No abstract

Late-season fertilization of bermudagrasses (Cynodon spp. L.C. Rich.) in the transition zone of the United States has traditionally been not recommended. This study was conducted to determine whether late-season fertilization could extend the duration of turfgrass color retention and visual quality without negatively impacting cold tolerance. Field plots of 'Midiron' and 'Tifway' bermudagrasses (C. dactylon 3 C. transvaalensis Burtt Davy), as well as 'Princess-77' and 'Riviera' bermudagrasses [C. dactylon (L.) Pers. var. dactylon] received applications of seaweed extract (SWE) (0.54 kg ha 21 ), N (49 kg ha 21 ), and Fe (1 kg ha 21 ) every 3 wk during the fall of 2001 and 2002.Visual turfgrass assessment showed that cultivar color ratings decreased as the fall progressed, with Princess-77 having greatest color retention in November of both years. Nitrogen was the only treatment to increase turfgrass color ratings relative to the control at the end of each growing season. Stolon samples removed from acclimated plants were artificially frozen to determine freezing tolerance. Midiron displayed the best freezing tolerance followed by Riviera, Tifway, and Princess-77. Chemical treatments did not have a significant effect on shoot regrowth from stolon nodes after freezing. In both years Midiron and Riviera displayed the quickest and greatest amount of spring greenup followed by Tifway and then Princess-77. Cold tolerance indicators proline and linolenic acid were highest in Midiron, followed by Riviera, Tifway, and Princess-77. Nitrogen, SWE, and Fe did not generally have an effect on linolenic acid and no consistent effects of these chemical treatments were noted on proline concentration. The results of this study indicate that judicious N applications during the fall can promote color retention and do not have a negative effect on bermudagrass cold tolerance.

problem with seeded bermudagrass cultivars the first winter after establishment. Researchers in Mississippi Bermudagrass [Cynodon dactylon (L.) Pers.] is an important turf-reported that the potential for winterkill during the first grass across the transition zone. A common concern is survival of winter following establishment is a critical factor in deseeded cultivars the first winter after establishment. The objective of this study was to determine the optimum seeding and N rates to ciding whether to use seeded cultivars (Philley and enhance stolon production. The cultivar Mirage was seeded in June Krans, 1998). Ahring et al. (1975) indicated that new of 1998 and 1999 at 12.2, 24.4, 36.6, and 48.8 kg pure live seed (PLS) plantings of seeded bermudagrass may be very susceptiha Ϫ1 . Urea nitrogen was applied as a split-plot treatment at the rates ble to freeze injury, but older plantings of the same of 48.8, 195.2, 390.4, or 585.6 kg N ha Ϫ1 growing season Ϫ1 . Fresh cultivar may survive because deep rhizomes are proweights of stolons harvested at the end of both growing seasons weretected from cold temperatures, or that they have become greatest at 12.2 kg PLS ha Ϫ1 rate, and decreased significantly as seeding more hardy. Generally, after surviving the first winter, rate increased. The same response to seeding rate was evident when seeded bermudagrasses are able to withstand average measuring stolon diameters in both years of the study. In 1999, 585.6 winter conditions across the transition zone. kg N ha Ϫ1 produced more stolons than 48.8 kg N ha Ϫ1 , indicating a significant positive linear response to N. The opposite was true with

Abbreviations: ACC, 1-aminocyclopropane-1-carboxylic acid; LT 50 , the low temperature that proved to be lethal for 50% of the plants; PGR, plant growth regulator.

Creeping bentrgrass putting greens require intense management due to stoloniferous growth (thatch accumulation) and excessive wear and traffic by equipment and golfers. Increases in thatch and soil compaction are often managed with cultivation practices, which lead to downtime for golfers. Field research was conducted in Knoxville, TN, and Elizabethtown, KY, to compare new and traditional cultivation methods for their impact on playability on creeping bentgrass putting greens. Treatments included air injection, dry sand injection, solid tine cultivation topdressed with sand, hollow tine cultivation topdressed with sand, and non-treated control. Treatments were arranged in a randomized complete block design replicated three times at two locations. As determined 15 minutes after treatments, air injection resulted in the least reduction of green turfgrass cover, no ball roll reduction from the control, and lower reductions in surface firmness compared to other methods tested. Hollow tine had the greatest reduction in green turfgrass cover, lowest ball roll distance, and greatest reductions in surface firmness. Air injection had a lower impact on surface characteristics than hollow or solid cultivation. Because turf cover, ball roll, and firmness can all affect putting green playability, these findings indicate that air injection cultivation has the smallest impact on golfers immediately after a cultivation event.