The Weakest Link
This is bad news: garlic mustard, which I've pretty well eliminated from our property but which has taken over the roadside margins along Goose Creek and hundreds of miles of Floyd County roads, is possibly creating disastrous effects on the eastern forest in general. It seems that a chemical given off by the plant (Alliaria petiolata) eliminates some of the good kind of fungus that some trees depend on for their nutrition:
...garlic mustard targets arbuscular mycorrhizal fungi (AMF), which form mutually beneficial relationships with many forest trees. These fungi have long filaments that penetrate the roots of plants, forming an intricate interwoven network that effectively extends the plant's root system. AMF depend on plants for energy and plants depend on the fungi for nutrients. When tree seedlings, which depend strongly on AMF, began to decline in the presence of garlic mustard, the researchers suspected that the invasive plant might thwart this symbiotic relationship.
"The mechanisms for this phenomenon and its potential long term impacts remain poorly understood," Stinson adds, "but one possibility is that invasive species may disrupt fragile ecological relationships that evolved over millions of years."
"This suggests garlic mustard invades the understory of mature forests by poisoning the allies of its main competitors," Stinson says. "By killing off native soil fungi, the appearance of this weed in an intact forest could stifle the next generation of dominant canopy trees. It could also invite other native and nonnative weedy plants that currently grow in low-AMF habitats, such as those disturbed by logging or development."
On the other hand, at least around here, this plant grows along margins, not in deep woods, far as I can tell. But apparently, at least in Ontario where this research was done, garlic mustard finds its way into clearings in the woods, so I'm certain it has the same potential in our forest. Our poor forests--one more insult to a long recent history of injury.
Here are some images so you can recognize garlic mustard on your own property, most easily found while in flower. If in doubt, crush and smell the toothed, heart-shaped leaves: you'll find just what the name suggests--a most definite aroma of garlic.
Comments
people here have been calling it black mustard and letting it grow ---
I will go after it
thanks for this post
Posted by: endment | May 25, 2006 7:47 AM
Fred, when is this pest in flower around these parts?
My pasture land has been used for grazing and haying in recent years and I need to learn what's growing out there.
Posted by: Rigel Morgan | May 25, 2006 8:52 AM
Mycorrhizae fungal spores (by SoilMoist, sold at rosemania.com) are the new item I put into my rose garden this year and it seems to be helping root growth. Probably will take a year or two to tell.
I've made a lot of other "improvments" in my rose regimen this year...better fungicides (yeah, I know the mycorrizhae is a fungus the antifungals like Mancozeb and Captan will kill...but I waited 3 weeks - they recommend 2 weeks - before I put any antifungals on the plants and bed this year.) Blackspot is way down especially on a couple of hybrid tea roses (Gypsy, Pearl, Pearl Essence, which I shouldn't be growing anyway, not here in cloudy and damp Bristol summers), but who can resist names like "Love and Peace" and "Touch of Class"?
Tea roses (the classic big, urn-shaped blooms that fully open into double/very double petal structures)...I think sometimes I am just being pigheaded by growing them when there are SO MANY easier roses (shrubs especially, KnockOut is unkillable..I tell my friends afraid of roses to buy a crummy looking KnockOut at Lowe's/WalWorld/local fruit stand and go upstairs, throw it out the second story window, and God will do the rest.) It grows like kudzu.
I HAVE gone to shrubs and other easier care roses and they really do a LOT better.
One shrub named "Lady Elsie May" I planted in '05 is the best rose bush I have...no blackspot, no bugs, no dropped leaves...heaven for rose growers!
And now there is a report in American Rose (mag of the American Rose Society) that tested fungicides and pesticides vs. compost tea...the tea did 40% better overall at controlling disease and bugs and growth was up to 50% better...maybe next year I'll listen to the wife and go natural. I already work in the chemical (nuke)industry...why buy their deadly products when something else works better and is free?
(Because I am lazy and like to think I am REAL high-tech and most of all want a solution to blackspot which denudes most of my roses of the lower 50% of their leaves by August.)
I need my old hippie perspective to overtake my corporate chemical mindset.
When a magazine & organization that is teetering on bankruptcy like ARS runs articles that show the "need" for their own ADVERTISERS' products is artificially created, you know SOMETHING must be up. Compost tea instructions, anyone?
ps Floyd County is heaven. I would LOVE to retire there - if it hasn't gone yuppie - and if I ever (doubt it - I'm 48) retire (I'm currently on strike)...
Art
Posted by: Art Bagnall | May 25, 2006 2:17 PM
We have garlic mustard everywhere, even in the ddep woods. i was just beginning to think that maybe it wasn't so bad, becasue it doesn't seem to be pushing out too many native wildflowers, when I heard about this new study. Now I'm wondering how many other invasives (including invasive earthworm spp.) might be damaging the mycorrhizae?
Posted by: Dave | May 25, 2006 8:29 PM