The two “scourge” weeds of our time are already rearing their ugly heads.
In recent years, Virginia buttonweed (VB) and doveweed (DW) have become the two most frustrating weeds we deal with along the Gulf Coast. But they can be dealt with, even at this time of year – if you spot-treat. That means, you can’t just spray the grass wall-to-wall.
I promised last week’s GardenLine listeners that I would explain everything in this week’s article, because some people still adhere to the old notion that VB and DW should only be controlled with cool-season herbicides. There are some newer products on the market, however, that are labeled for use on Virginia buttonweed. And since doveweed is very similar in leaf structure and growth pattern, these products should work on both.
There’s a big BUT, however, when using them in the heat of our Texas summers. You must SPOT TREAT only! Any blades of grass they hit will likely turn yellow.
A year ago, as I searched for an alternative to cool-season herbicides, I was confident that I would find a new product or two. Since then, I’ve learned that I don’t have any real confidence that the products I found won’t damage existing grass in hot weather. And that’s why I emphatically instruct that their applications should be done very early in the morning or on non-windy evenings when things have cooled down.
I know you were hoping to hear of some innovative new herbicide that would wipe out VB and DW right now, but my research didn’t turn up any silver bullet. So, the normal control regimen for these weeds is still the best: pull up as much as you can until a cool-season herbicide is permissible.
The only recommendation I have ever felt comfortable with is tedious, at best, to apply. AgraLawn Crabgrass Killer, which smells like cinnamon toast, is an organically derived powder, and it works. But you have to wet the blades first (preferably with a surfactant) and treat each one individually. It’s easy to waste the powder, and that also makes it the least cost-effective of all the herbicides. At roughly $20 a bottle, it only covers 100 sq. ft.
The cool-season herbicides I’ve touted for years on GardenLine are ferti-lome Weed Free Zone and Bonide Weed Beater Ultra. But we are nowhere close to the time we can use them with confidence, because they will flat out kill other grass when used in this kind of heat. That’s why my best advice is to wait for that cool-season herbicide window, likely not until late October. Even then, you’ll still need to pull out all the VB and DW you can. Just make it a daily or weekly routine. When you walk the dog, pull some out. When you check the mail, pull some out. In my estimation, it is better to pull out what you can when you can than allow it to overwhelm an area.
Anyway, here are a few herbicides that have been recommended for VB control. But there are no studies showing their safety with existing St. Augustine, Bermuda and Zoysia grasses, so proceed with caution. And do not use them around the base of any tree. As with atrazine, they are known to cause grave damage to tree root systems.
Note, also, that a couple are ridiculously expensive on a per-ounce basis compared to cool-season herbicides.
- TopShot Herbicide (Probably the most cost-effective)
- Fahrenheit (cheaper version of the costly Celsius)
- MSM Turf (often called Manor but a bit less expensive)
- Celsius (Known to be the most expensive)
Most of these will never be found at big-box stores. In fact, the expensive ones will likely only be stocked at feed stores, specialty garden shops, or mom-and-pop nurseries and garden centers. Those that don’t have them can easily order them. National and regional vendors won’t.
So, if you feel like giving them a try, I’ll be excited to hear listener case studies for them. If you have already had experience with any, call me this weekend or send me an email.
PHOTOS: Getty Images, manufacturers