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Effect of inoculation timing and hybrid resistance on yield loss attributed to Goss’ wilt and leaf blight in North Dakota

Elizabeth Bauske: North Dakota State University

<div>Goss’ wilt and leaf blight (Goss’) of corn (<em>Zea mays</em>), caused by <em>Clavibacter michiganensis</em> subsp. <em>nebraskensis</em>, was first documented in North Dakota (ND), USA in 2011. Grain corn acreage in ND has increased by 68% since 2011. To assess yield loss attributed to Goss’ in ND, inoculation timing by hybrid susceptibility field trials were established over six location-years. Trials were designed in a randomized complete block with a split-plot arrangement and four replications. Three corn hybrids (susceptible, moderately susceptible and resistant) with sub-88 day relative maturities were sown at each location. Inoculation timings included a non-inoculated check, V6-V10 (early-season), R1 (late season), and a sequential inoculation of V6-V10 and R1 (combination). Beginning 14 days after inoculation and continuing until corn reached maturity, disease severity was assessed in each plot. Test weight and yield were recorded at harvest. Under high disease pressure in 2016 and 2017, year-end disease severity values ranged from 21-52% and 12-61% on susceptible hybrids, respectively. Yield loss values in excess of 35% in 2016 and 30% in 2017 were associated with early season inoculations. Minor yield losses were observed on the resistant hybrid and the R1 inoculation treatment. Results from this research demonstrate the importance of hybrid selection when reducing economic losses attributed to Goss’.</div>