Evaluation of fungicides and a biocontrol agent for management of Phytophthora blight in snap beans, 2009.

摘要

Ten fungicides and one bio-based product were tested for control of Phytophthora blight in a research field at the Agricultural Experiment Station in Geneva, NY. The soil type in the trial was an Odessa silt loam, which is a poorly drained soil formedin clay lacustrine deposits. On 5 Jun, Titan snap beans were seeded (in a north south direction) using a two-row, Monosem vacuum planter at 7.5 seeds per ft at 30-in row spacing. Fertilizer (10-10-10 supplemented with manganese and zinc) was banded during planting at 350 lb/A. Treatments were arranged in a randomized complete block design with four replications. Each plot consisted of a single row measuring 35 ft long with 5 ft untreated buffer zones between blocks. Test materials were applied on 22 Jul (100% bloom-pin pod) and 30 Jul (late pin-small pod), using a CO2 backpack sprayer fitted with three 8002 flat fan nozzles delivering 68 gal/A at 50 psi at 2.25 mph. The sprayer was configured with one nozzle positioned above the center of the row andtwo 9-in drop nozzles horizontally angling into the canopy. Inoculum of Phytophthora capsici was applied using a Swiss-Mex SP1 backpack sprayer with a single 8003 nozzle delivering 25 gal/A. Zoospores of P. capsici were applied on 23 Jul (1.3 x 105 spores/fl oz) and 5 Aug (1.16 x 106 spores/fl oz). Orthene 75S (0.75lb/A) was applied using a Swiss-Mex SP1 backpack sprayer on 30 Jul for Mexican bean beetle control. Snap bean pods in 10 ft of row were hand harvested and evaluated on 14, 17 and 18 Aug. Podswere categorized as healthy or infected with Phytophthora blight, counted and weighed. Disease incidence and yield were calculated. Although 2009 was an exceptionally wet season, overhead irrigation was applied (0.5-in) on 23 Jul and 5 Aug prior to inoculation to enhance disease development. Monthly rainfall was 3.45, 4.99 and 4.16 in. for Jun, Jul and Aug, respectively.