Long-Term survival ofCorynebacterium sepedonicum on contaminated surfaces and in infected potato stems

The survival of the ring rot bacterium,Corynebacterium sepedonicum, on contaminated surfaces and in infected stems was investigated by root inoculating potato stem cuttings with aqueous suspensions prepared from these materials. The pathogen survived for 24 mo on contaminated surfaces of burlap, kraft paper, and polyethylene plastic held at 12% relative humidity (RH) at either 5 or 20°C. It persisted for less than 14 mo on surfaces held at 94% RH at either temperature. Infectious ring rot bacteria were also recovered from dried, infected potato stems held for 26 mo in an unheated machine shed. These results emphasize the importance of strict sanitation and disinfestation procedures in maintaining potato seed stocks free of bacterial ring rot.     

Survival ofCorynebacterium sepedonicum at freezing and at wide fluctuations between freezing and above-freezing temperatures

The survival ofCorynebacterium sepedonicum, the bacterial ring rot pathogen of potatoes, on burlap surfaces held at constant freezing and above-freezing temperatures and under wide fluctuations of these temperatures was investigated by root-inoculating potato stem cuttings with aqueous suspensions prepared from these surfaces. The pathogen survived and remained infectious on burlap for 53 mo at all constant freezing temperatures, and its infectivity did not diminish throughout this period at either ?20 or ?40°C. At 42 months, viable ring rot bacteria were no longer detected at a constant temperature of 5°C. In a second experiment, ring rot bacteria survived and remained infectious on burlap for 23 months at fluctuating temperatures of ?40 to 5°C and ?40 to 25°C, but only survived for 12 months at 25°C. However, results of this study indicate that wide fluctuations between freezing and above-freezing temperatures caused decreased infectivity of the pathogen.     

Persistence ofCorynebacterium sepedonicum in soil and in buried potato stems

The effect of moisture content and temperature on the persistence, in soil, of cells of the ring rot bacterium,Corynebacterium sepedonicum (Spieck. and Kotth.) Skapt. and Burkh., was followed with root-inoculated, rooted potato stem cuttings. Ring rot bacteria were still viable after 284 days in a sterilized Lethbridge silt loam moistened to field capacity and incubated at 15°C. However, the cells did not survive beyond 6 days in two non-sterile silt loams at field capacity and 20°C. In non-sterile Lethbridge silt loam, persistence of the pathogen increased as soil moisture content and temperature decreased. Cells persisted for 10 and 15 days, respectively, in soil at 50% field capacity held at 15 and 10°C. Ring rot bacteria were not recovered after 88 days from a non-sterile Lethbridge silt loam moistened to the wilting point and held at a temperature fluctuating between 10 and 20°C, or from soil at field capacity and at a temperature fluctuating between ?5 and +5°C. They survived for 362 days in soil at the wilting point at mean temperatures of 0 or ?10°C, but were not viable after 278 days in soil at field capacity and a mean temperature of ?10°C. In excised, infected potato stems held in a non-sterile Lethbridge silt loam, the pathogen persisted for 325 days in soil at the wilting point and a mean temperature of 0°C. These results suggest that soil infested with ring rot bacteria should be kept well moistened during warm periods to inactivate these bacteria and to ensure that they do not contaminate healthy tubers that may be stored or grown there later.     

Survival ofCorynebacterium sepedonicum on contaminated surfaces

Cells of ring rot bacteria,Corynebacterium sepedonicum, obtained from ring-rotted potato tubers were used to contaminate various surfaces found in storage areas and on machinery and clothing. The bacteria survived for at least 10 months on most of the surfaces when held in an unheated machine shed, and on burlap when held in a root cellar.     

Effect of the ring rot pathogen and latent potato viruses on ring rot symptoms and yield of potatoes

The ring rot bacterium,Corynebacterium sepedonicum (Spieck. and Kotth.) Skapt. and Burkh., and latent potato viruses (potato virus S and potato virus X) were investigated for their effect on ring rot symptom development on potato plants in the greenhouse and on symptom development and yield of potatoes in the field. Both virus-free (VF) and virus-infected (VI) Red Pontiac stem cuttings root-inoculated with ring rot bacteria in the greenhouse developed typical (T) ring rot symptoms, and symptom severity did not differ between VF and VI plants. In a field study, both VF and VI Russet Burbank seed pieces knife-inoculated with ring rot bacteria produced plants with atypical (A) and T ring rot symptoms as well as a combination of both types. The data suggest that more A than T symptoms develop on VI plants and more T than A symptoms develop on VF plants. Combined infection with the ring rot pathogen and the latent potato viruses resulted in greater yield losses of total and marketable Russet Burbank tubers than infection with the bacterial or viral pathogens alone.     

