Spraing is a collective term for diseases and disorders of

potato The potato () is a starchy tuberous vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are underground stem tubers of the plant ''Solanum tuberosum'', a perennial in the nightshade famil ...

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

s that cause brown streaks in the flesh of the potato. Spraing can be caused by two

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almo ...

, tobacco rattle virus (TRV) which is transmitted by trichodorid

nematodes The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (he ...

, or

Potato mop-top virus Potato mop-top virus (PMTV) is a plant pathogenic virus transmitted through the vector ''Powdery scab, Spongospora subterranea'' that affects potatoes. PMTV belongs to family of ''Virgaviridae'', and the genus ''Pomovirus'' (Potato mop-top virus) ...

(PMTV) transmitted by the

powdery scab Powdery scab is a disease of potato tubers. It is caused by the cercozoan ''Spongospora subterranea'' f. sp. ''subterranea'' and is widespread in potato growing countries. Symptoms of powdery scab include small lesions in the early stages of the ...

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

''Spongospora subterranea''. The two viruses may have synergistic effects in disease progression when both are present. Spraing like symptoms can also be caused by physiological defects or specific nutrient deficiencies, most notably Calcium. Control of the disease is generally by ensuring that seed is disease free although the strain transmitted by nematodes can be controlled to some extent by the use of

nematicide A nematicide is a type of chemical pesticide used to kill plant- parasitic nematodes. Nematicides have tended to be broad-spectrum toxicants possessing high volatility or other properties promoting migration through the soil. Aldicarb (Temik), a ...

s. TRV spraing vectored by free living nematodes (trichodorid) most typically occurs on light sandy soils during incidence of heavy rain or over irrigation. These conditions are ideal for the nematodes to swim to the surface in order to feed on the tubers and subsequently cause infection. During non wet periods they return to the depths of the soil profile making soil sample testing for trichodorid often unreliable. Different potato varieties show varying levels of resistance to TRV tuber symptoms. Thus avoiding using susceptible cultivars and careful irrigation management is often enough to avoid problematic symptoms. The resultant internal brown flecks can cause costly factory rejections for commercial growers due to loss of processed quality.

References

Potato diseases Viral plant pathogens and diseases {{Agri-stub