A. F. Reeves

Varietal differences in potato tuber greening

Greening reactions of 144 potato varieties (16 russet, 29 red, 99 white) were evaluated. Three components of greening (external color, internal color, and depth of color) were measured. In general, depth of greening was less in russetted varieties than in white varieties. Red varieties showed less discoloration for all three components. The three greening components appeared to be independent, and might be inherited separately.CompendioSe evaluaron las reacciones de verdeamiento de 144 variedades de papa (16 rosadas, 29 rojas, 99 blancas). Se midieron tres componentes de verdeamiento (color externo), color interno y profundidad del color). En general, la profundidad de verdeamiento fué menor en las variedades rosadas que en las blancas. Las variedades rojas mostraron menor decoloración relacionada con los tres componentes. Los tres componentes parecieron ser independientes y podrían heredarse independientemente.

Evaluation of potato varieties and selections for resistance to bacterial soft rot.

Potato varieties and selections were evaluated for resistance to bacterial soft rot caused byErwinia carotovora subsp. carotovora and Erwinia carotovora subsp. atroseptica in mist chamber. A randomized complete block design with a single treatment and 3 replications was used in this study. Potato lines were inoculated with bacterial suspension (10 tubers / line) using the puncture inoculation method and incubated for 4 days in a mist chamber at 21 C and 100 % relative humidity in the dark. Although there were differences in incidence of soft rot and in amount of weight reduction, most of the potato lines were susceptible to tuber soft rot. Mean incidence (%) of soft rot ranged from 10 to 100%. Mean reduction of tuber weight (%) ranged from 0.13 to 16.43 %. Among the varieties and selections tested, AF 522-5 was the most resistant to tuber weight loss, while AF 1424-7 was most susceptible. There were also significant differences between years, and a variety by year interaction. Testing over a period of years is recommended. A significant correlation coefficient of soft rot incidence (%) and reduction of tuber weight (%) was obtained (r=0.65; P=0.05), indicating that incidence was a fair measure of soft rot potential. However, the greater variability in results for incidence make weight loss a better measure of soft rot reaction. There was a significant difference among varieties in the reduction of tuber weight when potato lines were inoculated either 1 month or 2 months after harvest, but the interaction of time by year prohibits a conclusion as to which time gives a better test reaction. Late maturing varieties had slightly less weight loss than earlier maturing varieties.

Evaluation of potato clones for resistance to stem canker and tuber black scurf in field studies following artificial inoculation with Rhizoctonia solani AG-3 in Maine∗

Abstract Potato clones were evaluated for resistance to Rhizoctonia stem canker, stolon lesion and black scurf in field experiments during the 1997 and 1998 growing seasons. Seed pieces were inoculated with Rhizoctonia solani Anastomosis group 3 (AG-3) by dipping them in a slurry or suspension of inoculum. Uninoculated controls were also planted. Seed emergence was assessed beginning at two weeks after planting. After 60 days, incidence and severity (%) of stem and stolon cankers were assessed. The numbers of root and stolon lesions were also quantified. At harvest, the incidence of black scurf on tuber yield and numbers were also determined. Significant differences in emergence of potato seed pieces (%) were detected between inoculated and control treatments and the incidence of stem and root cankers differed among clones in both years. The incidence and severity of stem cankers and the numbers of stem and root lesions were not significantly correlated with the black scurf incidence on tubers. These studies suggest that various symptom types incited by Rhizoctonia can be important epidemiological factors in disease development.

Delta Gold: a new potato variety with yellow flesh, high solids and high quality for baking and processing.

Delta Gold is a medium-late maturing, round, yellowish-skinned, yellow-fleshed variety which is excellent for baking and processing. Its yields have been lower than Kennebec; however, specific gravities have been higher. It is moderately resistant to scab and early blight and immune to net necrosis and virus A.ResumenDelta Gold es una variedad de maduración semi tardía, con tubérculos redondos, de piel amarillenta y de carne amarilla, excelentes para horneado y procesamiento.A pesar que sus rendimientos han sido menores que los de Kennebec, su gravedad específica ha sido mayor. Es moderadamente resistente a la sarna y al tizón temprano e inmune a la necrosis en red y al virus A.

