Progress 10/01/00 to 09/30/05
Outputs
Ground ivy is a difficult to control weed on many turf sites. The reasons for this are not well understood. Ground ivy specimens from nine diverse locations in the U.S. and Canada were obtained. RAPD markers were used to determine if genotypic differences exist among the nine specimens of ground ivy. Few differences in banding patterns were detected among the ground ivy specimens indicating a high degree of genetic similarity among the specimens. Leaf shape, trichome density and internode length have been measured to determine if there are phenotypic differences among ground ivy specimens. Phenotypic differences do occur among the ground ivy specimens but the role of these phenotypic differences in control has yet to be determined. 2,4-D and herbicide mixtures containing 2,4-D are commonly used to control ground ivy. Ground ivy plants collected at each of the nine locations were treated with a single application of 2,4-D to determine the degree of susceptibility to
2,4-D. Ground ivy from five locations was highly susceptible to 2,4-D, ground ivy from two locations was susceptible to 2,4-D, ground ivy from one location was moderately susceptible to 2,4-D, and ground ivy from one location was slightly susceptible to 2,4-D. These findings indicate populations of ground ivy respond differently to 2,4-D and may be one of the reasons it is difficult to control ground ivy on turf sites. Research is continuing to determine possible mechanisms that explain the range of responses of ground ivy to 2,4-D.
Impacts
Ground ivy collected from diverse geographic locations varies in response to applications of 2,4-D, a commonly used herbicide to control ground ivy. The varying degree of response to 2,4-D may help explain why ground ivy is so difficult to control in some settings. If the mechanism that controls ground ivy response to 2,4-D can be identified then better control strategies can be developed.
Publications
- Reicher, Z.J., C.S. Throssell, and D.V. Weisenberger. 2000. Date of seeding affects establishment of cool-season grasses. Hort. Science 35(6):1166-1169.
- Sigler, W.V. 2000. Sensitivity of the microbial ecology of turfgrass soils to outside perturbation. Ph.D. dissertation, 128 p. Dept. of Agronomy, Purdue Univ. May, 2000.
- Reicher, Z.J., D.V. Weisenberger, G.A. Hardebeck, and C.S. Throssell. 2000. Turf safety of dithiopyr on newly seeded Kentucky bluegrass. Weed Tech. 14:550-555.
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Progress 10/01/98 to 09/30/99
Outputs
Fungicide applications are a necessary practice to manage disease development on many high quality turf sites. However, little is know about the effects that fungicides have on the resident microbial community of the soils supporting turfgrass sites. Soil bacteria are responsible for important processes including pesticide degradation, nutrient cycling, and organic matter breakdown. The objective of the research was to determine the short-term impact of fungicide introduction on the indigenous bacterial community of soil. Three soils, a putting green rootzone sand, forest, and an agricultural soil, were incubated with technical grade chlorothalonil at rates corresponding to 0x 0.2x, 1x, and 5x the high label rate of chlorothalonil application. The mass equivalent of 250 cubic cm of soil was incubated in plastic bags for two weeks. DNA was extracted from the soils prior to and after the two-week incubation period. PCR amplification was performed using primers specific
for bacterial cells only. Amplification products were analyzed for community structure changes using denaturing gradient gel electrophoresis. The sand was characterized by consistently lower quantities of extractable DNA when compared to the agricultural soil which, in turn, contained less DNA than the forest soil. These results suggest that the sand at this point in time, sustains a very low microbial biomass and potentially less microbial activity when compared to other soils with higher microbial biomass. The sand was a component of a newly established putting green and may be exhibiting a low biomass due to age, and disturbances due to construction and establishment. DGGE profiles indicate that chlorothalonil application dramatically impacted the microbial community of the sand. Banding pattern shifts were evident regardless of the rate of chlorothalonil application and included both new bands forming and native bands regressing. The documentable effect of chlorothalonil
application on the microbial community of the forest and agricultural soil was minimal. The relative richness of the forest and agricultural soil microbial communities may tend to mask subtle restructuring that may in fact, be taking place. Results indicate that the low biomass sand was impacted more by additions of chlorothalonil than the two soils of greater biomass. The sand and other soils under similar management are thought to be at the highest risk of stress at the microbial community level. Further research is necessary to characterize more specifically the nature of the population shifts occurring in the sand.
