Friday, April 3, 2009

Weekly Word on Weeds

Winter Annuals and Hand Weeding
Where did all that chickweed come from??? This time of year I look at my lawn and am surprised at how much chickweed there is in the yard. It didn’t seem like very much last fall or even just a month ago. But, when winter annual weeds begin to grow in the spring, they can grow very rapidly. AND, produce seeds for next year very quickly as well.
Now is the time to get the winter annual weeds out of the beds before they produce the bulk of their seeds for next year. Hand weed, spot spray with herbicides, hoe or shovel – regardless of the method you choose, do it now before they drop their seeds. Now is also the time to ask yourself -- “Why are these weeds here?” And, “what can I do differently next year to prevent these weeds”? Knowing that winter annual weeds germinate in the fall and early spring provides the opportunity to suppress or control them with a fresh lay of mulch applied in September or October. Where weed populations are heavy, a preemergence herbicide may be used in most landscape bed situations. Common herbicides containing pendimethalin (Pendulum & others), prodiamine (Barricade & others), trifluralin (Treflan or Preen), or isoxaben (Gallery, Snapshot & others) are labeled for use around many woody ornamentals. These herbicides control most winter annual weeds before they emerge. Granular formulations of trifluralin and pendimethalin can also be used around many herbaceous ornamentals. It is especially important to select the right herbicide based on the safety to ornamental plants. Horticulture Information Leaflet 644 (HIL644) provides some guidance for selecting safe and effective herbicides for color beds.
So, while you are spending this weekend hand weeding the beds, you will have plenty of time to think about what you can do differently next year to prevent all those pesky weeds from establishing.
Speaking of hand weeding – I have often said it is a futile effort to try and hand weed vetch. Typically, when you try to hand weed vetch, it just breaks off at the ground. But, the recent rains have provided an opportunity to control this and other hard to pull weeds. In wet soil, I’ve found that the vetch can be removed (yes, roots and all) if you grasp the tap root at the soil line and pull. The tap root comes up. Ok, not easily, but it does come out of the soil. When the soil dries out a bit more it is much more difficult to remove this weed, roots and all.

From: Dr. Joe Neal, Department of Horticultural Science, NCSU

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.