L. C. Peterson

A technique for evaluating the ability of selections to yield consistently in different locations or seasons

SummaryVarieties differ in their ability to produce a, dependable crop. In New York experience has shown Katahdin and Cobbler to be favorable in this respect, whereas Green Mountain has a reputation of being variableYield data over locations were analysed in all possible combinations of pairs of varieties. Estimates of the variety × location component of variance were obtained for each of these analyses. The average of these components for all combinations having a variety in common was defined to be the relative contribution by that variety to the variety × location interaction. In four of five analyses, Green Mountain had the highest relative contribution to the variety × location interaction, and Cobbler and Katahdin had a low contribution.

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.ResumenLa presencia del virus que causa tubérculos ahusados (PSTV) ha sido demonstrada en semillas y polen de plantas infectadas. Transmisión del virus por semilla obtenida de padres femininos libremente polinizados a las plantulas sucedió con frecuencia (promedio 31%) pero varió en colecciones individuales desde zero a 100%. La magnitud de la infección parece no correlacionarse con la variedad o con la edad de la semilla. Todas las infecciones con PSTV encontradas parecen haber sido causadas por cepas no muy virulentas. Se sugiere que solamente padres sanos sean usados para propagación.

Specific and general combining ability for yield in potatoes

SummaryForty-five lines were crossed to six testers to evaluate their general combining ability. These lines did not clearly represent a random selection of lines with respect to this character, though they had not undergone any formal selection in this respect. In these lines, the variance in specific combining ability exceeded the variance in general combining ability. Six or more testers are required to evaluate general combining ability in lines of this nature. The interaction of general combining ability and locations was less than the variation in SCA and locations.The variation in specific combining ability of a line was not related to the magnitude of its GCA effect.The general combining ability effects of 32 of the lines are given. Four of the better lines were B2368-4, La1859, I-1015-2 and I-1077W28-5.

The overwintering ofphytophthora infestans (Mont.) de Bary under long island conditions

SummaryInfected aerial shoots were produced by the growth of mycelium from diseased seed pieces both under controlled and field conditions. Infected plants growing in the cull pile also were incriminated as an important source of primary inoculum.The germination of sporangia ofP. infestans was markedly reduced or inhibited in soils obtained from potato fields on Long Island, due probably to the relatively high copper content of these soils. For this reason it is suggested that should overwintering spores be found they also would be unimportant in initiating the disease. No evidence could be obtained for a saprophytic existence of the pathogen in the soil. Solatium Dulcamara was the only wild perennial solanaceous plant of the eleven species inoculated on which the fungus could be induced to sporulate. It has never been found infected in its natural habitat.

The Tomato test for eliminating spindle tuber from Potato planting stock.

ArstractA lot of 792 tubers, of which about 20% were infected with the potato spindle tuber virus (PSTV), were subjected to greenhouse index tests, using tomato as a test plant. Tomato seedlings in the cotyledon stage were rubbed with the test material, either foliage or the surfaces of seed pieces cut from test tubers with a mellon-baller. Fourteen days later the test plants were inoculated with a severe strain of PSTV to detect the presence of mild strains. Tubers giving negative results were planted for propogation and those giving positive or doubtful results were planted in an observation plot. All potato plants were inspected visually and those in the observation plot were given an additional tomato test. The results indicate the validity and value of the tomato test for the elimination of PSTV from seed stocks before planting. The tuber test conducted in the winter was less efficient than the foliage test conducted in the spring. A modification of the test procedure is advocated in which two test plants are rubbed from each source, one to be challenged and one not. This increases the accuracy of the test, particularly during periods when symptoms of PSTV are poorly expressed.ResumenUn lote de 792 tubérculos, de los cuales más o menos 20% estaban infectados con el virus de papa ahusada (PSTV) fué sujeto de un ensayo de índice en invernadero, usando plantas de tomate como plantas de ensayo. Plantas germinadas de tomate con cotiledones fueron restregadas con el material de ensayo consistente ya sea de follaje, ya sea de las superficies de pedazos de papas cortadas de los tubérculos de ensayo con un cortador de melones. Catorce días más tarde las plantas de ensayo fueron inoculadas con una forma virulenta de PSTV para descubrir la presencia de formas blandas. Tubérculos que dieron resultados negativos fueron plantados para ser progados y aquellos que dieron resultados positivos o ambíguos fueron plantados en un lote de observación. Todas las plantas de papa fueron inspeccionadas visualmente y aquellas en el lote de observación recibieron un ensayo adicional con plantas de tomate. Los resultados indicaron la validez y la ventaja del ensayo por medio de plantas de tomate para la eliminación de PSTV de las papas antes de sembrar. El ensayo por medio de tubérculos conducido en invierno fue menos eficaz que el ensayo por medio del follaje hecho en primavera. Se recomienda una modificación del procedimiento de ensayo en la cual dos plantas de cada origen se restriegan y de las cuales una se examina y la otra no. Esto aumenta le exactitud del ensayo, especialmente durante los períodos cuando los síntomas de PSTV están pobremente expresados.

