Hail netting is an effective tool to protect apple orchards from both hail damage and major insect pests when draped and secured around rows of apple trees.
Draped netting is especially efficient for high density trellised apple trees, because the netting can be easily wrapped around narrow rows and secured under the canopy.
Use a tractor-operated applicator tool (such as Net Wizz) to apply and remove the netting. Very small orchards may be able to apply the netting by hand using ladders.
Apply draped hail netting as soon as possible after petal fall, once flower pollination is complete.
While draped hail netting and the net applicator are significant upfront expenses, this system provides savings on insecticide applications. It excludes codling moths and apple maggots as well as or better than conventional IPM programs, according to recent UMN research at two Minnesota orchards.
Overhead hail netting protects orchards from hail damage, but does not exclude insect pests.
Climate change and fruit crops: Excluding the elements (video: 00:09:12)
Types of hail netting for apple orchards
Draped netting
This guide focuses on draped netting. This type of netting is draped over individual rows of apple trees and secured under the bottom of the canopy with zip ties or clips.
The netting has small rectangular holes that are 3 by 1.5 millimeters in size. It comes in rolls on spools. The netting is lightweight, weighing 60 grams per square meter. It is applied in the early summer after petal fall and removed immediately before harvest.
This type of netting works best in high density trellised orchards such as the vertical axis, tall spindle, or spender training systems. It may work on rows of larger semi-dwarf trees if much wider nets are used.
Of the two types of hail netting systems, this system is more economical. It also has the significant added benefit of excluding insect pests.
Overhead netting
In contrast to draped nets, overhead net systems cover the entire orchard in one continuous layer above the top of the canopies. The continuous layer is made up of many long, row-width strips of net that are clipped together.
During the winter, the strips are separated and tied into bundles above each row. The nets are supported by trellis posts and wires.
Overhead netting does not exclude insect pests but does protect the fruit from sunburn. Sunburn is not a significant economic issue in Minnesota like it is in Washington state where this system is used occasionally.
If you are interested in overhead netting, contact the manufacturers of the products and visit farms where it is used, such as the Minnesota Landscape Arboretum’s “Farm at the Arb” demonstration orchard.
Equipment, supplies and installation
To install the draped netting system, you will need netting, an applicator tool, and plastic zip ties or clips.
The netting is sold on spools. Each piece of netting is 100 meters long (328 feet). It comes in various widths, with 12 meters as the maximum width. For orchards using tall spindle trellises with 16-foot tall line posts, purchase netting that is 23 feet wide.
To determine how many spools of netting to buy, calculate how many feet of linear row you have in your orchard. Add 10 feet to the beginning and end of each row, as the net will need to be tied off and secured to end posts at the beginning and end. Netting costs are lower for orchards with longer rows compared to many short rows.
A pull-behind net applicator makes it easier to drape the netting over the top of the tall trellis system. If you have just a few trees, you may be able to apply the netting by hand, but most operations will find that an applicator is necessary. An applicator for draped netting is sold under the name “Net Wizz.” If you have welding skills, you may be able to build your own applicator.
In addition to the netting and applicator, you will need zip ties or plastic clips to secure the long edges of the netting together underneath the tree canopies. This keeps the netting in place during high winds.
Apply draped netting as soon as possible after petal fall. Wait until bloom is complete, because pollinators are not able to access the blossoms through the nets.
At least three people are needed to use a tractor-operated netting applicator: a tractor driver, and one person on each side of the row to pull the sides of the nets down over the trees. After the netting is draped, walk down each row to zip tie the edges of the nets together under the tree canopy. A fourth person, if available, could apply the zip ties immediately as the nets are going on.
Tie the end of the net in a knot at the start of the row, and secure the knot to the end or anchor post. Cut the netting upon reaching the other end of the row, leaving enough length to tie the end into a knot and secure it to the end post or anchor post. Label each piece of netting with the row number it is used on, so that it can be re-used for the same rows in future years.
If a piece of netting is not long enough for the row, two pieces can be sewn or zip tied together. Holes or tears in the nets can be repaired through sewing and patching as needed.
Remove the hail netting right before harvesting the trees. Minimizing the time between net removal and harvest removes the risk of hail damage to uncovered trees.
If using a netting implement to remove the netting, consult with the manufacturer about how to use it for netting removal.
With proper use and storage, hail nets can be re-used annually for at least 10 years. As individual pieces become damaged, they can either be repaired or replaced.
Store the nets indoors on their spools. They should be elevated off of the ground or floor to prevent mouse damage and water accumulation. This can be achieved by storing the spools of nets on top of wooden pallets or shelves.
The spools are large, so make sure you have enough storage space before purchasing them.
Reviewed in 2023