Yield losses due to missing plants in potato crops

Missing plants in potato crops can be caused by diseases and other factors, and can result from non-emergence or from plants incapacitated at any time during the growing season. Field experiments were conducted to simulate missing plants and to estimate the resulting yield losses by removing different percentages of plants at random from plots at emergence and/or later stages. The recorded yield losses were not proportional to the percentage of missing plants. Two surveys of fields of table stock and seed stock of the cultivar Netted Gem in New Brunswick in 1972 showed that approximately 25% of the plants were missing at emergence, probably causing around8% loss in total tuber yield. Assuming all cultivars have similar levels of misses, the yield loss clue to missing plants at emergence in New Brunswick in 1972 was equivalent to a financial loss of approximately $1 1/2 million.     

The use of single,spaced potato plants to assess their tolerance of damage by potato cyst nematodes

Summary Potato clones and cultivars differ in their ability to tolerate damage by the potato cyst nematodes:G. rostochiensis andG. pallida. This paper reports a simplified field assessment whereby single, spaced plants are grown in heavily infested soils. These trials identified those clones which are either very sensitive to damage or those that grow and yield well in the presence of nematodes. The use of such a screening procedure in a breeding programme is discussed.     

The economic impact of potato late blight on US growers

Summary Potato growers have been able to control the fungus,Phytophthora infestans, that causes late blight with fungicides, but at an increasingly higher cost. A Delphi survey was conducted with thirteen experts to estimate the impact of late blight on potato yields, storage losses and fungicide use. It was estimated late-blight fungicides cost $77.1 million and lost revenue for US growers was an additional $210.7 million. These total costs, which average $507 per hectare, do not include non-fungicide control practices.     

The economic impact of investment in the Pacific Northwest potato variety development program

Genetic improvement has been the principle contributor to productivity growth in almost all field crops. The Pacific Northwest (PNW) had the highest rate of potato yield growth combined with the least amount of varietal change in any specialized major field crop-producing region in North America. A coordinated potato variety development program, jointly funded by the USDA, the three land grant universities, and the potato industry in the PNW, was established in 1984. The program developed 17 new potato varieties during the 1989–2001 period, two of them are emerging as successful processing varieties. Ranger Russet, released in 1991, and Umatilla Russet, released in 1998, possess several desired quality and production traits. The most important of these traits is 20% higher processing yield than present varieties. Since their release, there has been significant increase in the percentage of potato area planted with these new varieties. The weighted average adoption rate of these new varieties in the PNW in 2000 was about 16% of the area planted with potato. This represents 32.5% of Washington’s potato acreage, 14.3% of Oregon’s potato acreage, and 9.0% of Idaho’s potato acreage. The benefit to investments in the PNW Potato Variety Development Program attributed only to the flow of benefits from the adoption of Ranger Russet and Umatilla Russet is estimated at over $104.3 million in year 2000 and projected to increase to $213.595 million in year 2014 and thereafter. Rate of return to investment is estimated at 35%.     

Detection of potato virus M and potato virus S on test plants

Summary The influence of environment and virus isolate on PVM detection on eight plant species and PVS detection on six plants species was investigated.Lycopersicon chilense was the most reliable test plant for PVM andChenopodium quinoa for PVS. In both cases 12–24 days were required for the symptoms to appear. The most rapid development of PVM symptoms resulted from inoculation onPhaseolus vulgaris Red Kidney (4–8 days) and of PVS symptoms on detached leaves ofSolanum demissum Y (6–8 days). The detectability of the viruses on these test plants was, however, lower than onL. chilense andC. quinoa.

