Evaluation of some cucurbit genotypes for resistance to downy mildew based on AUDPC

Volume 11, Issue 1
March 2022
Pages 29-37

Document Type : Original Research

Authors

1 Department of Plant Protection, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran.

2 Department of Horticulture, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran.

Abstract
Downy mildew is one of the most important diseases of cucurbits in the world and Iran. The development of the disease was investigated in a commercial variety (Sakata® F1 Hybrid Saso), three hybrids and eight pure lines of cucumber, four pure squash lines, and one commercial cultivar of watermelon (Sakata® F1 Charleston Gray 243) in two consecutive years (2017 and 2018 spring and summer) at the experimental field of the University of Guilan, Iran to identify the sources of resistance. Plants were regularly inspected until the downy mildew symptoms appeared. The disease was measured using standard scale and Image J software at five stages in the plant growing season. Comparison of disease progress curves, final severity of the disease, and area under the disease progress curve (AUDPC) showed that cucumber B10 and A12 pure lines were the most susceptible and resistant in both years, respectively. None of the squash lines were infected in the first year, but in the second year, two lines showed the disease symptoms, and the severity of the disease in these lines was close to each other. The commercial cultivar of watermelon was not infected in both years.

Keywords

Subjects
1. Awasthi, L.P. 2015. Recent Advances in the Diagnosis and Management of Plant Diseases. Springer.
2. Cohen Y., Van den Langenberg K. M., Wehner T. C., Ojiambo P. S., Hausbeck M., Quesada-Ocampo L. M., Lebeda A., Sierotzki H. and Gisi U. 2015. Resurgence of Pseudoperonospora cubensis: The causal agent of cucurbit downy mildew. Phytopathology, 105: 998-1012.
3. Colucci, S. J., Wehner, T. C. and Holmes, G. J. 2006. The downy mildew epidemic of 2004 and 2005 in the Eastern United States. Universal Press, Raleigh, North Carolina: 403-410.
4. Holmes, G. J., Ojiambo, P. S., Hausbeck, M. K., Quesada-Ocampo, L. and Keinath, A. P. 2015. Resurgence of cucurbit downy mildew in the United States: A watershed event for research and extension. Plant Disease, 99: 428-441.
5. Lebeda, A. and Urban, J. 2004. Distribution, harmfulness and pathogenic variability of cucurbit downy mildew in the Czech Republic. Acta Fytotech Zootech, 7: 170-173.
6. Lebeda, A. and Cohen, Y. 2010. Cucurbit downy mildew (Pseudoperonospora cubensis)- biology, ecology, epidemiology, host-pathogen interaction and control. European Journal of Plant Pathology, 129: 157-192.
7. Neufeld, K. N. and Ojiambo, P. S. 2012. Interactive effects of temperature and leaf wetness duration on sporangia germination and infection of cucurbit hosts by Pseudoperonospora cubensis. Plant Disease, 96: 345-353.
8. Ojiambo, P. S., Paul, P. A. and Holmes, G. J. 2010. A quantitative review of fungicide efficacy for managing downy mildew in cucurbits. Phytopathology, 100: 1066-1076.
9. Thomas, C. E. 1999. Additional Evaluations of Cucumis melo L. Germplasm for Resistance to Downy Mildew. Hortscience, 34(5): 920-921.
10. Urban, J. and Lebeda, A. 2006. Fungicide resistance in cucurbit downy mildew- methodological, biological and population aspects. Annals of Applied Biology, 149: 63-75.