Visually Asymptomatic Leaf Loss in -Infected Blueberry Plants.

(Xf), a gram-negative bacterium, is a notorious, world-wide plant pathogen with an extended latent period that presents a challenge for early disease detection and control interventions. We used thermal imaging of tissue-cultured, experimentally Xf-infected blueberry plants to identify visually pre-symptomatic leaves and compared the minimum force required to dislodge symptomatic leaves from infected plants to leaves on uninfected (control) blueberry plants. For two different blueberry cultivars and one pathogenic isolate of , we found no statistical difference between the mean downward force for leaf dislodgement, regardless of symptom category, on Xf-infected blueberry plants.

Azole resistance mechanisms and population structure of the human pathogen on retail plant products.

is a ubiquitous saprotroph and human-pathogenic fungus that is life-threatening to the immunocompromised. Triazole-resistant was found in patients without prior treatment with azoles, leading researchers to conclude that resistance had developed in agricultural environments where azoles are used against plant pathogens. Previous studies have documented azole-resistant across agricultural environments, but few have looked at retail plant products.

Fatal Attraction: Spiders Lure Male Moth Prey with the Promise of Sex.

Predator-prey coevolution, particularly chemo-ecological arms races, is challenging to study as it requires the integration of behavioral, chemical ecology, and phylogenetic studies in an amenable system. Moths of the genus (Saturniidae) are colorful, diurnal, and fast and often fly well above the vegetation canopy layer. However, several species have been reported as being captured in spider webs, specifically species (Araneidae).

Assessment of Prickly Sida as a Potential Inoculum Source for Sida Golden Mosaic Virus in Commercial Snap Bean Farms in Georgia, United States.

Sida golden mosaic virus (SiGMV), an obligate pathogen that infects snap beans (), is known to infect prickly sida ( L.), which is a common weed in agricultural farms in Georgia. Prickly sida has also been reported as a suitable host of sweetpotato whitefly (), the vector of SiGMV.

Evidence of Infection and Associated Thermal Signatures in Southern Highbush Blueberry ( Interspecific Hybrids).

, a gram-negative bacterium vectored to plants via feeding of infected insects, causes a number of notorious plant diseases throughout the world, such as Pierce's disease (grapes), olive quick decline syndrome, and coffee leaf scorch. Detection of in infected plants can be challenging because the early foliar disease symptoms are subtle and may be attributed to multiple minor physiological stresses and/or borderline nutrient deficiencies. Furthermore, may reside within an infected plant for one or more growing seasons before traditional visible diagnostic disease symptoms emerge.

Shoot Maturation Strengthens FLS2-Mediated Resistance to .

Temporospatial regulation of immunity components is essential for properly activating plant defense response. Flagellin-sensing 2 (FLS2) is a surface-localized receptor that recognizes bacterial flagellin. The immune function of FLS2 is compromised in early stages of shoot development.

Endogenous salicylic acid suppresses de novo root regeneration from leaf explants.

Plants can regenerate new organs from damaged or detached tissues. In the process of de novo root regeneration (DNRR), adventitious roots are frequently formed from the wound site on a detached leaf. Salicylic acid (SA) is a key phytohormone regulating plant defenses and stress responses.

Distribution, Diversity, and Soil Associations of Wine Grape Plant-Parasitic Nematodes in Georgia, U.S.A., Vineyards.

Wine grape ( and hybrids) production in Georgia occurs in three distinct regions (North, West, and South) which can be characterized by sandy, sandy-loam, or sandy clay-loam soils. We studied plant-parasitic nematode (PPN) communities in 15 wine grape vineyards from the three primary growing regions to understand which nematodes are a concern and what soil characteristics are associated with their occurrence and relative abundance. Twelve genera of PPNs were detected throughout the state: , , , , , , , , , , , and .

Dispersal Kernel Type Highly Influences Projected Relationships for Plant Disease Epidemic Severity When Outbreak and At-Risk Populations Differ in Susceptibility.

