Didymella pinodes and its management in field pea: Challenges and opportunities

Didymella pinodes is the major pathogen of the ascochyta blight disease complex of field pea. The disease is endemic in all major field pea producing countries, frequently causing heavy losses in yield and quality. It is the most challenging of field pea diseases to manage, with most fungicides only partially effective and/or not cost-effective. In the absence of effective levels of host resistance, historically, the best management option has been delayed sowing and/or crop rotation to avoid major ascospore showers, but delayed sowing generally incurs a concurrent heavy yield penalty. This review evaluates world-wide progress in understanding critical components of black spot in terms of its management and evaluates opportunities both for new research and for development of more effective and sustainable management of this disease, using improved host resistance as a foundation to build and deploy more effective integrated disease management strategies. In the past decade, research has provided considerable new insights into potential ascochyta blight management strategies, including new insights into inheritance of host resistance, response to selection; and use of molecular technology, that together have demonstrated the potential to improve the level of host resistance. Significant improvements have been reported in the level of partial resistance of field pea with improved agronomic traits. Consequently, while the effect of this level of resistance in reducing D. pinodes infection remains to be quantified, for the first time such novel germplasm offers the prospect of revising and reintegrating the different disease management options at the farm level, based on deployment of such resistance. Combining this improved host resistance with both cultural management options and fungicidal application offers new opportunities. It is likely that previously restrictive cultural management and ineffective fungicidal control measures will re-emerge as effective and profitable practices when used in conjunction with partially-resistant germplasm. While this approach is an effective first stage to better manage ascochyta blight, future 'stacking' of broad antifungal genes on current moderately resistant varieties using genomic tools and/or GM technologies offers an avenue for even more effective control of D. pinodes. (C) 2013 Elsevier B.V. All rights reserved.