Impacts of dogwood anthracnose (Discula destructiva Redlin) on the fruitsof flowering dogwood (Cornus florida L.): Implications for wildlife

摘要

Flowering dogwood (Cornus florida L.) fruits are an important fall food-for many species of birds and mammals throughout the eastern United States. However, the rapid spread of the fungal disease dogwood anthracnose (Discula destructiva Redlin) has caused extensive mortality of dogwoods throughout the Appalachians. We examined the impacts of dogwood anthracnose on the production of inflorescences by flowering dogwoods in western North Carolina as an indication of fruit production. We also collected ripe fruits in the fall, weighed the pulps and analyzed them for protein, lipids, Ca, K, Mg and P. Only one-third of 173 live trees flowered. Large trees were significantly more likely to flower than small trees, and as disease severity increased, the probability of flowering decreased. Neither the mean number of inflorescences per tree nor mean pulp weight differed among two-size classes or three disease categories of trees. However, pulps from moderately infected trees contained significantly more Ca and P than pulps from lightly infected trees. Pulps from severely infected trees also contained higher levels of Ca than pulps from lightly diseased trees. A discriminant function analysis examining all six nutritional variables separated lightly diseased pulps from the other two categories along an axis represented by Ca, P and lipids. Moderately diseased pulps were separated from severely diseased pulps by K, P and protein. The most significant impact of dogwood anthracnose on frugivores will likely be the loss of flowering dogwoods from the landscape, with the concomitant loss of actual and potential fruit production.