Golf Course Management

FEB 2019

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

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02.19 GOLF COURSE MANAGEMENT 75 cause only specific genotypes have been able to colonize these greens initially or because selection has acted on genotypes over time to produce better adapted "putting green" genotypes (local adaptation). e specialized putting green genotypes also differ markedly in their reproductive strategy, with little al - location to specialized asexual reproduction (bulbil and gemmae production) compared with genotypes from native habitats. us, putting green genotypes may have a K-type strategy (more allocation to biomass related to staying in place), whereas the genotypes from native habitats exhibit an r-type strategy (more allocation to offspring and dispersing) (3, 5, 7). Putting greens are permanent fea - tures in terms of location in golf courses, but are highly managed, and therefore disturbed, habitats. Silvery-thread moss is known to be adapted to ephemeral habitats, often appear - ing and disappearing from the same site over the course of just a few years. Dispersal of silvery-thread moss Silvery-thread moss is capable of dispers - ing via asexual (shoot fragments, bulbils, gem- mae) and sexual (spores) structures, making it difficult to determine which of these micro - scopic entities is ultimately perpetuating the putting green invasion process. Identifying the primary dispersal mechanism(s) is critical when attempting to develop a successful inte - grated weed management strategy at the most effective spatial scale (1). Interestingly, silvery-thread moss has sepa - rate sexes (dioecy), so spores from a sporophyte should have an offspring male-to-female sex ratio of 1:1. However, in the field, research - ers observe a trend toward a greater number of female plants (70%) than male plants (30%) in native habitats (14). No males were identi - fied in samples collected from greens; 16 geno- types expressed female, and one genotype did not express sex. Putting greens are typically mowed daily at heights below 0.138 inch (3.5 millimeters), and this practice prevents the production of the long, stalk-like setae that eventually give rise to the spore-containing capsule of mosses (12). erefore, it is unlikely, if not impossible, for spores to be a dispersing agent from green to green. However, spores could serve as the initial inoculum during the "introduction" phase of the invasion process, but this hypoth - esis is not supported from this research, con- Shoot height 18 16 14 12 10 8 6 4 2 0 Shoot height (mm) Nutrients Water Green Nutrients Water Native Figure 4. The height of the tallest silvery-thread moss shoot at the conclusion of the experiment (day 150). Figure 5. A culture of silvery-thread moss collected from a putting green in Ohio was treated with nutrients (left) and compared with a culture of the same moss that received only distilled water (right). Photo by Lloyd Stark

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