Anthracnose Damage to Flowering Dogwood

Acidic deposition exposure significantly increases the susceptibility of flowering dogwood (Cornus florida L.) trees to injury by the fungal pathogen dogwood anthracnose (Discula destructive Redlin) (Anderson and others 1993, Britton and others 1996). Furthermore, controlled studies have implicated acid-induced nutrient deficiencies in this altered disease susceptibility (Britton and others 1996). Elevated disease susceptibility has also been associated with environmental conditions, (e.g., shade, low temperatures, wet cool summers, etc.) that result in low transpiration rates and thereby reduce the accumulation of Ca in plants (McLaughlin and Wimmer 1999). The association of Ca deficiency and anthracnose susceptibility is also supported by an increased resistance to this disease following lime application (USDA 1991). Based on this and other evidence, McLaughlin and Wimmer (1999) proposed that Ca deficiencies driven by low soil Ca concentrations, low transpiration rates or accelerated foliar leaching, or both, reduce the natural resistance of dogwood to anthracnose infection.