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Zusammenfassung An 8 bzw. 6 Pflanzenarten wurde die Reaktion auf eine Inokulation mit dem Kartoffel-M-virus (PVM) bzw. dem Kartoffel-S-virus (PVS) untersucht. Die Symptome sind in Tabelle 1 beschrieben. Untersuchungen, die in 3 temperaturkonstanten R?umen (16, 22 und 28°C) durchgeführt wurden, ergaben, dass unabh?ngig von der Temperatur nach Inokulation mit PVM aufLycopersicon chilense undSolanum rostratum Symptome auftraten, nach Inokulation mit PVS aufChenopodium quinoa, L. chilense undS. rostratum (Tabelle 2). Tests, die im Winter und im Sommer mit 12 Isolaten des PVM und 8 Isolaten des PVS durchgeführt wurden, ergaben, dass sich aufL. chilense undS. rostratum für PVM und aufC. quinoa für PVS unabh?ngig von der Jahreszeit und vom Virusisolat Symptome bildeten (Tabelle 3). Die am besten geeigneten Testpflanzen warenL. chilense für PVM undC. quinoa für PVS. Insgesamt wurden 200 Versuche zu verschiedenen Zeiten des Jahres durchgeführt (Tabelle 4). Jedoch, die vielleicht am besten geeignete Testpflanze für PVM istPhaseolus vulgaris Red Kidney und für PVS sind es abgeschnittene Bl?tter vonSolanum demissum Y, da die Symptome bereits wenige Tage nach der Inokulation mit allen getesteten Virusisolaten auftreten. Die Schwierigkeit bei der Verwendung dieser Testpflanzen ergibt sich aus der sehr starken Abh?ngigkeit der Symptomausbildung von den Versuchsbedingungen.

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Résumé La réaction au virus M et au virus S, respectivement de 8 et 6 espèces de plante, a été étudiée. Les sympt?mes qui sont apparus sur les plantestests, inoculées avec le virus M et avec le virus S, sont décrits dans le tableau 1. Des expériences conduites dans trois chambres à température contr?lée (16, 22 et 28°C) ont montré, qu'indépendamment de la température, le virus M produisait des sympt?mes surLycopersicon chilense etSolanum rostratum, et le virus S surChenopodium quinoa, L. chilense etS. rostratum (tableau 2). Des tests réalisés en hiver et en été avec 12 isolats de virus M et 8 isolats de virus S ont montré que les plantes-tests qui manifestaient chaque fois des sympt?mes, indépendamment de l'isolat utilisé, étaientL. chilense etS. rostratum pour le virus M, etC. quinoa pour le virus S (tableau 3). Deux cents tests réalisés sur la pomme de terre à différentes époques de l'année ont montré queL. chilense pour le virus M etC. quinoa pour le virus S étaient les plantes-tests les plus s?res (tableau 4). Toutefois, la plante-test la plus prometteuse est peut-être pour la détection du virus M,Phaseolus vulgaris Red Kidney; et pour la détection du virus S, les feuilles deSolanum demissum Y, car les sympt?mes étaient apparus quelques jours seulement après l'inoculation, quel que soit l'isolat testé. La difficulté d'utiliser ces plantestests réside dans le fait que le développement des sympt?mes est hautement dépendant des condition d'environnement.

     

Detectability and translocation of potato virus A in potato plants after artificial inoculation

Summary The tip leaflets of median leaves of plants of different ages of the very susceptible cv. Jara and the less susceptible cv. Krasava were dry inoculated with potato virus A (PVA). Movement of the virus was followed by using the A6 leaf test on different plant perts at intervals after inoculation. The technique was not very reliable but the results showed that in cv. Jara the rate of movement of virus within the plants and into the tubers was greater and less dependent on their age than in the less susceptible cv. Krasava. In cv. Jara. PVA reached the tubers with 6–7 days from inoculation but in cv. Krasava not until after 21 days and not at all if the plants were more than 6 weeks old when inoculated.     

Noise levels in potato packinghouses and dry-grading plants

Work stations in each of seven potato packinghouses and seven dry-grading plants, located in the Red River Valley, were surveyed for sound levels. Nine equipment categories were established in packinghouses and four in dry-grading plants for preliminary sound level determinations. In general, sound levels in packinghouses were acceptable; however, some dry-grading-plant equipment exhibited noise levels above suggested limits and required remedial attention. Follow up studies were then conducted in a representative dry-grading plant. Simple, practical noise-reduction practices such as proper maintenance of equipment were undertaken, and the noise in the plant was substantially reduced by these practices. Further separation from the noise created during the operations of the powered bulk scoop was provided with simple, easily fabricated barriers.     

