Goss39;s Wilt Management

Figure 1Goss’s wilt is caused by the bacterium Clavibacter michiganensis nebraskensis. This disease is common to the Corn Belt and can cause severe yield losses in corn. This trial was conducted to demonstrate the important role that genetic resistance plays in managing Goss’s wilt and determine the influence of different management practices on Goss’s wilt and corn yield.

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Study Guidelines

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In 2012, a study was conducted at the Monsanto Learning Center at Gothenburg, NE to evaluate management practices that may help maximize corn yield potential when Goss’s wilt is present. On April 23, three corn hybrids with different Goss’s wilt disease ratings and comparable relative maturities were planted in a randomized complete design with four replications for a total of 60 experimental units. Five management practices were tested:
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1. No-till
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2. 60 lbs/acre UAN and Hydra-Hume 0-0-1 gal/ acre applied November 7, 2011
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3. 60 lbs/acre UAN and Hydra-Hume 0-0-1 gal/ acre applied April 11, 2012
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4. Procidic®: applied April 25 (3 fl oz/acre), June 11 (10 fl oz/acre), and July 16 (14 fl oz/acre)
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5. Cover crop mix planted November 7, 2011 at a rate of 40 lbs/acre; killed one week before planting with a herbicide application including Roundup PowerMAX®, Harness®, and atrazine.
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Figure 2Weeds were managed with a preplant herbicide application of Degree Xtra® at 3.5 qts/acre, Roundup PowerMAX® at 28 oz/acre, and Sharpen® at 2 oz/acre applied on April 16 and a postemergence herbicide application of Roundup PowerMAX® at 28 oz/acre and Warrant® Herbicide at 2 pt/acre applied on June 11. No fungicide or insecticide applications were made. A total of 15 inches of water was applied through irrigation at 1-inch increments throughout the growing season. Plots were in a field that had previously been in a corn following corn rotation, which had a heavy infestation of Goss’s wilt in 2010 and 2011. Goss’s wilt developed primarily from natural inoculum that had overwintered in debris from the previous year’s crop.

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Results

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In this study, corn hybrids with Goss’s wilt disease ratings of 2 (tolerant) and 4 (intermediate) performed exceptionally well. With each of the five management practices in the study, the tolerant and intermediate hybrids yielded substantially more than the hybrid rated 7 (susceptible) for Goss’s wilt.
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Figure 3Of the five management practices investigated in this study, the use of cover crops had the greatest impact on maximizing yield potential for the hybrids with intermediate and susceptible reactions for Goss’s wilt disease (Figures 1 and 2). For all hybrids, including the hybrid rated 2, plant canopies appeared to be greener and healthier following the cover crop (Figure 3). This improved “plant vigor65533;? following cover crops may have contributed to maximized yield potentials even when Goss’s wilt occurred more severely on hybrids rated 4 and 7.

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Summary Comments

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In general, Goss’s wilt was not particularly severe in 2012. Therefore, intermediate hybrids may have performed better than expected under extremely severe Goss’s wilt, which is often associated with infection at seedling growth stages. The hybrid susceptible to Goss’s wilt yielded substantially less than the intermediate and tolerant hybrids, regardless of the management practice used. These results indicate that hybrid selection plays an important role in the successful management of Goss’s wilt and that susceptible hybrids should be avoided in areas that have a high likelihood of Goss’s wilt occurrence.
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Figure 4An additional demonstration plot at the Learning Center in 2012 included several different management options for controlling Goss’s wilt. This plot included three hybrids with Goss’s wilt ratings of 2, 4, and 7, planted in 30-inch rows. Management options in the demonstration plot were:

1. No-till
2. Strip tillage
3. Spring tillage on April 1 and April 15
4. Fall tillage on November 1, 2011 and spring tillage on April 1 and April 15
5. Fall tillage November 1, 2011 and spring tillage April 1
6. 60 lbs/acre UAN and Hydra-Hume 0-0-1 gal/acre applied November 1, 2011
7. 60 lbs/acre UAN and Hydra-Hume 0-0-1 gal/acre applied April 15, 2012
8. Procidic® : applied April 25 (3 fl oz/acre), June 11 (10 fl oz/ acre), and July 16 (14 fl oz/acre)
9. Cover crop mix planted November 7, 2011 at a rate of 40 lbs/ acre and killed one week before planting.

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Yield data from the demonstration plot supports the 2012 study as well as earlier studies at Gothenburg in 2010 and 2011. The tolerant and intermediate hybrids out-yielded the susceptible hybrid under every management option (Figure 4). While the average yield of the three hybrids in the demonstration plot was highest when the management options included tillage or cover crops (data not shown), hybrid selection was the major factor in maximizing yield potential.

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Hybrids that are susceptible to Goss’s wilt should be avoided in areas where Goss’s wilt is present. Even under conditions where Goss’s wilt infection is less than severe, yield potential of susceptible hybrids can be markedly compromised. Although hybrids with an intermediate reaction to Goss’s wilt can yield well in management systems that include tillage and/or cover crops, there is a risk that a severe outbreak of Goss’s wilt may impact yield potential. Where the threat of Goss’s wilt exists, selecting a welladapted hybrid that is tolerant to Goss’s wilt is a crucial step towards maximizing yield potential.​​​​​​