Tips for Managing Weeds in Berries in July

Here are some quick tips for dealing with various weed problems that usually arise in July:

Activating soil-applied herbicides:

Herbicides like Dual, simazine, Dacthal and Sinbar need about ½" (12 cm) of rain to be activated. If this doesn't fall within the first few days of application, it's time to get the overhead irrigation out. What if it rains heavily after herbicides are applied? If the herbicide has a high leaching potential (eg Sinbar), it may get washed into the root zone, injuring the crop. At the same time, because it is diluted at the soil surface (where weeds germinate), weed escapes may appear too soon.

Maximizing postemergent herbicides:

Venture L, Poast Ultra and glyphosate (eg Roundup, Vantage, Touchdown, etc.) are quickly absorbed into growing plants. If weeds are drought stressed, it may be better to wait until later when growth starts again.

Sun-shy herbicides:

Devrinol & Treflan are quickly degraded by ultraviolet light. That's why incorporation is required for these herbicides, Treflan usually by 2 tillage passes, and Devrinol either by tillage or rainfall (or irrigation). Gramoxone is quickly deactivated by sunlight, so apply in cloudy or drizzly conditions (rainfast in 15 minutes)

Wick wipers:

The trick is to get the wick wet and keep it wet. Fill the tube with herbicide well before application, allow it time to soak through. Do not use pure water in a wick wiper, as it will drip because it is not viscous enough. If you are expecting to use the wiper again soon, put the wick in a plastic bag, label & date it, and keep in a cool place. You might be surprised how often you use it if it is ready!

Carpet" weeds in strawberries:

There's lots of weed problems out there that will soon carpet the ground. Here's some comments on a few of them:

Common groundsel:

Not controlled by Sinbar. Cultivate frequently when weeds have one true leaf. New seedlings will be controlled by Devrinol (registered for use once a year) - prefer timing is Labour Day, applied and irrigated in. Lontrel applied at renovation will control established groundsel, but seeds may still be shed.

Field pansy (violet):

Use Sinbar 3X a year, especially at Labour Day to control seedlings. Cultivate frequently when weeds are small. Wick wipe patches with glyphosate when first observed to prevent seed set. Use Dacthal where available in early spring before weeds germinate. Repeat at renovation, Labour Day and pre-mulch.

Dwarf snapdragon:

Not controlled by Sinbar. Cultivate frequently when weeds are small. Wick wipe patches with glyphosate when first observed to prevent seed set. Use Dacthal where available in early spring before weeds germinate. Repeat at renovation, Labour Day and pre-mulch.

Hint:

Try some chemical renovation with Gramoxone to control existing carpets of weeds, and avoid bringing a new flush of weeds to the surface.

Weed in ponds:

Start early! Apply Aquashade (water soluble dye) early in the season before algae & weeds grow. Apply Reward (diquat) at dusk in late June when plants are growing vigorously. Apply Aqua-Kleen (2,4-D) early, and do not use it for irrigation of 2,4-D sensitive crops for at least 60 days. Wait until catkins form on cattails to apply Amitrol or Gramoxone.

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