The Delaware Department of Agriculture and the United States Department of Agriculture have published an online booklet for the Mid-Atlantic region, (from New Jersey to Virginia) that will help homeowners, and land managers with the difficult task of differentiting between problematic foreign invasive plants, and their native look-alikes.
The US Government spends billions of dollars each year trying to combat the rapid spread of invasive plants in waterways, national parks, and farmland, and the private industry spends equal that amount from their own budgets to do the same. The trouble with many invasive and rapidly growing plants is that they look much like their native cousins, who pose no ecological threat here in their home environment. For many land managers, including myself, differentiating between the native (and protected) plant, and the look-alike invasive plant can be difficult. This guide contains the best side-by-side compairisons between these plants that I have ever seen, including pictures, descriptions, and even reasons why the plant needs to be removed.
For those of us in the business who can’t tell the difference between “Giant Hogweed,” and a “Cow Parsnip,” this guide will help you properly identify the difference between the two, while giving you proven tips on the permanent erradication of the invasive. I particularly appreciate the hints it gives on handling some of the more noxious plants, for instance warning the reader that Hogweed sap on the skin causes chemicals burns when it’s exposed to sunlight.
The guide can be found online through this link and identifies 20 of the most common invasive plants that keep those of us in the ‘Green Industry’ on our toes. It’s a great link to bookmark on your browser, or to print out and have on hand during the growing season for quick identification.
Looking over some garden hedges recently, I discovered a type of gall on all six of the identical shrubs. The gall growths were hard, irregularly shaped, and about two inches in diameter. I looked over the area that the galls were attached to, and noticed that the galls were mostly growing in areas that had been pruned within the last one or two years, a sign that pointed to a bacterial gall instead of an insect gall. I snapped the gall off of the plant to have a closer look.
There are many types of gall with several specific causes, but they can generally be broken down into two categories: disease caused, and insect caused. Insect caused galls come in all shapes and sizes, both soft tissue growths, fuzzy growths, and firm growths. All of them hold either the eggs or larvae of a specific type of wasp or mite inside, and can contain hollow areas inside the gall where the creature lives and feeds. Insect caused galls may look strange and detract from the outward appearance of a plant, but they do not damage plants. Disease galls do damage a plant, and are initially caused by a bacterium that lives in the soil, although they are commonly spread from plant to plant by pruning, or grafting, when hedge shears have come into contact with an infected plant. The true damage caused by a bacterial gall is actually in and around the gall growth, where the unchecked growth of cell tissue distorts, or chokes off the flow of water and nutrients through the plant.
How To Discern Between Insect And Disease Caused Galls:
With the above pictured gall, I investigated the cause of the growth visually from the exterior appearance, and by dissecting the growth, to check for hollow areas inside the gall that would be a sign of insects. I found that the gall was solid throughout, with layers of disorganized tissue, and concluded that the gall was in fact Crown Gall, a bacterial infection. If you find a gall on one of your plants you will need to do these two things to determine the root cause. Identifying the shape of a gall is important, the shape and appearance of a gall can most often tell you what the root cause is. If you are unsure, or just curious, you can then dissect the gall to check the inside for insect life.
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