Browsing by Author "Brooks, Rachel K."

Now showing 1 - 5 of 5
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    The Inability of Spotted Lanternfly (Lycorma delicatula) to Vector a Plant Pathogen between its Preferred Host, Ailanthus altissima, in a Laboratory Setting
    Brooks, Rachel K.; Toland, Ashley; Dechaine, Andrew C.; McAvoy, Thomas; Salom, Scott M. (MDPI, 2020-08-09)
    With the recent introduction of the non-native spotted lanternfly (Lycorma delicatula) to the USA, research and concern regarding this insect is increasing. Though L. delicatula is able to feed on many different plant species, its preference for the invasive tree-of-heaven (Ailanthus altissima) is apparent, especially during its later life stage. Therefore, management focused on A. altissima control to help limit L. delicatula establishment and population growth has become popular. Unfortunately, the control of A. altissima is difficult. Verticillium nonalfalfae, a naturally occurring vascular-wilt pathogen, has recently received attention as a potential biological control agent. Therefore, we studied if L. delicatula fourth instars or adults could vector V. nonalfalfae from infected A. altissima material to healthy A. altissima seedlings in a laboratory setting. We were unable to re-isolate V. nonalfalfae from the 45 A. altissima seedlings or from the 225 L. delicatula utilized in this experiment. We therefore, found no support that L. delicatula could effectively vector this pathogen between A. altissima in laboratory conditions. Since L.delicatula’s ability to vector V. nonalfalfae has implications for the dissemination of both this beneficial biological control and other similar unwanted plant pathogens, future research is needed to confirm these findings in a field setting.
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    The invasive tree, Ailanthus altissima, impacts understory nativity, not seedbank nativity
    Brooks, Rachel K.; Barney, Jacob; Salom, Scott M. (Elsevier, 2021-06-01)
    Ailanthus altissima, the invasive forest tree commonly known as the tree-of-heaven, has been associated with decreased levels of plant species richness and native species diversity. However, this relationship with resident plants has been inconsistently found and the tree's influence on the seedbank has yet to be studied. To further understand the long-term impact of this tree, ten paired invaded-uninvaded sites were identified in Virginia, USA in a variety of different-aged stands. The herbaceous and woody understories for each plot were inventoried and soil samples were collected and grown out for 34 weeks in a greenhouse. All plants were identified to the most detailed taxonomic level possible. In total, 35 woody understory species, 62 herbaceous understory taxa, and 77 seedbank taxa were identified. The relationship between A. altissima presence and i) the proportion of individual plants that are native, ii) the proportion of species that are native, iii) the native diversity, and iv) the nonnative diversity were analyzed. In addition, models including the invasion age were also considered. We show that A. altissima invasions were associated with a decrease in the proportion of native plants and species in the understory, but not in the seedbank. Nonnative woody diversity also increased with A. altissima presence. Additionally, the impact on the nativity of the woody understory became more extreme over time. We end by discussing the benefits of both managing A. altissima invasions early to limit its overall impact and including the management of other nonnative plants in A. altissima restoration plans.
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    Invasive Tree-of-Heaven & Native Look-Alike Identification Drawings
    Brooks, Rachel K.; Bailey, Barbara; Sastre, Beth (Virginia Cooperative Extension, 2019-06-24)
    Provides identification drawings of Tree-of-Heaven and look-alike species of trees
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    Mortality of Great Rhododendron (Rhododendron maximum) in Virginia
    Brooks, Rachel K.; Hansen, Mary Ann; Bush, Elizabeth A.; Eisenback, Jonathan D.; Day, Eric R. (Virginia Cooperative Extension, 2019-08-21)
    Causes for the dieback of Great Rhododendron have not been identified at present time. Some species of fungi, insects, nematodes , and other organisms may be involved in the decline.
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    Phenology and Synchrony of Scymnus coniferarum (Coleoptera: Coccinellidae) with Multiple Adelgid Species in the Puget Sound, WA, USA
    Darr, Molly N.; Brooks, Rachel K.; Havill, Nathan P.; Hoebeke, E. Richard; Salom, Scott M. (MDPI, 2018-09-11)
    The hemlock woolly adelgid (HWA), Adelges tsugae, is an invasive pest of Tsuga spp. in eastern North America. Scymnus coniferarum is a predaceous beetle that was collected from HWA in the western United States. Limited knowledge of this insect in its native habitat led to studies to evaluate its potential for biological control of HWA. Seasonal abundance was sampled at six sites in Tacoma, WA, twice monthly, for one year on different host trees of potential adelgid prey. Tree species included Pseudotsuga menziesii, Pinus contorta, Pinus monticola, and Tsuga heterophylla. Scymnus coniferarum adults were found on all conifer species, except P. menziesii. Each conifer species supported a different adelgid species, suggesting S. coniferarum feeds on multiple adelgid species. More S. coniferarum were found on pine than hemlock. DNA barcoding of S. coniferarum found two distinct clusters that differed by 6% divergence. Beetles in each cluster were co-habiting the same conifer species, and they could not be distinguished morphologically. Further taxonomic studies are needed to understand the significance of DNA barcode sequence divergence. Because S. coniferarum was more frequently associated with pine adelgids than HWA, and because of remaining taxonomic uncertainty, S. coniferarum may not be suitable for HWA biological control.