Let's face it East Tennessee is pretty much the best place in the temperate world to be a plant. With copious amounts of rain and sun, moderate summers and mild winters life is pretty good for our oxygen producing friends. This hospitable climate is not isolated from alien invaders in spite of our nursery industries most feeble efforts to control them. Here are a few of my least favorite to deal with in order of how much I curse as I'm pulling them...
Yellow nutsedge (Cyperus esculentus)
One of the world's oldest cultivated crops and one of the world's worst agricultural weeds. Also known as tigernuts the small tubers from this tenacious weed are eaten in many countries around the world, particularly in Spain where it is the main ingredient in a popular beverage called chufas. Yellow nutsedge produces basal bulbs, tubers and rhizomes and during the dormant period the tubers are the only part of the plant to survive the cold weather. A single plant can produce thousands of tubers in a single growing season and they can be spread out away from the parent plant thus they can quickly colonize and outcompete many natives. If persistent it is possible to eliminate yellow nutsedge by pulling it but it will take several years to completely remove the tubers from the soil. Glyphosate based herbicides will work but will require several applications probably over several years. There is also a nutsedge specific herbicide with the active ingredient Halosulfuron-methyl, also sold under the name Sedgehammer. Nutsedge is easily identified by the grass-like flower heads and the v-shaped profile of the stem.
Another of the top ten world's worst weeds Johnson grass is now present on every continent except Antarctica. It spreads rapidly through seed (up to 100,000 per plant per year) and large woody rhizomes quickly choking out native vegetation and creating a monoculture that is very difficult to eradicate. As an added bonus the dried foliage contains hydrogen cyanide which can kill farm animals who graze on it. Id Johnson grass by its large size, up to ten feet, and a white line running down the center of the leaves. Be sure to positively id before eliminating as it can resemble some native warm season grasses.
There have been recent reports of Johnson grass becoming resistant to glyphosate based herbicides in several countries around the world so an eradication plan should include rotating type of herbicides used. Research has shown that the majority of rhizomes are found in the top six inches of soil so in heavily infested areas soil removal could work.
"Crito, we owe a cock to Asclepius. Pay it and do not neglect it." These were the final words of the great philosopher Socrates after drinking an infusion of poison hemlock for his crimes against the state. Poison Hemlock contains the alkaloid coniine (which is chemically very similar to nicotine) that affects the neuromuscular system, paralyzing the respiratory system and eventually leading to suffocation and death.
A member of the Apiaceae (Carrot) family the flower umbels look very similar to its close cousin Queen Anne's Lace (Daucus carota) but the two can be easily differentiated by size, hemlock can reach over 8 feet tall in one season, as well as the purple spots that dot the stems of poison hemlock. It is a biennial, producing a fine lacy basal foliage the first year followed the second season by fast growing flower stems.
Glyphosate based herbicides (Roundup) are very effective on poison hemlock but will probably require several applications. It's important to not let it go to seed as it is a vehement reproducer. Be very careful around this plant!
This weed is relatively new to North American gardens, first identified in Louisiana in the 1960's and becoming widespread throughout the southeast in the 1990's, most likely in nursery stock. A member of the mulberry family (Moraceae) this tenacious annual weed produces a tremendous amount of seed in a very short amount of time that it explosively discharges up to five feet from the parent plant. Persistence is the best method of control, pull seedlings as soon as possible as viable seed can be produced in a very short period of time. Glyphosate herbicides work well but take time to kill and mulberry weed might produce viable seed in the time it takes for the herbicide to work. Seed requires light to germinate so a generous layer of mulch could help.
Yellow Woodsorrel (Oxalis stricta)
One of the world's oldest cultivated crops and one of the world's worst agricultural weeds. Also known as tigernuts the small tubers from this tenacious weed are eaten in many countries around the world, particularly in Spain where it is the main ingredient in a popular beverage called chufas. Yellow nutsedge produces basal bulbs, tubers and rhizomes and during the dormant period the tubers are the only part of the plant to survive the cold weather. A single plant can produce thousands of tubers in a single growing season and they can be spread out away from the parent plant thus they can quickly colonize and outcompete many natives. If persistent it is possible to eliminate yellow nutsedge by pulling it but it will take several years to completely remove the tubers from the soil. Glyphosate based herbicides will work but will require several applications probably over several years. There is also a nutsedge specific herbicide with the active ingredient Halosulfuron-methyl, also sold under the name Sedgehammer. Nutsedge is easily identified by the grass-like flower heads and the v-shaped profile of the stem.
Johnson Grass (Sorghum halepense)
Another of the top ten world's worst weeds Johnson grass is now present on every continent except Antarctica. It spreads rapidly through seed (up to 100,000 per plant per year) and large woody rhizomes quickly choking out native vegetation and creating a monoculture that is very difficult to eradicate. As an added bonus the dried foliage contains hydrogen cyanide which can kill farm animals who graze on it. Id Johnson grass by its large size, up to ten feet, and a white line running down the center of the leaves. Be sure to positively id before eliminating as it can resemble some native warm season grasses.
There have been recent reports of Johnson grass becoming resistant to glyphosate based herbicides in several countries around the world so an eradication plan should include rotating type of herbicides used. Research has shown that the majority of rhizomes are found in the top six inches of soil so in heavily infested areas soil removal could work.
Poison Hemlock (Conium maculatum)
A member of the Apiaceae (Carrot) family the flower umbels look very similar to its close cousin Queen Anne's Lace (Daucus carota) but the two can be easily differentiated by size, hemlock can reach over 8 feet tall in one season, as well as the purple spots that dot the stems of poison hemlock. It is a biennial, producing a fine lacy basal foliage the first year followed the second season by fast growing flower stems.
Glyphosate based herbicides (Roundup) are very effective on poison hemlock but will probably require several applications. It's important to not let it go to seed as it is a vehement reproducer. Be very careful around this plant!
Mulberry Weed (Fatoua villosa)
This weed is relatively new to North American gardens, first identified in Louisiana in the 1960's and becoming widespread throughout the southeast in the 1990's, most likely in nursery stock. A member of the mulberry family (Moraceae) this tenacious annual weed produces a tremendous amount of seed in a very short amount of time that it explosively discharges up to five feet from the parent plant. Persistence is the best method of control, pull seedlings as soon as possible as viable seed can be produced in a very short period of time. Glyphosate herbicides work well but take time to kill and mulberry weed might produce viable seed in the time it takes for the herbicide to work. Seed requires light to germinate so a generous layer of mulch could help.
Yellow Woodsorrel (Oxalis stricta)
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