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Dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett, is a common foliar disease on golf courses. Of 284 isolates collected from Tennessee and northern Mississippi, 90 were tested for in vitro resistance to three commonly used fungicides. The estimated fungicide concentration required to inhibit growth by 50 and 90% varied among locations. Isolates at seven locations were resistant to iprodione, whereas isolates were resistant to propiconazole at only one location. Isolates at five locations were resistant to thiophanate‐methyl. Some isolates showed resistance to 1000 μg a.i. mL−1 iprodione and thiophanate‐methyl, whereas resistance occurred at 10 μg a.i. mL−1 propiconazole. Isolates at only one location exhibited resistance to both thiophanate‐methyl and iprodione, and isolates at only one location had resistance to all three fungicides. This study revealed that resistance to fungicides has developed in S. homoeocarpa in Tennessee and Northern Mississippi. These results also support the contention that repeated use of these three classes of fungicide may lead to development of resistant isolates of S. homoeocarpa

Evaluating species diversity and patterns of population genetic variation is an essential aspect of conservation biology to determine appropriate management strategies and preserve the biodiversity of native plants. Habitat fragmentation and potential habitat loss are often an outcome of a reduction in naturally occurring wildfires and controlled prescribed burning, as seen in Helianthus verticillatus (whorled sunflower). This endangered, wild relative of the common sunflower, Helianthus annuus, is endemic to four locations in Alabama, Georgia, and Tennessee, United States. Despite its endangered status, there is no recovery plan for H. verticillatus, and knowledge related to its basic plant biology and importance in ecosystem services is mostly unknown. In this study, we utilized 14 microsatellite loci to investigate fine-scale population structure and genetic diversity of H. verticillatus individuals found on two sampling sites within the Georgia population. Our results indicated moderate genetic diversity and the presence of two distinct genetic clusters. Analyses of molecular variance indicated that the majority of variance was individually based, thus confirming high genetic differentiation and limited gene flow between H. verticillatus collection sites. The evidence of a population bottleneck in these sites suggests a recent reduction in population size that could be explained by habitat loss and population fragmentation. Also, high levels of linkage disequilibrium were detected, putatively suggesting clonal reproduction among these individuals. Our study provides a better understanding of fine-scale genetic diversity and spatial distribution of H. verticillatus populations in Georgia. Our results can underpin an original recovery plan for H. verticillatus that could be utilized for the conservation of this endangered species and to promote its persistence in the wild.

Triple gene block 1 (TGB1) and coat protein (CP) sequences of 30 hosta virus X (HVX) isolates from Tennessee (TN), USA, were determined and compared with available sequences in GenBank. The CPs of all known HVX isolates, including those from TN, shared 98.3-100% and 98.2-100% nucleotide and amino acid sequence identity, respectively, whereas TGB1 shared 97.4-100% nucleotide and 97-100% amino acid sequence identity. TGB1 of TN isolates were all longer by one codon from that of a Korean isolate, which is the only sequence publicly available. Phylogenetic analysis of nucleotide and amino acid sequences of TGB1 and CP of all known HVX isolates, separately or combined, revealed a close relationship, suggesting that all of them are derived from a common ancestor. Phylogenetic analysis with the type member of each genus of the family Flexiviridae confirmed that HVX is a member of a distinct species of the genus Potexvirus.