Weeds we need to hate

At the height of the growing season, suddenly we are faced with weeds and more weeds. They seem to have jumped up out of every place they can get a foot hold.

The villains of this drama, the ones we need to hate, are definitely the invasive weeds identified by the Department of Conservation and Natural Resources.

These bad boys are plant killers.

Japanese Stilt Grass

I have Japanese stilt grass invading my lawn and flower beds. This annual grass is an ecological threat.

According to the Pennsylvania Department of Conservation and Natural Resources, stilt grass crowds out native species.

Worse than that, it changes the soil nutrient cycling process to inhibit tree survival and growth.

At dieback, it forms a thick smothering layer of thatch that inhibits the growth of other plants.

Controlling stilt grass takes a combination of methods. It can be weeded out since it doesn't root deeply. It can be mowed and kept short to inhibit seed dispersal.

Preventing it from going to seed is very important because it builds up a seed bank in the soil.

Since stilt grass propagates from seed, a pre-emergent weed killer may be helpful next spring.

If you can't control it by weeding and mowing, you can use a grass specific herbicide such as Sethoxydim (trade name Bonide Grass Beater Over-the-Top Grass Killer) and Fluazifop-P-Butyl (Ortho Grass B Gon Garden Grass Killer).

If you go this route, try a small test area to make sure it won't kill valuable plants.

Be sure to follow the label closely and heed all precautions. Know how to dispose of any leftover herbicide. There will be directions on the label.

Crown vetch

Crown vetch is currently in bloom. If you look closely around your garden, you may see tiny seedlings scattered here and there.

Seeding is one way this invasive weed gets a foothold, but not the only way. It grows an amazing root system.

The roots have fleshy rhizomes that can extend up to 10 feet so that an individual plant can cover 70 to 100 square feet in four years.

Like stilt grass, crown vetch displaces native plants. If you have it, you know that it grows over other plants, smothering them with its weight and dense foliage.

The vinelike stems are tough and hard to break. Even if you manage to pull it out, you will certainly break off part of the root system.

Each rhizome still in the ground can sprout new growth.

You can mow crown vetch. If you do so for several years, the plant will become depleted and die back.

The same thing is true if you kill the top growth by burning or through the use of a contact herbicide.

A word of caution, if you use a systemic herbicide like glyphosate (as in Roundup) be aware that systemic toxins can adversely affect pollinating insects.

It's better to weed whack the flowering parts before using a systemic.

Mile-a-Minute vine

Mile-a-Minute vine was introduced from the Philippines during the 19th and 20th century.

It can grow up to 6 inches in a day, and quickly smother native vegetation. It climbs trees and restricts available light for understory plants.

You're more apt to find it along the edge of the woods, and on unmaintained open land.

You may find it germinating from time to time in your flower beds since birds eat the fruit and drop the seeds.

The vine is not deep rooted and can be pulled manually. If it is in the lawn, you can mow it as well.

Don't let it form fruit since many wild animals will eat the fruit and spread the seeds.

Butterfly bush

Finally, a word about butterfly bush (Buddleja davidii).

This shrub is a favorite for many homeowners because it attracts butterflies. If you have a Buddleja, remove the spent flower clusters before they go to seed.

Buddleja has escaped the garden and naturalized into a variety of habitats.

It outcompetes native wildflowers, and once established in the wild, spreads its seeds far and wide.

Came over on the Mayflower

We also have a group of common weeds that were brought over by early settlers for their medicinal or other useful properties.

Among those are burdock, common mullein, Queen Anne's Lace, dandelion, lamb's-quarters, and many more.

The history of these weeds is interesting reading. Some are medicinal and some culinary. If you are an herbalist, you are probably already aware of these plants.

Most of them are not invasive and can be removed mechanically as they show up.

Need more information?

If you have a weed you want to know more about, bring a sample to the Master Gardener Green Line at Penn State Extension on Tuesday mornings through October. The address is Penn State Extension, Carbon County, 529 Lentz Trail, Jim Thorpe, PA 18229, or call 570-325-2788. Email CarbonExt@psu.edu.

I want to thank the PA Department of Conservation and Natural Resources for information about invasive weeds in Pennsylvania.

For more information, visit dcnr.state.pa.us/forestry/plants/invasiveplants/.

For more information about weeds that were brought to America by our ancestors, visit "We Came over on The Mayflower, Too! A Timeline of North American Invasive Species," at eattheinvaders.org/we-came-over-on-the-mayflower-too/.