Impacts
The soil microbial community is responsible for important processes including pesticide degradation, nutrient cycling, and organic matter breakdown. This research indicates that a newly constructed sand rootzone of a putting green had less microbial biomass than did an agricultural or forest soil. The microbial community of the sand was more susceptible to alterations from outside inputs such as pesticides. Further research is needed to determine the specific bacteria affected, their role in the soil community and if the biomass of the sand rootzone will increase as the rootzone ages.
Publications
- Reicher, Z.J., Weisenberger, D.V., and Throssell, C.S. 1999. Turf safety and effectiveness of dithiopyr and quinclorac for large crabgrass control in spring-seeded turf. Weed Technol. 13:253-256.
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Progress 10/01/97 to 09/30/98
Outputs
Frequent fungicide applications are common to high quality turfgrass sites such as golf course putting greens, tees, and fairways. Little research is available to determine the impact of fungicides on the resident soil microbial population. Based on the importance of soil microorganisms for processes such as nutrient cycling, organic matter decomposition, and pollutant degradation, the effect of fungicide application on these organisms was determined. Replicated field plots of creeping bentgrass turf maintained as a golf course fairway were treated with the fungicide chlorothalonil in a curative fashion at label rates. Adjacent field plots of creeping bentgrass were not treated to serve as a comparison. Soil samples were collected on a regular basis from fungicide treated and non-fungicide treated plots. After soil samples were collected, DNA was extracted from the soil, bacterial DNA was amplified, denaturing-gradient gel electrophoresis was conducting followed by
gel staining and visualization. Results indicate the soil bacterial population is highly diverse. The gel resulted in a gray smear generated from a large number of differing DNA sequences as they migrate through the gel. The soil bacterial population remained stable over the five-month (May-September) sampling period with only minor fluctuations of dominant members. Soil bacterial populations in chlorothalonil treated plots were consistent relative to soil bacterial populations from untreated plots. This may be due to the turfgrass canopy and thatch sorbing the applied chlorothalonil before it reached the soil as previous research has indicated. There is great diversity in the soil bacterial population in turfgrass soils. This diversity was unaffected by applications of chlorothalonil possibly due to the filtering action of the turfgrass canopy and thatch.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 10/01/96 to 09/30/97
Outputs
The study of microbial degradation of fungicides in turfgrass systems is important in order to understand the complete environmental fate of xenobiotic materials. This ongoing project investigates degradation as it may occur in the turfgrass canopy. Replicated field plots of creeping bentgrass turf maintained as a golf course putting green were treated with three fungicides. The fungicides were applied separately, either every 2 or 8 weeks for a 16 week period. At specified intervals after application clippings were collected and brought to the lab. A radiolabeled form of the same fungicide that was applied in the field was added to the clippings. Clippings were placed in flasks and incubated for 14 days. Evolved radiolabeled carbon dioxide was trapped and counted at specified intervals. Less than 5% of the radiolabeled fungicide was completely mineralized to carbon dioxide. Oxidation of the clippings following the trapping of evolved carbon dioxide revealed that over
75% of the radiolabeled fungicide was bound to the turfgrass leaves and probably unavailable for microbial degradation. The exact mechanism by which the fungicide became bound to the clippings is not known. These findings lead us to believe that microbial degradation of fungicides in the turfgrass canopy is limited. Most of the applied fungicide is bound to the leaf tissue in a manner where they are not available for degradation. Since the fungicides are bound to the leaf tissue they are not available to move into the environment.
Impacts
(N/A)
Publications
- Pitts, C.H. 1997. Fate of fungicides in the turfgrass environment; sorption and dissipation in grass clippings, and mineralization in the thatch and soil. M.S. Thesis, Purdue University, W. Lafayette IN. 63 p.
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Progress 10/01/95 to 09/30/96
Outputs
Fungicides are frequently applied to suppress diseases on golf course putting greens. Multiple applications of a single fungicide during the growing season is a common practice. Little is known about the fate of fungicides in the turfgrass environment particularly with multiple applications of the same fungicide throughout a single growing year. Field studies were conducted to determine the fate of the fungicide vinclozolin in grass clippings and thatch of creeping bentgrass turf (Agrostis palustris) and in the underlying soil. Average concentration of vinclozolin detected in grass clippings one day after the initial application was 700 mg g-1. Concentration of vinclozolin in grass clippings declined between each application. Amount of vinclozolin detected one day after application became progressively lower as successive applications were made throughout the summer. Vinclozolin concentrations in thatch were approximately 10 times lower than those in grass clippings.
