Identification and Management of Phytophthora Aerial Blight Caused byPhytophthora nicotianaeonCatharanthus roseus
- 1 April 2022
- journal article
- research article
- Published by Scientific Societies in Plant Disease
- Vol. 106 (4), 1271-1277
- https://doi.org/10.1094/pdis-06-21-1342-re
Abstract
Phytophthora nicotianae is the most common pathogen in nurseries and gardens, infecting both woody and herbaceous ornamental plants. Phytophthora aerial blight symptoms such dull water-soaked lesions on shoot tips and leaf petioles, girdling on the main stem, necrosis, and wilting of annual vinca were observed in a commercial greenhouse in Warren County, TN, U.S.A., in May 2016. The objective of this study was to identify the causal agent of Phytophthora aerial blight and develop a fungicide management recommendation for ornamental producers. Attempts to isolate the pathogen from symptomatic leaf tissue were conducted, and excised leaf pieces were embedded in V8 agar medium. Morphological characterization, PCR, sequencing, and pathogenicity test of the isolate FBG2016_444 were conducted to confirm the pathogen identification. The sequence identity was 100% identical to P. nicotianae, and a combined phylogenetic tree (internal transcribed spacer, large subunit of rDNA, and ras-related protein gene) grouped isolate FBG2016_444 within the clade of P. nicotianae. In the pathogenicity study, all inoculated annual vinca plant showed Phytophthora aerial blight symptoms, and P. nicotianae was reisolated, whereas noninoculated annual vinca plant remained symptomless. These findings confirmed P. nicotianae as the causal agent of Phytophthora aerial blight of annual vinca. In addition, two rates (0.078 and 0.156 ml·liter–1) and three application intervals (7, 14, and 21 days before inoculation [DBI]) of oxathiapiprolin (Segovis) were evaluated for their ability to reduce the Phytophthora aerial blight severity on annual vinca plants. The control groups were positive (nontreated inoculated) and negative (nontreated noninoculated) plants. Both rates and application timings of oxathiapiprolin significantly reduced Phytophthora aerial blight severity and disease progress (area under disease progress curve [AUDPC]) on annual vinca plants compared with the positive control. However, 0.078 and 0.156 ml·liter–1 of oxathiapiprolin applied at 7 or 14 DBI were the most effective treatments in reducing the disease severity and AUDPC on annual vinca plants. The plant growth parameters such as increase in height and width, total plant weight, and root weight were not influenced by the application of oxathiapiprolin. The findings reported in this study will help ornamental producers with better management of Phytophthora aerial blight of annual vinca.Keywords
Funding Information
- National Institute of Food and Agriculture (TENX-1926-CCOCP, TENX-S-1083)
This publication has 47 references indexed in Scilit:
- Characterization of Phytophthora spp. on Floriculture Crops in North CarolinaPlant Disease, 2011
- Co-occurrence and genotypic distribution ofPhytophthoraspecies recovered from watersheds and plant nurseries of eastern TennesseeMycologia, 2010
- Mefenoxam sensitivity and fitness analysis of Phytophthora nicotianae isolates from nurseries in Virginia, USAPlant Pathology, 2008
- Effect of Fertilization and Biopesticides on the Infection ofCatharanthus roseusbyPhytophthora nicotianaePlant Disease, 2007
- Development and application of a PCR‐based ‘molecular tool box’ for the identification of Phytophthora species damaging forests and natural ecosystemsPlant Pathology, 2007
- Phytophthora Species Associated with Diseased Woody Ornamentals in Minnesota NurseriesPlant Disease, 2007
- Foliage Blight of Vinca (Catharanthus roseus) by Phytophthora nicotianaeResearch in Plant Disease, 2004
- Etiology of Phytophthora drechsleri and P. nicotianae (=P. parasitica) Diseases Affecting Floriculture CropsPlant Disease, 2003
- Reduction of Phytophthora Blight of Madagascar Periwinkle in Florida by Soil Solarization in AutumnPlant Disease, 2000
- In Vivo Expression of Resistance to Metalaxyl by a Nursery Isolate ofPhytophthora parasiticafromCatharanthus roseusPlant Disease, 1992