Discovered in the Rock Today

By Franklin County Master Gardener Carol Kagan

Oh, how gently summer is sliding into autumn. I took a stroll around the yard in the cool of the morning, carrying my hot tea (known as checking the back 40 at our house).

Weeds are persistent little devils – they pop up in sidewalk cracks,in splits in the road tar,

in a miniscule spot between towering skyscrapers –

even without our help.

I discovered, behind the tall and wide ornamental grass, that my sedum has managed to find several small niches in the rock and has flourished there.

It’s good to know, at the end of the day, that even the good stuff is persistent.

Weeds, Part 3 Mile-a-Minute Vine

Mile-a-Minute Vine Smothering a Blackberry Stand in Eckhart Landscape

Persicaria perfoliata (formerly known as Polygonum perfoliatum) is on Pennsylvania's noxious weed list.  Pennsylvania's Department of Conservation and Natural Resources classifies it as an invasive species, which is defined as "...those species that are not native to the state, grow aggressively, and spread and displace native vegetation.  Invasive plants are generally undesirable because they are difficult and costly to control and can dominate whole habitats, making them environmentally destructive in certain situations."

If you've ever encountered it, then you'll understand where it gets other common names like Devil's Tail and Tear-thumb.

Mile-a-Minute Vine Smothering a Blackberry Stand in
 Eckhart Landscape

It was probably introduced from imported nursery stock from its native habitat in East Asia, and first noticed in York County, Pennsylvania in the 1940's.

It is an annual that is self pollinating, producing a small, blue berry that birds eat, spreading the seeds which can remain viable for years.

Small infestations can be managed by pulling (wear gloves) or mowing, if it's growing in places without other desirable plants.

Mile-a-Minute Vine Smothering a Blackberry Stand
 in Eckhart Landscape

A pre-emergent herbicide, like products containing the active ingredient Trifluralin (Preen is one example) can be effective in managing its spread.

A small weevil Rhinoncomimus latipes from China has been approved by the USDA for release as a biological control agent.

As always when using pesticides, be sure to read the label and follow the directions.

Japanese Knotweed - Invasive Weed

Japanese Knotweed at Edge of Eckhart Woods

I've neglected the weed series on the blog since the first post a year ago, but my colleague, George Hurd, the Penn State Extension Environmental/Resource Development Educator for South Central Pennsylvania wrote the following that will appear in this week's Extension News Column, and elsewhere, which prompted me to do this post.  Here's George:

Japanese knotweed is an invasive plant that is causing increased concern in Pennsylvania. Invasive plant species like Japanese knotweed are a considerable threat to biodiversity. Once these species are well established it is sometimes impossible to remove them. When removal is possible, it comes at a high cost financially and ecologically. Researchers at Cornell University estimate that invasive species are costing Americans more than $130 billion every year. Even controlling a single unwanted invader can carry a price tag in the millions.

In some cases, invasive plants are driving our rarest species closer to extinction. According to the U.S. Fish and Wildlife Service, an estimated 42 percent of the nation's endangered and threatened species have declined as a result of encroaching invasive plants and animals. Recent research has shown that some invasive species can cause the populations of even common species to collapse.

According to the USDA Forest Service, Japanese knotweed is a non-native, invasive plant from Asia that spreads quickly to form dense thickets that exclude our native vegetation. Displacement of native plants can alter the quality and quantity of wildlife habitat. Japanese knotweed can also alter soil chemistry and nutrient cycling. It poses a significant threat to riparian areas, where it can survive severe floods and is able to rapidly colonize scoured shores and islands. Once established, populations are extremely persistent. It shades out everything underneath it, preventing forest regeneration, eliminating populations of understory plants, and essentially stopping natural succession. It reproduces by seed and large rhizomes, which may reach a length of 40 to 60 feet. A small piece of rhizome can float down a river and begin to grow once it is deposited on land. These buried rhizomes have grown through 2 inches of asphalt!

