Abstract/Contents: | "This study was undertaken to determine the product's effectiveness when applied on various treatment dates to control a predominant Japanese beetle (JB) white grub population on a turfgrass area maintained at Penn State's Valentine Turfgrass Research Center. The turfgrass area consisted of perennial ryegrass (90%) and annual bluegrass (10%). Treatment plots were 6 Œ 8 ft, arranged in a RCB 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 6 ft boom, operating at 32 psi, and applied in 726 ml of water/48 ft2 or delivering 4.0 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 (5 May) the following soil and environmental conditions existed: air temp, 57 °F; soil temp at l inch depth, 52 °F; soil temp at 2 inch depth, 50 °F; RH, 44%; amt of thatch, 0.75 inch; water pH, 7.0; application time, late morning; soil, moist; thatch, moist; and clear skies. General soil conditions were as follows: soil textural class, silt loam soil; particle size analysis: sand, 17.3%; silt, 67.7%; clay, 14.9%; soil percent water content (percent by wt), 23.3; organic matter, 3.6%; CEC, 11.8; and soil pH, 6.2. The experimental area received 0.25 inch irrigation immediately after treatment. At treatment time two (5 Jun) the following soil and environmental conditions existed: air temp, 72 °F; soil temp at l inch depth, 64 °F; soil temp at 2 inch depth, 60 °F; RH, 77%; amt of thatch, 0.75 inch; water pH, 7.0; application time, mid-morning; soil, wet; thatch, wet; and overcast skies. General soil conditions were as follows: soil textural class, silt loam; soil particle size analysis: sand, 20.8%; silt, 64.8%; clay, 14.4%; soil percent water content (percent by wt), 23.6; organic matter, 3.7%; CEC, 11.9; and soil pH, 5.8. The experimental area received 0.25 inch irrigation immediately after treatment. At treatment time three (14 Jul) the following soil and environmental conditions existed: air temp, 73 °F; soil temp at l inch depth, 68 °F; soil temp at 2 inch depth, 66 °F; RH, 49%; amt of thatch, 0.75 inch; water pH, 7.0; application time, mid-morning; soil, moist; thatch, moist; and clear skies. General soil conditions were as follows: soil textural class, silt loam; soil particle size analysis: sand, 17.0%; silt, 69.8%; clay, 13.2%; soil percent water content (percent by wt), 24.2; organic matter, 4.0%; CEC, 11.0; and soil pH, 6.5. The experimental area received 0.25 inch irrigation immediately after treatment. Throughout the summer and early fall the area was irrigated on an as needed basis. Three one ft2 soil samples were removed from each replicate on 23 Sep and the total no. of JB and NMC grubs was recorded and converted to a ft2 count. Data were analyzed with ANOVA and the mean separation test used was WD. The area selected for the experiment had been infested with a natural population of JB and NMC grubs during the spring of 2008 with an avg of 21.6/ft2 white grubs present in late Apr. NMC grub populations were very low and not significant. Fall 2008 grub populations may have been suppressed by the extremely dry summer weather. Adult NMC's were monitored in 2008 with a black light trap maintained at the Valentine Turfgrass Research Center, while JB populations were monitored with floral/sex pheromone traps. Adult JB and NMC populations were late this year. NMC populations were minimal as the data indicates. Ten treatments provided significant suppression of JB grubs. No phytotoxicity was noted." |