Integration of Tillage, Chemical Seed Treatment, and Inoculation to Decrease Fusarium Root Rot of Kidney Beans
April 15, 2003
Consuelo Estevez de Jensen
James E. Kurle, James A. Percich, Tom Hovde, and Will Yliniemi
Department of Plant Pathology, Extension Educators, Wadena and Hubbard Counties respectively
University of Minnesota
Field experiments were conducted in 2001 and 2002 at Park Rapids and Verndale, MN on growers fields. The sites were selected for past history of root rot (Fusarium solani f. sp. phaseoli, Rhizoctonia solani and F. oxysporum). The soil type at each site is a Verndale, sandy loam (USDA classification). The field experiments were organized as a split-plot design with six replications. Main plots were tillage treatments consisting of either a shallow chisel (RT) or deep chisel (DT) and subsoiling (SS) with DMI. The subplots were a comparison between 1) the standard seed treatment (SST) consisting of Captan + Streptomycin + Lorsban and 2) the SST with Kodiak (Bacillus subtilis GBO3) and inoculation with HiStick N/T (Bacillus subtilis + Rhizobium). Plots consisted of twelve rows, 1,200 feet in length, 4.9 feet wide with row spacing of 30 inches. Each experiment was approximately 30 acres. Because these were collaborative trials with growers, tillage was carried out with their available equipment. In at Park Rapids in 2001 and 2002 spring tillage consisted of DT (12 inches depth) and SS to a depth of 18 inches. At Verndale tillage depth in both years in RT and SS was 6 inches and 18 inches depth, respectively. Plots were sown on June 7 and on June 14 in 2001 and 2002 at Park Rapids and Verndale, respectively. Dry bean cultivar Montcalm was sown at a rate of 80 lb/A.
CI values above 2000 Kpa were present in the upper 300 mm at both Park Rapids and Verndale after RT. Dry bean disease severity (DS) was decreased by Kodiak and inoculation with HiStick N/T at Park Rapids in 2001 and 2002 when compared to the SST (3.3 vs 4.5), respectively (Figure 1 and 2). Dry bean yields were lower at Park Rapids in 2002 than in 2001. Grain yield of dry bean was affected significantly by Kodiak and HiStick N/T at Park Rapids in 2001, and by both tillage and Kodiak plus HiStick N/T in 2002 (Table 1). Kodiak and HiStick N/T increased grain yield of dry beans at Park Rapids consistently in both years (Table 1).
At Verndale DS was not affected significantly by treatment, tillage or the interaction tillage with treatment in 2001. Kodiak and HiStick N/T resulted in a non-significant increase in dry bean yield at Verndale in 2001 (Table 2). Subsoiling also produced a non-significant yield increase of 5%. Tillage and Kodiak plus HiStick N/T decreased DS significantly in 2002. Plots with the SST alone had greater DS than the SST plus Kodiak and HiStick N/T. In Verndale dry bean yields were increased 11% by SS in 2002. Yields of plots sown with SST Kodiak and inoculated with HiStick were 10% greater than yield of plots sown with seed treated with SST alone (Table 2). At Park Rapids in both 2001 and 2002 deep tillage increased yields significantly. The effect of tillage differed between the two locations the combined treatment of SST plus Kodiak plus HiStick increased yield consistently at both locations at both years, although the yield increase at Verndale in 2001 was not significant. Sub-soiling does not always increase yield.
Chemical and biological seed treatments for Fusarium root rot control, 2002
A field experiment was conducted at Staples, MN in a Verndale sandy loam. Soil pH, mean P (Bray 1), and K were 6.5, 88 µg ml and 188 µg ml, respectively. The treatments were organized in a completely randomized block design with five replications. Plots were four rows wide and 4.5 m in length with row spacing of 76.2 cm. Dry bean cultivar Montcalm was sown on 4 Jun at a rate of 70 kg ha and harvested on 10 Sep. No nitrogen fertilizer, phosphorus or potassium was applied. Disease severity was assessed at flowering. Four biocontrol treatments were included: 1) Kodiak concentrate (Bacillus subtilis GBO3) applied to the seed in a slurry (0.08 g kgseed); 2) inoculation with HiStick N/T (Bacillus subtilis MBI600 + Rhizobium tropici UMR1899); 3) inoculation with HiStick (B. subtilis MBI600); 4) inoculation with HiStick (Rhizobium tropici UMR1899). Seed inoculation consisted in application of water to the seed (1 ml/lb seed) and then mixed the dampened seed with the inoculant (2.2g/lb seed), so that seeds were evenly coated. Inoculated seeds were allowed to dry and planted immediately. Biocontrol treatments were compared with two chemical seed treatments: Apron Maxx RTA directly applied to the seed (16 ml/lb seed); the standard seed treatment consisting of Captan 400 (2.4 g lb/ seed), Streptomycin (2.7 g lb/ seed) and Lorsban 50-SL (0.6 g /lb seed) alone or inoculated with HiStick N/T and an untreated control. Results were analyzed using ANOVA. Mean separation was performed using Fishers LSD.
Disease severity was low in 2002. However, disease severity, stand establishment and nodule dry weight differed significantly between treatments. Yield differences between Kodiak plus HiStick and the untreated control were also found. Chemical seed treatment affected Rhizobium survival by reducing nodule biomass. Yield increased with the use of Kodiak and inoculation with HiStick even in low disease pressure conditions. Reduced nitrogen fertilizer may represent an advantage for the grower because of lower costs and less adverse environmental impact.