Trellis system failure can spell disaster for small and commercial orchards, vineyards, hop yards and like producers, due to the loss of fruit combined with expensive repairs. A fallen or damaged trellis most often occurs due to a lack of support from either poor design, weak materials, or a combination of both. Orchards that practice high-yield growth and those that are located in regions prone to strong temperature swings or high winds will need to pay special attention to how their trellises are made.
Support Strategies for Trellis Systems
The success and longevity of your trellis systems will rely on how they've been constructed. Investing in high-quality, durable materials and using a design that offers as much stability as possible will be a significant benefit.
The type of crop you're producing and how you're managing growth will determine how your trellis system should be designed. Many orchards, for example, switched to trellis systems for the advantages of higher fruit yield, simplified management needs, earlier yields, and more consistent ripening. Apples, for example, are one of the largest trellis-grown crops in the United States and require very careful design to ensure proper support under heavy production. Hops, which are also grown using trellis systems, require strong support as well with the height of the their plant yield putting immense pressure on the trellis to perform.
Some common reasons behind trellis failure involve the anchors and posts. All trellis systems should have anchors in place. Anchors may come out of the ground under strain if they aren't placed deep enough, especially if they are in rocky or disturbed soil. It's better to place anchors deeper than needed than to have them pull out, potentially leaving your trellis toppling over.
Proper Use of Poles in a Trellis System
Posts are the foundation of a trellis and have the biggest impact on longevity. At minimum posts must be strong enough to last for a generation. Posts tend to break or fall for one of two reasons - they lean and fall because they've been placed too shallow or they break above ground because of inclement weather or inferior treated wood.
As a general rule, roughly 1/4 of the post should be in the ground or between 2.5' to 3'. Climate, post size, and estimated strain put on the trellis will dictate whether you need to go deeper or if you could install them shallower.
Posts breaking right above ground level are usually a sign that they weren’t driven deep enough in the ground, but weather can be another factor. If you tend to have mild weather and low winds but still have posts breaking, it's safe to say you'll need to upgrade to either a higher wood grade or better treatment.
Selecting High-Quality Posts for Trellises
Trying to save money by purchasing lower quality materials rarely ends well. A lot of stress and wear is placed on trellis posts, not to mention they will also be in direct contact with the soil. Purchasing a superior quality product will ensure you get maximum use out of your trellis while preventing issues during the growing season that could be devastating.
Agri-Max treated wood posts are a solid choice for all types of trellis systems. This brand offers CCA-treated Red Pine and Southern Yellow Pine (SYP) posts in a variety of sizes. SYP posts are very popular for orchard trellis use and come in 5" or 6" diameter with either 22' or 25' lengths. Red Pine is another option, with a 4", 5" or 6" diameter and lengths from 8’ to 22'.
All Agri-Max posts are kiln-dried prior to treatment, rated for ground contact and have a minimum retention of .40, with the option for a higher retention level as a special order. You'll also find cable and wire products to work with Agri-Max posts and poles if you're looking for a complete trellis system.
For more information on Agri-Max wood posts, contact Pine River Group's agricultural team to get some professional insight.