Campbell 14: A verticillium resistant round white potato variety

The Campbell 14 potato variety is a medium-late maturing variety with round to oblong, smooth, shallow-eyed, white tubers. This variety is intended primarily for fresh market; however, under some conditions chip color will be acceptable. Campbell 14 is resistant to verticillium wilt and to the net necrosis caused by the potato leafroll virus.ResumenLa variedad de papa Campbell 14 es una variedad de maduración medianamente tardia, con tubérculos blancos, entre redondos y oblongos, lisos y de ojos superficiales. Esta variedad es fundamentalmente destinada a ser comercializada sin procesar; sin embargo, bajo ciertas condiciones, el color que toma en la forma de hojuelas es normalmente aceptable. Campbell 14 es resistente a la marchitez por Verticillium y a la necrosis reticular causada por el virus del enrollamiento de las hojas de papa.

St. Johns: a round white potato variety for fresh market.

The St. Johns potato variety is high-yielding and late-maturing with attractive, round to oblong, white-skinned, white-fleshed tubers with mediumshallow eyes. Its major use is expected to be as a maincrop tablestock variety. Taste panels rated St. Johns better than or equal to Katahdin in texture, color, mealiness, and flavor. St. Johns tubers do not show the net necrosis caused by potato leafroll virus, and are resistant to golden nematode, corky ringspot, hollow heart, and blackspot bruising. St. Johns is also moderately resistant to greening, shatter bruise, verticillium wilt, early blight, common scab, the common race of late blight, leafroll,Fusarium sambucinum (dry rot) andErwinia carotovora (soft rot), although some breakdown has been reported in commercial storages. Symptoms of leafroll virus infection are somewhat difficult to detect.CompendioLa variedad de papa St. Johns tiene alto rendimiento y madurez tardia, y sus tubérculos son atractivos, redondos a oblongos, de piel y pulpa blancas y ojos semiprofundos. Se anticipa su uso principalmente como una variedad importante para el consumo. Los paneles de catadores calificaron a St. Johns mejor o igual que la variedad Katahdin en cuanto a textura, color, contenido de harina y sabor. Los tubérculos de la variedad St. Johns no muestran la necrosis reticular que causa el virus del enrollamiento de la hoja de la papa y son resistentes al nematodo dorado, mancha anillada, corazón vacío y mancha negra no infecciosa. También es moderadamente resistente al verdeamiento, golpes, marchitez porVerticillium, tizón temprano, sarna común, la raza común del tizón tardío, enrollamiento de la hoja, pudrición seca (Fusarium sambucinum) y pudrición blanda (Erwinia carotovora), aunque hay algunos informes de descomposición durante el almacenamiento con fines comerciales. Los síntomas de infección por el virus del enrollamiento de la hoja son un poco difíciles de detectar.

Prestile: a new round white potato variety.

Prestile is a late maturing potato variety with attractive, round to oblong, white-skinned, white-fleshed tubers with shallow eyes. Its major use is expected to be for tablestock in areas where Katahdin and Ontario are now grown. Prestile tubers are slow to sprout in storage and do not show the net necrosis caused by potato leafroll virus, but are quite susceptible to heat necrosis. This variety is immune to potato virus X, and is moderately resistant to common scab (Streptomyces scabies), verticillium wilt (Verticillium albo-atrum), and early blight (Alternaria solani). Prestile is susceptible to skinning and shatter bruise, and is difficult to kill, particularly when heavily fertilized.CompendioPrestile es una variedad tardía de papa con tubérculos atractivos, redondos a oblongos, de piel blanca y pulpa blanca y con ojos superficiales. Se espera que sea utilizada principalmente para consumo directo en zonas donde ahora se cultivan Katahdin y Ontario. Los tubérculos de Prestile tienen un brotamiento lento en almacenamiento y no presentan la necrosis en red causada por el virus del enrollamiento de la hoja, pero son bastante susceptibles a la necrosis por calor. Esta variedad es inmune al virus X de la papa y moderadamente resistente a la sarna común (Streptomyces scabies), marchitez por verticillium (Verticillium albo-atrum), y al tizón temprano (Alternaria solani). Prestile es susceptible a magulladuras y rupturas de la piel y es difícil de eliminar, especialmente cuando ha sido fertilizada en abundancia.

Somerset: a new chipping potato variety.

The Somerset potato variety is a medium-maturing variety with attractive, round to oblong, white-skinned, white-fleshed tubers with shallow eyes. Its major use is expected to be as a chipping variety in areas where potatoes are stored for some length of time, since its sugar content is lower than most varieties during storage, and it can be chipped after six months in storage. Somerset does not show the net necrosis caused by potato leafroll virus, and is immune to race 0 of Phytophthora infestans (late blight). Somerset is also moderately resistant to infection by Alternaria solani (early blight), and is only moderately susceptible to Verticillium wilt. Somerset is more susceptible to both common and acid scab than Superior, but less susceptible than Kennebec and Katahdin. It also has shown susceptibility to skinning and shatter bruise, but does not have a strong blackspot bruise reaction.

