The effect of acorn insects on the establishment and vigor of northern red oak seedlings in north-central West Virginia

Abstract

During a 2-year investigation into the effect of small mammals on northern red oak (Quercus rubra) acorn survival and germination, widespread germination failure and lack of seedling vigor was apparent in control quadrats on one of two watersheds under study. Insects were present in and on the failed acorns but it was unknown whether they were primary invaders or merely scavengers. The purpose of the present study was to determine: 1) the proportion of acorn failure that could have been attributed to insect infestation, and 2) the effect of cotyledon damage due to insects on the vigor of northern red oak seedlings. Northern red oak acorns were collected from good and excellent sites on the two watersheds in October 1993. All acorns located under the crowns of 40 study trees were collected and float-tested for viability. Samples of 18 apparently sound acorns were placed in mammal exclusion cages under each of the study trees; nine acorns were buried and nine were placed on the soil surface. In late spring of 1994, any failed acorns and seedlings with cotyledons attached were dissected. Insect presence or damage, percent cotyledon damage, and overall vigor were recorded. Anaylses of variance (ANOVAs) were used to compare: 1) mean seedling vigor by watershed, year, and treatment, 2) insect infestation rates on the two sites and between treatments in 1994, and 3) the effect of cotyledon damage on seedling vigor in 1994. Important results include the identification of three insect pests in germinating northern red oak acorns in north-central West Virginia and the finding that insect infestation may decrease vigor but does not necessarily preclude germination or seedling establishment.

Parent Publication

• Proceedings, 10th Central Hardwood Forest Conference

Citation

Gribko, Linda S. 1995. The effect of acorn insects on the establishment and vigor of northern red oak seedlings in north-central West Virginia. In: Gottschalk, Kurt W.; Fosbroke, Sandra L. C., ed. Proceedings, 10th Central Hardwood Forest Conference; 1995 March 5-8; Morgantown, WV.: Gen. Tech. Rep. NE-197. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 430-441