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Tobacco Rattle Virus (TRV) and Stubby Root Nematodes – Symptoms and Diagnosis

Symptoms of TRV:

Infected plants do not always show symptoms and symptom development depends on potato cultivar, virus strain and the environment.

TRV infected tubers can develop necrotic rings, arcs and flecks internally and on the surface. Symptoms are typically more obvious in the tuber flesh than on the surface. Flesh beneath necrotic spots may become corky which is the source of the common name for this disease, corky ringspot. As the disease advances, tubers may exhibit shallow corky depression, deep cracks, roughened skin as well as malformed shapes. Tuber symptoms may increase during storage. Although yield is not impacted by the disease, symptomatic tubers are unmarketable and crop losses can range from 6-55%. Leaf symptoms on potato are not common, but early in the season you may see mottled or misshapen leaves with yellow chevrons or rings. TRV rarely causes foliar symptoms on potato.

Click on the photos below to enlarge.

TRV tuber symptoms: Clockwise from top left, Clearwater Russet, Premier Russet, Ranger Russet and unknown cultivar. Photos courtesy of Neil Gudmestad, NDSU and Ken Frost, OSU

TRV tuber symptoms. Photos courtesy of Chuck Brown, USDA-ARS

Symptoms of Stubby Root Nematodes:

The feeding behavior of stubby root nematodes can cause stunting of root growth, hence the name “stubby root”. This stunting can limit the ability of the plant to uptake water and nutrients from the soil and can lead to reduction in yield. However, the primary impact posed by stubby root nematodes on potato is the transmission of TRV.

Diagnosis of TRV and Stubby Root Nematodes with lab tests:

Visual diagnosis of TRV is difficult because of the lack of foliar symptoms and the similarity of the tuber symptoms to that of PMTV and PVY. A diagnosis can be confirmed with lab tests including ELISA (enzyme linked immunosorbent assay) and PCR (polymerase chain reaction). Information on TRV diagnostic tests of foliar or tuber tissue can be found here Diagnostic Lab Testing.

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