| Abstract/Contents: | "This study was undertaken to determine the effectiveness of products applied at different timing intervals to suppress first generation annual bluegrass weevil (ABW) on a private golf course fairway adjacent to the rough in Bedford County. The turfgrass area consisted of annual bluegrass (70%) and perennial ryegrass (30%). Treatment plots were 7 Œ 4 ft, arranged in a complete randomized block design and replicated three times with a 1 ft barrier around all replicates. Liquid formulations were applied by using a CO2 sprayer with four 8002VS TeeJet nozzles mounted on a 7 ft boom, operating at 32 psi, and applied in 212 ml of water/28 ft2 or delivering 2.0 gal/1000 ft2. Granular formulations were applied with a hand-held shaker and mixed with fine top dressing sand to facilitate product distribution. At treatment time one (30 Apr) forsythia was in full bloom and the following soil and environmental conditions existed: air temp, 40 °F; soil temp at l inch depth, 48 °F; soil temp at 2 inch depth, 44 °F; RH, 64%; amt of thatch, 0.5 inch; water pH, 7.0; application time, late morning; soil, wet; thatch, wet; and cloudy skies. Immediately after application the experimental area was irrigated in with 0.1 inch of water. General soil conditions were as follows: soil textural class, silt loam; soil particle size analysis: sand, 23.8%; silt, 51.9%; clay, 24.4%; soil percent water content (percent by wt), 20.5; organic matter, 4.7%; CEC, 15.8; and soil pH, 5.9. At treatment time two (27 May) forsythia was 90% green and 10% gold (292 GDD; applications were made late because of extremely wet soil conditions which did not permit us to apply treatments at 50% green and 50% gold the following soil and environmental conditions existed: air temp, 68 °F; soil temp at l inch depth, 60 °F; soil temp at 2 inch depth, 56 °F; RH, 74%; amt of thatch, 0.5 inch; water pH, 7.0; application time, early afternoon; soil, moist; thatch, moist; and clear skies. Immediately after application the experimental area was irrigated in with 0.1 inch of water. General soil conditions were as follows: soil textural class, loam; soil particle size analysis: sand, 31.4%; silt, 46.6%; clay, 22.0%; soil percent water content (percent by wt), 26.3; organic matter, 6.9%; CEC, 18.0; and soil pH, 5.7. At treatment time three (3 Jun) forsythia was 100% green (383 GDD) and the following soil and environmental conditions existed: air temp, 69 °F; soil temp at l inch depth, 59 °F; soil temp at 2 inch depth, 58 °F; RH, 45%; amt of thatch, 0.5 inch; water pH, 7.0; application time, late morning; soil, moist; thatch, moist; and clear skies. Immediately after application the experimental area was irrigated in with 0.1 inch of water. General soil conditions were as follows: soil textural class, loam; soil particle size analysis: sand, 27.5%; silt, 48.9%; clay, 23.7%; soil percent water content (percent by wt), 32.3; organic matter, 6.7%; CEC, 15.9; and soil pH, 5.6. At treatment time four (11 Jun) forsythia was 100% green and the following soil and environmental conditions existed: air temp, 71 °F; soil temp at l inch depth, 64 °F; soil temp at 2 inch depth, 62 °F; RH, 46%; amt of thatch, 0.5 inch; water pH, 7.0; application time, late morning; soil, wet; thatch, wet; and clear skies. Immediately after application the experimental area was irrigated in with 0.1 inch of water. General soil conditions were as follows: soil textural class, loam; soil particle size analysis: sand, 36.4%; silt, 43.1%; clay, 20.5%; soil percent water content (percent by wt), 33.2; organic matter, 9.0%; CEC, 20.6; and soil pH, 6.1. The total amt of rainfall recorded for Apr was 4.61 inches (included some snow), May was 7.32 inches (included some snow and precipitation was recorded on 18 days), and 1-17 Jun was 2.61 inches. Two, 4 inch cup cutter sod samples were removed from each replicate on 17 Jun. The total no. of ABW teneral adults (still in the soil), pupae and larvae was recorded and converted to ft2. Data were analyzed with ANOVA and the mean separation test used was the WD. The area selected for the experiment had been infested with a natural population of ABW during 2007 and 2008. Various larval instars and pupae were present. The breakdown of ABW life stages only removed from all untreated checks follows: 46.6% first-second instars, and 50.5% third through fifth instars and 2.9 % pupae. Ten treatments provided significant reduction of ABW. No phytotoxicity was noted." |
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