Effect of acid deposition on trichome morphology and dogwood anthracnose biology

Abstract

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.