Effectiveness of hand pulling

[ccstoney]

Starry stonewort was identified in Stoney Lake in the Kawartha region of Ontario, Canada in 2018. We have two main areas of infestation. The first is a shallow wetland area and the bays on each end. The second is a large bay containing a marina, a resort and a golf club. In 2019 we found three smaller areas. We are interested in trying hand pulling the SSW next summer to see if we can minimize the spread in the new areas. Can anyone suggest best methods for this? The water in the new areas is probably 7-10 ft deep.

[pskawinski]

Manual removal can be a great option for any aquatic invasive plant, but keep in mind that SSW can regenerate from bulbils or fragments, so you would need to be very careful to get the entire plant each time. If you leave anything behind, you will not have accomplished much. This could be quite challenging at 7-10ft deep unless you have SCUBA gear or use a diver-assisted suction harvesting (DASH) system. Snorkeling to 7-10ft deep for plant removal is doable but challenging.

However you do this, you must reach down into the sediments by a few inches to lift the plant from the bottom. This will lift the bulbils out and keep the main thallus (stem) of the plant from breaking under stress. Simply yanking the plant from the top will likely break the stem and leave many bulbils behind. SSW tends to grow in soft sediments, so reaching into the sediments to dislodge the plant/bulbils is usually not difficult.

[ccstoney]

Thank you for that. Last summer I spoke to a gentleman from Grand Lake in Minnesota. They’ve had divers doing hand removal of a small patch of starry stonewort for a few summers. I believe they revisit the patch three times per season. With repetitive pulling the amount of starry stonewort has decreased. Is it possible that the bulbils can be exhausted over time?

[pskawinski]

Manual removal is a great option for any aquatic invasive plant. Grand Lake is a perfect example. Any bulbils left behind will sprout new plants, but yes, the supply of bulbils could be exhausted over time if each new plant / sprouted bulbil is removed before it can grow into a plant and produce more. A few fragments/bulbils will be left behind no matter what you do, whether you’re removing starry stonewort, Eurasian watermilfoil, narrow-leaf cattail, or anything else. The key to success is vigilance and working within your limits. Start small and be thorough. A common mistake with manual removal of AIS is trying to tackle a population that is too large from the beginning. The crew gets discouraged by slow progress and then gets sloppy, resulting in poor results.

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