Prepare to fight winter weeds

By Jeff Kollenkark | Weed Man

I am into weeds. I will apologize upfront. We have faced very warm and sometimes hot days, but I have noticed the appearance of several winter annual weeds starting to emerge in lawns and flower beds. I have seen sowthistle, prickly lettuce, and Poa annua popping up the past few weeks, which are indicators that our days are getting shorter and nights are getting cooler. That’s just fine for me as I am more than ready for a cool down.

If you’re like me, you won’t want these weeds getting a foot hold in your landscape. What can you do? First, I would be sure to remove or spray emergent weeds and not let them flower, which will result in the further spread of the unwanted pests. If they are already seeding, carefully pull or dig these out and dispose of them in your green waste can.

The next step would include applying a pre emergent herbicide to both the lawn and flower beds while they are nearly weed-free and allowing the irrigation water to activate them into the top inch or so of soil. Most of the common pre emergent herbicides (Amaze, Preen, Surflan, Halts, Dimension and Barricade) are root inhibitors, thereby stopping the weeds from developing a healthy root system while allowing existing plants to continue growing with minimal root suppression. The above list controls a large list of grassy and broadleaf weeds, but is often weak on the thistle and composite families. Commercial products often combine other pre emergent products to improve the weed control spectrum and pick up some of the more difficult weeds missed. This includes some rather pricey products like Gallery, Snapshot and Freehand. Ideally, pre emergent products need to go down mid-September into October to prevent the weeds from successfully emerging this winter. Complete weed control is rarely achieved.

Another approach includes the addition of mulch. Mulch can potentially add aesthetic value, reduce water loss, and reduce weed pressure. Pulling weeds is often much easier with a good mulch layer. Generally, mulch layers less than two inches deep are not very effective for weed control reduction. In order to maintain a two to four inch mulch layer, one needs to repeatedly add more mulch every few years as it breaks down over time.

Before you know it, we will be talking about crabgrass prevention and other foes like spurge, nutsedge and green kyllinga. Meanwhile, now is the time to plan for the coming onslaught of winter weeds in your landscape. Good luck!