Michael K. Thornton

Effect of Seedborne Potato virus Y on Performance of Russet Burbank, Russet Norkotah, and Shepody Potato

Potato virus Y (PVY) is one of the most important of the potato viruses, but little is known about the impact on yield of seedborne infection levels below 100%. Blending infected and healthy seed from different seed lots introduces the variable of performance differences between the seed lots, which may obscure the effect of virus alone. Seed lots containing various levels of seedborne PVY (0, 2, 10, 20, and 50% incidence of infected tubers) were created by combining in different proportions seed pieces from healthy and infected tubers from the same seed source. These seed lots were planted in replicated field plots at the University of Idaho Parma R & E Center in Parma, ID from 1995 to 1997. Regression analyses on data from the three consecutive seasons indicate that seedborne PVY has virtually the same negative impact on yield for all three cultivars.

Review Of The Sugar End Disorder In Potato (Solanum tuberosum, L.)

Processing quality has become increasingly important to the potato industry. A serious defect in product quality is the physiological disorder known as sugar ends, also referred to as dark ends, jelly ends, translucent ends, and/or glassy ends. Symptoms of the most common type of sugar end include relatively low starch and high sugar content in the basal end of the tuber. Tubers with the sugar end disorder produce French fries that are dark on one end, making the fries unacceptable to consumers. Sugar end potatoes cause time and profit losses at the processing plant and may require blending of loads to meet product specifications, along with the need to change processing protocols. Sugar end can be costly to growers if the tubers have insufficient quality and the crop is rejected for processing. Conditions conducive to the development of sugar ends include high soil temperatures, transitory soil moisture deficits, and insufficient or excess nitrogen fertilization. Tubers are most sensitive to these stresses during early bulking. Historically, several theories have been proposed concerning the mechanism of sugar end development. Research shows that stressed plants produce adequate amounts of assimilate to support continued tuber growth, but accumulate large amounts of sucrose in the basal tissues of the tuber immediately following stress. Accumulated evidence suggests that heat stress and water deficit induce changes in the activities of certain key carbohydrate metabolizing enzymes shifting the tuber from a starch synthesizing function to one of starch mobilization. Genetic resistance to sugar end development is known and the identified traits are highly heritable. This review summarizes sugar end investigations to-date, and presents a list of research-based crop management recommendations that assist potato producers in minimizing the potential for sugar end development in the field.ResumenLa calidad de procesamiento de papa se ha vuelto cada vez más importante para la industria. Un defecto serio en la calidad del producto es el desorden fisiológico conocido como punta azucarada, referido también como punta oscura, punta translúcida y/o punta vítrea. Los síntomas de los tipos más comunes de punta azucarada incluyen bajo contenido relativo de almidón y alto contenido de azúcar en el extremo basal del tubérculo. Los tubérculos con punta azucarada producen papas fritas que tienen un extremo oscuro, haciendo la fritura inaceptable para los consumidores. Las papas con extremo azucarado causan pérdida de tiempo y ganancias a la planta procesadora y puede requerir la mezcla de lotes de papa para satisfacer las especificaciones del producto, además de de la necesidad de cambiar los protocolos de procesamiento. La punta azucarada puede ser costosa para los productores si los tubérculos son de calidad insuficiente y el cultivo es rechazado para procesamiento. Las condiciones que conducen al desarrollo de este desorden incluyen altas temperaturas del suelo, deficiencia transitoria de agua e insuficiencia o exceso de fertilización nitrogenada. Los tubérculos son más sensibles al estrés durante su formación temprana. Históricamente, varias teorías han sido propuestas con relación al mecanismo de desarrollo de punta azucarada. La investigación demuestra que las plantas estresadas producen cantidades adecuadas nutrientes para favorecer el crecimiento continuo del tubérculo, pero que se acumula gran cantidad de sacarosa en el tejido de la base del tubérculo inmediatamente después del estrés. La evidencia acumulada sugiere que el estrés del calor y la deficiencia de agua inducen a cambios en las actividades de ciertos carbohidratos clave que metabolizan enzimas, cambiando así la función de síntesis de almidón del tubérculo por una de movilización del mismo. La resistencia genética al desarrollo de la punta azucarada es conocida y las características identificadas son altamente heredables. Esta revisión resume las investigaciones que se han hecho sobre punta azucarada hasta la fecha y presenta una lista de la investigación basada en recomendaciones de manejo del cultivo que ayude a los productores de papa a minimizar el potencial de desarrollo de punta azucarada en el campo.