Concentrations of vinclozolin in thatch one day after the initial application was 17 mg g-1. No vinclozolin was detected in thatch after the first two applications when application frequency was every four weeks and after the first four applications when application frequency was every two weeks. Concentration of vinclozolin in soil was 100 times lower than that of grass clippings and was less than 1 mg g-1 after the initial application. No vinclozolin was detected in soil samples taken from 4 to 61 cm below the soil surface follow.
Impacts
(N/A)
Publications
- FREDERICK, E.K. C.S. THROSSELL, M. BISCHOFF, and R.F. TURCO. 1996. Fate of vinclozolin in creeping bentgrass turf under two application frequencies. Bull. Envir. Con. and Tox. 57:391-397.
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Progress 10/01/94 to 09/30/95
Outputs
Early spring applications of broadleaf weed herbicides to turfgrass stands oftenprove ineffective in controlling weeds. Growing degree days (GDD) may be a more effective means of timing spring broadleaf herbicide applications than calendar dates. The objective of this research was to determine changes in total nonstructural carbohydrates (TNC) that are associated with increased control of dandelion (Taraxacum officinale Weber) with spring applied broadleaf weed herbicides. 2,4-D + 2,4-DP ester and 2,4-D + 2,4-DP amine were applied at several GDD thresholds to Kentucky bluegrass (Poa pratensis L.) swards heavily infested with dandelion. Treated dandelion tissues differed in TNC from control tissues when the ester formulation was applied at 77 or 82 GDD but not at 64 GDD. This coincides with the results of a concurrent investigation that showed 53, 94, and 100% control of dandelions was achieved by herbicide applications made at 64, 77, or 82 GDD. Changes in herbicide
efficacy with 2,4-D + 2,4-DP ester seemed to correspond to changes in TNC. Response of dandelion following treatment with 2,4-D + 2,4-DP amine were inconsistent and variable. Monitoring TNC of dandelion tissue may be an accurate method to determine optimum timing of spring applied broadleaf weed herbicides.
Impacts
(N/A)
Publications
- Robbins, DL. 1995. Effect of 2,4-D + 2,4-DP applications timed by growing degree day on soluble protein and carbohydrate pools of dandelion in the spring. M.S. Thesis, Purdue University, W. Lafayette, IN 90 p.
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Progress 10/01/93 to 09/30/94
Outputs
Fungicides are frequently applied to golf course turf to control diseases in order to provide high quality playing conditions demanded by golfers. The environmental fate of fungicides applied to turf has not been thoroughly investigated. A field study was undertaken to determine fate of the fungicide vinclozolin after 0, 4, and 8 applications made over a 4 month period. Results indicated that most of the vinclozolin was intercepted by the canopy and retained on the clippings. Vinclozolin concentration in clippings declined between applications and with each successive application. Vinclozolin residues in thatch were 10 times lower than detected in clippings. Again, vinclozolin residue detected in thatch declined between applications and with each successive application. Vinclozolin recovered from soil was 100 times lower than recovered in clippings. No vinclozolin was detected in soil at depth greater than 2.5 cm. These results indicate vinclozolin fungicide when
applied according to label directions does not pose a threat to subsurface water supplies.
Impacts
(N/A)
Publications
- FREDERICK, E.K. 1994, Environmental fate of fungicides applied to turfgrass. M.S. Thesis, Purdue University, W. Lafayette IN 30 p.
- FREDERICK, E.K., BISCHOFF, M., THROSSELL, C.S. and TURCO, R.F. 1994. Degradation of chloroneb, triadimefon, and vinclozolin in soil, thatch, and grass clippings. Bull. Env. Contam. Tox. 53:536-542.
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Progress 10/01/92 to 09/30/93
Outputs
Fungicides are applied frequently to golf course turf to provide high quality playing conditions demanded by golfers. Separate investigations have been conducted to determine the impact of frequent fungicide applications on the growth of creeping bentgrass (Agrostis palustris Huds.) and to determine the rate of fungicide degradation in soil, thatch, and grass clippings. When applied in a single application at 3X or 9X fungicides caused a short term decrease in visual quality in some instances, but few detectable difference in root or shoot growth or water soluble carbohydrate content. Fungicides applied at the recommended rate 3 and 9 times over a four week period caused few consistent differences in root or shoot growth. When fungicides are applied judiciously and at the recommended rate few negative effects on growth and performance of creeping bentgrass would be expected. A laboratory study was conducted to determine degradation rates of three fungicides in soil,
thatch, and grass clippings. Results indicate fungicides degrade rapidly in soil, fairly rapidly in thatch, and more slowly in grass clippings. Detection limits for fungicides in soil, thatch, and grass clippings were reached 21, 40, and >56 days following application, respectively. These results indicate fungicides will degrade fairly rapidly in the turf ecosystem and lessen the potential for environmental contamination.
