Sugarbeet Root Maggot Control, 1995

Abstract

Abstract Experimental plots were established approximately 10 miles east of Hazelton, ID. The soil type was Portneuf silt loam and the plots were furrow irrigated. Eight treatments and an untreated check were replicated 4 times in a RCB design. Individual plots were 6 rows (22 inch row spacing) by 30 ft. Alleys were cut between plots to give 25 ft of row per plot. On 18 Apr all plots were planted at which time sidedress applications of Temik and band applications of Temik, Counter, and Aztec were made. Temik was placed 2 inches to the water side of the furrow and 2-3 inch deep for the sidedress applications (SAP). Aztec, Counter and the other Temik application were applied as a 4 inch band over the row (i.e., behind press wheel) and chain incorporated (BAP). On 25 May, post-emergence band applications (BPE) of Temik, Counter and Lorsban were made. Temik and Counter were applied as a 4 inch band (BPE) over the row and chain incorporated. Lorsban was applied as a 3-4 inch banded spray (early fly emergence, EF) using a CO2-pressurized backpack sprayer (20 gpa at 30 psi). On 12 Jun, a Lorsban treatment was made (peak fly emergence, PF) using a CO2 pressurized backpack sprayer as previously described. On 1 Aug after most larval feeding had ended, five adjacent beets were dug from the middle of rows two and five to give 10 beets per plot for rating root maggot damage. Weights of the 10 beet samples were also taken at this time. The beets were washed and rated for damage using 2 rating schemes: The five point system was 0 = no scars; 1 = \-b small scars of pinhead size; 2 = 5-10 small scars to 3 large scars; 3 = more than 3 large scars; 4 = one-half to three-quarters root area blackened by scars; 5 = more than three-quarters of root area damaged, dying beet. The seven point system was 0 = no damage; 1 = l-4 small scars of pinhead size; 2 = 5-10 small scars, or up to 3 larger scars; 3 = more than 3 large scars; 4 = 4 large scars to one-quarter root surface covered with scars; 5 = one-quarter to one-half root surface covered with scars; 6 = one-half to three-quarter root area blackened by scars; 7 = more than three-quarter root surface blackened, dying beet. On 14 Sep sugar beets in rows 3 and 4 (middle 2 rows) in all treatment plots except the Aztec treatment, were machine lifted, hand topped and untared weights were taken for yield estimates. All data were analyzed using ANOVA and Student-Newman-Keuls.