It’s summertime, what should I be doing with my invasive plants?

Invasive species and invasive species management change with the seasons.  Some invasive species are more recognizable at certain times of the year and the success of control techniques often depend upon the right timing.  The River to River CWMA is creating a series of article about invasive species in the different seasons.  Be sure to also read THIS article on invasive species in fall.

You’ve spent all spring pulling garlic mustard and are gearing up for your fall and winter treatments of woody invasive plants. But what should you be doing with invasive plants during the summer?

It is tempting to stay indoors and avoid the heat, ticks, and chiggers that come with summer, but this time of year is ideal for controlling several invasive species. Herbaceous plants, such as Japanese stiltgrass and teasel are good targets for those warm summer months. Both of these species flower and set seed in the summer and then die (stiltgrass is an annual and teasel is a biennial). To effectively control infestations, you need to eliminate seed production; which means controlling them in the summer. Control teasel by spraying the rosettes or young bolting plants in early summer or hand-pulling the flowering plants in midsummer. For Japanese stiltgrass, wait until mid-summer to spray infestations. You can mow, hand-pull, or weed-whip infestations of stiltgrass anytime in the summer before flowering. Be sure to revisit control areas to follow up and retreat any new growth.



These invasive species are best controlled
during the summer months.  Clockwise from
top-left is johnsongrass, Japanese stiltgrass,
teasel, and Chinese yam.



Johnsongrass and Chinese yam are both best targeted in summer. While these two are both perennial plants, they are most vulnerable in the summer months. Look to treat Johnsongrass in early summer, just before it flowers. Chinese yam is best controlled in June, before the aerial tubers (bulbils) are formed.

Good information, including control recommendations for these and other species, can be found on the River to River CWMA Species of Concern page: http://www.rtrcwma.org/species.html

Working the summer comes with its own set of safety risks. Overheating and dehydration are real possibilities. Be sure to take plenty of breaks and drink lots of water when working on hot days. Also, it is a good idea to avoid working alone during the summer. Having someone else with you can ensure speedy treatment if necessary.

Another factor to consider when working in the summer is the impacts heat can have on herbicides. Excessive heat can increase the ability of herbicides to volatize, where the herbicide turns to vapor and can drift away. This can be a serious problem. The loss of the active ingredients from the herbicide mixture due to volatilization can drastically reduce its effectiveness. Additionally, those vapor pockets that form can drift over and damage non-target plants. You can reduce the risk of excessive volatilization by not using ester-based herbicides when the temperatures are over 90°F.

Summer is a great time of year to get out and control certain invasive species. Using the proper precautions will keep your treatments effective and you safe. Lastly, don’t forget to find time between all of your summer invasive plant treatments to set aside at least a few days to go fishing and camping!

Fall is the time to identify many woody invasive species

Invasive species and invasive species management change with the seasons.  Some invasive species are more recognizable at certain times of the year and the success of control techniques often depend upon the right timing.  The River to River CWMA is creating a series of article about invasive species in the different seasons.  Be sure to also read THIS article on invasive species in summer.

With the arrival of autumn comes the changing of the colors of leaves and the ripening of fruits. Along with that, also comes the opportunity to easily find woody invasive plants. Many of these invasive species turn distinctive colors or stay green longer than native species, allowing for easy identification. Also, with the cooler temperatures, the disappearance of ticks and chiggers, and the senescence of posion ivy, it is a great time to be out in the woods.

Here are some tips on what to look for when identifying some of our common woody invasive plants.

Oriental bittersweet
Oriental bittersweet is a woody vine that climbs up and over trees and shrubs, particularly along forest edges. In the fall, bittersweet leaves turn a bright yellow color and the fruit on female plants mature and the covering splits open to reveal scarlet red berries (called arals). Look for the yellow leaves surrounding the trucks of trees or draping over the top of shrubs or lower branches of trees.

Bush honeysuckle
Bush honeysuckle is a shrub that can be found growing along the edge or within the interior of a forest. Like bittersweet, it also has yellow leaves and bright red berries. Bush honeysuckle is unique in that it is often one of the last plants to remain green in the fall and one of the first plants to green up in the spring. In the fall, looking for honeysuckle shortly after the trees have lost their leaves is often the best time to spot this species. Look for small shrubs (10-15 feet tall) densely covered in leaves that are dark green turning to bright yellow.

Burning bush
Burning bush is a common ornamental shrub used in landscaping, but is starting to spread into wildlands in southern Illinois. This species is instantly recognizable in the fall by its bright red fall color and its upright growth form. Late in the fall, burning bush levaes turn from a dark green to a deep red in color. Often, during this turn, the leaves will have somewhat of a purplis or maroon tinge. Upon closer inspection, the branches will usually show some type of corky wings.

Autumn olive
Autumn olive is large shrub or small tree that is very common across southern Illinois, particularly in grassland or field settings. This species also keeps its leaves longer than most of our native species. When it still has its leaves, autumn olive can be recognized by the silvery coloration of the underside of the leaves. This coloration gives the entire plant a shiny, silverly sheen that stands out and separates it from any other shrub species.