G. E. Kleinkopf

Influence of irrigation and nitrogen management on potato yield and quality

The effects of irrigation, water and nitrogen management on yield and quality of the Russet Burbank cultivar are discussed relevant to developmental stages of growth. Recent research on the interactions of irrigation and nitrogen management on total and U.S. No. 1 yields and specific gravity are presented. Total and U.S. No. 1 yields decline with increasing soil moisture stress. Yield of U.S. No. 1 potatoes is particularly sensitive to short periods of irrigation deficit during tuber initiation. Total yield appears most sensitive to short periods of irrigation deficit during tuber bulking. Allocation of longer term irrigation deficits during years of limited water supply should be either a) avoided during mid-season tuber bulking, or b) uniformly distributed over the entire tuber bulking growth period. Yield increases with higher total available soil nitrogen under deficit irrigation, but the yield response diminishes as the amount of total seasonal water decreases. The influence of irrigation and nitrogen availability is also discussed for specific gravity and tuber maturity. Seasonal (split) nitrogen management is proposed as a method to improve yield, quality and nitrogen fertilizer use efficiency of indeterminant cultivars.

NITROGEN FERTILIZER EFFICIENCIES ON POTATOES

Nitrogen fertilizer efficiencies must be known to successfully apply N fertilizer according to crop growth needs. The objective of this study was to determine the recovery, partitioning, and translocation of N fertilizer applied at different times for potato production. Russet Burbank potatoes were fertilized preplant with15N-depleted ammonium sulfate, and during early and late tuber growth with urea containing K15NO3 in 1978 or (15NH2)2CO in 1980. All N applications increased tuber yields above the control treatments. The N recovery efficiency was 60% for the preplant N application, and over 80% and near 60% for the N applications during tuber growth in 1978 and 1980, respectively. Good agreement was found between the isotope and difference methods of determining N recovery efficiencies. Labeled N was initially concentrated in the stems and leaves, particularly if applied during tuber growth. Over 80% of the assimilated, labeled nitrogen was found in the tubers at the start of plant maturation. These data indicate that a significant improvement in N fertilizer efficiency would result from split N fertilizer applications made according to crop growth needs.CompendioPara una aplicación exitosa del fertilizante nitrogenado se debe conocer la eficacia del mismo, de acuerdo con las necesidades de crecimiento del cultivo. El objectivo de este estudio fue determinar la recuperatión, división, y transporte del fertilizante nitrogenado aplicado en diferentes periodos en la productión de papas. Se fertilizaron papas del cultivar Russet Burbank con sulfato de amonio carente de15N, antes de la siembra, y con úrea conteniendo K15NO3 durante el crecimiento inicial y final de los tuberculos en 1978 o con (15NH2)2CO en 1980. Todas las aplicaciones de N incrementaron los rendimientos en tubérculos por encima de aquellos en los tratamientos testigo. La eficacia en la recuperación del N fue 60% para la aplicación de N anterior a la siembra, y más de 80% y cerca de 60% para las aplicaciones de N durante el crecimiento de los tubérculos, en 1978 y 1980, respectivamente. Se considerró que la eficacia más baja en 1980 fue causada por una deficiencia de P al final de la temporada. Se encontró buena relación entre el método del isótopo y el de las diferencias, para la determinación de la eficacia en la recuperación del N. El N marcado se concentrró inicialmente en los tallos y hojas, principalmente cuando fue aplicado durante el crecimiento del tubérculo. Se econtró en los tubérculos más de 80% del nitrógeno marcado asimilado al inicio de la maduración de las plantas. Estos datos indican que una mejora significativa tendría lugar en la eficacia del fertilizante al dividir las aplicaciones del fertilizante nitrogenado efectuadas de acuerdo con las necesidades de crecimiento del cultivo.

Sprout inhibition in storage: Current status, new chemistries and natural compounds