Mature-plant resistance of potato plants against potato virus YO (PVYO)

Summary Mature-plant resistance of potato plants against potato virus Y^O (PVY^O) was studied in field experiments in 1976–1979 in southern Sweden. At intervals of 7 days, from mid June until mid August, PVY^O was mechanically inoculated to one well-developed upper leaf per stem of each plant. Each week, a new group of plants were inoculated. In 1976–1977, the natural spread of PVY^O by aphids was studied in relation to three different stages of potato plant development. The results of mechanical inoculation demonstrated that mature-plant resistance increases during July in southern Sweden but there were great differences between developmental stages. Early planting with sprouted seed resulted in plants with a considerable mature-plant resistance in mid July when late developed potato plants still were very susceptible.

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Zusammenfassung In Südschweden wurden zwischen 1976 und 1979 Untersuchungen durchgeführt, um zu prüfen, wann und in welchem Mass die Sorte Bintje im Sommer eine Altersresistenz gegen das Kartoffelvirus Y^O (PVY^O) ausbildet. 1977 wurden drei Gruppen von Kartoffelpflanzen unterschiedlicher Entwicklungsstadien mit PVY^O mechanisch inokuliert und von Mitte Juni bis fast Mitte August wurden jede Woche neue Gruppen von Pflanzen inokuliert. Nach der Ernte Anfang September wurden die Knollen auf PVY^O geprüft. Ebenso wurde die natürliche übertragung von PVY^O durch L?use von PVY^O-Infektorpflanzen auf benachbarte gesunde Pflanzen in drei verschiedenen Entwicklungsstadien untersucht. Die Ergebnisse der mechanischen Inokulation von Kartoffelpflanzen-früh und normal entwickelt-zeigen, dass die Altersresistenz der Sorte Bintje im Juli anstieg und Anfang August fast vollst?ndig ausgebildet war. Wurden die Kartoffeln sp?t gepflanzt, waren die Pflanzen Ende Juli noch sehr anf?llig für eine mechanische Inokulation und ein grosser Teil der Knollen war PVY^O-infiziert (Abb. 1, Tab. 2). Die natürliche übertragung von PVY^O bei verschiedenen Entwicklungsstadien der Pflanzen zeigte, dass die Zahl PVY^O-infizierter Knollen anstieg, wenn die Kartoffeln sp?t im Vergleich zur normalen Pflanzzeit gelegt wurden, mit und ohne Vorkeimung (Tab. 3). Die st?rkere Ausbreitung von PVY^O im Jahr 1976 gegenüber 1977 (Tab. 3) k?nnte mit dem st?rkeren Auftreten und der früheren Ausbreitung der L?use, vor allem vonRhopalosiphum padi (Tab. 4), im Jahr 1976 in Beziehung stehen.

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Résumé Des expérimentations sont menées dans le sud de la Suède entre 1976–1979; elles ont pour but de déterminer à quel moment et jusqu'à quelle limite des plantes de la variété Bintje présentent la résistance à maturité vis-à-vis du virus Y^O (PVY^O) au cours de l'été. En 1977, trois groupes de plantes à différents stades de développement sont inoculés mécaniquement avec PVY^O et chaque semaine, de la mi-juin à la mi-ao?t, de nouveaux groupes sont inoculés. Après la récolte, début septembre, des tubercules sont indexés pour déterminer PVY^O. La dissémination naturelle de PVY^O par les aphides, est également étudiée à partir de plantes-sources de PVY^O vers des plantes voisines saines, présentant trois différents stades de développement. Les résultats de l'inoculation mécanique de plantes à deux stades de développment précoce et normal, montrent que la résistance à maturité augmente pendant le mois de juillet pour la variété Bintje et est pratiquement totale vers le début du mois d'ao?t. Lorsque la plantation est tardive, les plantes sont encore très sensibles à l'inoculation mécanique et une forte proportion de tubercules est contaminée par PVY^O (figure 1, tableau 2). La dissémination naturelle de PVY^O pour des plantes à différents stades, montre que la proportion de tubercules atteints de PVY^O augmente lorsque les tubercules sont plantés tardivement par rapport à la date normale, avec ou sans prégermination (tableau 3). La dissémination plus importante de PVY^O en 1976 par rapport à 1977 (tableau 3) pourrait être correlée à celle des aphides également plus importante et plus précoce en 1976, notamment celle deRhopalosiphum padi (tableau 4).

