These are the toughest weeds to control. Here’s how to eliminate them
I’m focusing on lawns for the second week in a row because it’s a topic that’s on everyone’s mind all through the gardening year. It’s also because I want another springboard to remind you to apply pre-emergent weedkiller granules the last week of August or the first week of September (that’s now!) to prevent germination of winter and early spring weeds. You must apply Dimension, Halts or Balan now to stop germination of annual bluegrass, rescuegrass and ryegrass. Once they sprout it’s too late and you get no second chance. Follow that up with Gallery granules to prevent germination of winter annual broadleafed weeds (clover, dandelions, henbit, chickweed, etc.). I’ll let you read the label and ask your retail supplier for specific instructions.
Other really tough weeds…
I made a list of the most difficult weeds we encounter locally and how I advise gardeners to deal with them. My remedies will need to be brief, but again, your nursery professional can supply the details.
Smilax briars
Sprays don’t really work on this weed. The leaves are too sparse and they’re far too waxy. Mowing alone will eliminate most of it. Digging the few remaining tubers or large, fleshy roots with a sharpshooter spade will quickly eliminate it.
Trumpetvine
People plant the wild form because it’s cheap and it looks pretty in nature. But it’s extremely invasive, sending up sprouts all over your yard. Cut the mother plant off at the ground. Drill into the stump and fill the “reservoirs” with a broadleafed weedkiller concentrate to let it soak into the stump. Repeat 24 hours later. You may have to remove widespread sprouts with a sharpshooter for a while.
Bamboo
No weed is more aggressive. Bamboo is a grass, so our long-proven grass-killer glyphosate will do a fair job of killing the tops. Use one of the brands that contain only glyphosate (no other active ingredient). Apply it to vigorous new growth in May or June with a pump sprayer, keeping it only on the bamboo foliage. You will assuredly have to repeat, perhaps for a couple of years. In all honesty, front-end loaders are better options if you can justify one.
Poison ivy
This one’s easy to kill. You just have to be careful not to dose yourself up with its toxins. Broadleafed weedkiller sprays (containing 2,4-D) will eliminate it when applied to the leaves, especially while it’s growing actively in spring. If it’s growing up tree trunks, use a long-handled ax to cut through its stems. Macerate the stumps and pour broadleafed weedkiller at full strength onto the cut wood, taking care in the process not to let it run onto the ground. Wear long sleeves and pants, socks and shoes and disposable gloves and stand aside so oils from the stems won’t spew onto your flesh. Leave the stems in place on the trunks until they fall to the ground a year or two later. Remember that all parts of poison ivy contain the oil that causes allergic reactions.
Nutsedge
It’s not a grass (as we’ve mentioned before). Grasses have round stems. Sedges have triangular stems. Nutsedge is tenacious, spreading by underground rhizomes. The only effective controls are products designed specifically for it, including original Image, Sedgehammer, and Sedge Ender. The control season is essentially over for this year, so make plans to attack it late next spring.
Dallisgrass
This is a perennial, clump-forming weed that does not produce runners. Its blades are extremely dark green, and its seedheads emerge within a day or two after mowing. They are distinguished by their black, peppery specks. We no longer have a selective herbicide (MSMA) to control it, so the best remedies are either to dig clumps out with a sharpshooter spade before your lawn becomes overrun with the weed or to spot treat with a glyphosate. To minimize damage to “good grass” you don’t want to kill, consider cutting the bottom out of a 1-gallon milk jug and inserting your spray wand through the top. Press the jug down over the dallisgrass clump and spray within the jug.
K.R. bluestem
I doubt if the King Ranch would want to hear the thoughts home gardeners have of their plant introduction from 80 years ago. It has escaped pasturelands to invade our lawns. It seeds quickly and freely, and again we have no chemical means of control. Your best options are to mow frequently to keep it from going to seed and to maintain your lawn in peak condition.
St. Augustine invading bermuda
Back when we had access to MSMA it was an easy job to get rid of St. Augustine before it took over a bermuda lawn. St. Augustine won’t tolerate the old herbicide while bermuda does. But with MSMA gone, you have to keep the St. Augustine out manually. That may mean by putting in an edging strip to stop it at the border, or it might mean pulling it out by hand or following its runners with a sprayer filled with glyphosate (which would also kill the bermuda). There is just no good solution unless you’re willing to watch your lawn be overtaken by the dominant grass. Probably the best solution is to create a barrier bed of flowers, shrubs or groundcovers to separate the two grasses.
Neil Sperry hosts“Texas Gardening” from 8 to 10 a.m. Sundays on WBAP/820 AM. Reach him during those hours at 800-288-9227. Online: http://neilsperry.com.
This story was originally published August 23, 2018 at 8:00 AM with the headline "These are the toughest weeds to control. Here’s how to eliminate them."