Variable
On cherry, limits cracking (main reason for its installation on cherry).
Pollination not disturbed a priori except in cherry with very confined systems.
On cherry, strong impact on defoliation of scaffold branches and strong increase in vigor (requiring very good pruning control).
On cherry, in the particular case of very confined protection systems (very low tunnels) which are not the majority of situations, an advancement in maturity is noted.
On apple, limitation of sunburn and advancement of maturity are cited by Canadian literature, but this has not been observed and/or validated in France.
Wetness outside tarps more frequent than under tarps. Nevertheless, high wetness indices under tarps in some cases.
No significant temperature differences under tarp or outside tarp.
On clear days, up to 40% light interception under tarp compared to an uncovered orchard. Interception by tarps is less (10%) on cloudy days.
Quality of production: Variable
Variable
Apple: a priori, on the varieties (clones) studied, no negative influence of the tarp on fruit coloration despite reduced intercepted light. Results need validation over several seasons and varieties. The same applies to physico-chemical fruit characteristics (firmness, acidity). Depending on load, differences in firmness and acidity were observed under tarp, but observations need continuation.
Cherry: generally little influence of tarp on fruit quality, except in very confined systems (advanced maturity thus higher sugar content for the same harvest date).
Functional Biodiversity: No knowledge on impact
No knowledge on impact
A priori, tarp is not a barrier for beneficial insects.
"Economic" criteria
Operational costs: Increasing
Increasing
Apple, equipment cost (without trellising):
- Hail net: €0.25 – 0.40/m². Complete equipment: €1/m²
- Rainproof tarp combined with hail net: €1.30 – 1.40/m². Complete equipment: €1.70/m²
- Rainproof tarp alone: €1/m²
Cherry
- Raised hoop system (tunnel): equipment cost about €50,000/ha
- Single row system under experimentation (no cost/ha available)
"Social" criteria
Working time: Increasing
General working time increasing
Installation time in an experimental prototype on apple (excluding trellising):
– Tarp separate from hail net: about 100 h/ha
– Tarp combined with hail net: about 150 h/ha
Opening and closing time of tarps per year:
– Apple single plot (tarp-net): 40-60 h/ha per operation
– Cherry hoop system: 150-300 h/ha depending on system
– Cherry single row tarp-net system: 70-100 h/ha per operation
Annual working time increasing, especially if managing tarp folding during cherry or summer apple harvest.
Observation time: Increasing
Increasing
On apple: Monitor shoots and fruits from potential first spots (around May, depending on contamination dates) and then monthly follow-up of percentage of scabbed shoots and fruits until harvest.
On cherry: Regular fruit checks during sensitivity period to moniliosis.
4. Organisms favored or disadvantaged
Favored pests
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged pests
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Moniliosis | pathogen (pest) | Moniliosis and other storage diseases on cherry by limiting fruit cracking by rain (under study, not validated). Moniliosis on mirabelle plum (under study but not validated) | |
| Pear scab | pathogen (pest) | Expected effect but not studied | |
| Apple scab | pathogen (pest) | Under experimentation for 4 years | |
| vegetable crop flies | pest, predator or parasite | On cherry, the tarp-net system under experimentation should help control flies |
Favored beneficial insects
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged beneficial insects
| Organism | Impact of the technique | Type | Details |
|---|
Favored climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
Disadvantaged climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|---|---|
| Frost | Rainproof tarps could provide protection against frost (effect observed in 2012 in Southwest France) |
5. For further information
- Rainproof covers. A range of available systems.
- -Arregui M.
2004
Réussir Fruits et Légumes, 227, 60-61.
- Rainproof tarps in apple orchards.
- -Zavagli F., Verpont F., Giraud M., Favareille J.
2014
Phytosanitary meetings for pome fruits Ctifl/SDQPV, March 19-20, 2014, Ctifl, Lanxade Center, Prigonrieux.
- Control of cracking by plastic cover.
- -Charrel Y.
2004
Horta del Rossello, 217, 4.
- Protection against cracking. Still a high cost.
- -Arregui M.
Technical brochure, 2002
Réussir fruits et légumes, 212, 64-67.
- Protection of apple trees against scab: the rainproof tarp, an innovative method under study.
- -Zavagli F.
CTIFL, Technical brochure, 2013
Infos-Ctifl, 289, 22-29.
To access the brochure see link
- Undercover apples.
- -Mitham P.
Good Fruit Grower, 2008
January 15, 2008, 20-21 (Canadian reference)
6. Keywords
Pest control method: Physical control
Mode of action: Barrier
Strategy type regarding pesticide use: Substitution
Annexes
S'applique aux cultures suivantes
Défavorise les bioagresseurs suivants
Défavorise les accidents climatiques
