by Carl Strang
As chance would have it, there are very few patches of second-year garlic mustard plants at Mayslake Forest Preserve this year, and none that will suit the next stage in my experimental study of best methods for manual removal of these invasive European biennials. There are, however, abundant seedlings.
Last week I paid a final visit to last year’s experimental plots to count seedlings. These are areas, divided into square meter units, in which I either uprooted plants, or clipped them at soil surface level, or left them alone as controls, in April. I have found that uprooting garlic mustard is effective in March or April, and clipping also is effective but surprisingly so in April (practically none survive).
In the process I am looking into the possibility that uprooting plants disturbs the soil and increases seedling germination, a possible negative side effect. Earlier I found that pulling tiny second-year plants in March does not encourage additional seedling germination. Uprooting larger second-year plants in April disturbs the soil more. I found last year that same-year seedling germination is not increased, however. Would the same be true in the following season?
The bottom line answer is, yes. The total number of seedlings in 9 square meters of controls was 6125 (range 262-1444, median 724). Clipped areas produced 5954 seedlings (range 249-1397, median 491). Uprooted squares contained 5595 seedlings (range 150-1286, median 515). Differences were not statistically significant. That puts to rest, in my mind at least, concerns about the common practice of uprooting.
So, I am done I think with hands and knees work. The next stage, which now will need to wait until next year, will be to try clipping with a cutter that allows more efficient, faster removal than one-by-one hand clipping.