• Leptographium complex

    Leptographium species associated with root-feeding beetles in Southern pine stands and their interaction with the host

    We study Leptographium and Grosmannia species associated with root-feeding beetles in the southeastern forests. Our research objectives are to elucidate the fungal species carried by native and exotic root-feeding beetles in healthy and unhealthy pine stands, to determine the pathogenicity of the different Leptographium species, and to analyze the host response to colonization by the fungi.

    This project is a collaboration with Dr. Gandhi (Forest Entomologist at Warnell, UGA) and Dr. Klepzig (Jones Ecological Research Center).

  • Laurel wilt disease diagnosis

    Use of LAMP for in-field early detection of the laurel wilt disease causing agent

    We are developing and validating a LAMP (loop mediated isothermal amplification) based assay for the rapid, in-field, early detection and identification of the causal agent of laurel wilt disease (LWD). Laurel wilt is a devastating disease which is decimating redbay and threatening other lauraceous species, including sassafras throughout the eastern USA, California bay on West Coast and commercial avocado. The disease is caused by Raffaelea lauricola, an invasive fungal pathogen vectored by the redbay ambrosia beetle. Early detection and rapid sanitation of infected plants are crucial steps to slow disease spread, and critical components of an integrated pest management program.

    LAMP is an innovative molecular technology that meets all the major technical and economic requirements for successful in-field implementation by non-technical users, and has been already optimized for the detection of tree pathogens using portable devices (e.g., sudden oak death and ash dieback). In addition, despite being performed in few simple steps, LAMP is highly sensitive, and potentially able to detect the pathogen even in asymptomatic tissues, or directly on the insect vectors. Trained forest health monitoring personnel, equipped with portable devices, will be able to confirm the diagnosis of LWD in both symptomatic and asymptomatic samples, or identify a potential insect vector, in as short as 30 minutes, without having to rely on traditional, costly, time-consuming laboratory procedures.

    This project is a collaboration with Dr. Fraedrich (USDA Forest Service), and is funded by the USDA FS Special Technology Development Program

  • Little leaf disease

    Assessing the interaction between littleleaf disease and Ips outbreaks on the Oconee Ranger District

    This study is part of a bigger project aimed at identifying the drivers of the recent Ips avulsus beetle outbreak on the Oconee Ranger District. The pathology component of the project is looking at the incidence of Phytophthora cinnamomi, a root pathogen which causes littleleaf disease on pine trees. The presence/absence of P. cinnamomi  is assessed via isolation on selective media from soil and root samples, followed by molecular confirmation of the pathogen identity. Phytophthora species other than P. cinnamomi are also monitored.

    This project is a collaboration with Dr. Gandhi, Dr. Morris (Forest Entomologist at Warnell, UGA), and Ms. Beard (USDA Forest Service), and is funded by the USDA FS Chattahoochee-Oconee National Forest

  • Sugarberry decline and mortality

    Investigating the causal agents of the decline and mortality of Celtis Laevigata

    Sugarberry or southern hackberry (Celtis laevigata) is a medium size tree that is common in many forest types throughout the southeastern USA. A decline and mortality of the species has been recently observed in both forest and urban areas of South Carolina and Georgia, but causes of the disease are not understood. Trees affected by the disease exhibit an array of symptoms including leaf chlorosis, development of smaller than normal foliage, early leaf drop/thinning crowns, and a progressive crown dieback which occurs over one to several years. The stems and roots of affected trees develop a brownish discoloration in the phloem early in the disease cycle, and the discoloration appears to spread throughout the phloem as trees succumb to the disease. A number of insect pests and potential pathogens have been associated with the decline, however, at this time most of these appear to be secondary opportunistic organisms rather than primary causal agents.

    Phytoplasmas, viruses and bacteria, including fastidious bacteria, have all been associated with various types of decline and are notoriously difficult to diagnose and not readily identified in symptomatic trees without using molecular approaches. The objective of this project study is to determine if and what types of bacteria and phytoplasmas are associated with the phloem of declining sugarberries by using a metabarcoding approach, with the overarching goal of moving forward with the understanding of the causal agent(s) of the sugarberry decline.

    This project is a collaboration with Drs. Cram, Fraedrich, Olatinwo and Ulyshen (USDA Forest Service), and is funded by the USDA FS Special Technology Development Program and the USDA FS Southern Research Station.