Weather Risks: Strategies to Mitigate the Risk of Wind Damage
Table of Contents
- Production insurance
- Tree row orientation
- Tree support
- Strong anchorage
- Limb spacing
- Summer pruning
This in the 5th in a series to help apple and tender fruit growers in Ontario assess the weather risks that can damage their trees and crops. It is important to recognize the weather risks at each location, and develop strategies to reduce or eliminate the impact on your business operation.
What it is
Winds may break branches (especially the tree's leader), cause blowing soil and fruit russeting, bruise fruit and/or knock it off, snap graft unions (which kills the tree), and stress tree support systems, especially when carrying a full crop load, and/or if the ground is saturated. Windy conditions can hamper spray operations, discourage bee activity and pollination, make ladder work hazardous, and distract harvest workers. Diseases like fire blight, canker and fruit rots can gain entry through damage from wind.
When it occurs
Wind damage often occurs when weather systems are swiftly changing from low pressure to high pressure, changing from moist, humid air to cooler, drier air. Thunderstorms build up in the unstable air, and the leading edge of the storm front carries strong or gusty winds. Spring weather often includes strong winds that limit spraying time, and may reduce bee activity and fruit set. The fall harvest sometimes coincides with hurricanes moving up from the south, with strong winds and heavy rains that loosen soil around roots of trees that are heavy with crop.
Where it occurs
Wind damage is a common weather risk for tree fruit growers, because severe storms are frequent throughout the year and often include strong winds. Tornadoes occur less frequently, but cause much more damage in localized areas.
What can you do
Some of these potential mitigation strategies may help reduce or eliminate damage due to winter injury:
- Production insurance (PI): Production insurance can cover yield loss from fruit blown to the ground, and unmarketable fruit with limb rubs. It may cover future yield loss from broken limbs or graft unions. For apples, tree insurance can also cover trees broken off at the union if the loss is greater than 7% of your total trees. PI is purchased well before the season, and can give you peace of mind that at least some of your input costs will be covered. Your premiums will depend on the coverage you choose, your claim history, and the yield potentials of your orchards. Over time, your premiums can be reduced if you are lucky enough not to have claims. However, some growers struggle with the premium costs (especially in their start-up years or if they have claims) and the fact that PI is not intended to fully cover your loss, either in yield or price. There is also the problem of reduced coverage levels in the years after your crop is reduced, due to the effect of the loss on your long-term average yields. Also, spot loss insurance is not available, so growers with multiple orchard sites may be penalized when good yields occur on the non-damaged sites.
- Windbreaks: Windbreaks located on the windward side of your orchard will protect trees and fruit for a distance of 10 times their height. Reducing wind in this area can improve spraying conditions, bee activity for pollination, fruit quality through less russeting from blowing soil, and reduce graft union breakage. However, windbreaks take time to establish and take some acreage out of production.
- Tree row orientation: Aligning tree rows with the direction of the prevailing wind will allow wind to flow through the orchard without damaging trees or fruit. Depending on the topography and layout of your farm, this may not always be possible or desirable - usually, a north-south orientation of rows is preferred for optimum sunlight interception. However, on the windiest sites, it may be prudent to choose the wind protection.
- Tree support: Trees that are not supported immediately after planting will blow in the wind, which alters their growth and reduces subsequent fruiting. Early support will also avoid union breakage, or limb breakage, especially the leader. If the full trellis cannot be installed, use a temporary stake to support the leader and prevent breakage.
- Strong anchorage: Recent experience with strong winds, including tornadoes, has shown that when the end anchors hold, the trellis holds. Maximizing the strength of the trellis, especially the end anchors, is key to avoiding wind damage. Invest in materials and proper design to match the weight of your crop and the worst expected winds to reduce breakage and limb rubs.
- Limb spacing: Properly spaced scaffold branches will help reduce fruit damage from limb rubs. This structure has the added advantage of better light interception and improved fruit quality. However, more detailed pruning has increased labour costs.
- Summer pruning: Removing first year branches around the fruit before harvest will reduce limb rubs in windy weather. Summer pruning can also improve spray penetration and improve fruit colour and quality. However, there is an increased labour cost for summer pruning.
Avoiding or reducing wind damage is an ongoing challenge for many fruit growers. The extensive damage from a short period of strong winds is discouraging, and the subsequent loss from diseases can be devastating. As erratic weather patterns produce more wind events, growers should consider more options to avoid wind damage. The investment in intensive orchards and high-valued varieties may encourage more investment in wind strategies in the future.
For more information:
Toll Free: 1-877-424-1300