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Web URL(s): | http://www.swss.ws/wp-content/uploads/docs/2010 Proceedings-SWSS.pdf#page=198 Last checked: 08/01/2013 Requires: PDF Reader Notes: Item is within a single large file |
Publication Type:
| Report |
Author(s): | McNulty, Brendan M. S.;
Askew, S. D. |
Author Affiliation: | Virginia Tech University, Blacksburg, VA |
Title: | Aeroponics as a means to elucidate herbicide effects on turfgrass root regeneration |
Section: | Weed management in turf Other records with the "Weed management in turf" Section
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Meeting Info.: | Little Rock, Arkansas: January 25-27, 2010 |
Source: | 2010 Proceedings, Southern Weed Science Society. Vol. 63, 2010, p. 148. |
Publishing Information: | Champaign, Illinois: Southern Weed Science Society |
# of Pages: | 1 |
Keywords: | TIC Keywords: Aeroponics; Agrostis stolonifera; Bensulide; Cumyluron; Golf greens; Herbicide evaluation; Poa annua control; Preemergence herbicides; Seasonal behavior
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Abstract/Contents: | "Aeroponics is the process of growing plants in an air or mist environment without the use of an aggregate or liquid medium to support plant roots. Aeroponics differs from hydroponics in that plant roots are suspended in air and sprayed with nutrient solution rather than free floating in nutrient solution. Aeroponics is important for turfgrass culture in the laboratory because it allows for a more oxygen rich environment compared to hydroponics. Growing turgrass[turfgrass] and other plants in an aeroponics system allows for repetitive and accurate measurement of root responses that would be more difficult to obtain when plants are grown in soil. Annual bluegrass (Poa annua L.) is a common winter annual grassy weed found in creeping bentgrass (Agrostis stolinifera L.) golf course putting greens. Many turf managers struggle with control of this weed due to it being a prolific seed producer, an invasive species, as well as containing many biotypes within the species. There are currently two pre-emergence products that are labeled for annual bluegrass control on creeping bentgrass putting greens; bensumec and oxidiazon. Neither of these products offer post emergence activity on annual bluegrass. Cumyluron is a new herbicide under evaluation by the Helena Chemical Company. It offers pre and post emergence control of annual bluegrass in creeping bentgrass putting greens with safety to the desired turf. Through previous trials at Virginia Tech, it was observed that control of annual bluegrass by cumyluron occurs slowly. Annual bluegrass population reductions are often noted in the second year of cumyluron treatments. We hypothesized that cumyluron had a differential effect on root regeneration of annual bluegrass and creeping bentgrass, thus, granting a competitive advantage to creeping bentgrass over time. An experiment was devised to test this hypothesis using aeroponics units to directly deliver concentrations of cumyluron to the roots of creeping bentgrass and annual bluegrass plants. The trial was initiated in April of 2009 and repeated in June and December the same year at the Glade Road Research Center in Blacksburg, VA. Eight aeroponics units were constructed and placed in a greenhouse with supplemental lighting to provide a minimum of 400 μmol/m2/sec photosynthetically active radiation on a 14 hour photoperiod. Each aeroponics unit consisted of 16 plants, 8 annual bluegrass and 8 creeping bentgrass, that were supplied nutrient from a 38 L sump dedicated to each chamber. Upon initiation, all foliage was cut to 39 mm and all roots were cut to 52 mm. Herbicides were applied directly to each sump containing nutrient and thoroughly mixed. The eight treatments included a nontreated check, a bensulide comparison at the label rate of 9000 g ai/ha, and 6 rates of cumyluron including 1720, 860, 172, 86, 17.2, and 1.72 g ai/ha. The trial continued for 17 days after initial treatment with ratings taken at 3, 10, and 17 days after initiation to evaluate root regeneration and foliar response after the initial cutting. Assessments included root and foliar dry weight in grams (g), normalized difference vegetative index (NDVI) (fraction of 1), and root length (cm). The interaction of species with herbicide treatment was never significant and data were pooled over species for discussion of herbicide treatment differences. At 17 days after treatment (DAT) there were no differences in dry foliar biomass and visually-evident foliar responses were seldom observed. NDVI differed significantly with decreasing values as cumyluron rate increased but these trends were poorly correlated with correlation coefficients of less than 0.4. Root length and root weight however, exhibited a strong correlation to the rate of cumyluron applied. Overall, increasing the concentration of cumyluron applied directly to roots of creeping bentgrass and annual bluegrass will decrease both the root biomass and length of both species. Root length of bensulide treated plants was equivalent to the highest rates of cumyluron at 10 DAT but were significantly longer at 17 DAT. Presumably, bensulide either had less residual activity in the nutrient solution or plants of both species were able to recover from bensulide more quickly. From these data we can reject our hypothesis and conclude that cumyluron does not exhibit interspecific differences in root response between creeping bentgrass and annual bluegrass. Our future work will evaluate seasonal root fluctuations of annual bluegrass and creeping bentgrass and vertical profiling of cumyluron on putting greens to determine if annual bluegrass is simply more exposed to cumyluron in the field due to interspecific differences in seasonal root fluctuations." |
Language: | English |
References: | 0 |
Note: | This item is an abstract only! |
| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete): McNulty, B. M. S., and S. D. Askew. 2010. Aeroponics as a means to elucidate herbicide effects on turfgrass root regeneration. South. Weed Sci. Soc. Proc. 63:p. 148. |
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| Web URL(s): http://www.swss.ws/wp-content/uploads/docs/2010 Proceedings-SWSS.pdf#page=198 Last checked: 08/01/2013 Requires: PDF Reader Notes: Item is within a single large file |
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