View this PowerPoint presentation: Targeted Weed Killer: Precision Foam Herbicide Delivery System. It explains the advantage of using foam herbicide: less risk to desirable plants because of reduced drift or overspray ; an increase in herbicide uptake because the foam keeps the herbicide in contact with foliage longer; improved visibility because foam is easier to see than liquid; and reduced herbicide waste because the precision reduces waste. We offer six different before-and-after examples such as the one shown in the following photos:
Note this: in this application, the chemical used was glyphosate which is a non-selective herbicide. If that herbicide had contacted the grass, it would have killed the grass too. As shown in the photos, that didn’t happen. This is a testament to just how precise you can be with the Green Shoots System. z
You have an unwanted tree growing vigorously in the wrong place – in the middle of a flower bed or in a native grass planting or next to a building foundation. You know you need to remove it. Winter is actually a great time of year to do this. Herbicides work fine in the winter if applied correctly. See Reinartz 2002.
If you simply cut the tree or bush down, you will soon get something far worse in the spring: a multi-stemmed bush like the one shown below on the right side.
There is a simple way to prevent this from happening: use the Green Shoots Foam Herbicide System to precisely apply a concentrated herbicide to the stump immediately after cutting to kill the stump. So here is what you do.
- Cut back the tree or bush – If it is a big tree or bush, I typically cut off the upper branches first and leave a tall stump anywhere from knee to shoulder height. Clear out the branches so you have room to work.
- Prepare the Foam Herbicide Dispenser according to the instructions. Be sure to read the herbicide label.
- Cut the stump close to the ground – try to cut it within 2 to 4 inches of ground level.
- Immediately apply the foam herbicide to the cambium layer of the stump. This is a thin layer of live inner bark just inside the outer bark.
The Green Shoots Foam Herbicide System has several advantages over standard herbicide sprays:
- Precision – This is critical when you are applying to the narrow ring of live inner bark less than 1/10 inch thick. With a liquid spray, the application is so imprecise – you may miss your target. At the very least, you will waste herbicide trying to hit the target.
- Less Drip – The foam herbicide sticks to the target and will slowly soak in. Liquid sprays will bead and drip off the target.
- Visibility – the foam is visible for some time after the application. This helps in identifying what part of the target you have treated.
For more information about the Green Shoots Foam Herbicide System, visit the Green Shoots website.
Post contains content updated on August 20, 2018:
I remind people every year that late summer and fall are great times to apply herbicides to kill perennial invasive plants. I have discussed the timing of herbicide applications in several previous posts. So, get out and enjoy that cooler weather (it will come) and, for those of us farther north, beautiful fall colors!
In terms of priority, I would put perennial weeds into three groups for purposes of application timing: First are the perennials that need to be treated before a frost. Plants such as bindweed, crown vetch, and Japanese knotweed, die back after a frost. Therefore they need to be treated in late summer or early fall before a killing frost.
Second are the plants such as perennial thistles. Canada thistle is a prime target. Canada thistle can be treated a little later in the fall because it is more frost tolerant. In fact, this frost tolerance can be used to your advantage. If nearby desirable plants have died back or lost their leaves, you can apply herbicide to the thistle with less potential for damage to the desirable plants. Just make sure you apply the herbicide to foliage that is still green.
Third are the woody perennial weeds. These can be treated with cut stem or frill treatments from the fall into late winter (just do it before warm temperatures start pushing plant sugars up to the branches for leaf out). The application should be into the vascular system of the tree or shrub, e.g., cut stump, frill, or injection. The Directions for the Green Shoots Foam Herbicide System show how to do these applications.
You can also do foliar applications to woody perennials in the late summer and fall. Timing can be a little tricky: if you have had a drought, the leaves of the weed tree may be sparser and may not absorb the herbicide as well.
Green Shoots sells concentrated glyphosate in quanitites that are ideal for homeowners who are tackling woody brush or weed trees. We sell a 16 ounce bottle of concentrated glyphosate (41% active ingredient). Many stores sell what they call concentrated glyphosate. Don’t be fooled. Usually the concentration is well under 20%.
Especially if you are doing cut stump or frill treatments, a concentrate is essential. Glyphosate works well on plants in a concentrated form. It is almost like a quarterback blitz – glyphosate works better with a quick rush than with steady pressure. That’s why you need the concentrate.
Feel free to contact me with any questions. Just go to the Green Shoots website for contact info.