Teton Russet: An Early-Maturing,Dual-Purpose Potato Cultivar Having Higher Protein and Vitamin C Content,Low Asparagine,and Resistances to Common Scab and Fusarium Dry Rot

Teton Russet is an early-maturing, medium-russeted, potato cultivar with high merit for both fresh-pack and processing. In early harvest trials in the Pacific Northwest, Teton Russet had total yields similar to Russet Norkotah, and higher than Ranger Russet and Russet Burbank. Marketable yield of Teton Russet in the early harvest trials was also comparable to or higher than Russet Norkotah in Washington and Oregon, and higher than Ranger Russet and Russet Burbank at these sites, as well as in Idaho. In full-season trials, while total yield of the earlier-maturing Teton Russet tended to be lower than Ranger Russet and Russet Burbank, marketable yield was generally higher than Russet Burbank across the majority of sites due to its higher percentage of U.S. No. 1 tubers. Teton Russet is suitable for processing, with acceptable fry color following up to 8 months of storage at 8.9 °C. Uniformity of fry color was also very consistent. Teton Russet has shown lower levels of the amino acid asparagine relative to Ranger Russet and Russet Burbank which may contribute to lower acrylamide levels in French fries and other processed potato products. Teton Russet is notable for having resistance to common scab (Streptomyces spp.) and Fusarium dry rot, and is moderately resistant to tuber net necrosis. Analyses have also shown Teton Russet to have significantly higher protein levels than Russet Norkotah, Ranger Russet, and Russet Burbank, as well as higher vitamin C content than Russet Norkotah and Russet Burbank. Teton Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.     

Pomerelle Russet: an Early Maturing Potato Variety with High Yields of U.S. No. 1 Tubers Suitable for Fresh Market and mid-Storage Processing and Tolerance to Potato Mop-top Virus

Pomerelle Russet is an early maturing fresh potato variety, which produces moderately high early-season (95–110 days after planting) yields of long tubers with brown-russet skin. It is notable for its very attractive, smooth tubers and resistances to internal and external defects with a high percentage of U.S. No. 1 tubers. Fresh merit ratings for Pomerelle Russet in trials conducted in Idaho, Oregon and Washington were consistently higher than Russet Burbank and Russet Norkotah. Early harvest yields for Pomerelle Russet are generally comparable to Russet Norkotah with a higher percentage of U.S. No. 1 tubers. Compared to Russet Burbank and Russet Norkotah, Pomerelle Russet has greater resistance to Potato mop-top virus, soft rot, corky ringspot and tuber infections from late blight. It also has higher protein and vitamin C concentrations than Ranger Russet, Russet Burbank and Russet Norkotah, indicating that it can provide an enhanced level of dietary protein and vitamin C relative to these standard potato varieties. Pomerelle Russet has moderate specific gravity and good resistance to sugar ends. It also has moderately long dormancy, about 30 days shorter than Russet Burbank. Average post-harvest processing ratings for Pomerelle Russet were similar to Ranger Russet and greater than Russet Burbank. Pomerelle Russet also has maintained acceptable fry color for about 180–200 days in storage at 8.9 °C, indicating potential for processing out of mid-term storage, with improved fry color uniformity relative to industry standards. However, its primary use appears to be as a high quality, early fresh variety.     