Influence of heat stress on dry matter production and photo-assimilate partitioning by four potato clones

Partitioning patterns of14C labeled assimilates were studied to determine their relationship to dry matter accumulation and distribution in four potato clones (Desiree, DTO-28, LT-1 and Russet Burbank). Plants placed in growth chambers at 35/25 C day/night temperature and 12-hour photo-period two weeks after tuber initiation were compared with plants grown continuously at 25/12 C. Two weeks after temperature treatments were begun, the most recently expanded leaf was labeled with14CO2 for 30 minutes, and plants were harvested 20 hours or 15 days later. High temperature reduced total dry matter production and altered dry matter distribution in favor of vines at the expense of tubers. Partitioning of14C assimilates generally followed the pattern of dry matter distribution. Potato clones exhibited variation in14C assimilate export from labeled leaves and in partitioning to vines and tubers. Assimilate partitioning to tubers was not consistently higher in clones considered heat tolerant.CompendioSe estudiaron las formas de distribución de los productos de la fotosíntesis marcados con14C para determinar su relación con la acumulación de materia seca y su distribución en cuatro clones de papa (Desirée, DTO28, LT-1 y Russet Burbank). Se compararon plantas colocadas en cámaras de crecimiento a 35/25 C de temperaturas diurna/nocturna y 12 horas de fotoperiodo dos semanas después del inicio de la tuberización, con plantas en crecimiento continuo a 25/12 C. Dos semanas después de iniciarse los tratamientos térmicos, se marcó la hoja más recientemente expandida con14CO2 por 30 minutos y se cosecharon las plantas 20 horas o 15 días más tarde. La temperatura alta redujo la productión total de materia seca y alteró la distribución de la misma en favor del follaje a expensas de los tubérculos. La distribución de los productos de la fotosíntesis marcados con14C siguió generalmente la forma de distribución de la materia seca. Los clones de papa exhibieron variación en la exportación de los productos14C asimilados de las hojas marcadas y en la distribución de éstos en el follaje y en los tubérculos. La distribución de los productos asimilados en los tubérculos no fue consistentemente mayor en los clones considerados como resistentes al calor.

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 practicesCompendioLa compactación y erosión del suelo son problemas presentes en muchos de los campos de papa del noroeste del Pacífico. Se quería determinar si una aradura profunda zonal podría reducir estos problemas y mejorar los rendimientos de papa y/o su grado sin impactar negativamente sobre otras prácticas culturales de producción. Se condujeron estudios al Sur de Idaho, en seis localidades, durante dos años, con diferentes suelos y métodos de irrigatión, para determinar los efectos, de una aradura profunda zonal efectuada inmediatamente después de la siembra, sobre el rendimiento en tubérculos y su grado. Se efectuaron comparaciones de acumulación-aradura en tres localidades donde las tasas de aplicación de agua por aspersión eran más altas que las tasas de infiltración en el suelo. Russet Burbank fue considerada durante ocho localidades-años y Russet Norkotah en dos. La aradura profunda zonal mejoró consistentemente el grado de los tubérculos o incremento el tamaño de los mismos. La mejora más notable se efectuó bajo irrigación por surcos. La aradura profunda zonal también tuvo la tendencia a incrementar el rendimiento total, en ocho de las diez localidades-años. La acumulación-aradura mejoró el rendimiento y grado, pero no sucedió lo mismo con la aradura profunda zonal sin acumulación-aradura cuando las tasas de aplicación de agua fueron altas. En ninguna de las localidades la aradura profunda zonal disminuyó significativamente el grado de los tubérculos o el rendimiento. La aradura profunda zonal no tuvo efectos apreciables sobre la configuratión del lomo del surco o sobre la localizatión de las secciones de los tubérculos-semillas. Bajo irrigación por surco se produjeron grietas superficiales y aguda licuefacción (‘water piping’), pero no constituyeron problemas significativos. Los resultados fueron similares para ambos cultivares. Se requieren estudios adicionales para incorporar exitosamente la aradura profunda zonal entre las prácticas de productión comerciales.

