John S. Niederhauser

Observations on races ofPhytophthora infestans in Mexico during 1956–1957

SummaryIn 1956 a high proportion of races0, 1, 2 and4 were found on varieties ofSolatium tuberosum lacking genes for resistance to late blight. More highly specialized races, such as1.2.4, 1.3.4, and1.2.3.4, were obtained from lines of S.demissum and from hybrids ofS. demissum xS. tuberosum.In 1957, races0 and4 were isolated fromS. demissum found in the Rio Frio area of Mexico. Race0 was obtained from an “r”-type clone ofS. demissum in the Santa Elena Experiment Station in the valley of Toluca.Seedlings resistant to race1.2.3.4 ofS. bulbocastanum yielded isolates of the pathogen identified as races4, 2.4, and3.4, which indicated the presence of new races of this species.Intraspecific variation in the degree of field resistance against late blight was noted among clones ofS. cardiophyllum, S. oxycarpum, S. stoloniferum, S. demissum andS. bulbocastanum.

The Potato Association of America and International Cooperation 1916–1991

ConclusionsThe PAA can take jusifiable pride in the history, contributions, and current role of its members in international cooperation. The future opportunities for continuing and expanding this international cooperation constitute a major challenge to the PAA and its membership as we proceed into the next decade and the next millenium.

Bibliografia Latinoamericana Sobre Papas by Alvaro Montaldo

This is a comprehensive bibliography listing 1899 Latinamerican publications on potato research. The references are arranged alphabetically by author, with an arbitrary closing date of 1962. A list of the libraries which provided the basis of the bibliography is included, as well as a list of the journals, bibliographies, and other publications that were consulted. Eleven appendices and an index complement the main text, and include:

Abstracts of papers presented at Annual Meeting

HEILIGMAN, F., AND I. R. W A G N E R EFFECTS OF CHLORO-IPC ON SPROUTING AND LOSSES IN WHITE POTATOES DURING STORAGE The use of 3-Chloro-lsopropyl-N-Phenyl Carbamate (Chloro-IPC) reduced losses in white potatoes stored at 55, 72, and 85 ° F. when compared to untreated controls. The material was effective when used as a dip, as a spray, or when incorporated in water emulsion potato wax. The treatment controlled sprouting and reduced weight losses during storage. There is some evidence that the material may have some indirect effect in controlling losses caused by microbial decay. H O Y M A N , WM. G. COMPARATIVE REACTIONS OF ATTACHED AND DETACHED LEAVES TO P H Y T O P H T H O R A I N F E S T A N S Thirty potted potato selections 6 to 12 inches in height and detached leaves from them were simultaneously inoculated with zoospores from a culture of race 0. The inoculations were made in a plastic-covered chamber at 70 ° F. and 100 per cent relative humidity. The reaction of each of the 30 selections was recorded as soon as symptoms appeared and the final reading was made the eighth day following inoculation. Sporulation occurred on attached and detached leaves of 8 selections. Sporulation also occurred on the attached leaves of one selection, whereas the reaction of the detached leaf consisted of large lesions. The symptoms on both types of leaves of the 3 selections consisted of necrotic spotting. The attached leaves of 4 selections showed no symptoms, whereas the detached leaves showed definite necrotic spotting. No reaction was evident on leaves of 14 selections.