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.
Some people still adhere to the old notion that VB and DW should only be controlled with cool-season herbicides. I have promised GardenLine listeners that I would explain how to control them at other times of the year. There are some newer products on the market that are labeled for use on VB and since DW 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 these products 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.
In the fall and winter months, you can and should still use the cool season herbicide treatments. The only other 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 can’t use them with confidence when it is warm because they will flat out kill other grass when used in the 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.
But in the warmer months, we have found in the past 3 years that old school MSM herbicides do work on VB & DW, as long as you’re spot treating. 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. Also note that some are ridiculously expensive on a per-ounce basis compared to cool-season herbicides.
Fahrenheit is the most reasonably priced and readily available in the gulf coast market. But all these herbicides below are considered those MSM variations.
• MSM Turf
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.
If you feel like giving them a try, I’ll be excited to hear listener anecdotal studies for them. If you have already had experience with any, call me on the show or send me an email.