A major component of managing potato quality in storage is effective sprout inhibition. Sprouting causes increased weight loss, reduced tuber quality and impedes air movement through the potato pile. The primary method to control sprouting in storage is with postharvest applications of isopropylN-(3-chlorophenyl) carbamate (chlorpropham; CIPC). CIPC inhibits sprout development by interfering with cell division. However, a recent Environmental Protection Agency mandate, from the requirements of the Food Quality Protection Act (FQPA) of 1996, resulted in a reduction in allowable CIPC residue on fresh potatoes in the United States from 50 ppm to 30 ppm.This mandate coincides with tolerance reductions or restrictions for use of CIPC in other parts of the world. CIPC is an effective sprout inhibitor although factors such as storage conditions, application technology, and cultivar can impact that effectiveness. Alternative sprout inhibitors to CIPC continue to be evaluated. Essential oils (e.g., caraway, peppermint, spearmint, clove) or their components (e.g., s-carvone, eugenol), and hydrogen peroxide-based materials, physically damage the developing sprout and suppress sprout elongation. However, repeated or continuous application of these compounds may be necessary for efficacy. Substituted naphthalenes (e.g., dimethyl naphthalene, diisopropyl naphthalene) may help reduce the amount of CIPC applied and/or our dependency on CIPC for sprout suppression in storage. The objective of this review is to summarize the current use of CIPC for potato sprout inhibition in storage and to review the status of current research on other postharvest applied compounds or materials that may be used as alternatives for CIPC.ResumenUno de los componentes mas importantes en el manejo de la calidad de la papa almacenada es la inhibición del brotamiento. El brotamiento produce un incremento en la pérdida de peso, tubérculos de baja calidad e impide el movimiento de aire a través de las pilas de papa almacenada. El método principal para el control del brotamiento en el almacén es la aplicación de isopropilN-(3-clorofenil) carbamato (clorprofam; CIPC). El CIPC inhibe el desarrollo de los brotes porque interfiere con la división celular. Sin embargo, un mandate reciente sobre requisites de la Agencia de Protección Ambiental, en el Acta de Protección de la Calidad de los Alimentos (FQPA) de 1996, dio como resultado la reducción de 50 ppm a 30 ppm de residuos de CIPC, permisible en la papa fresca para consumo en los Estados Unidos.Este mandato coincide con las reducciones de tolerancia o de restricciones para el uso de CIPC en otras partes del mundo. El CIPC es un inhibidor efectivo del brotamiento, aunque factores tales como, condiciones de almacenaje, tecnologia de aplicación y el cultivar mismo pueden tener impacto sobre esa efectividad. Los aceites esenciales (por ejemplo, de la alcaravea, de diferentes closes de menta y del clavo de olor), o sus componentes (tales como el s-carvone, eugenol) y materiales con base de peróxido de hidrógeno, deteriorait físicamente los brotes en desarrollo y suprimen su alargamiento. Sin embargo, para su eficacia pueden ser necesarias repetidas o continuas aplicaciones de estos compuestos. En reemplazo, se puede reducir la cantidad de CIPC aplicada y/o la dependencia en el CIPC para supresión del brotamiento en el almacén utilizando naftalenos (tales como dimetil naftaleno, diisopropil naftaleno). El objetivo de esta revisión es resumir el uso actual del CIPC como inhibidor del brotamiento de las papas almacenadas y hacer un examen de la situación actual de la investigación sobre otros compuestos aplicados, después de la cosecha o materiales que puedan ser utilizados como una alternativa para el CIPC.

Biological Control of Fusarium Dry Rot of Potato Tubers Under Commercial Storage Conditions

Lack of effective chemicals impedes control of Fusarium dry rot of stored potato tubers destined for processed and table stock use. Biological control of dry rot incited byGibberella pulicaris (anamorph=Fusarium sambucinum) has been demonstrated in laboratory studies but not in commercial storage environments. Several Gram-negative bacterial strains that were efficacious and amenable to production in liquid culture in laboratory studies were selected for pilot studies in Idaho and for bin trials at commercial storage houses in Idaho and North Dakota. In the first year of pilot studies,Pseudomonas fluorescens S22:T:04 (≈1 x 108 cfu/ml) decreased dry rot caused byG. pulicaris by 19% when coinoculated with the pathogen compared to controls and to the fungicide thiabendazole (TBZ) applied at label rates. In second year pilot studies,P. fluorescens P22:Y:05 andEnterobacter cloacae S11:T:07 (≈4 x 108 cfu/ml) reduced the severity of disease incited byG. pulicaris (25% and 17% average disease decrease, respectively) when antagonists were applied after pathogen inoculum. Treatment effects on dry rot that developed from inoculation withNectria haematococca (anamorph=Fusariumsolani var.coeruleum) were variable and influenced by interactions between antagonists, a wetting agent, and TBZ. In commercial storage bin trials,E. cloacae S11:T:07 reduced naturally occurring levels of dry rot by an average of 21% compared to 14% for TBZ, demonstrating that this antagonist was effective when produced using a liquid culture medium and methodology that approximates commercial practices for producing biomass.

