Pre-emergents for Poa Annua

Asked August 31, 2013, 2:37 PM EDT

I am finding a lot of pre emergent on line for controlling this nasty little guy, but so many of the products don't seem to work well using in lawns (Snapshot 2.5 seems the favorite but the bag label says not to use on lawns but everywhere else I read says it is safe for lawns). I need something that I can put down because I have to keep killing off my lawns and redoing them do to this invasion. Do you have any suggestions for what works best around here?

Polk County Oregon lawns and turf weed issues

1 Response

Hello:

Annual bluegrass is one of the more common grassy weeds in lawns in the Willamette Valley, and is very well adapted to growth in our climate, and so it proves to be difficult to control. There are a number of herbicides registered for control of this weed in lawns. Note that Snapshot is not one of them and if the label does not specifically include turf as an approved application site the product should not be used there. The product list I have is below and I do not know if any of these are available to homeowners, or those without a pesticide applicators permit. You may need to work with a landscape service to have these products applied for you. The products currently labelled are:
Pendulum (pendimethalin); Prograss (ethofumesate); Balan (benefin); Bensumec (bensulide); Dimension (dithiopyr) and Quali-Pro Prodiamine (prodiamine). Since annual bluegrass can develop resistance to herb icides quite rapidly, rotation is important of products.
Cultural approaches are also important in managing bluegrass. Raising your mowing height will provide more competition for this weed. Avoid fall nitrogen applications. If you plan to aerate the lawn, do so in spring, not fall. Fell free to contact me directly if you would like further information-I am in the Polk County Extension office most Wednesdays and Fridays.