Weed control in container nurseries

Weed control in container nurseries

Proper herbicide application and smart hand weeding can help growers reduce costs.

March 14, 2018

Weed management in container nursery crops can be costly. Some research estimates overall costs, including herbicides, labor for application, and hand weeding, can be over $4,000 per acre. Growers in the Southeastern U.S. utilize multiple applications of PRE herbicides each year, yet labor to hand weed pots continues to be a significant expense. Several strategies have been investigated to try to reduce overall weed control costs. A summary of this information was presented at the 2016 Nursery Crop Weed Management Field Day, which took place in Hickory, N.C. on site at Hawksridge Farms. This event featured on-site demonstrations and explored the economics and efficacy of weed control strategies in container nurseries.

The event focused on research from Dr. Joe Neal’s lab. Neal is a professor of weed science in North Carolina State University’s Horticultural Science department and an extension specialist with the NC Cooperative Extension.

One of the topics addressed was herbicide application. Accurate and uniform herbicide application is crucial to achieving high levels of weed control in container nurseries. Neal provided several basic tips for improving coverage with hand-carried, hand-cranked “belly-grinder”-style applicators.

  • Maintain consistent walking speed. Use a metronome to help with this.
  • Maintain consistent cranking speed. Use a metronome to help with this.
  • Size of the beds matters! Keep nursery beds between six and eight feet wide (for an eight to 10 foot swath width).
  • Use center rudder position only. Do not use the spreader held at an angle.
  • Refill the hopper when the level drops to about 25 percent full. Don’t wait until it runs out.
  • Start walking and cranking before opening the hopper.
  • If the wind is more than 5 mph, don’t make the application. Wait for a calmer day.
  • When using lower spreader settings, spread granules in one direction using single direction, parallel passes.
  • Calibrate your spreader.

Sanitation is an oft-overlooked key factor in nursery weed control. This involves identifying sources of weeds at the nursery and making changes to reduce the amount of seeds being spread. Some typical on-site sources of weeds include substrate, pot storage areas, reused containers, roadways and liners. Neal’s team provided several tips to eliminate weed seeds from these common sources.

  • Keep substrate piles weed free.
  • Use new or clean containers.
  • Keep propagation areas weed free.
  • Clean beds between crops.
  • Treat non-crop areas for weeds.
  • Start with clean liners.
  • Get rid of old, weedy stock or keep them clean.

Neal’s lab also presented research on hand-weeding that claimed that though the practice is labor-intensive, it can save a grower money if done frequently.

When pots were hand-weeded every two weeks, the cumulative amount of weeds removed was reduced by 74 percent, compared to when pots were weeded just before herbicides were applied at eight-week intervals.

Researchers found if growers proactively set a hand-weeding schedule every two weeks instead of waiting until the plants appear “weedy,” they can reduce their overall labor costs by an average of 36 percent. For more insight into the research, along with more detailed information about each session, visit Dr. Neal’s website.