In silico study of biologically invading organisms provide a means to evaluate the complex and potentially cryptic factors that can influence invasion success in scenarios where empirical studies would be difficult, if not impossible, to conduct. I used a disease event simulation program to evaluate whether the two most frequently used types of plant pathogen dispersal kernels for epidemiological projections would provide complementary or divergent projections of epidemic severity when the hosts in a disease outbreak differed from the hosts in the at-risk population in the degree of susceptibility. Exponential dispersal kernel simulations of wheat stripe rust ( var ) predicted a relatively strong and dominant influence of the at-risk population on the end epidemic severity regardless of outbreak disease levels.

Delays in Epidemic Outbreak Control Cost Disproportionately Large Treatment Footprints to Offset.

Epidemic outbreak control often involves a spatially explicit treatment area (quarantine, inoculation, ring cull) that covers the outbreak area and adjacent regions where hosts are thought to be latently infected. Emphasis on space however neglects the influence of treatment timing on outbreak control. We conducted field and in silico experiments with wheat stripe rust (WSR), a long-distance dispersed plant disease, to understand interactions between treatment timing and area interact to suppress an outbreak.

Differences in distribution and community structure of plant-parasitic nematodes in pecan orchards between two ecoregions of Georgia.

In Georgia, pecans are commercially grown in the Piedmont and Coastal Plain ecoregions which are characterized by sandy-loam, sandy, and/or clay soils. If well-drained, these soils are suitable for pecan production, but the soil characteristics differ enough between ecoregions in which the plant-parasitic nematode (PPN) communities could differ substantially. We studied PPN communities in pecan orchards to evaluate the potential for ecoregion differences.

Positive selection and intrinsic disorder are associated with multifunctional C4(AC4) proteins and geminivirus diversification.

Viruses within the Geminiviridae family cause extensive agricultural losses. Members of four genera of geminiviruses contain a C4 gene (AC4 in geminiviruses with bipartite genomes). C4(AC4) genes are entirely overprinted on the C1(AC1) genes, which encode the replication-associated proteins.

Patterns of Seed-to-Seedling Transmission of pv. , the Causal Agent of Cotton Bacterial Blight.

Cotton bacterial blight (CBB), caused by pv. , was a major disease of cotton in the United States in the early part of the twentieth century. The reemergence of CBB revealed many gaps in our understanding of this important disease.

Plant Pathogen Invasion Modifies the Eco-Evolutionary Host Plant Interactions of an Endangered Checkerspot Butterfly.

New plant pathogen invasions typified by cryptic disease symptoms or those appearing sporadically in time and patchily in space, might go largely unnoticed and not taken seriously by ecologists. We present evidence that the recent invasion of (Dermateaceae) into the Pacific Northwest USA, which causes foliar necrosis in the fall and winter on (plantain), the primary (non-native) foodplant for six of the eight extant Taylor's checkerspot butterfly populations (, endangered species), has altered eco-evolutionary foodplant interactions to a degree that threatens butterfly populations with extinction. Patterns of butterfly, larval food plant, and disease development suggested the ancestral relationship was a two-foodplant system, with perennial spp.

Assessment of Quinone Outside Inhibitor Sensitivity and Frogeye Leaf Spot Race of in Georgia Soybean.

Frogeye leaf spot (FLS), caused by the fungal pathogen K. Hara, is a foliar disease of soybean ( L. [Merr.

The Distribution of Onion Virulence Gene Clusters Among spp.

is a gram-negative bacterium and the primary causal agent of center rot of onions in Georgia. Previous genomic studies identified two virulence gene clusters, HiVir and , associated with center rot. The HiVir gene cluster is required to induce necrosis on onion tissues via synthesis of pantaphos, (2-hydroxy[phosphono-methyl)maleate), a phosphonate phytotoxin.