Impacts
(N/A)
Publications
- FREDERICK, E.F., BISCHOFF, M., THROSSELL, C.S., and TURCO, R.F. 1993. Degradation of chloroneb, triadimefon, and vinclozolin and soil, thatch, and grass clipping.
- REICHER, Z.J. 1993. Non-target effects of fungicides on creeping bentgrass (Agrostis palustris Huds.). Ph.D. Dissertation, Purdue Univ., W. Lafayette, IN. 92 p.
- REICHER, Z.J. and THROSSELL, C.S. 1993. Efficacy of fall and spring applied preemergence herbicides for annual grass control in Kentucky bluegrass turf. Int. Turfgrass Soc. Res. J. 7:273-276.
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Progress 10/01/91 to 09/30/92
Outputs
A three year field study examining the impact of frequent fungicide applicationson growth and physiology of creeping bentgrass putting green turf was completed in 1992. Preliminary results indicate 16 applications of fungicides per year for three years had minimal impact on shoot and root growth of creeping bentgrass. Soluble carbohydrate of leaf tissue was not affected by fungicide applications. Results suggest that non-target effects of frequent fungicide applications on creeping bentgrass do not affect growth and vigor of the turf plants. The degradation of three fungicides applied to turfgrass clippings, turfgrass thatch, and soil was studied in laboratory experiments. Each fungicide was applied to clippings, thatch, and soil and incubated in plastic bags. Samples were removed at several intervals to determine amount of fungicide degradation. Preliminary results showed that rate of fungicide degradation in soil was most rapid, degradation thatch intermediate, and
degradation in clippings the slowest. After 56 days the parent fungicide was still detectable in turfgrass clippings. The slow degradation of fungicides in clippings will be studied further.
Impacts
(N/A)
Publications
- DELL, C.J., C.S. THROSSELL, M. BISCHOFF, AND R.F. TURCO. 1992. Estimation of sorption coefficients for fungicides in soil and turfgrass thatch. J. Environ. Qual. Accept. for pub.
- ORICK, J.C. 1992. Irrigation scheduling techniques for cool-season turfgrasses. M.S. Thesis. Purdue Univ., W Lafayette IN. 85 p.
- REICHER, Z.J., AND C.S. THROSSELL. 1992. Efficacy of fall and spring applied preemergence herbicides for annual grass control in Kentucky bluegrass turf. Proc. Int. Turf. Soc. Accept. for pub.
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Progress 10/01/90 to 09/30/91
Outputs
Turfgrass canopy temperature of Kentucky bluegrass (Poa pratensis L.), perennialryegrass (Lolium perenne), and tall fescue (Festuca arundinacea Schreb.) mowed at 2.5, 5.0, 7.5, and 10.0 cm height was measured under conditions of optimum transpiration and no transpiration. Mowing height and turfgrass species did not have a consistent effect on turfgrass canopy temperature regardless of transpiration condition. Turfgrass canopy temperature was 5 to 15(degree) higher for non-transpiring turf than turf transpiring at the optimum rate under the same weather conditions. Sorption of three fungicides in turfgrass thatch and underlying soil was studied in laboratory experiments. Freunlich isotherm values (K(subscript f)) for thatch and soil were 59.70 and 6.65 for triadimefon, 117.3 and 14.93 for chloroneb, and 467.08 and 46.64 for vinclozolin, respectively. This suggests that thatch, and to a lesser extent soil, will sorb fungicides, which will decrease the potential for these
compounds to contaminate ground water. Preemergence herbicides are widely used to control annual grasses in turf stands. Field studies were undertaken to determine if sequential applications using different preemergence herbicides for each application were as effective as sequential applications using the same preemergence herbicide for each application.
Impacts
(N/A)
Publications
- THROSSELL, C. S. and N.S. HEWISON. 1991. A useful tool for turfgrass students searching the United States Golf Association Turfgrass Information File. J. Agr. Ed. Accept. for publ.
- DELL. C. J. 1991. Estimation of sorption and desorption coefficients for turf-applied fungicides in thatch and soil. M.S. Thesis. Purdue Univ. 36 p.
- REICHER, Z. J., THROSSELL, C. S., and J. L. LEFTON. 1991. Annual grass control in cool season turf with sequential applications of unlike preemergence herbicides. Weed Tech. Vol. 5 387-391.
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