Effect of temperature and latent viruses on atypical ring rot symptoms of Russet Burbank potatoes

The ring rot bacterium,Corynebacterium sepedonicum (Spieck. and Kotth.) Skapt. and Burkh. [Clavibacter michiganense subsp.sepedonicum (Spieck et Kotth.) Davis et al.], and latent potato viruses (potato virus S and potato virus X) were investigated for their effect on atypical (ATYP) ring rot symptom development on Russet Burbank potato plants at different temperatures. Plants grown at 21 C from stem cuttings root-inoculated withC. sepedonicum developed typical wilting and chlorotic symptoms of ring rot that were equally severe on virus-free (VF) and virus-infected (VI) plants. All VF and VI plants grown at 15 C from inoculated stem cuttings exhibited ATYP symptoms that included extreme stunting, resetting, and chlorotic symptoms of ring rot. More severe ATYP symptoms developed on VI than on VF plants. Up to 5 wk after inoculation withC. sepedonicum, ATYP symptom severity ratings of both VF and VI plants increased and declined thereafter. The ATYP severity ratings were highly correlated with fresh weight of plants with high severity ratings being associated with low fresh weights. These results emphasize the need to determine the role of temperature and viral pathogens on ring rot symptomology in existing and newly developed potato cultivars and thereby enable better field detection of bacterial ring rot.     

Payette Russet: a Dual-Purpose Potato Cultivar with Cold-Sweetening Resistance,Low Acrylamide Formation,and Resistance to Late Blight and Potato Virus Y

Payette Russet is a full season, russet-skinned potato cultivar notable for its cold-sweetening resistance and associated low acrylamide formation, making it ideally suited for processing into French fries and other potato products. Low asparagine and reducing sugar concentrations in Payette Russet tubers contribute to an 81 % reduction in acrylamide content in French fries relative to cultivars Ranger Russet and Russet Burbank following eight months storage at 9 °C. In three years of evaluations in the Western Regional Potato Variety Trials, average yield of Payette Russet was intermediate between Ranger Russet and Russet Burbank, but Payette Russet had the highest U.S. No. 1 yield when averaged across all eight trial locations. Acceptably low tuber glucose concentrations (<0.10 % glucose FWB) were maintained in Payette Russet following up to nine months storage at temperatures as low as 5.6 °C with consistently acceptable French fry color scores obtained (USDA value ≤2.0). Reducing sugars are also maintained uniformly throughout Payette Russet tubers, resulting in a low incidence of sugar ends and reduced mottling in French fries relative to standard processing cultivars. Long tuber dormancy also benefits long-term storage for processing. With its russet skin, Payette Russet could also be used for fresh-pack, and its assemblage of disease resistances makes it especially suitable for organic production, or for use by growers and companies seeking greater sustainability in their production. Payette Russet is resistant to foliar and tuber late blight, common scab, and has extreme resistance to PVY conferred by the presence of the Rysto resistance gene. Payette Russet also has a moderate level of resistance to Verticillium wilt, early blight, and corky ringspot. It is susceptible to Fusarium dry rot (F. sambucinum), therefore production and storage management guidelines are provided to minimize tuber infection. Payette Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center. Blackspot bruise expression for Payette Russet is similar to Russet Burbank and reduced relative to Ranger Russet. Payette Russet was more susceptible to shatter bruise, internal brown spot, and tuber weight loss in storage relative to the industry standard cultivars. Payette Russet was released in 2015 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest (Tri-State) Potato Variety Development Program.     

Freeing Russet Burbank potato plants from ring rot by stem cutting and tuber propagation

Apical stem cuttings removed from potato plants (cv. Russet Burbank) infected withCorynebacterium sepedonicum and expressing mild symptoms of bacterial ring rot were demonstrated to be free from the pathogen. This material remained free of ring rot through two additional stem cutting generations and when grown in the field for four successive tuber generations.     

Susceptibility of potatoes to bacterial rot and weight loss as a function of wound-healing interval and temperature

A study was conducted to determine the feasibility and advantages of wound-healing potatoes at lower than recommended temperatures. The progress of wound-healing at 6, 9, and 16°C, of tissue taken from Russet Burbank potato tubers, was evaluated by inducing weight loss with high temperature or decay organisms following various curing intervals. Increasing the wound-healing temperature resulted in a greater resistance to weight loss and a decreased susceptibility to infection byErwinia carotovora subsp.carotovora. Resistance to weight loss increased as wound-healing temperature increased following 6 and 16 day intervals. However, weight loss induced after 21 days of healing appeared to level off at 9°C indicating maximum development of a wound barrier. Loss due to rot, after inoculation of fresh cores withE. carotovora, was directly proportional to incubation time and temperature. When wound-healing progress was measured by loss of fresh weight induced by elevated temperatures or rot, the advantages of woundhealing at 16°C compared with 9°C decreased significantly after 21 days of curing. Wound-healing at approximately 9°C for 25 days was found to be the best compromise temperature for keeping rot progress and weight loss at a minimum while allowing the process of healing and maturation to occur.     