     

New disease symptoms observed on field-grown potato plants with potato spindle tuber viroid and potato virus Y infections

Summary Potato spindle tuber viroid (PSTV) and potato virus Y (PVY) were isolated from plants of cultivar Kennebec with severe necrotic symptoms in the field. In the greenhouse, severe necrotic symptoms were reproduced only when potato plants were infected either simultaneously with PSTV+PVY, or with PSTV prior to PVY infection. Thirteen additional potato cultivars were tested in the greenhouse for this synergistic reaction and eight developed necrotic responses similar to cv. Kennebec. PVY concentration was significantly higher in doubly infected plants, compared with those infected with PVY alone.     

Elimination by chemotherapy of potato virus S from potato plants grown in vitro

Summary Potato virus S was eliminated from systemically infected stem cuttings of five potato cultivars after three passages in nutrient media containing 0.003% of the synthetic riboside ribavirin (Virazole). Treatment effects could be detected after only two passages which also revealed differences in cultivar response. Treated plants transferred to ribavirin-free culture media and to soil remained PVS-free. This simple method is less time-consuming than the usual meristem (axillary) tip culture procedures combined with chemotherapy or heat treatment.     

Agronomic performance of potato germplasm selected for high resistance to verticillium wilt

A three-year study was conducted from 1991 through 1993 to evaluate the field performance of potato clones that had been selected for resistance to wilt symptom development and stem colonization byVerticillium dahliae. The total yield, size distribution, and specific-gravity of these highly resistant clones were compared with standard cultivars and two parent clones with high Verticillium resistance and high yield, A66107-51 and A68113-4. Two groups of Verticillium resistant germplasm were selected in 1991. One group was the highly resistant progeny from a cross between A66107-51 and A68113-4. The second group consisted of hybrids between wild species accessions with high Verticillium resistance and cultivated diploid and tetraploid germplasm. Twenty-one out of 125 progeny clones from the A66107-51 × A68113-4 cross were highly resistant to Verticillium infection and were tested in yield trials for two years. Another eight selections had high Verticillium resistance but such low yield of seed tubers that they were tested only one year for yield. Eleven of the original 29 highly resistant selections were significantly lower in total yield than Russet Burbank. Only one clone was significantly higher in yield than RB, and none outyielded either of the resistant parents. Reddale and Century Russet had moderate to high Verticillium resistance, respectively. Both outyielded Russet Burbank and were comparable with the high yielding resistant parents. Of 15 interspecific hybrids tested in 1991, only four had sufficient yield to produce seed for yield trials and good wilt resistance after three successive seasons of evaluation. We concluded from this study that selecting at early stages of variety development strictly for Verticillium resistance is likely to be inefficient. Rather, selection should be for yield and other agronomic criteria in Verticillium infested fields.     

The pattern of assimilate movement in potato plants

Summary Leaves at nodes 5, 7 and 9 (numbered from the base) on separate batches of plants were supplied with¹⁴CO₂ at flowering and to further batches of plants 20 and 40 days after flowering. Of the tubers formed on a plant 20% arose from that portion of the stem within an arc of ±45 from the supply leaf but they contained 47% of the activity detected in all of the tubers.     

Acquisition of potato leafroll virus byMyzus persicae from secondarily-infected potato plants of different genotypes

Summary The acquisition of potato leafroll virus (PLRV) byMyzus persicae nymphs from the top leaves of potato plants was studied throughout a growing season in relation to the antigen titre in those leaves and the feeding behaviour of the aphid. Secondarily-infected plants of eight potato genotypes with different levels of field resistance served as virus sources. Early in the growing season, plants were efficient sources for virus acquisition. The amount of viral antigen detected inM. persicae nymphs fed on the top leaves was strongly correlated with the titres of viral antigen in these leaves. Virus acquisition from the top leaves of older potato plants was markedly impaired and could not be correlated with their virus titre. With increasing age of the potato plants and the development of virus symptoms, the virus titre in the leaves declined and the initial weak correlation between the virus titre and field resistance ratings disappeared. Thus, screening secondarily-infected potato plants for field resistance to PLRV based on the concentration of viral antigen in leaves or in aphids fed on them should be avoided later in the growing season. The feeding rate ofM. persicae, measured by the number of honeydew droplets excreted, did not account for the reduced uptake of virus from older plants since it was not influenced by the age of the plant. Throughout the growing season, the feeding rate ofM. persicae nymphs on PLRV-infected plants was higher on genotypes with low levels of field resistance to PLRV than on genotypes with high ones.     