According to the Ohio Department of Natural Resources, Japanese knotweed is an upright, shrub-like, semi-woody perennial that can grow to over 10 feet in height. The bamboo-like hollow stems of Japanese knotweed are reddish brown, smooth, stout, and swollen at joints where the leaf meets the stem. The base of the stem above each joint is surrounded by a membranous sheath. Although leaf size may vary, they are normally about 6 inches long by 3 to 4 inches wide, broadly oval to somewhat triangular and pointed at the tip. The minute greenish-white flowers occur in attractive, branched sprays in late summer through early fall. Small winged fruits appear later and are triangular, shiny, and very small, about 1/10” long.

This plant is difficult to control. According to PA DCNR, the key to successful knotweed management is controlling the rhizomes. Mechanical methods alone are largely ineffective. It may be possible to pull single plants if they are not well established and soil conditions allow for complete rhizome removal. Any portions of the root system left behind after grubbing or hand pulling will allow the plant to re-sprout. The herbaceous stems of knotweed can be cut or mowed quite easily. Cutting alone will not control the plant but when performed after June 1 will significantly reduce the height of the regrowth. According to the Penn State Japanese Knotweed Fact Sheet, foliar herbicide applications made after July 1 and before the first killing frost are most effective at injuring the rhizomes. Using both mechanical and chemical controls is one of the most effective forms of knotweed control, particularly for small patches and sensitive areas.

Japanese Knotweed at Edge of Eckhart Woods

The botanical name is Fallopia japonica (was Polygonum cuspidatum) and has been classified by Pennsylvania's Department of Conservation and Natural Resources (DCNR) as invasive, with the potential to threaten Pennsylvania's natural lands.

Another Invasive Plant, Japanese Barberry along with the Knotweed
at Edge of Eckhart Woods

To learn more about Japanese knotweed, plan to attend the Thursday, June 13, meeting of the Cumberland Woodland Owners Association. PA DCNR Bureau of Forestry specialists will speak about the impact of Japanese knotweed and control methods. The meeting will be at 7:00 PM, at the Franklin County Ag Heritage Center which is located at 185 Franklin Farm Lane in Chambersburg. The meeting is open to the public. You do not have to be a member of the association and there is no cost to attend. The workshop is handicap accessible. If you need specific accommodations, please contact Penn State Cooperative Extension in advance at 717-263-9226.

The Cumberland Woodland Owners Association is an organization of private forestland owners and others interested in forestry issues in south central Pennsylvania. The mission of the association is to provide information, education and an exchange of ideas to its members and others about the methods and benefits of proper forest management. For more information about the Cumberland Woodland Owners Association and the meeting, contact Fred Peabody at 717/776-3565 (email: fredp5@earthlink.net).

George Hurd is the Penn State Cooperative Extension Environmental/Resource Development Educator serving Adams and Franklin Counties. Penn State Extension in Adams County is located at 670 Old Harrisburg Road, Suite 204, Gettysburg PA 17325-3404. Phone 334-6271 or e-mail AdamsExt@psu.edu.

Victory Garden 2012 Log - July 9th

Continuing with the science behind Integrated Pest Management, but with plants as the potential pests, we discussed weeds at the July 9th Victory Garden class.  Although the definition of a weed is for the most part, subjectively defined by the individual, "One person's weed is another's wildflower", or as Emerson said, "A weed is a plant whose virtues have not yet been discovered", there exists in most states, a Noxious Weed List, where the state has created regulations that define certain plants as so detrimental to society, that it is illegal to grow them.  Pennsylvania's list and management program can be found here, and its regulatory scheme is summarized here.




Busy Busy Busy


Garden chores that kept us busy included ...



Picking Beans



Picking Cukes



Thinning Turnips



Thinning turnips

Tying Tomatoes

Weeds Part 1 - Poison Hemlock

Poison Hemlock - Conium maculatum
Photo Credit C. Mayer

I've always had a sneaking admiration for weeds.  We gardeners spend a whole lot of time creating a perfect spot to nurture a plant - rich, organic soil, regularly fertilizing for its nutrient needs, watering during a drought, etc. and yet still lose specimens. 