The transmission of Potato Virus S by the cutting knife and retention time of infectious PVS on common surfaces

The transmission of PVS by the cutting knife in potato cvs Norland, Kennebec and Russet Burbank was studied in the field and greenhouse. Field studies showed transmission to Norland via tuber infection was significantly less than for Kennebec and Russet Burbank (P = 0.01). However, significant cultivar differences were not found in the greenhouse (P = 0.05). Contamination of the cutting knife by cutting through sprouts resulted in significantly greater numbers of plants infected for cv Kennebec than when sprout contact was avoided (P = 0.05). Although the same trends were observed for cv Norland and Russet Burbank the differences were not significant (P = 0.05). Infectious PVS particles were readily recovered from materials commonly contacted during potato cultivation, storage and processing. Retention time of infectious PVS was usually greater when materials were held at 4°C and 100% relative humidity than at ambient greenhouse conditions. Retention times ranged from 0 hr (PVS not recovered) to 180 hr on unpainted wood. Results demonstrated the need for strict indexing and sanitation procedures during the production of PVS-free potato seed.     

Summit Russet: A new russet potato variety with good fresh market and frozen processing qualities

Summit Russet (A84118-3), the result of the cross A77236-6 x TND329-1Russ, was released in 2003 by the USDA/ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington. The vines of Summit Russet are erect, with very thick stems, large yellowish-green leaves and abundant white flowers. The tubers are tan, with medium russet skin, long-flattened shape, a slightly prominent eyebrow, white flesh, and moderately prominent pith. Tuber dormancy is very long. Summit Russet was compared with Russet Burbank in trials across the Pacific Northwest for yield, quality, and disease response. In general, Summit Russet produced similar or lower total yields than did Russet Burbank, but higher U.S. No. 1 yields. In Idaho variety trials, Summit Russet exhibited resistance to second growth, growth cracks, blackspot bruise, and stem-end discoloration, and moderate susceptibility to hollow heart and shatter bruise. In comprehensive product quality evaluations, Summit Russet was rated superior to Russet Burbank for french fry quality and similar for baked potato quality. French fry quality was retained after long-term storage. In replicated disease trials, Summit Russet was found to have good resistance to common scab, early blight tuber rot, and Verticillium wilt, and moderate resistance to Fusarium dry rot and tuber net necrosis caused by PLRV. It demonstrated susceptibility to late blight, foliar PLRV, PVX, PVY^o, and bacterial soft rot. Biochemical analysis of Summit Russet tubers showed them to be higher in total solids and sucrose, and lower in dextrose than those of Russet Burbank. Tuber glycoalkaloid concentration as measured from tubers produced in 1994–1996 trials was 6.7 mg 100 g¹.     

The use of constant and alternating temperature regimes and tissue culture to obtain PVS—Free potato plants

Growth of 6 potato virus S (PVS)-infected potato clones in tissue culture in temperature regimes alternating between supraoptimal (40°C–45°C) and optimal (25°C) temperatures was compared to incubation of etiolated shoots at constant moderate temperatures (37°C) to obtain virus-free plants by shoot tip culture. Both procedures were effective in obtaining PVS-free propagative material. Virus-free plants were obtained in 5 of 6 clones by the alternating temperatures procedure and in 4 of the 6 clones by the constant 37°C incubation prior to shoot tip isolation. Heat tolerance, virus inactivation, and development of pathogen-free buds from the heat-treated plants depended upon the potato cultivar and the type of culture media in which the tips grew, but these characteristics did not coincide in any clone. The variety Chieftain was the least tolerant to the high temperatures and no virus-free individuals were recovered. White Rose was the most heat resistant, but Russet Burbank resulted with the highest percentage of PVS-free plants. The virus was eliminated from the variety Kennebec only by the alternating temperature treatments. Exposing potato plantlets in the alternating temperature regimes prior to isolation and regeneration of shoot tips was slightly better than the traditional method of incubation of plants at constant moderate temperatures that the plant will withstand and offers a new option in freeing plants of more tenacious viruses.     