Mineral element content of potato plants and tubers vs. yields

Linear equations for estimating the amounts of N, P, K, Ca, Mg and S removed from the soil as a function of yield are given for Russet Burbank potatoes. The equations were obtained from chemical analyses of potatoes grown using various ratios and rates of fertilizer, planting dates and harvest dates during 1966 to 1969 in the Columbia Basin of the state of Washington. The percentage mineral element composition of the tubers remained relatively uniform for the different ratios and rates of fertilizer but varied some due to the length of season. The correlation coefficients of chemical composition of the vines with chemical composition of tubers were low as were those relating amount in vines to yield. The correlation coefficients relating amounts of elements in the tubers to yield were 0.9 or greater.     

Growth and yield of potato plants grown from microtubers in fields

Despite many reports of thein vitro production of microtubers, little is known about plant growth and yield from microtubers planted in the field. This study clarified differences in growth and yields between potato plants grown in the field from microtubers and from conventional seed tubers. The experiments were performed at Hokkaido University, Japan, over four years. Conventional seed tubers of about 50 g and microtubers of two sizes (0.5–1.0 g and 1.0–3.0 g) of the latematurity cultivar Norin 1 were planted, and plant growth and tuber yields were analyzed. The microtuber plants had a lower initial increase in root and leaf area index than conventional seed tuber plants, but had the same leaf area index after about 40 days from emergence. The first tuber formation in microtuber plants was about 7 days later than in conventional seed tuber plants, while tuber bulking occurred about 14 days later in microtuber plants. Consequently, the onset of tuber weight increase was later in microtuber plants, but the rate of increase thereafter was similar between conventional seed tuber and microtuber plants. At harvest the tuber fresh weight of microtuber plants was 82% that of conventional tuber plants, suggesting a potential for using microtubers for field planting.     

Spindle tuber virus in seeds and pollen of infected potato plants

The presence of potato spindle tuber virus (PSTV) in seed and pollen of diseased plants was demonstrated. Transmission through the seed from open-pollinated female parents to the seedlings occurred frequently (average 31%) but varied in individual collections from zero to 100%. The amount of transmission did not appear to be correlated with variety or with age of the seed. All PSTV infections encountered appeared to be caused by mild strains. It is suggested that only healthy parents should be used for breeding purposes.     

An economic evaluation of consumer characteristics affecting fresh potato consumption

The purpose of this report was to relate several economic and social characteristics of consumers to level of fresh potato consumption. National cross-sectional data were used to identify consumption patterns using the least squares regression procedure. Relationships were estimated for white and nonwhite households The relationships for white households indicated that price of fresh potatoes, family income, number of meals eaten-at-home, family size, and expenditures for sweet potatoes were important determinants of weekly fresh potato consumption. Regional, urbanization and seasonal differences were also apparent for white households. Age and expenditures for processed white potatoes were less critical in determining consumption patterns The relationship for the nonwhite households was similar structurally to the white household relationship in many respects. Actually, age, expenditures for sweet potatoes and processed white potatoes and a couple of shift variables were the only ones which did not exhibit statistically significant coefficients. Seasonal and regional differences were noted.     

Ineractions between a mild and a severe strain of potato spindle tuber viroid in doubly infected potato plants

Potato (Solarium tuberosum) plants co-infected with a mild and a severe strain of potato spindle tuber viroid (PSTVd) were analyzed by return-polyacrylamide gel electrophoresis for the presence of both strains in vegetative and reproductive plant parts. Both strains were detected in the anthers, flowers, inflorescences, leaves, ovaries, ovules, petals, pistils, roots, sepals, stolons and tubers. Only mild strain was detected from pollen in the cultivars tested. True potato seed (TPS) were not doubly infected when they were obtained from co-infected maternal parent plants pollinated with pollen from healthy plants. Also, when maternal plants infected with severe strain were pollinated with pollen from healthy plants or from those infected with the mild strain, TPS were not doubly infected. A small number of TPS with double infection was obtained when co-infected or mild-strain-infected plants were pollinated with pollen containing the severe strain (singly or doubly infected). The number of TPS containing mild strain predominated in a ratio of 7:1 over TPS containing the severe strain. This study indicates that segregation of strains from doubly-infected plants probably takes place during pollen formation and persists through seed development.