Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
Several individuals have expressed concern about rotational restrictions to the Prosaro® and Caramba® labels and how this prohibits their ability to use these products for management of DON produced by Fusarium Head Blight if they are double cropping lima beans behind small grains. If we look at the 100 studies conducted in 14 states over an 11 year period we see that the most efficacious fungicides are indeed Prosaro and Caramba (see table below). However, Proline® provides suppression only marginally less than Prosaro and Caramba in terms of FHB severity and is equivalent in terms of suppression of DON. Unlike the Caramba and Prosaro labels, Proline has a 30 day plant back restriction, allowing it to be used in situations where growers are following small grains with lima beans. In a scab favorable year Prosaro would be a viable substitute for Prosaro and Caramba in these situations. It also will control the more common foliar and head diseases we encounter in the Mid-Atlantic. As usual, remember that optimal control (Over 75% reduction in FHB severity and DON) can be achieved by combining a moderately resistant variety and applying the recommended fungicide close to Feekes 10.5.1. Remember that using either moderately resistant varieties or fungicides alone will not provide sufficient suppression of DON in a FHB favorable year.
Table 1. Results of 100 Fusarium Head Blight uniform fungicide trials conducted in 14 states over a 10 year period.
From: Paul et al., 2008. Efficacy of triazole –based fungicides for fusarium head blight and deoxynivalenol control in wheat: A multivariate meta-analysis. Plant Disease 98:999-1011