Seed management in Tennessee : development of seed zones for Tennessee and distribution and protection of northern red oak (Quercus rubra L.) acorns

Currently, seedlings of many hardwood species are grown at the East Tennessee State Nursery for reforestation purposes and distributed for planting throughout the state. Guidelines for hardwood seed movement through genetic testing are lacking in Tennessee, causing nurseries to distribute seedlings to sites that can have a very different environment than that of the seed origin. For instance, if seedlings are genetically predisposed to respond to certain levels of environmental factors, and those factors are limited, poor growth or even failure of establishment may result. A practical system for collecting seeds was developed to ensure seedling adaptability in the environments in which they are planted. The seed zone map for Tennessee was developed using a Geographic Information System that integrated weather, elevation and physiographic data, resulting in 21 zones within the state.

Models to predict acorn production in a given year would greatly benefit resource managers, however, acom production varies on all levels from the individual to the population. The variation also occurs over time. Both biotic and abiotic factors have been ascribed as the causes of this variation, from the acorn weevil to regional weather patterns. The reproductive process of northern red oak (Quercus rubra L.) is a two-year event, which increases the chances of predation or lost signals between the unfertilized egg and the pollen. In northern red oak, no research has been conducted on the effects of crown competition on acom distributions, which could also contribute to acom production variation.

A two-year study was initiated using northern red oak seed orchard trees that originated as a progeny test in 1973. Branches with flowers and acornets were selected in each quadrant and in the upper and lower sections of the crown. The same branches visited every three weeks during the growing seasons and the number of flowers and acornets on each branch was tallied. Varying levels of crown competition were demonstrated by use of open-grown trees and trees in a forest-like condition with heavy crown competition. Results indicate that open-grown trees tend to produce the majority of flowers and acornets in the south quadrant of the lower section of the crown. Other trees with varying levels of competition exhibited random flower and acornet distribution patterns throughout the crown quadrants. Competition did have an effect on distributions; however, more research needs to be conducted.

Weevils of the Curculio genus consume the cotyledonary tissue of maturing northern red oak acorns. Weevil damage reduces the number of viable acoms available for nursery planting if a significant portion of cotyledons is destroyed. In addition, seedling attributes, e.g., height, within northern red oak genetic families is proportional to the amount of cotyledonary tissue an atom has at planting time. Protection of acom crops from insect predation would increase the number of viable acoms for planting and reduce cotyledon damage within each acom, resulting in more seedlings with better growth. A study was designed to evaluate the effectiveness of an insecticide on controlling weevil damage on two trees in a northern red oak seedling seed orchard. Each tree was divided in half using polyethylene tarps. An insecticide. Capture_®, was applied to one half of the tree, and the other half was used as a control (unsprayed). The trees were sprayed every three weeks. After maturation, the acorns were collected, dissected, and evaluated for insect damage. Results indicate that acorns on the sprayed side had a greater amount of healthy cotyledon tissue than the acoms from the control side. Capture_® was effective in protecting acoms from weevil infestation, but did not protect the acoms from any other damage agents classified, such as the stony gall wasp, (Callirhytis fructuosa Weld.). These other damaging agents, however, have not significantly affected acom yields in this specific orchard.