• Print
• Share

Managing farm windbreaks to reduce frost injury

Windbreaks are valued by farmers for the protection they provide to sensitive fields of fruit and vegetables from damaging winds. Windbreaks moderate wind speed during spring and summer to extend the window-of-opportunity to apply insecticides, fungicides and herbicides efficiently and reduce spray drift off-site.

Conifer windbreaks along the downwind edge of fields have been shown to filter out and catch as much as 80 percent of drifting insecticide and fungicide before it leaves the target area, depending on the tree species used, foliage density and the condition of the tree row. Research shows that one or two rows of conifers, particularly spruce, will provide an ideal windbreak for most effective crop protection and spray drift reduction.

Frost pockets however, can sometimes be a problem for sensitive horticultural crops along windbreaks where dense branches that extend to the ground create a barrier for adequate air drainage. Solid rows of eastern white cedar are particularly prone to cause frost accumulation due to dense foliage right to the ground. Where frost has caused damage previously, some farmers find it useful to thin out or in some cases prune off the lowest branches along conifer windbreaks.

Thinning out the lower branches until numerous small windows of the adjacent field can be seen through the lower canopy will create unobstructed pathways to improve air drainage. Many examples of branch thinning can be seen on tobacco land where sandy soils are prone to wind erosion, where crops are very susceptible to wind damage, and crops such as tobacco and tomatoes are very sensitive to spring frost.

Figure 1. Having the lowest 3 or 4 feet of branches thinned out and not removed entirely can maintain good wind protection for the crop while still allowing adequate air drainage to prevent frost pockets from forming. Late winter or early spring is a good time to thin out branches.

Figure 2. With all branches removed to about 6 feet from the ground, too much wind may flow under this windbreak and may not be effective at catching drifting fungicide or insecticide spray. This windbreak is still better than having no windbreak established.

Figure 3. This new windbreak has excellent weed management using herbicide and a single line of trickle irrigation for dry summer periods. It consists however, entirely of eastern white cedar where foliage can become a bit too thick for ideal windbreak protection. Cedar can be alternated with spruce and pine to add diversity to a healthy windbreak.

Thinning out the lower branches of windbreak trees may not prevent frost injury during severe frost conditions however it can help reduce the incidence of frost injury that is associated with inadequate air drainage along windbreaks. Windbreak design works best where numerous windbreaks are planted and coordinated across larger farming regions and neighboring farmers work together to manage wind. All windbreaks, whether yours or the neighbours, should be protected from herbicide drift that can kill trees.

Think about the amount of energy invested in fuel for tillage, pest control, weed control, planting - all the work that requires fuel to grow our crops. Windbreaks help protect the expenditure of energy or, windbreaks protect the investment in energy consumed to produce agricultural crops. Windbreaks are important for energy conservation.