Golf Course Management

FEB 2017

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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80 GOLF COURSE MANAGEMENT 02.17 earthworms, causing them to surface, desic- cate and die. The product can significantly suppress casting by Aporrectodea, which are typically the most common earthworms in temperate-zone fairways and soil-based greens (6,7). Although Early Bird gave 85% or better suppression of A. peiensis casts at one day after treatment, casting on those plots had re - sumed by seven days after treatment, probably because of re-infestation by worms crawling from nearby untreated portions of the greens (9). The saponins in Early Bird, which dis - rupt the mucus coatings on earthworms, work mainly on contact and probably have little or no residual activity (6). A product containing soluble sulfur (15%) plus surfactant (Cast - Clear, The Lawn Co.) and one with concen- trated natural pyrethrins (6%) + piperonyl butoxide (ExciteR, Prentiss) failed to suppress A. peiensis casting in short-term trials (9). How does an invasive Asian earth- worm end up on golf courses? Asian earthworms, including Amynt as peiensis, have become established around the banks of lakes and rivers as the result of anglers discarding bait (3), and they may also be transported as cocoons in compost, mulch or soil (1). Amynt as reproduce asexu - ally — offspring develop from unfertilized eggs enclosed in tiny, lemon-shaped cocoons no bigger than a grain of rice. The eggs can remain dormant for months or even years be - fore hatching if environmental conditions are not suitable. Inadvertent transport of even a single cocoon could potentially establish a population (3). The superintendent and grounds crew members at the golf course where most of this research was done were adamant that their A. peiensis problems started during the year after course renovations were made with crude (non-sterilized) sand dredged from banks of the Ohio River. Sand from the same supplier was anecdotally linked to sev - eral other Kentucky courses where we found the pest (authors' conversations with superin - tendents). Amynt as peiensis is established along banks of the Ohio and Kentucky riv - ers, as well as those of other large and smaller rivers throughout the central U.S. (4). The species, referred to by anglers as "green stink - worm," "green riverworm" or "green worm," is a popular catfish bait, and where and how to dig it is discussed on websites devoted to that pastime. We visited a riverbank favored by catfish anglers on a medium-sized river — about 1.2 miles from the aforementioned infested course — where turning over a few shovelfuls of river sand and silt yielded large numbers of A u - peiensis (Figure 5). Although finding the same Asian earthworm in sand along riverbanks and on greens and surrounds of a golf course to which such sand had been transported does not prove an association, it suggests a probable sce - nario by which A. peiensis may be introduced to golf courses in crude river sand. It might also be introduced as cocoons or active life stages in compost or mulch (1), by anglers dumping bait around golf course lakes or ponds, or in irriga - tion water drawn from such sources. Presently, no pesticides are labeled for con - trolling earthworms in North America (8). Given the extensive damage that Amynt as species are capable of causing to forest ecosys - tems, gardens and golf courses, and given the ease with which they may be spread, we hope that regulatory agencies will recognize the need for registered pesticides to help manage these invasive pests, at least in horticultural settings. In the meantime, superintendents should be able to manage green stinkworms with either of the pre-mix insecticide formulations (Aloft or 0 5 10 15 20 Aloft, full rate Aloft, half rate Triple Crown Untreated Avg. no. of casts/10.8 square feet (1 square meter) Pretreatment 1 2 4 8 Weeks after treatment Figure 6. Season-long control of Amynthas hupeiensis casts on sand-based putting greens. Treatments were applied on May 22, 2014, and were watered in with about 2 ⁄3 inch of irrigation.

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