War on Weeds

Fall is a good time to wage war on many perennial weeds.

Fall weed control: Get a jump on perennial weeds

The issue: Remember all the dandelions in your lawn and garden last spring? It’s easy to put them on the back burner in the fall, but this is actually a good time to wage war on many perennial weeds. The cooler fall temperatures signal to perennial plants that it is time to draw energy reserves down into the roots. A herbicide application at this time of year on perennial weeds can kill, or seriously knock them back.

Integrated control options:

· Mechanical: Mechanical control works well on seedlings and simple perennials like dandelion and common mallow. Seedlings just need to be separated from their roots. If the plants are more mature, then digging up the roots a couple of inches below the soil level will really knock them back. Broadleaf weed seedlings are also very susceptible to heat, so a weed burner may be a good option in areas that cannot be tilled.

· Cultural: Competition from desirable plants can help reduce the ability of many perennial plants to get established.

· Biological: Biological control is geared more toward individual species or plant families.

· Chemical: Fall herbicide application is especially effective on creeping-spreading perennial weeds, such as field bindweed (morning glory) and Canada thistle. If you have a large area to treat, chemical application can save time. In addition, many of the herbicides used on lawn weeds, such as 2,4-D and dicamba, are not as volatile with cooler, fall temperatures and will cause less damage to non-target plants.

Combine them:

Perennial weed control should be in our minds throughout the year. Use different techniques to help improve the effectiveness of your control efforts. Always read and follow herbicide label directions.

For more information, contact Ron Patterson, University of Idaho Extension horticulture/agriculture educator in Bonneville County.