We posted an animated video on YouTube showing how to kill a weed tree using foam herbicide. The video also explains why foam herbicide works better than liquid herbicide for cut stump applications.
Invasive vines can really take over. They primarily crowd out desirable species by shading them, but they can also girdle stems of desirable plants and cut off the free flow of plant sugars to the canopy.
To control them with herbicide, there are several things to keep in mind. First, a foliar application to vine foliage is almost always a bad idea. Usually the foliage of the vine is too intermingled with the foliage of desirable plants. Even if you can segregate the foliage of the invasive from the desirable, spraying upward where vines grow is inadvisable. You will likely end up with more spray mist on yourself than on the target vine.
Second, don’t pull the vine down from the canopy. If you do, you may do more damage to the desirable plant by breaking branches and tearing into live plant tissue (if the vine has adhesive pads that attach to stems). Focus your efforts instead on killing the vine and leaving it in place. If you want to speed its decay and to lessen strangulation of a desirable plant, cut notches into the vine stem. Again, avoid cutting the desirable plant.
Third, you will probably have better luck killing the vine if you apply the herbicide in late summer, fall, or even winter. Those are the times when the plant is translocating sugars to the roots which is also where you want the herbicide to flow.
If you want to prevent the vine from producing seeds, here is a trick that I use. After the vine has leafed out but well before it has produced fruit or seeds, cut the vine as high as you can from where it is rooted. Then allow the vine to regrow. It probably will do so vigorously with multiple new sprouts from near the cut. The trick is that you will do your treatment below this cut and new sprouts. This not only should prevent the vine from flowering and producing seeds, it will also sap the roots of energy and make the herbicide application more effective.
One way to apply herbicide is to use what is called a cut stump method (shown above). With this method, you cut the stem of the vine close to the ground – generally two to four inches above the ground from where the vine is rooted. (if the vine is rooted in multiple locations, you will need to cut and treat near each root clump.) Don’t cut so close to the ground that dirt gets on the cut face of the stump (dirt neutralizes herbicides such as glyphosate). But don’t cut too high because the treatment will be less effective. Then immediately treat the stump face with a concentrated foam herbicide. Apply the foam herbicide in a ring near the outer perimeter. You want to make sure the herbicide contacts the living plant tissue called the cambium which is just inside the outer bark. Green Shoots Foam Herbicide works great for this because you can precisely stack the foam right on the cambium and it will slowly soak in. If you wait more than about 10 to 15 minutes after cutting the stump, I would recommend re-cutting before applying the herbicide. Plants seal off wounds surprisingly quickly and this reduces the effectiveness of the herbicide. Follow the instructions on the label for the herbicide and the dispenser.
Another method is a frill treatment. With this method, you scrape or cut away some of the outer bark to expose live, inner bark as shown in the photos above. This method work especially well if the vine stem is horizontal because it provides a better surface on which to apply the herbicide. If you can try to remove bark from around the perimeter of the stem. Again, Green Shoots Foam Herbicide works great for this because the foam will cling to the frilled tissue. (Liquid herbicides on the other hand will drip right off.)
Be sure not to get herbicide on desirable plants. I even avoid getting herbicide on the outer bark of desirable plants. Although you may read that water-based herbicides won’t penetrate the protective, waxy layers of cork, it makes sense not to risk harm.
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
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).
With wipe applications, a device is used to “physically wipe” an herbicide onto a plant. Johnson et al. 2012 (link). Because these applications are precise and controlled and generally made only to a portion of the plant, the herbicide concentration in the spray solution typically used is higher than with other foliar applications. Green et al. 2003 (link). For example, for AquaMaster (an herbicide containing glyphosate), the label recommends solutions having from 18% active ingredient to 54% active ingredient for wiper applicators.
The herbicide wiping method can be used very effectively with the foam herbicide dispenser from Green Shoots (link). The photos above show an application of foam herbicide I made with the Green Shoots Foam Herbicide Dispenser to a weed tree (maple seedling) located in a planting bed.
The herbicide solution used in this case had approximately 20% active ingredient (i.e., a low concentration for the typical wiper applications). Moreover, I applied very small amounts of herbicide foam to the leaves. Nonetheless, it appears the woody weed completely died. We will keep testing less concentrated solutions in order to minimize herbicide usage as much as possible.
Wiping with an herbicide foam has real advantages. The wiped foam herbicide is much less prone to drip. Traditional herbicide wipers work with sponges or canvas which can become saturated and drip. Moreover, clumps of herbicide foam stick better to plant surfaces than large herbicide droplets from a standard wiper system. Finally, with foam herbicide wiping, there are no sponges or canvas cloths that may become contaminated with dirt and dust or that need to be cleaned afterwards.
We will keep testing wipe application techniques on various plants and will post blog updates and videos.