Western russet: A new potato variety with excellent fresh market and frozen-fried processing quality and field resistance to common scab and PVYo

Western Russet, designated experimentally as A7961-1, and resulting from the cross A68113-4 x Bel-Rus, was released in 2004 by the USDA/ARS and the agricultural experiment stations of Idaho, Oregon, and Washington. The foliage of Western Russet is spreading, with medium-sized olive-green leaves and abundant white flowers. The tubers are tan, with medium russet skin, oblong shape, a slightly prominent eyebrow, white flesh, and distinctly visible pith. Western Russet was compared with Russet Burbank in trials across the Pacific Northwest for yield, quality, and disease response. In general, Western Russet produced lower total yields than Russet Burbank, but on average and depending on location, similar U.S. No. 1 yields. When observed for defect problems, Western Russet exhibited resistance to second growth, growth cracks, shatter bruise, stem-end discoloration, and heat necrosis, moderate resistance to hollow heart, and moderate susceptibility to blackspot bruise. In product quality tests, Western Russet was rated similar to Russet Burbank for french fry and dehydrated potato flake quality and slightly inferior for baked potato quality. In replicated evaluations, Western Russet was found to have good field resistance to common scab and PVY^o, and moderate resistance to verticillium wilt and tuber net necrosis caused by PLRV. It demonstrated susceptibility to late blight, foliar PLRV, dry rot, soft rot, and tuber early blight. Biochemical analysis of Western Russet tubers showed markedly higher vitamin C content than those of Russet Burbank. Tuber glycoalkaloid concentration in tubers produced in a 1988 trial was 1.0 mg 100 g^?1.     

The incidence of decay and factors affecting bacterial soft rot of potatoes

The incidence of tuber decay in rail car shipments of potatoes from the State of Washington was determined from 1965 to 1969 inclusive. Reinspection certificates revealed that 7.9% of the rail cars of potatoes shipped during this period were rejected due to tuber defects; tuber decay accounted for 63% of these rejected cars. Percentage of rejections due to tuber decay was greater for Russet Burbank than for Norgold Russet potatoes. Temperature, moisture, and oxygen levels influenced development of bacterial soft rot in freshly harvested potatoes and in potatoes stored for 3 months at 35 F (2 C) previous to treatment. When tuber surfaces were kept dry, no soft rot developed in 11 days over ranges of 50–70 F (10–21 C) and 2–20.5% oxygen levels. Freshly harvested tubers partially immersed in water did not rot when cooled to 40 F (4.4 C) in < 24 hours and held for 8 days under either 20.5 or 4% oxygen levels; however, tubers, rotted when stored similarly but at 50 F or higher temperatures. Partially immersed tubers incubated for 1 day or longer at 70 F developed soft rot in a low oxygen (4%) when later stored for, 8 days at 40 F. When rot occurred, the amount was always greater under lower oxygen levels irrespective of storage temperature. Of various cooling methods tested in rail cars loaded with 100 lb (45.4 kg) sacks of potatoes, prechilling of tubers and icing of cars prior to loading lowered floor temperatures most rapidly. Icing cars after loading lowered floor temperatures the slowest. In a carton shipment, the temperature remained above 68 F (20 C) in cartons after 8 days in transit, even though the wall and floor temperatures had cooled to near 55 F (12.8 C) by the second day. Oxygen level surrounding, tubers in the center of car loads of 100 lb sacks of potatoes was approximately 20.5% after 8 days transit.     

