The incidence of potato viruses X,Y and S in the Chilota potato collection

The 530 potato clones of the Chilota collection of the germplasm bank from the Universidad Austral de Chile were tested for potato viruses X (PVX), Y (PVY) and S (PVS) by means of NCM-ELISA (nitrocellulose membrane enzyme-linked immunosorbent assay). Four clones (0.8%) healthy for all 3 viruses simultaneously were detected. These clones could be resistant to the above mentioned viruses.     

The effect of separate infections by potato viruses X and S on Netted Gem potato

Numbers and specific gravity of Netted Gem potato tubers were unaffected by mottle and latent strains of potato virus X (PVX) and by potato virus S (PVS). Neither latent PVX nor PVS affected yield but mottle PVX alone and latent PVX combined with PVS reduced tuber size and yield (P = 0.05).     

Effects of systemic insecticides on potato growth and their interaction with metribuzin

Effects of the soil systemic insecticides aldicarb, phorate, and disulfoton on potato growth were measured from 1984–1986 on the cultivars Russet Burbank and Centennial. In all seasons, aldicarb was observed to cause a significant promotion of flowering and in one season also caused increased haulm growth. Phorate caused a reduction in these growth parameters in one season. Temporary effects on early season yields were observed from the aldicarb treatment in one year but final yields were never significantly affected by insecticide use alone. During 1985–1986 additional treatments were investigated involving insecticide combinations with the herbicide metribuzin to determine possible insecticide-herbicide interactions. Phorate-metribuzin combinations caused synergistic metribuzin injury symptoms, decreased haulm growth and yield in 1986. Metribuzin also decreased yields of aldicarb treated potatoes in 1986 and disulfoton treated potatoes in 1985. Disulfoton-metribuzin combinations decreased flowering in 1985. These data suggest that soil systemic insecticides can have direct effects on potato growth, independent of effects on pest suppression, and that they may interact with other crop protection chemicals.     

The effect of potato virus X on the yield of the potato variety Hudson

The effect of a mild strain of PVX on the yield of the recently released potato variety Hudson was determined in split-plot experiments at three locations in New York. Two other varieties, Katahdin and Bake-King, were included for comparison. The yield data compared were total tuber yield, tuber yield > 2 1/4 in. and > 1 7/8 in. diameter and tuber number> 2 1/4 in. and > l 7/8 in. diameter. The effect of the mild strain was not great. Hudson appeared to be more tolerant to the mild strain of PVX than the other two varieties although the variety X virus interaction was very low.     

Treatments that improve serological detection of potato viruses X,S, M and Y

Summary It was found that addition of an equal volume of 0.2% sodium sulphite or a mixture of sodium sulphite and sodium azide (both 0.2%) to expressed leaf sap improved serological detection of viruses and prevented non-specific reactions. Incubations of the preparations at 20–24°C gave better serological detectability than incubating at 10–12°C. If the sap was centrifuged, better results were subsequently obtained if centrifuging had been done at 4200 or 5900 g than at lower values.     

Detection of potato leaf roll virus and potato viruses M,S, X and Y by dot immunobinding on plain paper

Summary Potato leafroll virus and potato viruses M, S, X and Y in green leaves were detected by dot immunobinding (DIB) on plain paper and on nitrocellulose membranes. On both materials, DIB could detect the presence of very small amounts of virus, e.g. 30 pg of purified PVX. The sensitivity of the DIB test on plain paper and on nitrocellulose was compared to Double Antibody Sandwich ELISA (DAS-ELISA) by serial dilutions of infected plant sap made in healthy plant sap. Detection of potato viruses by DIB on plain paper and nitrocellulose was found to be equally sensitive whereas DAS-ELISA was 2 to 8 times more sensitive. Possible simplifications of the DIB procedure to suit the requirements of a routine method were examined. The use of the DIB method for routine testing of potato viruses is discussed.     