Two cycles of phenotypic recurrent selection for high specific gravity

SummaryThe results of two cycles of recurrent selection for high specific gravity clearly indicate the effectiveness of this method for this attribute. An average gain of about .004 units of specific gravity of the second cycle over the first as measured in two locations in two seasons was significant beyond the .005 level.The results of seedling hill selection show that small gains can be made, but that these are not consistent enough for general application to seedling selection. In the situation where selection is for extremely high specific gravity, a moderate selection threshold would be generally effective.The coefficients of inbreeding and parentage of the selections of each cycle are presented.

Wauseon: A new potato variety resistant to golden nematode with good processing quality

Wauseon was released December 7, 1967, by the Crops Research Division of the United States Department of Agriculture and the Agricultural Experiment Station of New York. Wauseon, tested under the pedigree number B5036-40, was selected from a cross between U S D A seedling B5149-8 and Katahdin. The seedling ]35149-8 was selected for a parent because of its midseason maturity and resistance to late blight, scab, latent mosaic, and the golden nematode (Heterodera rostochiensis Woll.) . The Katahdin parent is widely known for its adaptation and resistance to mild mosaic and net necrosis. The pedigree of Wauseon follows:

Selection for freedom from after cooking darkening in a potato breeding program

INTRODUCTION After-cooking-darkening is one of the most common defects found in potatoes. It is world-wide in its occurrence and although it has no known effect on either flavor or nutritional value, the objection to potatoes which darken when cooked lies mainly in their unsightly appearance. During the last 60 years much effort has been placed on the cause and on the conditions that affect after-cooking-darkening. Yet, very little attention has been given to varietal response. Parker (5) stated that no pronounced differences existed between varieties and that darkening was influenced more by soil conditions than by the variety itself. Nash (4) and Smith et al. (10) found little tuber darkening in early maturing varieties while almost all of the late maturing varieties blackened when cooked. On the other hand, Rieman et al (7) reported that some early and late varieties exhibited equal amounts of darkening. Nash (4) reported marked differences in tuber darkening between varieties grown under the same environmental conditions. Tottingham (12) conducted a series of greenhouse studies over a period of years and found that after-cooking-darkening appeared primarily as a varietal characteristic. Rieman et al. (7) tested nine varieties for five years at nine widely separated locations and found varietal differences. They also tested clonal selections of some of these varieties and found that they behaved like their parental stocks in respect to after-cooking-darkening. They crossed clones which did not darken with those which did and on the basis of their results suggested that whiteness was dominant or incompletely dominant to gray. Pollard (6) and Muneta (3) also reported the existence of varietal differences. The purpose of this study was to study genetic variability for aftercooking-darkening, to estimate components of variance and to find appropriate ways for selecting for freedom from after-cooking-darkening in potato breeding programs.

Hudson: A high yielding variety resistant to golden nematode

The cross between Kennebec and B3945-6, made by L. C. Peterson resulted in a population segregating for golden nenlatode resistance. The progeny I1077-14 x X96-56 was one of a series produced by A. E. Kehr at Iowa State University in 1955 for a study of combining ability for yield (3) . The cross between NIF-1 and 56N18-4 was made by R. L. Plaisted in 1962~ as part of another series of progeny tests (1) .

Resistance of some American potato varieties to the late blight of potatoes

It is now well over a century since the late blight of potatoes struck almost simultaneously with such devastating results on the European and the North American continents. Because of its destructive potentiality, and the economic importance of the potato as a food crop, an intensive search was initiated for the cause and means of control of the new potato disease. Progress, at first, was naturally slow. It had not been determined that fungi could cause a diseased condition in plants. In fact, it was commonly accepted in the scientific circles of the time that the fungus always associated with the new disease of the potato was not the cause but rather the result of a diseased condition. With this type of thinking it was wholly logical to attribute the cause of the potato disease to unwholesome weather conditions during the growth of the plant, or to a degeneration of the potato as a result of continued vegetative propagation by the use of tubers. This last theory, although perhaps amusing in the light of present knowledge, was, nevertheless, very important. I t stimulated the importation and propagation from seed of varieties from South America, the home of the potato, in the hope that vigor could be regained by growing plants from true seed. For all practical purposes, this was the beginning of the development of resistant varieties i.e., the search for a usable source of resistance in existing varieties. The outstanding early American potato breeder who subscribed to the above theory was the Rev. Mr. Chauncey E. Goodrich of Utica, New York. Through the consular service in South America, Goodrich imported several varieties of potatoes. Although he failed to find blight resistance, his influence on subsequent potato breeding in the United States was extensive. He definitely showed that improved varieties could be produced by plant breeding methods (7) . From an imported variety which he called Rough Purple Chili, the Rev. Mr. Goodrich produced the seedling Garnet Chili. This variety, in turn, is one of the progenitors of several of the older American varieties, including Early Rose, Early Ohio, Prolific, Trimnph and perhaps even the Irish Cobbler (3) . Resistance to late blight was not entirely lacking among the American varieties. Evergreen is an outstanding example. This variety, in a numerical classification of resistance fronl 1 to 4, with 4 representing the most susceptible class, was rated as 3 and sometimes as 2 (7). Evergreen, also known by such names as No Blight and Blight Proof, has persisted for vears in Central New York, where, because of its blight resistance and good cooking quality, was grown mainly for home consmnption. With the appearance of new, high yielding varieties and improved methods of late blight control, the popularity of Evergreen has greatly diminished. Within relatively recent years, we have witnessed the introduction