Influence of calcium and nitrogen fertilizer on creeping bentgrass infected with dollar spot under cool temperatures

Abstract

Dollar spot, caused by the fungal pathogen Clarireedia homoeocarpa Bennett, is a wide-spread disease of creeping bentgrass (Agrostis stolonifera L.) that in the north central region of the U.S., occurs as early as March. Over-dependence on fungicides has resulted in widespread resistance, necessitating non-chemical treatment approaches. The objective of this experiment was to assess the effects of N and Ca fertilizers on creeping bentgrass for dollar spot tolerance under cool temperatures.In a chilling chamber, a single application of Ca or N fertilizer significantly reduced dollar spot disease cover by 47% or 34%, respectively, compared to the untreated control. Application of both Ca and N, however, appeared to be antagonistic and resulted in only a 14% reduction of disease cover. Application of Ca, not N, improved root production but reduced shoot growth in the 4-week period regardless of dollar spot, resulting in an elevated root to shoot ratio. Root architecture, including total root length, surface area and total tips, was also improved following a Ca only application.Collectively, these results suggested that Ca might play a beneficial role in improving the stress tolerance of creeping bentgrass, and building healthier and stronger root systems in the spring-like conditions. Although a single application of Ca does not adequately suppress dollar spot, future research might be of interest to explore optimal application strategies in order to reduce over-dependence on fungicides.