| Abstract/Contents: | "This study was undertaken to determine product effectiveness when applied in May, Jun, and Aug to control a predominant Northern masked chafer (NMC) white grub population on a turfgrass area maintained on a golf course driving range in Centre County, PA. The turfgrass area consisted of fine fescue (40%), perennial ryegrass (40%) and Kentucky bluegrass (20%). Treatment plots, 6 ^D#x 8 ft, were 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 28 psi, and applied in 363 ml of water/48 ft2 or delivering 2.0 gal/1000 ft2. Ambient condition during mid morning on 12 May (treatment time one) were cloudy with air temp = 52°F and RH = 69%. General soil conditions were as follows: soil textural class, silt loam; soil particle size analysis: sand, 35.7%; silt, 47.1%; clay, 17.3%; soil percent water content (percent by wt), 15.5; organic matter, 4.6%; CEC, 15.3; and soil pH, 5.4. Soil was dry with temp at 1 and 2 inch depth = 53 and 54°F, respectively. Thatch, 0.125 inch thick, was also dry and water pH was 7.0. The experimental area was irrigated post treatment with 0.1 inch of water. Conditions during the early morning on 14 Jul (treatment time two) were cloudy with air temp = 77°F and RH = 74%. Soil was dry with temp at 1 and 2 inch depth = 71 and 69°F, respectively. Thatch, 0.125 inch thick, was dry and water pH = 7.0. At that time, general soil conditions were as follows: soil textural class, silt loam; soil particle size analysis: sand, 23.5%; silt, 52.5%; clay, 23.9%; soil percent water content (percent by wt), 15.4; organic matter, 6.7%; CEC, 17.4; and soil pH, 5.4. The experimental area was irrigated post treatment with 0.25 inch of water. Conditions during the early morning on 12 Aug (treatment time three) were cloudy with air temp = 75°F and RH = 77%. Soil was dry with temp at 1 and 2 inch depth = 70 and 68°F. Thatch, 0.25 inch thick, was dry and water pH = 7.0. At that time, soil particle size analysis: sand, 26.4%; silt, 55.8%; clay, 17.8%; soil percent water content (percent by wt), 9.8; organic matter, 5.3%; CEC, 13.9; and soil pH, 5.5. The experimental area was irrigated post treatment with 0.25 inch of water. Throughout the summer and early fall the area was placedon a regular fairway irrigation schedule. Three one ft2 soil samples were removed from each replicate on 28 Sep and the total number of Northern masked chafer (NMC) and JB grubs was recorded. Data was analyzed using Waller-Duncan k ratio (WD; P ≤ 0.05). The area selected for the experiment had been infested with a natural population of NMC and JB during the spring of 2005. An average of 13.0/ft2 grubs were present on 16 May. Adult flight of NMC was monitored in 2005 with a black light trap maintained at the Valentine Turfgrass Research Center. The first adult NMC was collected on 24 Jun. Adult NMC flight peaked between 2-8 Jul, and the last NMC adult was collected on 28 Jul. JB adults were observing flying late this season. Second instar, as well as, third instar grubs were present. Drought conditions delayed development of scarab grubs in 2005. All treatments provided significant suppression of NMC and JB grubs disregarding date applied. All treatments significantly reduced combined JB and NMC grub populations. No phytotoxicity was noted." |
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