Zone-subsoiling effects on potato yield and grade

Soil compaction and erosion are problems in many Pacific Northwestern potato fields. We wanted to determine if zone-subsoiling would reduce these problems and improve potato yields and or grade without adversely impacting other production practices. Studies were conducted in Southern Idaho at six locations over two years on different soils and with different irrigation methods to assess the effects of zone-subsoiling immediately after planting on tuber yield and grade. Reservoir-tillage comparisons were made at three locations where sprinkler water application rates were higher than soil infiltration rates. Russet Burbank was represented by eight location-years and Russet Norkotah by two. Zone-subsoiling consistently improved tuber grade or increased tuber size. The biggest improvement was under furrow irrigation. Zone-subsoiling also tended to increase total yield in eight of ten location-years. Reservoir-tillage improved yield and grade, but zone-subsoiling did not without reservoir-tillage when water application rates were high. At no location did zone-subsoiling significantly decrease tuber grade or yield. Zone-subsoiling had no appreciable effects on hill configuration or seed-piece dislocation. Surface cracking and “water piping” occurred under furrow irrigation but were not significant problems. Results were similar for both cultivars. Additional studies will be needed to successfully incorporate zone-subsoiling into commercial production practices     

The elimination of potato viruses X,Y, S and M in meristem and explant cultures of potato in the presence of Virazole

Summary Incorporation of Virazole into potato explant and meristem culture media results in a higher percentage of virus-free progeny plants from virus-infected explant and meristem donor plants than are produced in tissue cultures in the absence of Virazole. Viruses eliminated, singly and as complexes, include potato viruses X, Y, S and M. The need for sensitive virus tests to distinguish between virus suppression and elimination is discussed and protein-A-linked immunoelectron microscopy is described and quantified for potato virus X.

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Zusammenfassung In der vorliegenden und einer früheren Arbeit (Cassells & Long, 1980) zeigte Kultivierung von Explantaten auf einem Medium für Gewebekultur mit Virazole (Ribavirin) einen signifikanten Anstieg virusfreier Adventivschosse gegenüber der Kontrolle. Diese Adventivschosse wie auch Kartoffelpflanzen zweiter Generation verhielten sich auch gegenüber den empfindlichsten immunoelektronen-mikroskopischen Tests virusfrei. In Gegenwart von Virazol ergab auch Meristemkultur einen h?heren Anteil virusfreier Pflanzen als bei Fehlen dieser Verbindung. Die Kartoffelviren X, Y, M und S sowie Viruskomplexe konnten aus den Sorten May Queen, King Edward, Kerr's Pink und Golden Wonder eliminiert werden (Tabellen 2 und 3). Die Ergebnisse der Anwendung und der Quantifizierung der Protein A-gebundenen Immuno-Elektronenmikroskopie (PALIEM) werden ebenfalls dargestellt (Abb. 1).

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Résumé Cette étude a montré, comme d'autres travaux préliminaires (Cassels & Long, 1980), que le fait de cultiver des boutures sur un milieu de culture de tissus contenant du virazole (ribavirine) permettait d'augmenter de fa?on significative le nombre de tiges aventices indemmes de virus par rapport au témoin. Ces tiges adventices, dans le cas de plants de deuxième génération, sont apparues indemmes de virus par l'analyse des tests les plus sensibles de microscopie immuno-électronique. En présence du virazole, la culture de méristèmes montre également un taux plus élevé de plants indemmes de virus que sans l'application de virazole. Les virus concernés sont les virus X, Y, M, S ainsi, que les complexes viraux, provenant des variétés May Queen, King Edward, Kerr's Pink et Golden Wonder (tableau 2 et 3). Sont également indiqués les résultats qualificatifs et quantitatifs de la microcopie immunoélectronique avec utilisation de la protéine A (PALIEM) (figure 1).

     

Maintenance,symptoms and distribution of potato viruses X,S, Y,A, M and leafroll in potato tissue culture plantlets

Maintaining potato viruses X, S, Y, A, M and leafroll in tissue culture plantlets is a convenient, cost and space effective alternative to the use of greenhouse plants. Of these six viruses, only certain strains of PVX induced symptoms in tissue culture plantlets. Nevertheless, all infected tissue culture plants were found to be more reliable than greenhouse grown plants as virus-infected controls in enzyme-linked immunosorbent assay (ELISA) testing. Another advantage of maintaining viruses in tissue culture plantlets was the elimination of contamination by other viruses or other pathogens. Leaves, stems, and roots of virus infected plantlets were tested separately for antigen levels by ELISA. In these tests, the stems and leaves of all but PVA infected tissue culture plants consistently gave positive ELISA values. In contrast, root tissue from PVY infected tissue culture plantlets was not reliable for PVY detection. In all cases, the viruses detected in the original source material were detected in the resulting tissue culture plantlets.     