Specific gravity of Russet Burbank potatoes

Variability in specific gravity of Russet Burbank potatoes was documented in a single 32 hectare field. Maximum variation was 40 units among individual tubers within hills (one unit equals one part in 1000th of specific gravity measurement) and 15 units among hills. Field site variability of 10–15 units was common between sampled grid lines in the field; but bulked samples (truckloads) reduced the sampled variability to 8–10 units. When the samples were taken from bulked lots as opposed to single hill samples, the variability decreased. Grower lots, which were pooled samples from several truckloads, showed specific gravity differences of 2–7 units even though all lots were from the same field. These variations among specific gravity samples should be taken into account when considering total solids content in any lot of potatoes.Degree of russetting of the skin and hollow heart also influenced specific gravity measurements. Measured differences between peeled and unpeeled lots of 10 units in specific gravity corresponded to 2% difference in total solids content. Statistically, the variance of the peeled lot was one half that of the unpeeled lot, therefore, to minimize the measured differences due to skin type, peeled potatoes could be used for the specific gravity measurements.CompendioSe probó la variabilidad en la gravedad específica de las papas Russet Burbank en un solo campo de 32 hectáreas. La variación máaxima entre tubérculos individuales dentro de los puntos de siembra fue de 40 unidades (una unidad es igual a una parte por milésimo de la gravedad específica medida) y 15 unidades entre puntos de siembra. Fue común encontrar una variabilidad de 10–15 unidades entre las diferentes muestras tomadas en el terreno convenientemente dividido; pero muestras al granel (camionadas) redujeron la variabilidad de las muestras a 8–10 unidades. Cuando las muestras fueron tomadas de lotes al granel en oposición a muestras de un solo golpe o punto de siembra, la variabilidad disminuyó. Los lotes de los productores, que fueron una mezcla de muestras tomadas de varias camionadas, mostraron diferencias de 2–7 unidades en la gravedad específica aún en el caso que todos los lotes fueran del mismo campo. Estas variaciones en las muestras, en cuanto a gravedad específica, deben tomarse en cuenta cuando se considere el contenido total de sólidos en cualquier lote de papas.El grado de reticulado de la piel y el de corazón vacío influencian también las mediciones de la gravedad específica. Las diferencias en las mediciones de la gravedad específica entre lotes pelados y sin pelar, que fueron de 10 unidades, corresponden a un 2% de diferencia en el contenido de sólidos totales. Estadísticamente, la variancia de los lotes pelados fue la mitad que la de los lotes sin pelar, por lo tanto, para minimizar las diferencias en las mediciones, debidas a las condiciones de la piel, se podrian usar papas peladas para las medición de la gravedad específica.

Management of silver scurf (Helminthosporium solani) with fungicide seed treatments and storage practices

Thiabendazole insensitive strains ofHelminthosporium solani, the causal agent of silver scurf, make controlling the disease with seed treatment difficult. Potato tuber seed treatments and environmental storage management practices were investigated as means to minimize silver scurf. Fungicide seed treatments were evaluated for control ofH. solani; disease was evaluated during the growing season, at harvest, and after 5 months of storage. Silver scurf was observed on progeny tubers eleven weeks after planting. Fungicides that reduced silver scurf incidence and severity on the seed resulted in reduced incidence and severity of the disease in the progeny tubers at harvest and significantly lower disease ratings after storage. Only small increases in disease incidence (0-8%) were seen after storage. Thiophanate-methyl with mancozeb, Captan with mancozeb, and fludioxonil were among the most effective in reducing the incidence and severity of silver scurf on seed and in progeny tubers (Incidence on progeny tubers at harvest for these three treatments were 3%, 9%, and 8% respectively). Thiophanatemethyl alone was not effective for control of silver scurf (48% incidence compared to 43% incidence for the untreated control).Environmental conditions in storage affected disease development. Reduced humidity (85%) during the curing period (0–3 weeks after harvest) significantly reduced (11%) the surface area of tubers infected with silver scurf. Free moisture on the tuber surfaces during storage significantly increased (15%) tuber surface area infection.H. solani was shown to survive in soil and on some potato storage building materials for up to 9 months. The silver scurf disease of potatoes can be suppressed using effective seed treatment and storage management.