Relationship between leaf gas exchange characteristics and productivity of potato clones grown at different temperatures

The rate of dark respiration (Rd) and net photosynthesis (Pn) at various leaf temperatures was examined in three potato clones (Solatium tuberosum L.) differing in heat tolerance. Plants were grown at low (25/12 C, day/night) and high (35/25 C) greenhouse air temperatures for five weeks, beginning two weeks after tuberization. Gas exchange characteristics were measured by manometric and infrared gas analyzer techniques. Respiration:photosynthesis ratios were calculated as indicators of leaf carbon balance. High greenhouse temperature reduced whole plant and tuber growth rate of all clones, however, the reduction was highest in the cultivar Russet Burbank (heat sensitive). Gas exchange characteristics did not explain differences in heat tolerance. The heat tolerant cultivar Desiree had Rd similar to Russet Burbank, while the clone DTO-28, also heat tolerant, had lower Rd of mature leaves than Russet Burbank or Desiree. However, all clones had similar Rd of immature leaves. There was no apparent relationship between heat tolerance and Pn for the three clones. DTO-28 had lower respirationrphotosynthesis ratios of immature and mature leaves than Russet Burbank 4 weeks after the start of the high temperature treatment. Desiree had respiration:photosynthesis ratios as high as Russet Burbank. At different sampling times, Rd increased in a linear and curvilinear manner with increasing leaf temperature up to 40 C. Heat tolerant and sensitive clones had similar rates of increase in Rd with increasing leaf temperature. Simultaneous measurement of Rd and Pn did not help explain differences in heat tolerance among clones. However, determination of respirationrphotosynthesis ratios may help explain the physiological basis for heat tolerance of some clones.CompendioLa tasa de respiración en oscuridad (Ro) y fotosíntesis neta (Fn) a varias temperaturas foliares fue examinada en tres clones de papa (Solanum tuberosum L.) que difieren en su tolerancia al calor. Las plantas fueron desarrolladas en invernaderos de temperaturas bajas (25/12 C día/noche) y altas (35/25 C) por cinco semanas, empezando dos semanas después de la tuberización. Las caracteristicas de intercambio gaseoso fueron medidas por técnicas manométricas y de análisis infrarrojo de gases. Las proporciones de respiración:fotosíntesis fueron calculadas como indicadoras del balance carbónico de la hoja. La temperatura alta del invernadero redujo la tasa de crecimiento de los tubérculos y de la planta en general en todos los clones, aunque la reducción fue mayor en el cultivar Russet Burbank (sensible al calor). Las características de intercambio gaseoso no explicaron las diferencias en la tolerancia al calor. El cultivar Desiree, tolerante al calor, tuvo una Ro similar a la del cultivar Russet Burbank, mientras que el clon DTO-28, también tolerante al calor, tuvo una Ro menor que la de Russet Burbank o Desiree en las hojas maduras. Sin embargo, todos los clones mostraron una Ro similar en las hojas inmaduras. No hubo una relación aparente entre la tolerancia al calor y la Fn de los tres clones. DTO-28 presentó menores proporciones de respiración:fotosíntesis que Russet Burbank en las hojas maduras e inmaduras, cuatro semanas después de iniciado el tratamiento con temperatura alta. Las proporciones de respiración:fotosíntesis de Desiree fueron tan altas como las de Russet Burbank. La Ro aumentó en forma lineal y curvilínea cuando se incrementó la temperatura foliar hasta 40 C, en diferentes épocas de muestreo. Los clones tolerantes y sensibles al calor mostraron tasas similares de incrementó de la Ro cuando se aumentó la temperatura foliar. La medición simultánea de Ro y Fn no ayudó a explicar las diferencias en la tolerancia al calor de los clones. Sin embargo, la determinación de las proporciones de respiración:fotosíntesis puede ayudar a explicar la base fisiológica para la tolerancia al calor de algunos clones.

