tobacco rattle virus in potatoes

Tobacco rattle virus (TRV) causes potato's economically important corky ring spot (CRS) disease. Soil-dwelling nematodes of the genus Trichodorus and Paratrichodorus transmit the tobacco virus.

Corky ring spot is becoming economically important in several potato-producing areas in the United States primarily because of the spread of the virus and because of restrictions on the use of current chemical control options. 'old.

Infections of the tobacco virus have been reported in potato production areas in California, Colorado, Florida, Idaho, Michigan, Minnesota, North Dakota, Oregon, Washington and Wisconsin. This virus has many different species, including potatoes, tobacco, corn, barley, sunflower, ornamentals (tulip, iris, etc.) and various weeds. Soil-dwelling root-knot nematodes of the Trichodorus and Paratrichodorus groups transmit the virus.

Nematicides, soil fumigation and resistant species can be used for nematode management. Detecting and quantifying viruliferous nematodes is important for making planting and management decisions.

Symptoms

Internal symptoms caused by TRV are often confused with symptoms of tuber necrosis caused by the potato tuber virus (see NDSU Extension publication "Potato Tuber Viruses: Mop-top Management," A1777). Tuber necrosis symptoms caused by TRV appear as rusts/brown arcs, central rings or deep browning of tuber cells that later dry up into cork-like tissue (Figure 1 ). Rings or arcs can also appear outside the skin of the tuber (Figure 2) and are very similar to the symptoms caused by potato virus Y (PVYntn).

 Figure 1. Characterization of TRV symptoms in potato.

Figure 2. The appearance of external arc-like marks on tuber skin. These symptoms are similar to symptoms produced by PVYntn strains.

Important tip: Signs of necrosis in some skins increase with the time the potatoes are stored. Signal strength varies from species to species (Figure 3), field to field, region to region and year to year. Laboratory testing is the best way to identify a particular virus.

 Figure 3. Different types of necrosis are caused by TRV in potato varieties. From top to bottom: some varieties of red Russet market varieties.

Disease Development

Stubby root nematodes are obligate parasites, meaning they must feed on host plants to survive. The life span of root nematodes is short and ranges from 16 to 20 days.

Females lay eggs, and the young go through four moults to adulthood. All stages (small and large) of nematodes feed on and destroy plant root cells by feeding on the cells left outside the plant. The nematode's adult and juvenile stages can transmit TRV when feeding on a plant root or tuber.

The tobacco virus is acquired by nematodes while feeding on diseased potato plants or weed areas. In the field, CRS spreads when infected nematodes move from diseased to healthy plants. The virus is lost during the moulting of the young nematode, and the nematodes reacquire the virus when they feed on the roots of infected plants.

Stubby root nematodes prefer sandy, moist, cool soils and are very tolerant of soil moisture and temperature. The tobacco virus is introduced into new areas by moving infected soil and planting infected seeds.

Testing for the presence of vector nematodes before planting is important to help farmers make planting decisions. Soil samples can be collected year-round if the soil is not too dry, wet or frozen.

Collect samples from a depth of 12 to 18 inches of soil and send them for nematode detection. Based on soil results, growers can consider implementing nematode control strategies.

Tobacco Control management

Here are some strategies to reduce the risk of contracting the virus from tobacco:

• Discard fields with high TRV. This is one of the best control options.
• Avoid planting varieties that are not sensitive to TRV (see Table 1). Use virus-free seeds. It is the most effective strategy for controlling TRV. Planting clean seeds is important because TRV can survive in infected tubers and spread from one season to the next.
• Practice crop rotation using TRV non-edible alfalfa Control weeds to reduce root nematode populations. Common weeds such as chickweed, nightshade and purslane can act as TRV hosts, and proper weed management greatly reduces CRS mortality.

The movement of the nematode root (horizontal and vertical direction) in the soil makes the nematode system difficult. No chemical completely controls the vector. Using products based on 1,3 dichloro propene (Telone™) provides partial control of vector nematodes. Oxamyl-based products used during planting and after planting also provide some control of nematode pests.

Planting nematode- and blight-resistant potato varieties is a primary method of disease control. A recent study conducted in North Dakota evaluated 63 common potato cultivars for susceptibility to tuber necrosis caused by TRV (Table 1).

Table 1. The level of sensitivity of potato varieties to infection caused by the tobacco virus is based on the 2015 and 2016 tests conducted in North Dakota.

Infrequent types (Incidence less than 5 per cent)

Superior, Centennial Russet, Rio Colorado, Castle Russet, Bintje, Lelah, Russian Banana, Ciklamen, Oneida Gold, Gala

Non-Resistant Species (Incidence greater than 5 to 10 per cent)

Alturas, Austrian Crescent, Mega Chip, Goldrush

Well-Resistant Species (Incidence greater than 10 to 15 per cent)

Teton Russet, Dakota Ruby, Modoc, Red Gold, Chipeta, Dakota Crisp, Pike

Susceptible Type (Incidence greater than 15 per cent)

French Fingerling, Lamoka, Russet Norkotah CO8, Premier Russet, Red Endeavor, Dakota Russet, Russet Burbank, Chieftain, Freedom Russet, Yukon Gold, Ranger Russet, Viking, Snowbird, Sage Russet, Russet Norkotah, Kennebec, Dark Red Norland, Marcy, Alpine Russet, Clearwater Russet, Dakota Trailblazer, Bannock Russet, Russet Norkotah 278, Red Norland, Russet Norkotah, 296, Russet Norkotah CO3, Silverton Russet, Snowden, Waneta, Huckleberry Gold, Red LaSoda, Dakota Pearl, Gemstars Russet, Nicolet, Dakota Jewel, Umatilla Russet, Colorado Rose, Classic Russet, Red Thumb, Pinnacle