POSTERS: New and emerging diseases
Characterization, pathogenicity, and fungicide sensitivity of Pestalotiopsis spp. on strawberry in the U.S.
Juliana Baggio - Gulf Coast Research and Education Center, University of Florida. James Mertely- Gulf Coast Research and Education Center, University of Florida, Bruna Forcelini- Corteva Agriscience, Rafaela G Ruschel- Sao Paulo State University, School of Agriculture, Natalia Peres- University of Florida - Gulf Coast Research and Educ
Pestalotiopsis spp. have been known to cause strawberry fruit rot. In recent reports from Florida and other strawberry producing areas, the fungus was associated with root and crown rots. The taxonomic status is confusing as two novel genera, Neopestalotiopsis and Pseudopestalotiopsis, have been described. During the 2018-19 season, a severe outbreak was observed in two Florida fields where leaf, fruit, petiole, crown, and root symptoms were present. Currently, there are no fungicides labeled to control this disease in the U.S. Therefore, morphological and molecular characteristics, pathogenicity, and fungicide sensitivity of isolates from Florida were evaluated. Colonies were white, circular, and cottony on the upper side. On the bottom, root, crown, and petiole isolates were pale luteous to orange; and leaf and fruit isolates were white to pale yellow. Optimum temperatures for mycelial growth and sporulation were 25 and 30°C, respectively. In pathogenicity tests, all isolates were able to produce root and crown rot symptoms. However, on fruit, disease incidence and severity were higher with leaf and fruit isolates. Thirty-eight isolates were screened in vitro for their sensitivity to azoxystrobin, captan, fluopyram, penthiopyrad, flutriafol, tetraconazole, fludioxonil, and thiophanate methyl. Only captan and fluodioxonil significantly inhibited mycelial growth. Moreover, resistance to QoI fungicides was confirmed by the presence of the G143A mutation in the cytb gene. Molecular studies are currently being performed to determine the taxonomic status of Florida isolates.