Early weed control is a critical component of establishing a new planting. Newly planted fruit trees compete poorly against fast growing weeds for water and nutrients. This competition can severely limit a new block's growth, which can ultimately reduce potential yields in the third year by 50 percent (Breth and Tee, 2013). Weeds also harbor insects and diseases, provide habitat for rodents, and can serve as hosts for viruses, further complicating effective orchard management (Stivers et al., 2017).  

Weed management for a new orchard should begin with excellent site preparation. Prior to planting, your orchard site can be cultivated, allowed to fallow until weeds emerge, and then treated with a post-emergence herbicide to control problematic perennial weeds. Cover crops can then be planted to compete against emerging weeds, subsequently mowed and incorporated back into the soil. In the fall prior to tree planting, you can seed the planting site with your preferred orchard sod mix. This will give the sod for the row middle some time to establish. You can then kill the sod in the rows with glyphosate two weeks prior to planting the orchard (R. Crassweller, 2018).  The killed sod in the rows will act as a mulch for the trees at planting.

Once the trees are planted and the soil has had time to settle, a mix of pre-emergence herbicides should be utilized. There are a number of pre-emergence formulations that can be used in newly established orchards (they require the soil around the trees be settled before applications are made), and a few provide some post-emergence control when weeds are in the seedling stage.  These are listed below, and more in-depth product descriptions can be found in the 2018 Cornell Tree Fruit Guide.

• Surflan (oryzalin) controls most annual grasses and some broadleaf weeds. It controls pigweed, but not ragweed or PA smartweed. Surflan can be used in new plantings as soon as the soil has settled, but requires ½ to 1 inch of rain prior to seed germination to be effective.
• Prowl (pendimethalin) controls annual grasses, and some broadleaf weeds, including lambsquarters and pigweed when used as a pre-emergent. Prowl 3.3EC can be used in non-bearing trees in newly planted orchards. Using the higher rate will give a longer window of control.
• Chateau SW (flumioxazin) provides pre-emergent control of grasses and broadleaves, and will also control emerging broadleaf seedlings when they are between 2 and 6 inches tall. It must be applied prior to pink bud. It can be applied to trees that have been established less than 1 year, but trees must be protected with non-porous tree wraps.
• Goaltender (oxyfluorfen) has pre and post-emergent activity on young seedlings. It controls broadleaf weeds, and should be combined with a grass herbicide. It can only be applied to trees when dormant.
• Sinbar (terbacil) controls most annual grasses and broadleaf weeds, and has some activity against perennials like quackgrass, horsenettle, and nutsedge. Sinbar requires rainfall within 3-4 days after application to effectively move into the germination zone. It can be used in newly planted trees at very low rates once the soil has settled.   Do not use on soils coarser than sandy loam, this would include high gravel content soils in the Hudson Valley.
• Solicam (norflurazon) controls most annual grasses and many annual broadleaf weeds, and suppresses nutsedge and quackgrass. It requires rain to move into the seed germination zone, and is often combined with another pre-emerge that has greater efficacy against broadleaf annuals.

This initial treatment can be combined with post-emergence herbicides to control any weed seedlings that may have already emerged (Always check the label before combining any products). Additional follow-up spot treatments of post-emergence herbicides should be performed to control weeds that escape your initial treatments. Be careful to avoid contact with the trunks and green tissues of the young trees.  The application of white latex paint to trunks affords some protection, but the use of spiral tree guards should be discouraged in regions with high dogwood borer pressure, such as the Hudson Valley.

You might also consider developing an orchard weed log or map for your blocks to fine tune your weed management plan.  When you see weeds in the orchard, write down their location, the species that are present, and the average height, growth stages, and percentage of ground cover for each species. These records can help you schedule your post-emergence treatments. They can also help you select an appropriate herbicide mix in your future applications when you have more herbicide options as the block matures. Having these notes to look back on will also allow you to recognize your long term persistent weed trends, and determine the effectiveness of your weed management program (Stivers et al., 2017).

By being proactive with weed management in the first few years, you can get your trees off to a great start to maximize your future potential yields.

Breth, D., and L. Tee. 2013. New Findings in Weed Control in Young Apple Orchards. New York Fruit Quarterly. 21(4):13-18.

Crassweller, R. 2018. Orchard Establishment - Site Selection and Preparation. Penn State Extension. 24 April 2018.

Stivers, L., T. Baugher, and M. Basedow. 2017. Integrated Weed Management: Weed Scouting for Fruit Production. Penn State Extension. 25 April 2018.