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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #347571
Title: First report of damping-off of dent corn seedlings caused by Pythium graminicola in Georgia

Author
item LI, YONGGANG - Northeast Agricultural University, China
item LIU, JINXIN - Northeast Agricultural University, China
item ZHAO, TONGXUE - Northeast Agricultural University, China
item Li, Shuxian
item JI, PINGSHENG - University Of Georgia

Submitted to: Plant Disease
Publication Type: Research Notes
Publication Acceptance Date: 1/16/2018
Publication Date: 7/1/2018
Citation: Li, Y., Liu, J., Zhao, T., Li, S., Ji, P. 2018. First report of damping-off of dent corn seedlings caused by Pythium graminicola in Georgia. Plant Disease. 102(7)1464. https://doi.org/10.1094/PDIS-10-17-1692-PDN.
DOI: https://doi.org/10.1094/PDIS-10-17-1692-PDN

Interpretive Summary: Corn is an important crop produced in Georgia with a farm gate value of over $250 million annually. An unknown disease was observed on corn seedlings in commercial corn fields in Tift County, Georgia, in April 2015. Stems of corn seedlings were brown, water-soaked, soft, decayed, and broke off easily. A fungus-like organism was isolated and identified as Pythium graminicola based on its structure and DNA sequences. In greenhouse tests, all plants treated with the pathogen showed disease symptoms, while non-treated plants were healthy. This is the first report confirming stalk rot of corn caused by P. graminicola in Georgia in the United States. The occurrence of this new disease needs to be considered in developing and implementing disease management programs in corn production.

Technical Abstract: An unknown disease was observed on corn seedlings in commercial corn fields in Tift County, Georgia, in April 2015. Stems of corn seedlings were brown, water-soaked, soft, decayed, and broke off easily. Disease incidence ranged from 2 to 3%. A fungus-like organism was isolated from all infected stem samples and identified as Pythium graminicola based on morphological characteristics. Sequences of the internal transcribed spacer regions of rDNA (ITS1-5.8S-ITS4) showed 99% identical to a P. graminicola isolate CBS 327.62 Results from greenhouse pathogenicity tests showed that all inoculated seedlings showed symptoms identical to those observed in the field 10 days after inoculation. No disease occurred on the control plants treated with autoclaved wheat seeds. Pythium graminicola was re-isolated from diseased plants and the identity was confirmed based on morphological characteristics and ITS sequence analysis. To our knowledge, this is the first report of P. graminicola causing disease on corn in Georgia. Corn is one of the most economically important field crops in Georgia, and the occurrence of this new disease needs to be considered in developing and implementing disease management programs in corn production.