Bean Mold Management Tools and Rotational Systems Management Planning

Bean Mold Management Tools and Rotational Systems Management Planning

Summary

In the second year of this project, our emphasis has been again on demonstrating Contans (Coniothyrium minitans, Cm) efficacy in the field. In addition, we investigated the impact of cover crop species on white mold sclerotial survival.

We followed white mold sclerotial viability over a two-year period (September 2009-September 2011). One low rate (1.5 lbs/A) post-harvest Contans treatment applied in September 2009 to flailed diseased snap bean residues destroyed 95% of the white mold sclerotia generated on a diseased bean crop over a two-year period; there were more than four times more viable sclerotia after two years in the control treatment (22% of the original number of sclerotia) than in the Contans treatment (5% of the original number of sclerotia).

Beans were planted in the fields in July 2010. At bean harvest in September, percent foliar white mold necrosis for 91G (white mold susceptible variety) and OR-6230 (moderately white mold-resistant) was approximately 23% and 7.5%, respectively, in the control fields, and approximately 7% and 1%, respectively, in the Cm treatment fields. The lowest foliar disease severity was observed in the moderately resistant plants grown in Cm-treated fields.

At harvest, pod white mold incidence in 91G and 6230 was approximately 17% and 11%, respectively, in the control fields, and 7% and 3% in the Cm treatment fields. The lowest pod disease incidence was observed in the 6230 plants grown in Cm treated fields.

In 2011, foliar disease severity was 50% lower in the Contans treatment fields than in the control fields (9% vs 18%), but pod disease incidence was slightly higher (17% vs 14% incidence). We do not understand at this time why there was less foliar disease severity in the Contans treated fields but higher pod disease incidence. As was shown in 2010, the moderately resistant cultivar OR-6230 exhibited significantly less foliar and pod disease incidence than 91G.

Overall, vetch cover cropping resulted in the largest number of intact and living sclerotia, whether on the surface or buried. Cover cropping with oat or oat mixtures numerically reduced sclerotial survival (although only the Walken and Walken/vetch treatments were significantly differerent) when compared to the control when the sclerotia were left on the soil surface; vetch cover cropping had no impact on survival. Overall, cover crop treatments significantly increased colonization of sclerotia by fungi when the sclerotia remained on the soil surface or were buried at two inch depth.

More than 100 farmers and agricultural professionals learned about project results at the processed vegetable grower meetings in January 2010 and 2011.

Grower and processor representatives discussed project results and plans at the Oregon Processed Vegetable Commission reports and presentations meetings in January and February 2010, 2011 and 2012.

Objectives/Performance Targets

1. To evaluate the impact of a low rate Contans application on the following factors, in the second field season following the application:

a) sclerotial survival,
b) sclerotial colonization by Coniothyrium minitans and other fungi,
c) disease incidence in plantings of susceptible and moderately resistant bean varieties.

2. To evaluate the impact of Monida and Walken oats, common vetch and oat/vetch cover crop mixtures on white mold sclerotial survival.

Accomplishments/Milestones

We demonstrated that one low rate (1.5 lbs/A) post-harvest Contans treatment applied in September 2009 to flailed diseased snap bean residues destroyed 95% of the white mold sclerotia generated on a diseased bean crop over a two-year period; there were more than four times more viable sclerotia after two years in the control treatment (22% of the original number of sclerotia) than in the Contans treatment (5% of the original number of sclerotia). We showed that cover cropping increases fungal colonization of white mold sclerotia.

A group of 15 farmer and processor representatives discussed project findings and plans at Oregon Processed Vegetable Commission meetings in winters 2009-10, 2010-11 and 2011-12. In addition, 30 farmers and agricultural professionals walked the field trials and discussed the results at a 2010 summer field day at the OSU vegetable farm, and more than 100 growers and agricultural professionals learned about project findings at the Oregon Processed Vegetable grower meeting in January of both 2010 and 2011.

Collaborators: