Entomology Commons^™

Interactions Among Insect Defoliation, Insecticide Treatments, And Growth Rate In American And Hybrid Chestnuts, Ashley Elizabeth Case

Masters Theses

The American chestnut, Castanea dentata, was once one of the most useful and abundant canopy trees in eastern North American forests. Over the last 200 years, the species has been decimated by two exotic pathogens, Phytophthora cinnamomi and Cryphonectria parasitica, killing millions of trees and reducing surviving Castanea dentata to short-lived sprouts. Cryphonectria parasitica-resistance breeding programs are currently producing advanced backcross generations, which are being compared with pure American chestnut in field tests of growth performance and Cryphonectria parasitica resistance. The Asiatic oak weevil, Cyrtepistomus castaneus, has been identified as a common defoliator of chestnut seedlings in these …

Assessment Of Pityophthorus Juglandis Colonization Characteristics And Implications For Further Spread Of Thousand Cankers Disease, Jackson Audley

Masters Theses

Nonnative, invasive forest insect pests are a significant threat to the health of global forest resources. Thousand cankers disease, a recently described disease threatening walnuts, is the result of an invasive insect-pathogen complex in which the walnut twig beetle (Pityophthorus juglandis Blackman) is a vector to the associated fungal pathogen, Geosmithia morbida. Both are native to the southwestern U.S. into northern Mexico, however, have been found well beyond their historic range, and now threaten black walnut (Juglans nigra) in the eastern U.S. Beetles have likely been spread via the transport of infested walnut logs.

The goal …

The Life History And Control Of Pityophthorus Juglandis Blackman On Juglans Nigra L. In Eastern Tennessee, Katheryne Avery Nix

Masters Theses

In the last decade, western states have experienced an increasing mortality rate in Juglans nigra L., black walnut, as a result of the fungal species Geosmithia morbida Kolařík et al. that results in numerous cankers that girdle the branches, resulting in dieback and tree mortality. The only known vector of G. morbida is the walnut twig beetle (WTB), Pityophthorus juglandis Blackman. This newly recognized disease/insect complex has been named Thousand Cankers Disease (TCD) due to the quantity of cankers produced by G. morbida.

Recently, TCD was discovered in the eastern U.S. To limit the spread of TCD in eastern …