Field evaluation of the efficacy of SP2700 for control of seedling diseases in rice, 2014

摘要

An experiment was established in a field of League-type soil (sand 3.2%, silt 32.4%, clay 64.4%, organic matter 3.8 to 4.8%, and pH 5.5) at the Texas A&M AgriLife Research and Extension Center, Beaumont, TX. The field was naturally infested with the seedling disease pathogens after many years of rice production. Plots consisted of seven 16-ft rows, and spaced 7 in. between rows. Three treatments (see table) were arranged in a randomized complete block design with four replications. Seeds were treatedwith 1 or 3% (v/v) of SP2700 (SePRO Corporation, Carmel, IN) prior to planting. Rice was drill seeded at 80 lb/A on 28 Apr. On 21 and 29 May, plots were sprayed with 9 or 18 fl oz/A of SP2700 using a CO2 pressurized sprayer equipped with a boom of threeTeeJet 8002 nozzles spaced 16 in. apart that delivered 20 gal/A at 30 psi. Plots received 65 lb /A of urea (46-0-0, N-P-K) on 14 May and 391 lb/A of urea prior to permanent flood on 10 Jun. Weed control as well as irrigation followed local recommendations. On 30 May, stand, height and vigor of seedlings were determined. Stand was rated as the number of seedlings in the central row of plot and converted to stand per row foot. Height of three seedlings randomly selected from each plot was measured. Vigorwas rated on a scale of 0 to 100 where 0 represents dead plants or poorest in growth and 100 represent excellent vigor. On 2 Jun, ten randomly-selected plants were collected from each plot and they roots were washed in water and examined individually for the symptoms of seedling diseases. The percentage of plants showing the symptoms on the roots was assessed as disease incidence. The percentage of root area showing the symptoms was also assessed as disease severity. Rice was harvested using a plot combine on 8 Sep. Grain yield and moisture were determined, and rice yields were adjusted to 12% moisture content. Data was subject to ANOVA using SAS version 9.4. Means were separated using Fisher's protected LSD test.