78 



SCIENCE 



[N. S. Vol. XXXIII. No. 837 



often severely attacked by the scab fungus, par- 

 ticularly on the nuts, and the crop partially or 

 totally destroyed. The Fusicladium attacks the 

 young leaves as they unfold in the spring. The 

 young leaflets and the leaves are successively at- 

 tacked through the growing season while they are 

 developing. Each leaf and leaflet as it reaches 

 maturity becomes immune, or nearly so, to the 

 fungus infections. The fungus also attacks the 

 young growing twigs, but particularly the nuts. 

 The nuts continue to develop through the summer 

 and remain susceptible until late in September. 



Infections take place at definite periods, namely, 

 the warm, rainy, humid spells that occur so fre- 

 quently in the southeastern states. An interest- 

 ing feature was found in relation to the life his- 

 tory of the disease, namely, that a plant louse 

 which becomes common on the pecan in May 

 punctures the epidermis in a regular way along 

 the veins and veinlets. The punctures of this 

 plant louse are used as points of entrance by the 

 Fusicladium. The fungus can also enter in the 

 direct way and such diseased spots are irregu- 

 larly located over the leaves, fruit and twigs, but 

 the spots due to aphis infections are arranged in 

 regular lines along the veinlets and far exceed in 

 number all other spots on the leaves. The fungus 

 evidently is also assisted in its germination and 

 growth by the honey dew copiously secreted by 

 these aphids. 



Spraying experiments showed that bordeaux 

 mixture controlled the scab thoroughly and is 

 probably the best fungicide for treating it. Di- 

 luted lime-sulphur solution also controlled the 

 scab nearly as well and killed the aphids, thus 

 making it a promising mixture to use, at least 

 in part of the treatments. The unfortunate fact 

 that the nuts remain susceptible throughout the 

 summer makes treatment diflScult and expensive, 

 so th.at four or five, and even six sprayings may 

 be necessary for success. 



Extensive observations through the south by a 

 number of pecan students, as well as the experi- 

 ence of practical pecan growers and nurserymen, 

 have shown that a large number of varieties are 

 reasonably resistant to this disease. These varie- 

 ties have nearly all originated from Louisiana 

 stock, or at least from trees grown in the humid 

 regions adjacent to the Mississippi and the gulf. 

 Since many of the finest paper-shell varieties are 

 commercially resistant to the scab fungus, they 

 should, of course, be selected for cultivation in 

 the humid southeastern states. Furthermore, in- 

 stead of recommending the treatment by spraying 



of the badly scabbing varieties, it is suggested 

 that these varieties, as well as susceptible seed- 

 lings, be top-worked to resistant sorts. 

 Bubams' Flora Pyreruea: Dr. E. L. Greene. 

 W. W. Stockbebqeb, 

 Corresponding Secretary 



THE PHILOSOPHIOAL SOCIETT OF WASHINGTON 



The 40th annual meeting (686th regular meet- 

 ing) was held on December 17, 1910. President 

 Woodward in the chair. 



After hearing the reports of the secretaries, the 

 treasurer and the auditing committee, the annual 

 election for the selection of officers for the calen- 

 dar year 1911 was taken up, and the following 

 officers were duly elected: 



President — ^A. L. Day. 



Vice-presidents — L. A. Fischer, C. G. Abbot, 

 E. B. Rosa and G. K. Burgess. 



Treasurer — L. J. Briggs. 



Secretaries — R. L. Faris and W. J. Humphreys. 



General Committee — E. Buckingham, W. S. 

 Eichelberger, E. G. Fischer, B. R. Green, R. A. 

 Harris, P. G. Nutting, F. A. Wolff, W. A. De- 

 Caindry and J. A. Fleming. 



After the election of ofiicers a buffet luncheon 

 was served. 



R. L. Faeis, 



THE AMEEICAN CHEMICAL SOCIETT 

 NOBTHEASTEKN SECTION 



The one hundredth meeting of the section was 

 celebrated by a dinner held at the Exchange Club, 

 Boston, on December 16. President Wilder pre- 

 sided, and there were one hundred members and 

 guests present. 



The evening was devoted to a consideration of 

 " The Conservation of our Natural Resources." 

 Hon. Curtis Guild, Jr., ex-governor of Massachu- 

 setts, spoke on the conservation of forests for 

 the sake of both timber and water, and he urged 

 the duty of the federal government to provide 

 national reservations in the east as well as in 

 the west. 



Mr. H. M. Wilson, of Pittsburgh, assistant chief 

 of the Bureau of Mines of the Department of 

 Commerce and Labor, described the work of this 

 bureau and dwelt particularly on the progress in 

 the prevention of coal mine disasters and in the 

 care of injured miners. 



Kenneth L. Maek, 



Secretary 



