I was just beginning to work on pulling Wild Carrot from the prairies when another invasive plant jumped in and demanded immediate attention. Teasel, Dipsacus sylvestris, has a growth pattern similar to that of the Wild Carrot. It is a non-native invasive biennial plant that remains as a basal rosette of leaves during its first year and in year two puts all of its energy into producing a crop of seeds.
The Teasel seed head is quite interesting and shows up in many craft items and occasionally in SF film productions as a strange life form of non-terrestrial origin. An average plant will produce six to ten seed heads.
Inside each seed head are row after row of seeds. By my count, each seed head produces about 750 seeds. That means each plant has the potential to produce several thousand offspring.
One of the keys to controlling this plant is to keep these seeds from being scattered around the field.
Teasel plants are covered with spines and solidly anchored in the ground, so pulling the plants is not a desirable control method. It’s much easier to collect the seed heads after the seeds have been made and the plant is beginning to die.
If the seed heads are plucked too early, the plant will respond by producing new flowers, so it is important to wait until the leaves are shriveling before collecting any seed heads. The dieing plants are easy to see, so it’s a fairly simple process to wander through the field popping their heads off. The work goes pretty quickly when there are only a few plants scattered across the field.
The other controlling consideration in seed head collection is the need to gather them before the seeds begin to come loose. Normally, this whole process occurs later in the year and there are a couple of weeks in which to do the collecting. This year’s weird weather pattern has accelerated the timetable so the plants are dieing early and the interval before seed drop has shortened. A few days ago, the plants were still looking green and alive. Now they have dried to the point that seeds are falling. Each shake of the plant dislodges seeds. Instead of snapping the seeds off by hand, I’ve got to use the more gentle method of snipping the stalks with hand pruners.
My collecting bucket hangs by a belt at my waist. I’ve found that a square bucket remains more stable as I walk among the tall plants. The collected seed heads will go at the bottom of a fresh compost heap. By the time they again see the light of day, the seeds will have long since decomposed.