Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2008
Publication Date: 6/15/2008
Citation: Kirk, W.W., S.L. Gieck, J.M. Crosslin, and P.B. Hamm. 2008. First report of corky ringspot caused by Tobacco rattle virus on potatoes (Solanum tuberosum) in Michigan. Plant Disease 92:485. Interpretive Summary: Tobacco rattle virus (TRV) is transmitted to developing potato tubers by the stubby root nematode. Once infected, tubers develop various internal defects including dark spots, rings, or corky tissue, called corky ringspot (CRS). These defects render the tubers unmarketable and can result in serious economic damage to the potato grower. The CRS disease has previously been reported from Washington, Oregon, Idaho, Colorado, and Florida. This is the first report of TRV on potatoes in the state of Michigan.
Technical Abstract: Potato is the most important agricultural commodity in Michigan and is grown for table stock, chip processing and for seed. Tubers are either processed or fresh packed immediately following harvest or sent to storage. When tubers (cv. FL1879) were removed from two storages representing two separate fields in Huron County in February and March, 2007, substantial internal necrosis was observed in 1-2% of the tubers. Symptoms included arcs similar to those caused by Tobacco rattle virus (TRV). This virus is transmitted by a number of species of stubby-root nematodes (Paratrichodorus or Trichodorus spp.). To confirm the presence of TRV, nucleic acid extractions were made from these tubers and were tested for TRV by reverse transcription polymerase chain reaction (RT-PCR) using primers specific to the 16 Kd open reading frame on genomic RNA-1. Samples from both storages were positive. The 463 bp RT-PCR product was sequenced and was 99.6% identical to the corresponding region of two TRV isolates from Florida and Washington. In addition, sap from the FL1879 samples was used to mechanically transmit the virus to tobacco Samsun NN, which produced typical TRV symptoms, and also tested positive with antiserum specific to TRV upon subsequent ELISA testing. Stubby-root nematodes have been previously reported from Michigan. Corky ringspot can result in substantial losses, with entire potato fields being rejected due to internal tuber damage. This disease has been previously found in the United States in California, Colorado, Florida, Idaho, Washington, Oregon and likely in Indiana. This is the first report of corky ringspot and TRV on potato in Michigan.