Biological control of post-harvest late blight of potatoes

Abstract Introduction of US-8 genotypes of Phytophthora infestans has coincided with an increase in severity of potato late blight in North America. As alternatives to chemical fungicides, 18 bacterial strains patented as biological control agents (BCA) of both sprouting and Fusarium dry rot were cultivated in three liquid media and screened in wounded potato bioassays for their ability to suppress late blight incited by P. infestans (US-8, mating type A2). Washed or unwashed stationary-phase bacteria were mixed with fungal zoospores to inoculate potato wounds with 5µL containing ∼108 bacterial CFU/mL and 2×104 zoospore count/mL. Disease suppressiveness was evaluated after tubers were stored a week at 15°C, 90% relative humidity. One-fifth of the 108 BCA treatments screened, reduced late blight by 25–60%, including among other strains Pseudomonas fluorescens S22:T:04 (showing most consistency), P22:Y:05, S11:P:12 and Enterobacter cloacae S11:T:07. Small-scale pilot testing of these four strains, alone and in combination, was conducted under conditions simulating a commercial application. Suspensions of 4×104 P. infestans sporangia/mL were sprayed at a rate of 1.6 mL followed by 0.8 mL of bacteria treatment at ∼5×109 CFU/mL per each of 90 unwounded potatoes. Three replicate boxes per treatment (30 tubers per box) were randomized in storage and maintained 4 weeks at 7.2°C, 95% relative humidity. All BCA treatments significantly reduced disease; and unwashed bacteria outperformed those washed free of culture broth. Disease suppression ranged from 35% up to 86% the first test year and from 35 to 91% the second year. Highest overall performance rankings significantly above the control were achieved by the following strains in culture broth: four-strain mix > P. fluorescens S22:T:04> P. fluorescens S11:P:12. Combined with previous demonstrations of dry rot and sprout suppression, the consistent late blight control by these strains and strain mixtures suggests the commercial feasibility of a single treatment for broad spectrum suppression of post-harvest potato diseases and sprouting.

Dimethylnaphthalene and diisopropylnaphthalene for potato sprout control in storage : 1. Application methodology and efficacy

Dimethylnaphthalene (DMN) and diisopropylnaphthalene (DIPN) isomers applied as sprout suppressants to stored potatoes (cv. Russet Burbank) were evaluated for effects on sprout length and weight compared to chlorpropham (CIPC). One application of CIPC at 22 mg a.i. kg-1 of tuber fresh weight (f.w.), and one or two applications of DMN and DIPN at 100, 200, and 300 mg a.i. kg-1 f.w. were applied as thermal aerosol fogs. Two applications of DIPN at 300 mg a.i. kg-1 f.w. were as effective as CIPC in suppressing sprout growth during ten months of storage. DMN also suppressed tuber sprout growth but was not as effective as two applications of DIPN or one application of CIPC. One application of DIPN or DMN at 300 mg a.i. kg-1 f.w. was an effective suppressant of sprout growth on a short-term basis. Whole tuber residue analyses were also conducted. After ten months in storage, DMN and DIPN residue concentrations were equal to or less than those of CIPC.

Potato sprout inhibition and tuber quality after treatment with high-energy ionizing radiation

The use of industrial-type linear accelerators may be an alternative treatment for controlling sprouts in potatoes during long-term storage. The technical aspect of treatment has been described and may include largescale treatment of bulk potatoes as they are moving along a system of conveyors either to or from storage. The objective of the study was to evaluate the use of a linear accelerator for long-term sprout control under commercial storage conditions and the effects on tuber quality. An 18-MeV linear accelerator was used to provide sprout-inhibiting irradiation to various lots of ‘Russet Burbank’ potatoes. Successful sprout suppression was achieved with doses of 40 to 50 Gy (0 g sprout weight after 9 months of storage at 7.2 C) while higher doses caused undesirable increases in reducing sugars in the tubers. Glucose concentrations of treated tubers (0.25% fresh tuber weight) were higher after treatment than the untreated controls (0.08%), but returned to control levels after 2 to 6 months in storage. Glucose concentrations in treated tubers were significantly reduced with storage management for reconditioning by increasing the storage temperature for one month (from 7.2 C to 14.4 C) resulting in glucose concentrations near control concentrations. By increasing the dose-rate from the accelerator, recovery of tuber glucose concentration due to radiation treatments was significantly faster than when the dose was given more slowly. Potato tubers irradiated with high rates (100 Gy) of high-energy electrons exhibited an increase in soft rot and dry rot incidence in storage. Disease development in potatoes treated with sprout inhibiting doses of radiation (50 Gy) increased in lots with a high rot potential. Treated lots with low rot potential were successfully stored for 8 months or more without an increase in rot potential or shrinkage. Selection of lots for irradiation treatment should include some preliminary evaluation for development of disease in long-term storage.ResumenEl uso de acelerador linear de irradiación de tipo industrial puede ser un tratamiento alternativo para controlar el brotamiento de los tubérculos de papa durante periodos largos de almacenaje. El aspecto técnico del tratamiento ya fue descrito anteriormente y puede incluir el tratamiento en gran escala de grandes volúmenes de papa a medida de que se transportan del o hacia el almacén. El objetivo de este estudio fue evaluar el uso de un acelerador lineal para controlar el brotamiento por largo tiempo, bajo condiciones comerciales de almacenamiento y su efecto sobre la calidad del tubérculo. Se utilizó un acelerador lineal 18-MeV para aplicar la irradiación de inhibición del brotamiento a varios lotes de papa ‘Russet Burbank’. Se consiguió una mejor supresión de brotes con dosis de 40 a 50Gy (0g de peso de brotes después de nueve meses de almacenaje a 7.2 C), mientras que dosis más altas causaron el aumento indeseable de azúcares reductores en los tubérculos. Las concentraciones de glucosa de los tubérculos) tratados (0.25% del peso fresco del tubérculo) fueron más altas después del tratamiento que en los testigos sin tratar (0.08%), pero volvieron a niveles del testigo después de dos a seis meses de almacenaje. Las concentraciones de glucosa en los tubérculos tratados se redujeron significativamente con un manejo de reacondicionamiento del almacén, incrementando la temperatura por un mes (de 7.2 C a 14.4 C), lo que dio como resultado que las concentraciones de glucosa estuvieran cercanas a las del testigo. Incrementando la velocidad de aplicación del acelerador, la recuperación de la concentración de glucosa de los tubérculos, debida a los tratamientos de radiación fue significativamente más rápida que cuando se aplicó más lentamente. Los tubérculos de papa irradiados con tasas altas (100 Gy) de electrones de alta energía mostraron en el almacén un incremento en pudrición blanda y pudrición seca. El desarrollo de enfermedades en papa tratada con cantidades de radiación inhibidoras de brotes (50 Gy) incrementó el potencial de pudrición. Los lotes tratados, con potencial bajo de pudrición fueron muy bien almacenados por ocho meses sin presentar un incremento de pudrición o arrugamiento. La selección de lotes para el tratamiento de irradiación debería incluir evaluación preliminar para el desarrollo de enfermedades en almacenamiento prolongado.