Fall is generally the best time to control perennial weeds. Perennials are moving sugars from above-ground sinks – in particular foliage – to underground sinks – rhizomes and roots, for example. for overwintering. In order to kill perennial weeds, these underground sinks must be destroyed.
Fall offers other benefits as well – cooler weather, less dense foliage, and fewer bugs!
What is the best way to kill invasive perennials? Several rules hold. Apply herbicide only to living tissue. Perhaps that’s obvious. That can be green leaves or stems or vascular tissue.
Since most people are probably least familiar with vascular treatment methods, I will discuss those. Photos above show each of these methods step-by-step. One method is to do a cut stump application. With this method a weed tree is cut down and herbicide is applied to the cut-surface of the stump. For most homeowners who used water-based herbicides, you should apply the herbicide soon after the cut is made. (There is debate about how soon but I try to do it within a few minutes if possible.) Two keys to this method are: first, make the cut as close to the ground as possible (e.g., 2 to 3 inches if possible); second, make sure you apply herbicide to the outer edge of the stump just inside the bark. This will ensure herbicide gets introduced into the phloem which will carry the herbicide into the root system. The Green Shoots foam herbicide system works great with this method because the foam stays on the cut-surface and doesn’t drip down the sides of the stump.
Another method is a frill application where the tree is left standing and cuts are made into the bark of the tree. Use a knife or chisel on smaller trees and a hatchet on larger trees to make the cuts. Apply herbicide to the exposed vascular tissue. These cuts should be made as close to the ground as possible. Of the two methods, I find the cut-stump method to be the most effective. However, the frill method probably takes less work especially when you are dealing with big trees.
For green-stemmed perennial weeds, I use a slightly different method. I bend the stem near the ground and apply the herbicide at the bend. For some reason, this method works better than just cutting off the stem. I don’t know why. The Green Shoots foam herbicide system works especially well with this method because the foam sticks tightly to the bend in the stem unlike methods that use liquid herbicide. This technique can be often be used even after the leaves are nipped by frost as long as the stem is still green.
For all these methods, use a concentrated herbicide mixture. For example, if I am using a glyphosate-based herbicide, I typically use a concentration of about 35 % active ingredient.
There are a number of benefits to these methods of application. First, they are very effective. I typically have a 100% kill-rate using the Green Shoots foam herbicide system with these methods. Second, they protect the environment. The methods allow for very targeted applications. And with Green Shoots foam, the herbicide sticks well to the target surface and very little drifts through the air or drips off onto other plants.
Treating a tall weed with herbicide or weed killer can be a challenge – especially if the target weed is near desirable plants. Conventional sprays are difficult to control. Fine droplets are hard to see, so it is difficult to know what you are treating with the herbicide spray. Moreover, the fine droplets in sprays have a tendency to drift. And, when the droplets do land on the target weed, they may bead and roll off the leaf.
This video shows an application to a perennial thistle using the Green Shoots Foam Herbicide System (link to video). Note how precise the herbicide application is – without drift, drip, or off-target spray. Toward the end of the video you can see the results where the weed has dead fifteen days after treatment.
We just finished a video on how to control Canada thistle using the Green Shoots foam herbicide system (link). The video shows how our small foam herbicide dispenser creates a thick foam herbicide that sticks well to leaves and green stems. In the video we use the small foam herbicide dispenser and physically wipe small amounts of foam to the leaves and green stem.
We are using glyphosate herbicide with the wiping technique. The label that accompanies the herbicide you use should explain more about herbicide wiping. Many labels recommend a
33% to 100% solution for use with wiping. However, you can use a less concentrated herbicide solution than that. We are using a 10% concentration in this video.
Background on Canada Thistle – Canada thistle (Cirsium arvense) is an invasive thistle in North America and is identified as a noxious weed in many states. It is an exotic or non-native species brought to North America from Europe (not Canada!) possibly as early as the 1600s. Since that time, Canada thistle has invaded prairies and grasslands, especially in the Midwest, Great Plains, and southern Canada. It out-competes desirable, native species like grasses and wildflowers. In this way, Canada thistle degrades wildlife habitat and reduces ecological diversity.
Canada thistle has rhizomes (underground stems) that grow laterally and up to a depth of about 3.5 feet. New shoots develop from the rhizome and thus a stand of Canada thistle might orginate from one rhizome.
Other common names include: Californian thistle, Canadian thistle, creeping thistle, field thistle, corn thistle, perennial thistle, field thistle. For more information on Canada Thistle, visit the United States Department of Agriculture National Agricultural Library (link).