Kelly Oten

During the mid 1950s, nearly 70% of mature Fraser fir in natural stands was lost due to impacts of the invasive insect balsam woolly adelgid. Since the 1980s, there has been substantial regeneration and recovery in most Fraser fir stands across its native range. Recently, a new wave of mortality has been noted in several of these stands. The purpose of the proposed research is to document the extent of new Fraser fir mortality across its range, determine what age cohort (mature versus regenerated) is being affected, and identify potential factors underlying the observed mortality.

The Hemlock Woolly Adelgid is a destructive invasive insect pest of hemlock forests in the Southern Appalachian Mountains. Beneficial bacterial endosymbionts of the adelgid play key roles in the insect's biology, including the digestion of nutrients, defense against natural enemies, and resilience to environmental stress. The PI and his US Forest Service collaborators have recently demonstrated that silvicultural release of infested hemlock trees to increase light exposure and resource availability can make trees more resilient to adelgid infestation. Processes underlying why release is beneficial to the tree are not fully understood, but it is hypothesized that both behavioral responses to sunlight and physiological effects of increased temperatures on the part of the adelgid are involved. The study proposed here will explore the interactions of the adelgid and endosymbionts associated with heat stress across of set of previously established silvicultural release plots to better understand the mechanisms underlying the success of silvicultural release on hemlock health.

The Asian longhorned beetle is an invasive tree-killing insect found in South Carolina in 2020. USDA-APHIS is actively trying to eradicate this infestation, but many bottomland hardwood areas are difficult to reach with large equipment to perform traditional management methods. Previous work at NCSU indicates felling trees and letting them lay is an effective alternate method. This research will assess its efficacy when implementing this practice as part of the eradication program.

Establishment of biocontrol agents in Western NC where species acclimated to cooler climates might be more successful, confirming emerald ash borer phenology models for overwintering stages, recovery attempts where parasitoids have been released but emerald ash borer populations have declined.

The research proposed will test Coretect, and imidacloprid-based insecticide, as a planting time treatment for multi-year control of piercing-sucking insect pests of Fraser fir Christmas trees. Pests such as the balsam woolly adelgid, balsam twig aphid, and elongate hemlock scale are important pests that routinely require regular application of foliar applied insecticides multiple times throughout a rotation for effective control. In pest management systems for other conifer species, a single CoreTect tablet placed in the planting hole provides four to five years of protection against most piercing-sucking insects. This project will test for similar effectiveness in Fraser fir. Reduced usage of foliar applied insecticides during the first four to five years of a rotation could yield significant financial savings for growers and reduce human and environmental pesticide exposure.

This is for a second year of funding on a current project. The overall goal of this project is to provide the USDA-APHIS ALB program with alternative management options when cut, remove, and chip is not logistically feasible or environmentally responsible.

Ash (Fraxinus) tree species in North America face a significant threat from the emerald ash borer (Agrilus planipennis, EAB), an exotic beetle native to Asia that was first detected in 2002 infesting urban forests surrounding Detroit, MI. Since its accidental introduction, this invasive pest has spread to 35 states, the Canadian provinces of Ontario, Quebec, New Brunswick, Nova Scotia, and Manitoba, and killed hundreds of millions of ash trees. The first detections of EAB in North Carolina occurred in 2013 in Granville, Person, Vance, and Warren counties, and it has since spread to a number of additional counties throughout the mountains, Piedmont, and upper coastal plain where it threatens to extirpate all four ash species native to the state. Of particular concern is the loss of green ash (F. pennsylvanica) which is planted widely as a shade tree in urban and suburban areas and is an important timber species in the state. It is valued for both wood products and biomass production and is considered a premier species for dual wastewater treatment and bioenergy production systems. Classical biological control, the importation and release of natural enemies from a pest������������������s native range, is one of the primary management strategies currently utilized to combat the EAB infestation in North America. Three parasitoid species from Asia are currently released, one that targets EAB eggs and two that target EAB larvae. The larval parasitoids target specific EAB larval stages, so the proper timing of releases to coincide with appropriate larval stages is critical. Current EAB phenology is based on field studies conducted in Michigan and other nearby Midwestern states; these data are currently being utilized to time parasitoid releases throughout the infested range. However, EAB larval parasitoids have failed to establish south of the 40th parallel which suggests a phenological mismatch between the timing of parasitoid release and the presence of appropriate EAB life stages in the southern United States. This mismatch is supported the NC Forest Service and NCDA&CS field data that indicates EAB overwinters as larvae in central North Carolina while most studies in the north report EAB overwintering as prepupae. Data are lacking for the year-round phenological progression of EAB life stages in central North Carolina in order to understand the best time to release parasitoids and maximize their chance of establishment.

The purpose of this project is to determine a more efficient way to manage ALB in forested stands. In May 2020, ALB was detected in South Carolina for the first time. The previous southern-most detection was in southwestern Ohio. Previous ALB infestations in the northeastern and midwestern U.S. occurred where ease of accessibility or weather allowed the option of cutting, removing, and chipping ALB host trees. However, the South Carolina detection occurred in both urban and rural river and palustrine forested wetlands that are challenging to access with traditional tree removal equipment. In more northern infestations, wet areas froze during the winter, and equipment could access infested trees during this time. The current infestation in South Carolina occurs in areas that remain wet and inaccessible to tree-removal machines without incurring significant damage to the native ecosystem.

Ash (Fraxinus) tree species in North America face a significant threat from the emerald ash borer (Agrilus planipennis, EAB), an exotic beetle native to Asia that was first detected in 2002 infesting urban forests surrounding Detroit, MI. Since its accidental introduction, this invasive pest has spread to 35 states, the Canadian provinces of Ontario, Quebec, New Brunswick, Nova Scotia, and Manitoba, and killed hundreds of millions of ash trees. The first detections of EAB in North Carolina occurred in 2013 in Granville, Person, Vance, and Warren counties, and it has since spread to a number of additional counties throughout the mountains, Piedmont, and upper coastal plain where it threatens to extirpate all four ash species native to the state. Of particular concern is the loss of green ash (F. pennsylvanica) which is planted widely as a shade tree in urban and suburban areas and is an important timber species in the state. It is valued for both wood products and biomass production and is considered a premier species for dual wastewater treatment and bioenergy production systems. Classical biological control, the importation and release of natural enemies from a pest������������������s native range, is one of the primary management strategies currently utilized to combat the EAB infestation in North America. Three parasitoid species from Asia are currently released, one that targets EAB eggs and two that target EAB larvae. The larval parasitoids target specific EAB larval stages, so the proper timing of releases to coincide with appropriate larval stages is critical. Current EAB phenology is based on field studies conducted in Michigan and other nearby Midwestern states; these data are currently being utilized to time parasitoid releases throughout the infested range. However, EAB larval parasitoids have failed to establish south of the 40th parallel which suggests a phenological mismatch between the timing of parasitoid release and the presence of appropriate EAB life stages in the southern United States. This mismatch is supported the NC Forest Service and NCDA&CS field data that indicates EAB overwinters as larvae in central North Carolina while most studies in the north report EAB overwintering as prepupae. Data are lacking for the year-round phenological progression of EAB life stages in central North Carolina in order to understand the best time to release parasitoids and maximize their chance of establishment.