Reducing Weeds in Berry Crops: Part 4

In March, we talked about 3 things to do before planting to reduce weed problems - site selection, crop rotation and preplant cleanup. In May, we focused on things to do at planting time - stale seedbed, switching to plasticulture, banding fertilizer and using trickle irrigation. In July, we looked at things to do throughout the growing season - managing field edges, spot treating weed patches, weed scouting, and chemical renovation. Let's look at things we can do in the fall to reduce weeds:

1. Clean mulch: Avoid introducing problem weeds into your fields with your mulch. Whether you grow your own straw or purchase it, it is very important to use straw that is free of weed seeds and cereal grains. Some growers have paid custom growers to apply hormone herbicides each spring on the cereal to control broadleaf weeds like dandelions and thistles. However, applying preharvest glyphosate on cereal where the straw will be used for strawberry mulch is not recommended. We have had several incidents in Ontario and Quebec where glyphosate residues remained on the straw, and damaged strawberry plants as they grew through the mulch the next spring.
2. Spot treatments: Fall is a good time to revisit the weed patches that were spot treated through the summer. In fact, for some weeds, fall is the best time for treatments because weeds have resumed active growth after the summer's heat and drought. Glyphosate can be very effective on quackgrass regrowth in the fall, even after a light frost. Dandelion control with 2,4-D is very effective late into the fall (again even after a light frost). Spot treatments of weeds from field edges can be very effective at this time of year.
3. Weed scouting: A final assessment and mapping of weeds at this time of year will provide you with important information to plan your weed management strategies for next year. It may be easier to identify weeds in the fall with flowers and seedheads present. If you still have unknown weeds, collect several specimens (include as much of the roots, leaves and flower structures as possible to help identify it). Store samples in a paper bag inside a plastic bag to preserve them for several days.

In the past 4 columns, I've talked about a dozen options to reduce weeds in your fields, and I'm sure there are more that have been useful in your operations. No single one of these will totally control your weed problems. However, using all applicable options, in addition to your herbicide, tillage or mulching treatments, will contribute to a more successful Integrated Weed Management (IWM) system for your berry crops.

Related Links

• Reducing Weeds in Berry Crops: Part 1
• Reducing Weeds in Berry Crops: Part 2
• Reducing Weeds in Berry Crops: Part 3
  

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