Potato chip color ratings of advanced selections from the Maine potato breeding program

Seven named varieties and three numbered selections from the University of Maine potato breeding program were compared for chip color at various conditions and lengths of storage. Although all selections tested were equal to or better than Kennebec in chip color, only Allagash Russet equaled Monona. Storage at 45° F (7.2° C) produced acceptable chip color at all time periods tested. After long term storage at 45° F, reconditioning at 55° F(12.8° C) was ineffective in improving chip color. Following storage at 38° F (3.3° C) acceptable chip color could be produced only by reconditioning at 70° F (21.1° C) for at least two weeks.ResumenSiete variedades y tres selecciones del programa de mejoramiento de papa de la Universidad de Maine, Orono, fueron comparadas por el color de los chips, bajo varias condiciones y duración de almacenaje. Aunque todas las selecciones probadas fueron iguales o mejores a Kennebec en cuanto al color de los chips, sólo Allagash Russet igauló a Monona. El almacenamiento a 45°F (7.2°C) produjo un aceptable color de los chips en todos los períodos de tiempo probadas. Después de un período de almacenaje a 45°F, el reacondicionamiento a 55°F (12.8°C) fue inefectivo para mejorar el color de los chips. Después del almacenaje a 38°F (3.3°C), un color aceptable de los chips pudo ser producido sólo después de un reacondicionamiento a 70°F (21.1°C) durante dos semanas por lo menos.

Mainestay: A high-yielding, round white potato variety for fresh market

The Mainestay potato variety is high-yielding and late-maturing producing attractive, round, white-skinned, white-fleshed tubers with medium-shallow eyes. Its major use is expected to be as a maincrop tablestock variety. Mainestay appearance ratings are similar to those of Katahdin, and greening in Mainestay tubers is less than in Kennebec. Most boil and bake qualities were rated equal to Katahdin in at least half of the tests, and Mainestay usually has a low incidence of internal defects. However, purple streak, heat necrosis, vascular discoloration, and heat sprouts have been seen on occasion. Mainestay tubers do not show the net necrosis caused by potato leafroll virus, and have shown very little hollow heart or blackspot bruising. Mainestay is susceptible to common scab and acid scab, but moderately resistant to verticillium wilt (Verticillium, albo-atrum andV. dahliae), early blight (Alternaria solani), rhizoctonia (Rhizoctonia solani), dry rot (Fusarium sambucinum), and pink rot (Phytophthora erythroseptica). It is moderately susceptible to the common race of late blight (Phytophthora infestans). Mainestay tubers are slow to mature after vine kill, and additional time is required prior to harvest in order to allow for proper periderm development and to reduce storage losses.ResumenMainestay es una variedad de papa de alto rendimiento y maduración tardía que produce atractivos tubérculos de forma redonda con cáscara y pulpa blanca y con ojos medianamente profundos. Se espera que su uso principal sea para el consumo directe. La calificación para la apariencia de Mainestay es similar a la de la variedad Katahdin y el verdeamiento de sus tubérculos es menor al de Kennebec.La mayorá de sus cualidades para la cocción y ebullición fueron calificadas como iguales a las de Katahdin en al menos la mitad de las pruebas efectuadas, pero Mainestay por lo general tiene una incidencia baja de defectos internos. Sin embargo, se han observado ocasionalmente estrías púrpuras, necrosis causada por el calor, descoloración vascular y brotamientos causados por el calor. Los tubérculos de Mainestay no muestran la necrosis reticulada causada por el virus del enrollamiento de la papa, y han mostrado muy pocos síntomas de corazón vacío o manchas negras causadas por golpes. Mainestay es susceptible a la sarna o sarna ácida, pero se muestra moderadamente resistente a la verticilosis (Verticillium albo-atrum yV. dahliae), rhizoctoniasis (Rhizoctonia solani), pudrición seca (Fusarium sambucinum) y pudrición rosada (Phytophthora erythroseptica). Es moderadamente susceptible a la raza común del tizón tardío (Phytophthora infestons). Los tubérculos de Mainestay tienen una maduración lenta luego de la muerte del follaje y se necesita un tiempo adicional previo a la cosecha para permitir el desarrollo adecuado de la peridermis y para reducir las pérdidas de almacenamiento.