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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Fungicides for Control of Powdery Mildew on Sugar Beet, 2001.

Authors
item Turini, T. - UC COOP EXT. HORTVILLE, C
item Gerik, James
item Lewellen, Robert

Submitted to: Fungicide and Nematocide Tests
Publication Type: Other
Publication Acceptance Date: June 1, 2002
Publication Date: December 31, 2002
Citation: TURINI, T.A., GERIK, J.S., LEWELLEN, R.T. COMPARISON OF FUNGICIDES FOR CONTROL OF POWDERY MILDEW ON SUGAR BEET, 2001.. FUNGICIDE AND NEMATOCIDE TESTS. 2002.

Interpretive Summary: Powdery mildew was first detected on 9 Mar and severity increased to levels that allowed us to detect treatment differences by 19 Apr. Plants treated with Eminent, Procure, and Microthiol Special had lowest disease severity. In addition, BAS 500 + Latron B-1956 provided similar control to the best performing materials, but disease was more severe on the upper leaf surface. All materials consistently provided significant levels of control compared to the non-treated control on lower leaf surfaces and only Quadris did not reduce disease severity on the upper leaf surface.

Technical Abstract: The study was conducted to compare fungicides for control of powdery mildew on sugar beets. The trial was conducted at Imperial Valley Research Center in Brawley, CA. On 10 Oct 2000, sugar beet seed (cv. 'Rival') was sown and irrigated on Holtville silty clay. Beds were spaced 30 in. center to center. Each plot consisted of four 30 in rows 50 feet long. Plots were separated by one untreated planted row. The experimental design was a Latin Square with six replications. The treatments consisted of Eminent 1E (950 ml/ha), Microthiol Special 80W (6.7 kg/ha), Procure 50WS (0.56 kg/ha) BAS 500 02F (672 ml/ha + Latron B-1956 0.06 %), Quadris 2.08F (1125 ml/ha), and non-treated control. On 14, 29 Mar and 19 Apr, materials were applied in 30 liters of water per hectare with a CO2 pressurized backpack sprayer at 207 kPa. Maximum and minimum temperature ranges (oC) were as follows: Dec 20-27, -1-7; Jan 14-26, -1-4; Feb 14-29, -1-10; Mar 19-33, 3-14; Apr 22-37, 4-14; May 27-41, 9-21. Rainfall quantities (mm) are as follows: Dec 0.00, Jan 3, Feb 14, Mar 14, Apr 0.00, May 0.00. On 19 Apr and 16 May, powdery mildew severity on upper and lower leaf surfaces on each of 10 randomly selected leaves per plot was rated. The rating scale was based on percentage of leaf surface covered with powdery mildew, as follows: 0 = 0%, 1 = 20%, 2 = 40%, 3 = 60%, 4 = 80% and 5 = 100%. Disease ratings were analyzed using Latin Square Analysis of Variance and LSD (P=0.05) was used to separate means. Powdery mildew was first detected on 9 Mar and severity increased to levels that allowed us to detect treatment differences by 19 Apr. Plants treated with Eminent, Procure, and Microthiol Special had lowest disease severity. In addition, BAS 500 + Latron B-1956 provided similar control to the best performing materials, but disease was more severe on the upper leaf surface. All materials consistently provided significant levels of control compared to the non-treated control on lower leaf surfaces and only Quadris did not reduce disease severity on the upper leaf surface. All treatments produced significantly more tonnage of beets compared to the control, and all treatments except Procure produced significantly more extractable sugar compared to the control.

Last Modified: 9/2/2014
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