Evaluation of fungicides for control of Asian soybean rust in Hidalgo County, Texas, 2008.

摘要

A trial was established in a commercial field in Hidalgo County, Texas to determine the efficacy of six fungicides for management of Asian soybean rust (ASR). The soil type in the field was a Willacy fine sandy loam. The field was planted to ‘Vernal’ on 28 Aug with a plant population of 100,000/A. Each plot was 2 rows wide (30-in. spacing) by 25 ft in length. Plots were separated by 2 border rows that were not treated. Each treatment was replicated 4 times in a randomized complete block design. Fungicides were applied once with a CO2 backpack sprayer, at 40 psi in a spray volume of 20 gal/A, using XR Teejet 8002VS flat fan tips. Four nozzles, spaced 19 in. apart, treated two rows. The spray solution included 0.124% Induce, a nonionic wetter and spreader adjuvant. Fungicides were applied 22 Oct (R3 stage), 9 days after the detection of rust in the field. Temperature, leaf wetness, and precipitation were monitored in this field using data loggers. On 23 Oct, plots were treated with Steward and Orthene for insect control. The field was furrow irrigated as needed. Plots were evaluated for ASR using the upper leaves of the canopy (50 leaflets/plot) on 3 Dec. Leaflets with visible lesions were counted to obtain disease incidence and percentage of diseased leaf area was estimated to obtain disease severity. A portion of each plot (8.7 ft/row) was harvested by hand on 30 Dec and machine-threshed. Yields were adjusted to 13% moisture.