Relative efficacy of strobilurin formulations in the control of downy mildew of sunflower

The efficacy of three commercial formulations of strobilurins, viz., trifloxystrobin, kresoxim-methyl, and azoxystrobin was evaluated against sunflower downy mildew disease caused by Plasmopara halstedii under laboratory, greenhouse, and field conditions. Complete inhibition of sporangial sporulatio...

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Published in:	Journal of pest science Vol. 83; no. 4; pp. 461 - 470
Main Authors:	Sudisha, J, Niranjana, S. R, Sukanya, S. L, Girijamba, R, Lakshmi Devi, N, Shekar Shetty, H
Format:	Journal Article
Language:	English
Published:	Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-12-2010 Springer Berlin Heidelberg Springer Nature B.V
Subjects:	Agriculture Airborne microorganisms Azoxystrobin Biomedical and Life Sciences Disease control Downy mildew Ecology Entomology Foliar applications Forestry Formulations Fungicides Germination Greenhouses Helianthus Helianthus annuus L Kresoxim-methyl Life Sciences Plant Pathology Plant protection Plant Sciences Plasmopara halstedii Seed and foliar treatments Seed germination Seed treatments Seedlings Seeds Sporulation Strobilurin Sunflowers Vigor β methoxyacrylic acid group formulations β methoxyacrylic acid group formulations Seed and foliar treatments Disease management L
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Summary:	The efficacy of three commercial formulations of strobilurins, viz., trifloxystrobin, kresoxim-methyl, and azoxystrobin was evaluated against sunflower downy mildew disease caused by Plasmopara halstedii under laboratory, greenhouse, and field conditions. Complete inhibition of sporangial sporulation, zoospore release, and motility was observed with 2 μg ml⁻¹ in trifloxystrobin, and 5 μg ml⁻¹ for azoxystrobin and kresoxim-methyl. Seed treatment with different concentrations of strobilurins enhanced seed germination and seedling vigor of sunflower to varying degrees compared to control. Highest seed germination was recorded at 10 μg ml⁻¹ in kresoxim-methyl, and maximum seedling vigor was noticed with trifloxystrobin at 30 μg ml⁻¹. The effect of strobilurins was tested as seed treatment, foliar application, and seed treatment followed by foliar application. Under greenhouse conditions none of the concentrations used, either as seed treatment and foliar application, were phytotoxic. For the three strobilurins, the seed treatment along with foliar application enhanced the protection of the plants as compared to only the treatment of seeds. Foliar spray treatments alone provided an intermediate control of the disease. Trifloxystrobin showed a better effect than kresoxim-methyl and azoxystrobin. Disease curative activity of trifloxystrobin was higher compared to kresoxim-methyl and azoxystrobin. Tested fungicides when applied on adaxial leaf surface showed partial translaminar activity, and disease inhibition was marginal. Loss of trifloxystrobin and azoxystrobin activity over time was low, indicating stable rainfastness residual activity. A trend in protection against downy mildew disease similar to greenhouse results was evident in the field trials. This is the first report of strobilurins exhibiting high activity against P. halstedii and is a promising fungicide for controlling sunflower downy mildew disease by seed treatment and foliar spray.
Bibliography:	http://dx.doi.org/10.1007/s10340-010-0316-3 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	1612-4758 1612-4766
DOI:	10.1007/s10340-010-0316-3