Is a disease killing it? Will the "loss" be temporary? Can we encourage it?
|Withering, discolored leaves on garlic mustard (Alliaria petiolata). |
Is this the beginning of the end of a great scourge?
But this spring, a number of stewards have reported similar experiences:
"I visited three areas where we’ve had major garlic mustard infestations.
In one, I found a few stragglers. In the other two I found none at all.
It’s almost spooky."
"We have definitely had this experience at Deer Grove, but what I saw today is more than the effect of steady pulling. The odd thing this year is that I am not seeing even the occasional random stem. I walked miles and miles and saw 3 stems total."
"I had the same experience 2 days ago at Schaumburg Road. I walked a couple miles through the woods and saw about 10 plants. The only exception was one 3 acre grove. Now to figure out the difference between that 3 acre grove and the other 100 acres."
For a couple of years, we've noticed a few sickly plants like that at Somme. We decided not to pull them (but to snip off any forming seed). If this is a disease, and if it's not doing any other harm, we wanted it to spread. These results are being found at sites scores of miles distant. At many areas farther away, garlic mustard infestations are still virulent."Your report of the decline of garlic mustard is consistent with my
observations over last 3 or 4 years in NE IL and NW IN. Many sites I visit
have had a dramatic reduction in Gm. Many Gm plants have crinkled leaves
after blooming. I believe a virus is responsible based on how other
species respond to pathogenic viruses.”
Mike Tuttle found some research on viruses attacking garlic mustard:
A number of the comments (below) make interesting suggestions.
There's been some discussion about volunteers moving sick plants to new populations. Is that legal? Probably not. Federal agencies certainly wouldn't do it without doing a lot of very expensive research first. The viruses referenced above also infect some crops (like turnips).
Here's something of a parallel - but in this case with gypsy moths. I once heard that staff folks from one forest preserve went to areas of sick gypsy moths to gather infected caterpillars - and released them in areas the gypsy pests were starting to over-run. I observed one area said to be treated this way. The moths came through in numbers sufficient to attract breeding yellow-billed and black-billed cuckoos. But they did not defoliate whole trees, and the infestation was over after a year or two.
Are there people who are experts at this kind of thing?