An enhanced multiplication of potato virus X is not related to a synergistic reaction between the potato viruses X and Y

Summary Greenhouse experiments demonstrated a differential interaction between potato viruses X and Y in two potato cultivars. Enhancement of PVX synthesis in doubly infected plants occurred only in the PVY-susceptible potato cv. Ulla, whereas PVX multiplication was almost completely inhibited in the doubly infected PVY-resistant cv. Franzi. However, a synergistic effect was also evident in the latter cultivar in the form of a growth inhibition of the plants. An increased multiplication of one or both of the viruses is, therefore, not related to a synergistic reaction.     

Combined effects of potato viruses X and S on yield of Netted Gem and White rose potatoes

Eradicating potato viruses X and S from Netted Gem (Russet Burbank) and White Rose potatoes increased their yielding potential by 11 to 38% in British Columbia, Oregon and California but there was no yield increase in Washington. The virus-free plants produced 10 to 32% more tubers than infected ones.     

Simultaneous detection of potato viruses Y,leafroll, X and S by DAS-ELISA technique with artificial polyvalent antibodies (APAs)

Summary A modification of the double antibody sandwich-enzyme linked immunosorbent assay (DASELISA) was used to try to detect simultaneously PVY, PLRV, PVX and PVS in both leaf and sprout samples, using artificial polyvalent antibodies (APAs). Each virus, singly or in a mixture, was detected with similar sensitivity using either specific antibodies or APAs. The APA for all four viruses is suitable for routine leaf testing, but only the APA for PVY+PVX+PVS is suitable for routine sprout testing.     

The effect of water stress on potato growth,development, and yield

The effect of water stress on plant morphology, production rate and marketable yield is discussed based on the literature. Compared to other species the potato is a drought sensitive plant. The reduction of yield as a result of water stress can be caused by reduced leaf area and/or reduced photosynthesis per unit of leaf area. Water shortage during the tuber bulking period decreases yield to a larger extent than drought during other growth stages. The relationship between the stress parameters relative water content (RWC), leaf water potential (LWP) and stomatal diffusion resistance on the one hand and photosynthesis on the other is discussed. Further it is shown how the amount of water needed by the potato crop depends on climate, soil and plant characters. Finally the effect of water stress on marketable yield and varietal differences to shortage of moisture are discussed.     

Evaluation of the enzyme-amplified ELISA for the detection of potato viruses A,M, S,X, Y,and leafroll

Various parameters,e.g. types of microtiter plate for DAS-ELISA (double antibody sandwich-enzyme-linked immunosorbent assay), use of fresh or frozen amplifier solutions for enzyme-amplified-ELISA, and use of sodium diethyldithiocarbamate (NaDIECA) in sample buffer in cocktail-ELISA were evaluated for the detection of potato viruses A, M, S, X, Y and leafroll from potato foliage. Dynatech Immulon immunoplates provided higher readings for all viruses. Fresh amplifier solution in amplifed-ELISA was superior to frozen solutions. Amplified ELISA gave only marginal improvement in the sensitivity over the standard DAS-ELISA. Addition of NaDIECA in sample buffer did not improve the detection of viruses in DAS-, amplified-, or cocktail-ELISA. Cocktail-ELISA can reduce antigen incubation time to as short as 15 min for PVA, PVM and PVX; 1 hr for PVY and PLRV; and 2–4 hr for PVS using pre-coated plates. Although amplified-ELISA is slightly more sensitive than DAS-ELISA for certain potato viruses, it is not suitable for large-scale indexing of potato viruses in Seed Certification Laboratories, in view of the additional steps needed in carrying out this procedure.     

Influence of seed placement on Russet Burbank potato yield and grade

Potato seed pieces were hand planted with different spacings in the row and percentages of doubles to determine the effects on total yield and tuber size distribution. The objective was to determine acceptable performance levels for commercial potato planters. Average tuber size increased as the percentage of double seed pieces decreased or as the in-row spacing between single seed pieces increased. Yield of tubers smaller than 113 g was the most sensitive parameter and they increased as in-row spacing decreased and as the percentage of double seed pieces increased. Yield of tubers larger than 283 g increased as in-row spacing increased but only for the first year. Total yield was not affected by the change of in-row spacing or the percentage of doubles.