Then, you notice a dandelion thriving in the crack of a sidewalk in the most inhospital location possible, with no help at all from us.

So, here’s another new feature I hope to do for the blog – a regular entry highlighting a weed of some sort that you might notice in your gardens, or, like this week's entry, conspicuously growing alongside the road. But before we get into the details on this particular weed, let’s start off with some background about the plants that will be in this series, or What are Weeds and Why Should We Care?  From the Penn State guide:

There are numerous definitions of a weed, including:

• a plant out of place and not intentionally sown 
• a plant growing where it is not wanted 
• a plant whose virtues have not yet been discovered. (R.W.Emerson) 
• plants that are competitive, persistent, pernicious, and interfere negatively with human activity (Ross, et. al.) and many others.

No matter what definition is used, weeds are plants whose undesirable qualities outweigh their good points, according to man. Our human activities create weed problems since no plant is a "weed" in nature. Though we may try to manipulate nature for our own good, nature is persistent. Through the manipulation process, certain weeds are controlled, while, other more serious weeds may thrive because favorable growing conditions for them also have been meet. Weeds are naturally strong competitors and those weeds that can best compete always tend to dominate. Both humans and nature are involved in plant breeding programs. The main difference between the two programs is that man breeds plants for yield, while nature breeds plants for survival.

So there is nothing inherent to a plant that automatically classifies it as a weed; it must have some human, subjectively-defined aspect that makes it harmful, or even an arbitrarily assigned "I don't want it growing there" decision on the part of the gardener to designate it as such.  So in many cases, one person's "weed" is another person's "wild flower."  In subsequent posts, we'll discuss Pennsylvania's regulatorily defined noxious weeds, and touch on invasive plants, as well, but for now, let’s look at a plant you may have noticed in bloom right now, growing alongside the road - Conium maculatum, or Poison Hemlock.





Poison Hemlock, or Conium maculatum
Photo Credit C. Mayer



The common name pretty much sums up why it’s considered a weed – its toxicity. The plant’s infamy was secured back in ancient Greece when it was used as a means of execution, with its most notable victim being the philosopher Socrates.  The plant is native to Europe, but was brought over here as an ornamental plant, where it escaped cultivation and is now widespread along roadsides, hiking trails, ditches and field borders. 

Although grazing animals will avoid it given alternatives, it can cause problems in fields harvested for hay or silage. It merits a chapter in Amy Stewart’s book, Wicked Plants. Botanically, it is a bienniel in the same family of plants as carrots, parsley, and Queen Anne's Lace.  The poisonous compounds it produces are in the same family of chemicals as nicotine, but at much higher concentrations than found in tobacco plants.

Here are five basic safety rules to avoid accidental poisoning:

• NEVER eat any part of an unknown plant whether in your yard or in the wild.
• NEVER chew on jewelry made from plant parts such as seeds. Children should not be allowed to use them for teething or "play jewelry".
• NEVER attempt to make your own "Nature tea" unless you know the plant you are using and you know that the recipe is from an authoritative source.
• IF YOU GROW YOUR OWN HERBS for cooking, make sure that they are properly identified. Some poisonous plants resemble common herbs.
• DO NOT ALLOW CHILDREN to pick anything in the yard without your supervision. This rule should apply even for your garden vegetables and fruit.

Note the mottled red stem
Photo Credit C. Mayer

In addition to its toxicity, Pennsylvania's Department of Conservation and Natural Resources (DCNR) in its Fact Sheet says,

Poison hemlock may act as a pioneer species quickly colonizing disturbed sites and displacing natives during early successional series. The presence of C. maculatum degrades habitat quality and could indicate a management problem on an ecological preserve.

I think with all those undesirable characteristics, classifying this one as a weed is pretty easy.  If you have any suggestions for particular weeds that you would like to see covered in this series, feel free to mention them in the comments section.