Trellis systems are used for cane support with trailing and semi-erect cultivars to keep the fruit off the ground and with erect cultivars that will be allowed to grow tall before being topped. Positioning canes on a trellis improves sunlight exposure, air movement, and spray penetration throughout the canopy. Using a trellis system will make the planting easier to manage. Easier harvest results in cleaner picking, lessening the attraction of picnic, sap, June, and Japanese beetles that can result from the presence of overripe and rotted fruit. Trellising can also make floricane removal easier. Construct trellises prior to the first harvest season.
Growers use a variety of trellis support systems to support canes. Your trellising goal is to minimize labor and maximize yield. Each trellis type has its advantages and disadvantages, and most can be modified according to your needs. Evaluate each trellis system to determine what type best suits your needs.
Many different types of trellis systems exist. Consider the following factors when selecting which type to use: cost of materials and construction; availability of competent, trained labor; and climatic considerations, such as the potential for cold injury.
Line posts are used to position wires at desired heights above the ground. Posts can be either wood or metal. Wood line posts stand up to stresses—such as wind perpendicular to the trellis—better than metal posts. If wood posts are used, they should be treated for in-ground use. Unless heavy metal posts are used for line posts, it is advantageous to use a wood line post every second to third post. Drive or set posts 2 feet into the ground with 5 feet remaining above ground. Wood posts should have a top diameter of about 4 inches. For hand harvested crops, set posts no more than 25 to 30 feet apart. The end posts, where wire tensioning is done, should be larger than line posts (suggest a minimum of 8 feet in length with a 6 inch top diameter to allow them to be driven 3 feet into the ground). Generally, wood is used for end posts. Use anchors to further support end posts.
The top wire on the trellis is the load-bearing wire. Use a 121⁄2 gauge high tensile electric fence wire. The lower wires are for cane positioning and do not need to be as heavy. A 14 gauge high tensile wire should be adequate.