Influence of the Environment and Vegetable Cropping Systems on Plant-Parasitic Nematode Communities in Southern Georgia.

Plant-parasitic nematodes (PPN) limit yields of vegetable production in the United States. During the spring and fall cropping seasons of 2018, 436 fields in bare ground and plastic bed cropping systems were randomly sampled from 29 counties in southern Georgia. The incidence (%), mean relative abundance, and maximum relative abundance (nematodes per 100 cm of soil) of the 10 different PPN genera detected in 32 vegetable crops in bare ground and plastic bed cropping systems include spp.

Consequences of Long-Distance Dispersal for Epidemic Spread: Patterns, Scaling, and Mitigation.

Epidemics caused by long-distance dispersed pathogens result in some of the most explosive and difficult to control diseases of both plants and animals (including humans). Yet the factors influencing disease spread, especially in the early stages of the outbreak, are not well-understood. We present scaling relationships, of potentially widespread relevance, that were developed from more than 15 years of field and in silico single focus studies of wheat stripe rust spread.

Losing a battle but winning the war: moving past preference-performance to understand native herbivore-novel host plant interactions.

Introduced plants can positively affect population viability by augmenting the diet of native herbivores, but can negatively affect populations if they are subpar or toxic resources. In organisms with complex life histories, such as insects specializing on host plants, the impacts of a novel host may differ across life stages, with divergent effects on population persistence. Most research on effects of novel hosts has focused on adult oviposition preference and larval performance, but adult preference may not optimize offspring performance, nor be indicative of host quality from a demographic perspective.

Low relative error in consumer-grade GPS units make them ideal for measuring small-scale animal movement patterns.

Consumer-grade GPS units are a staple of modern field ecology, but the relatively large error radii reported by manufacturers (up to 10 m) ostensibly precludes their utility in measuring fine-scale movement of small animals such as insects. Here we demonstrate that for data collected at fine spatio-temporal scales, these devices can produce exceptionally accurate data on step-length and movement patterns of small animals. With an understanding of the properties of GPS error and how it arises, it is possible, using a simple field protocol, to use consumer grade GPS units to collect step-length data for the movement of small animals that introduces a median error as small as 11 cm.

Apparent power-law distributions in animal movements can arise from intraspecific interactions.

Lévy flights have gained prominence for analysis of animal movement. In a Lévy flight, step-lengths are drawn from a heavy-tailed distribution such as a power law (PL), and a large number of empirical demonstrations have been published. Others, however, have suggested that animal movement is ill fit by PL distributions or contend a state-switching process better explains apparent Lévy flight movement patterns.

Degree of host susceptibility in the initial disease outbreak influences subsequent epidemic spread.

Disease epidemics typically begin as an outbreak of a relatively small, spatially explicit population of infected individuals (focus), in which disease prevalence increases and rapidly spreads into the uninfected, at-risk population. Studies of epidemic spread typically address factors influencing disease spread through the at-risk population, but the initial outbreak may strongly influence spread of the subsequent epidemic.We initiated wheat stripe rust f.

Biased correlated random walk and foray loop: which movement hypothesis drives a butterfly metapopulation?

Animals in fragmented landscapes have a major challenge to move between high-quality habitat patches through lower-quality matrix. Two current mechanistic hypotheses that describe the movement used by animals outside of their preferred patches (e.g.

Implications of nonadventitious rhizome spread on reproduction, inbreeding, and conservation for a rare grassland legume.

Small population size, genetic diversity, and spatial patterns of vegetative spread are important aspects to consider when managing populations of rare clonal plant species. We used 5 variable nuclear simple sequence repeat nDNA loci to determine the extent of genet rhizome spread, examine the possibility of very small population sizes, and project how Bombus spp. (bumblebee) foraging may impact selfing (through geitonogamy) for a threatened lupine (Lupinus oreganus Heller) that sprawls through nonadventitious rhizomes.