Q. My lawn and garden are overrun with nutsedge this year. What should I do to get rid of it and prevent it from recurring?
A. Yellow nutsedge is a very challenging weed to control, and worse in wet years. An interesting local name just in the Jefferson City area is "watergrass," which describes its preferred habitat. One of the biggest challenges for controlling it is that it is a perennial with a unique survival method. It forms little "nutlets" (hence the name) on underground roots, and when you pull it up, they are often left behind to sprout later.
Thus, the best way to control this plant (unfortunately) is with systemic herbicides, of which there are only two active ingredient chemistries available (to home gardeners). One is glyphosate (popularized by the Roundup brand), and it's only considered "fair" in effectiveness. Another problem with it is it will kill most anything else adjacent that is sprayed. A more effective product to control it is either of the active ingredients halosulfuron or sulfentrazone, with some common brand names being Hi-Yield Nutsedge Control, SedgeHammer and Ortho Nutsedge Killer for Lawns. These products are quite effective, but, to perform optimally, should have been applied in June. For this late in the year, they may kill it, but spraying them twice, about 10 days apart, will increase their effectiveness. These products are not cheap, so spot-spraying will be a better approach. They are labeled for lawns and around established woody plants, but not for use around annual flowers, vegetables or fruit crops.
A very good MU Extension publication addresses this topic, and we can send the link or print and mail it if requested. Alternately, try a Google search for "Yellow Nutsedge Control - Purdue University." Now, for the bad news, it takes two to three years of consistent herbicide use to control nutsedge. Mowing high and having a good, dense stand of turf will help to out-compete it. A dry summer will cause it to back off some. But the nutlets can survive for up to three years.
Q. I know I had moles in my yard because of their tunnels that push up my lawn, but lately all these mounds are appearing. I can't find tunnels next to them. Are these by the moles, or what are they?
A. The mounds are from moles, and you are likely seeing a change due to the recent hotter weather. The term used to describe them is "molehills." Moles generally tunnel deeper as it gets hotter. This may be because their primary food source (earthworms) have moved deeper as well, for cooler temperatures or more moisture. But some of these deeper tunnels are for building dens. This type of tunneling creates the need to push out some dirt, thus the mounds. Don't be alarmed by the dens; moles have only one litter annually, which is in the spring.
Since these tunnels are deeper, you aren't seeing them; and this makes it harder to set traps. These deeper runs are considered ideal for killing with a fumigant, though. Another option is to put a bait down there, but you need to find the tunnel below the molehill. Baits that taste like worms are considered quite effective, with three common brands being Talpirid, Motomco Mole Killer and Tomcat Mole Killer. Carefully read the label and follow instructions of any fumigant or baits used. The MU Extension has a publication that gives more details - just call or stop by for a copy.
Q. What is going on with Japanese beetles this year? It seems like they are hanging around forever this summer.
A. You are right; they are around way longer this year than normal. We have trapped them at the Extension Center since 2008, and they normally peak about four to five weeks after first emerging. This year they first emerged in early June and are peaking eight to nine weeks later. Why? Blame it on the rain! We've had one of the wettest years in Missouri's history for May, June and July combined. The excess moisture likely delayed their emergence, and with much of this rain easing in the last half of July, and the weather turning hot, here they came. In past years it has seemed like when they started to decline, it was abrupt. So we can hope they'll be coming to an end soon, but we were at record-setting catches from July 24 through Aug. 3.
The local Master Gardener hotline is staffed from 12:30-4:30 p.m. Tuesday and Friday afternoons; call 634-2824 then or anytime to leave a message. The Central Missouri Master Gardeners are a volunteer group of 191 members, 122 of whom are Cole County residents, who maintain 11 beautification sites in Cole County. Master Gardeners must complete a basic training program of at least 30 hours of horticultural training including landscaping, lawns, vegetables, flowers and fruits, as well as 30 hours of volunteer service.
Have a gardening question of your own? Submit it via email to [email protected] for possible inclusion in a future "Ask a Master Gardener" column.