Mail Tribune 100: February 1, 1914
Professor O'Gara has received the following from Professor P.J. Parrott, entomologist of the New York experiment station at Geneva, N.Y.:
"Professor P.J. O'Gara, plant pathologist, Medford, Ore.
"Dear Sir: My attention has recently been called to an article by you showing the comparative cost of the efficient sulphur in sodium-sulphur and lime-sulphur preparations. You doubtless know that this past summer we have carried on a series of experiments with calcium, barium, sodium and potassium polysulphides, testing them on the basis of their sulphur content, namely 13/4 ounces sulphur per gallon in the dormant spray, and from 3-10 to 1-10 ounce of sulphur in the summer spraying. While trees were moderately infested, these different preparations gave quite similar results on the San Jose scale; but when trees were very much infested the calcium and barium preparations were somewhat more efficient. Many of these new sulphur preparations, when used at advertised strengths, were not as efficient as lime-sulphur solution as ordinarily employed, which I attributed to the small amount of sulphur in the diluted preparations. In other words, the compounders of the chemical insecticides, in order to have their preparations compare well with lime-sulphur with reference to cost, were advising their preparations be used at too great dilutions.
"One noticeable result in all our experimental work was that when arsenate of lead was used with the sodium and potassium preparations we had a great amount of foliage injury, resulting in some cases of the complete defoliation of apples, pears and peaches, and occasionally with dropping of the fruit. I thought you would be interested in these results.
"With kindest regards, I am very truly yours,"
"P.J. PARROTT, Entomologist."