Factors contributing to the blackspot bruise potential of Idaho potato fields

Blackspot bruise is a major problem in the fresh market and frozen french fry industry. The blackspot bruise potential of Russet Burbank and Ranger Russet in Idaho potato fields was determined by surveying commercial fields during 1993 and 1994. Management factors were monitored to determine what practices were contributing to blackspot susceptibility in addition to mechanical damage. The survey included 17 Russet Burbank and 3 Ranger Russet fields in 1993, and 28 Russet Burbank and 8 Ranger Russet fields in 1994. The 1993 season was unusually cool and wet whereas 1994 was warmer than normal, resulting in a wide range of environmental conditions for the 2 year study. Blackspot bruise potential was determined at different stages of tuber physiological maturity by collecting samples several weeks prior to normal harvest, immediately before harvest, and after storing sub-samples for several months. The blackspot bruise potential was measured by both impact and abrasive peel tests.Field maturity was the factor most consistently related to blackspot potential both years. In 1994 a multiple regression of 3 independent variables — field maturity index, specific gravity, and percent available soil water at tuber sampling, compared with the blackspot potential as the dependent variable gave a correlation coefficient of r = 0.73 (p = 0.001). Due to the cool, wet growing season in 1993, there was not enough variability in specific gravity and available soil water among the fields sampled for these factors to correlate with the blackspot potential. The available fertility data, although not complete for all fields, indicated no direct relationship between N, P, or K fertilization and blackspot potential. Preharvest samples in late August had lower blackspot potential than harvest samples in mid September, and storage samples in February had the highest susceptibility. There was a consistent increase in blackspot severity when tubers were equilibrated at 4 C compared with 10 C prior to bruising.

Development of Rhizoctonia solani on Stems, Stolons and Tubers of Potatoes I. Effect of Inoculum Source

Rhizoctonia solani may affect potato growth, yield and grade through lesions on stems and stolons and through development of black scurf on daughter tubers. R. solani inoculum can be found on seed potatoes and in the soil, although the relative importance of each inoculum source is unknown. Field studies at Parma and Aberdeen, Idaho, were conducted in 2004 and 2005 to evaluate the importance of each source of inoculum on the subsequent development of this disease. Seed of cultivars Ranger Russet (2004) and Russet Burbank (2005) was washed and sorted into three (2004) and two (2005) levels of black scurf. Prior to planting, the plots were inoculated with R. solani cultures mixed with vermiculite at low, medium and high rates. Each level of seed inoculum was planted at each level of soil inoculum. Significantly greater levels of disease on stems and stolons was consistently found on plants grown from high inoculum seed compared to low inoculum seed. However, significant effects of soil inoculum level on stem and stolon disease were rarely seen. In contrast, both seed and soil inoculum level influenced the development of black scurf on daughter tubers. The largest response to soil inoculum level was seen when seed inoculum was low.ResumenRhizoctonia solani puede afectar el crecimiento de la papa, el rendimiento y calidad a través de lesiones en tallos y estolones y por el desarrollo de costras negras en los tubérculos producidos. El inoculo de R. solani se puede encontrar en tubérculo semilla y en el suelo, aunque se desconoce la relativa importancia de cada fuente de inoculo. Durante 2004 y 2005 se condujeron estudios de campo en Parma y Aberdeen, Idaho, para evaluar la importancia de cada fuente de inoculo en el desarrollo subsecuente de esta enfermedad. A semilla de los cultivares Ranger Russet (2004) y Russet Burbank (2005) se les lavó y agrupó en tres (2004) y dos (2005) niveles de costra negra. Antes de plantar, los lotes se inocularon con cultivos de R. solani mezclados con vermiculita a niveles bajo, medio y alto. Cada nivel de inoculo a la semilla se plantó en cada uno de los niveles de inoculo al suelo. Se encontraron consistentemente niveles significativamente mayores de enfermedad en tallos y estolones de plantas que crecieron en altos niveles de inoculo en la semilla comparados con los de niveles bajos. No obstante, raramente se vieron los efectos significativos de los niveles de inoculo en el suelo sobre la enfermedad en tallo y estolón. En contraste, ambos niveles de inoculo en semilla y suelo, influenciaron el desarrollo de la costra negra en los tubérculos generados. La mayor respuesta al nivel de inoculo en el suelo se observó cuando el nivel de inoculo a la semilla era bajo.