Efficacy of chlorine dioxide for disease control on stored potatoes

The post-harvest application of chlorine dioxide (ClO2) was evaluated as a disease suppressant for stored potatoes. Chlorine dioxide was prepared by acidifying a buffered sodium chlorite solution with a food grade acid.In vitro studies verified the effectiveness of C1O2 at low concentrations (ED50 = 2 to 122 ppm) againstErwinia carotovora (soft rot),Fusarium spp. (dry rot) andHelminthosporium solani (silver scurf). Evaluations of tubers inoculated withPhytophthora infestans (late blight) andFusarium spp. or infected withH. solani and then treated with ClO2 either going into storage or through the humidification system resulted in a lack of disease suppression. Inconsistent performance of C1O2 in storage appeared to be a result of several contributing factors. Chlorine dioxide concentrations varied greatly (up to six-fold), depending upon the method of activating and diluting sodium chlorite solutions. Chlorine dioxide is a gas soluble in water and, therefore, is easily released from solution (25% –75% loss) into the air when applied as an aqueous spray. Chlorine dioxide reacts quickly with the tuber and associated organic matter, thereby reducing the effectiveness. Applying higher than currently registered rates may be necessary to achieve measurable disease suppression.ResumenEl diéxido de cloro (ClO2) en aplicaciones de postcosecha ha sido evaluado como un supresor de enfermedades de papa cosechada. El dióxido de cloro se preparó acidificando una solución amortiguada de clorito de sodio con un ácido de consumo humano. Estudios in vitro verificaron la efectividad del ClO2 a bajas concentraciones (ED50 = 2 a 122 ppm) contraErwinia carotovora (pudrición blanda),Fusarium spp. (pudrición seca),Helminthosporium solani (costra plateada). Las evaluaciones de tubérculos inoculados conPhytophthora infestans (tizón tardío) yFusarium spp. o infectados conH. solani y luego tratados con ClO2, ya sea aplicado al almacén o a través del sistema de humidificación, no dieron el resultado deseado, o sea que no suprimió las enfermedades. El comportamiento inconsistente del ClO2 en almacenamiento parece ser el resultado de varios factores. Las concentraciones de dióxido de cloro variaron enormemente (hasta seis veces), dependiendo del método de activación y dilución de las soluciones de clorito de sodio. El dióxido de cloro es un gas soluble en agua, por lo tanto es fácilmente puesto en libertad en el aire a partir de la solución (25%–75% de pérdida) cuando se aplica como solución acuosa. El dióxido de cloro reacciona rápidamente con el tubérculo y la materia orgánica asociada, reduciendo de este modo su efectividad. Para alcanzar una supresión perceptible de las enfermedades puede ser necesaria una aplicación de mayores cantidades que las corrientemente registradas.