Millennium Russet: A dual purpose russet potato variety

Millennium Russet is a medium-late variety with long tubers having light russet skin and white flesh. It has potential as a fresh market and processing (french fries) variety. The tuber type of Millennium Russet is similar to Russet Burbank, but with better external and internal quality. The marketable yield, tuber set, and specific gravity are higher than Russet Burbank. Tubers show good fry color when processed from cold storage (7.2 C). Millennium Russet has a bland flavor and is less mealy and discolored than Russet Burbank. Chemical maturity of Millennium Russet occurs at approximately the same time as Russet Burbank, but it has lower sucrose levels in the bud and stem end. The glucose levels of Millennium Russet were 50% less than Russet Burbank throughout the first 4 months of storage at 10 C. Low glucose levels in the stem end of Millennium Russet when processed out of storage suggest tolerance to stress and low vulnerability to sugar end. Millennium Russet is resistant to common scab and corky ring spot, moderately resistant to dry rot, pink rot, and black scurf, and moderately susceptible to Verticillium wilt, bacterial wilt and brown rot. Millennium Russet is more sensitive to blackspot bruise than Russet Burbank, but more resistant to shatter bruise. Tuber yield of Millennium Russet was less responsive to nitrogen rates when compared with Russet Burbank, but tuber size distribution was more responsive to increases in in-row spacing.     

Ring rot symptom development on potato cultivars and lines in southern Alberta

Summary Plants were grown in the field from seed pieces of potato cultivars injected with ring rot bacteria (Corynebacterium sepedonicum). Symptoms were produced with both 18 and 180 colony forming units (cfu) on cvs Norchip and Red Pontiac and with 180 cfu on cv. Belrus plants. Tuber symptoms were detected in all cultivars except Belrus and Teton. Tuber progeny produced plants that developed top symptoms on all cultivars except those of cv. Nooksack, Russet Burbank, and Teton. Tuber progeny of the second crop produced both plants and tubers with symptoms developing only in the cv. Nooksack. In another 3-year experiment, variability in the disease response of selected cultivars and lines was examined following knife-inoculation of tuber seed with a high level of ring rot bacteria. Significant correlations between top and tuber symptoms were detected, but they were not high enough to make unnecessary the examination of both top and tuber symptoms in ring rot disease selection studies. Contribution no. 3879111     

GemStar russet: A potato variety with high yield, good culinary quality, excellent fresh market appearance, and resistance to common scab

GemStar Russet, derived from the cross Gem Russet x A8341-5, was released in 2004 by the USDA/ARS and the agricultural experiment stations of Idaho, Oregon, and Washington. The foliage of GemStar Russet is dark yellowish-green, spreading, with large leaves and abundant white flowers. The tubers are brown, medium to heavily russeted, oblong, with a slightly prominent eyebrow, white flesh, and indistinct pith. GemStar Russet was compared with Russet Burbank and Russet Norkotah in trials across the Pacific Northwest for yield, quality, and disease response. Except for locations in southern Idaho, in general, GemStar Russet produced slightly lower total yield than Russet Burbank, but much higher U.S. No. 1 yield. When compared with Russet Norkotah, GemStar Russet produced similar total and U.S. No. 1 yields in early harvest trials but higher total and U.S. No. 1 yields in late-harvest trials. When observed for defect problems, GemStar Russet exhibited resistance to second growth, growth cracks, and stemend discoloration, moderate resistance to blackspot and shatter bruising, but a high level of susceptibility to hollow heart. In product quality tests, GemStar Russet was rated superior to Russet Burbank for french fry quality and comparable for baked potato quality. GemStar Russet was found to be immune to PVX, resistant to common scab and powdery scab, moderately resistant to Verticillium wilt, tuber net necrosis caused by PLRV, and corky ringspot. It demonstrated susceptibility to late blight, PLRV, dry rot, soft rot, and ringrot and extreme susceptibility to PVY^o. Biochemical analysis of GemStar Russet tubers showed them to be higher in protein and much higher in vitamin C than those of Russet Burbank or Russet Norkotah. Three-year average for tuber glycoalkaloid concentration was 1.5 mg 100 g^?1.     

Efficacy of disinfestants against potato ring rot and blackleg bacteria

Some disinfestants are claimed to be more effective than others in controlling ring rot (Corynebacterium sepedonicum) and blackleg (Erwinia carotovora varatroseptica) bacteria on contaminated surfaces. Of the readily available disinfestants tested mercuric chloride (0.1%) and formaldehyde (2% and 5%) were the most effective against blackleg bacteria, and bleach (10%) mercuric chloride (0.1%) and formaldehyde (5%) were the most effective against ring rot bacteria on metal, wooden and burlap surfaces.