Response of sweet Spanish onion cultivars and numbered hybrids to basal rot and pink root

Yellow sweet Spanish onion cultivars and numbered hybrids were evaluated for disease resistance, bulb yield, and bulb size in field trials on a soil heavily infested with the pathogens that cause pink root and basal rot. Hybrid lines exhibited lower incidence of basal rot and pink root than named cultivars in both 1990 and 1991. Resistance to basal rot was not closely related to level of pink root infection. Hybrids that exhibited a low level of pink root infection had the healthiest roots and produced the highest bulb yields. Extensive replacement of infected roots with healthy new roots was a common characteristic of pink root-resistant hybrids. Adoption of numbered onion hybrids resistant to pink root and basal rot could reduce the current dependence on fumigation as the primary control method for these soilborne diseases.

Dry matter accumulation in potato clones under seasonal high temperature conditions in Pakistan

The effects of seasonal high temperatures on potatoes were investigated under field conditions near Peshawar, Pakistan. Five potato clones (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) were grown during the spring season at two locations. Canopy development, vine dry weight and tuber dry weight were determined at 13-day intervals, starting 68 days after planting (DAP). Tuber yield was higher in heat tolerant clones compared to heat susceptible clones. Location significantly affected tuber dry weights. Tuber dry weights of Russet Burbank were consistently lower than those of DTO-28. Ground canopy cover of DTO-28 occurred earlier and reached maximum at 75 DAP, compared to 90 DAP for Desiree. DTO-28, because of its high tuber yield under cool as well as hot temperatures, and its relatively early bulking, should be a promising clone for a short duration crop in hotter regions.CompendioSe investigó el efecto de las altas temperaturas de estación sobre plantas de papa en condiciones de campo, cerca de Peshawar, Pakistan. Durante la estación primaveral se sembraron cinco clones de papa (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) en dos localidades. Se determinó el desarrollo del follaje, el peso seco de las ramas y de los tubérculos, a intervalos de 13 días a partir de los 68 días después de la siembra (DAP). El rendimiento fue más alto en clones tolerantes al calor que en clones susceptibles al calor. La localidad afectó en forma significativa al peso seco de los tubérculos. El peso seco de los tubérculos de Russet Burbank fue menor, de manera consistente, que el de los tubérculos de DTO-28. El follaje cubrió el campo más temprano en el clon DTO-28, alcanzando su punto máximo a los 75 DAP, comparado con 90 días para Desiree. El clon DTO-28 puede ser promisorio para cultivos de corta duración en regiones mas cálidas, debido a su alto rendimiento en condiciones tanto frías como calientes y a su desarrollo relativamente precoz.

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.