Submitted to: Fungicide and Nematocide Tests
Publication Type: Other
Publication Acceptance Date: 12/20/2002
Publication Date: 2/20/2003
Citation: PAULITZ, T.C., MCKINLEY, A., REINERTSEN, S. EVALUATION OF SEED TREATMENT WITH PROTEGE AND IN-FURROW APPLICATION OF QUADRIS FOR THE CONTROL OF RHIZOCTONIA ROOT ROT IN SPRING BARLEY. FUNGICIDE AND NEMATOCIDE TESTS. 2003. Vol. 58 CF008. Interpretive Summary:
Technical Abstract: An experiment was conducted on the McGregor Research Farm near Colfax, WA on a Palouse silt loam, pH 5.6, 2.39% O.M. No-till plots had been direct seeded with spring wheat in 2001, winter wheat in 2000, and chemical fallowed in 1999. The following treatments were applied to seed: Protégé 100 FS (azoxystrobin) at 0.375 fl oz/cwt seed (Protégé low); Protégé 100 FS at 0.75 fl oz/cwt (Protégé high); control; Quadris (2.08 lb a.i./gal) in the seed furrow at 3.3 fl oz/A (Quadris low); Quadris in the seed furrow at 6.5 fl oz/A (Quadris high); and Maxim applied to seed at 0.08 fl oz/cwt. Plot size was 7 X 70 ft. The experiment was arranged in a randomized complete block design, with four blocks, and all treatments were randomized within each block. All plots were planted with spring barley on 8 Apr 02 with a Great Plains minimum-till drill, at 1.25 in. depth. Seedlings were harvested from the plots on 4 Jun 02, from three locations within each plot, five plants per location. Plant height, number of seminal roots and number of crown roots were counted on each plant. Roots were washed, digitally scanned to create TIF files, and analyzed with WinRhizo (Regents Instruments Inc, Québec, Canada) to determine root length, average root diameter, and number of root tips. These detailed root measurements provide quantification of Rhizoctonia damage, and have been correlated with Rhizoctonia induced root rot in greenhouse tests. Roots were also plated onto a semiselective medium (water agar + 1 ppm benomyl + 100 ppm chloramphenicol), to determine the percentage of roots infected with either species. Soils containing roots from these locations were assayed for the presence of Rhizoctonia spp. using a toothpick baiting technique. Seed treatment with Protégé at both low and high rates significantly increased the yield of spring barley by 8.6 and 10.6%, respectively. Seed treatment with the low rate of Protégé significantly increased seedling height, while the higher rate significantly increased the number of seminal roots, total root length, and the number of root tips. Both R. oryzae and R. solani AG-8 were recovered from the experimental plots, with R. oryzae being predominant. However, due to large variation within plots, there was no effect of treatments on the percentage of roots colonized by Rhizoctonia spp. or the frequency of recovery from the soil with the toothpick assay. Quadris applied in the seed furrow and Maxim applied to seeds had no positive effect on any measured variable.