The Research and Marketing Act project initiated last year, on Soil Erosion Control and Stable Crop Production, was strengthened by increased financial support and another project, Establishing a Cooperative National Research Program to Develop Practical Methods and Equipment for Weed Control, was started during the year. The investigations undertaken under the latter funds were directed primarily at solving problems of fundamental importance in the field of weed control.
These included studies of environmental factors affecting the persistence of herbicides in the soil and studies to determine the biochemical basis for the action 2,4-D in plants. Important contributions have been made during the year by the insecticidal-plant section, in establishing a close correlation between total chloroform extractives and rotenone and toxicity assays of Derris roots. This correlation has been shown to hold not only for clones grown in Puerto Rico, but also for those grown in Nicaragua. Since evaluations for rotenone and total toxicity are tedious and expensive, the establishment of the correlations is important for evaluation studies.
The plant-breeding section achieved significant progress in making a large number of crosses between Jersey and moist-flesh varieties of sweetpotatoes. The Jersey varieties, though grown widely in the Middle-Atlantic States and in the Midwest, flower rarely or not at all on the continent. Three Jersey varieties were brought to flower at Mayagüez during the year and were crossed with various other varieties. These crosses will make possible varietal improvement in both major groups of sweetpotatoes— by introducing badly needed Fusarium-wilt resistance into the Jersey varieties, and by introducing superior setting and root characters into the moist-flesh varieties.
The horticulture group, in addition to initiating the cooperative cotton investigations, has completed important publications on tropical vines and shrubs. The entomologist also issued important publications on the coconut rhinoceros beetle and on Cinchona pests and their control.
The following changes occurred in the Federal Staff during the year: Thomas Theis was appointed plant pathologist on April 6. 1949. Roberto Ferrer Delgado was transferred from agronomist under insular funds to scientific aide under Federal funds.
There were several changes during the year in the personnel employed on funds provided by the Government of Puerto Rico. Filiberto Montalvo Durand was appointed to the position of agronomist on November 1, 1948. Hector R. Cibes Viadé resigned as agronomist on November 30, 1948, to take graduate work at Rutgers University.
The vacancy was filled by Felix A. Jimenez, appointed April 1,1949.
The Government of Puerto Rico continued to support certain station activities. The Insular Legislature appropriated funds amounting to $45,000 for the Federal Experiment Station to carry out cooperative experimental work on problems of particular interest to Puerto Rico, including investigations on vanilla, spices, weed control, essential oils, and bamboo.
