No. 2, September, 1920] PATHOLOGY 267 



2037. Era, A. A. The true nature of plant diseases. Amer. Bot. 26: 20-23. 1920.— The 

 author contends that in favorable situations plants produce substances thai render them 

 resistant to disease ami thai if horticulture is properly conducted the plants will ward off 

 disease by becoming immune. — W. N. CI 



2038. Felt, E. P. New Philippine gall midges. Philippine Jour. Sci. 14: 287-294. 1919. 

 —This paper is supplemental to one published in the Philippine Journal of Science for 1918. 

 It describes the gall midges and their food habits, but the appearance of the galls is left for 

 a subsequent paper.- -.Mix rt R. Si 



2039. Ferdinandsen, C, and O. Winge. A Phyllachora parasitic on Sargassum. Myco- 

 Logia 12: 102-103. 9 fig. 1920.— See Bot. Absts. 5, Entry 1941. 



2040. Fletcher, J. J., and C. T. Musson. On certain shoot-bearing tumors of Euca- 

 lypts and Angophoras, and their modifying influence on the growth habit of the plants. Proc. 

 Linnean Soc. New South Wales 43 : 191 233. PI. 4~26. 1919.— See Bot. Absts. 5, Entry 1888. 



2041. Foex, Et. Note sur une maladie du poirier. [Note on a pear disease.] Bull. Soc. 

 Path. Veg. France 6: 102-104. Sept. -Oct., 1919. — A canker on pear branches in France is 

 described and regarded as identical with the disease described by Griffon and Maublanc. 

 Diplodia griffoni Sacc. or Sphaeropsis pseudo-diplodia Fckl., the pyenidial form of Physalo- 

 spora cydoniac, was found on the cankers and is regarded as the cause. Cutting out of cankers 

 and spraying with Bordeaux are recommended. — C. L. Shear. 



2042. Foex, Et. Au sujet dun epi de ble partiellement charbonne. [Regarding a partially 

 smutted head of wheat.] Bull. Soc. Path. Veg. France 6: 105-106. 1919. — A case is reported 

 in which a head of wheat showed the lower spikelets smutted by Ustilago tritici and the upper 

 apparently healthy. Three of the unsmutted grains were grown and produced plants free 

 from smut. It is suggested in explanation that the apparently sound spikelets escaped infec- 

 tion or the infection remained dormant. Peglion is cited as having examined similar cases 

 partially smutted by Tillet%a caries without finding traces of mycelium in the unsmutted 

 spikelets. A thorough microscopic examination of such cases is necessary in order to deter- 

 mine with certainty whether a partial or undeveloped infection has taken place. — C. L. Shear. 



2043. Foex, Et. Note sur une maladie de l'orge et de l'avoine. [Note on a disease of rye 

 and oats.] Bull. Soc. Path. Veg. France 6: 118-124. Nov. -Dec, 1919. — A disease of oats and 

 rye somewhat resembling foot rot is described. A species of Fusarium was found on the dis- 

 eased stems. This was compared with F. rubuginosum and other species reported on grain 

 but no positive identification made. Soil sterilization and burning of all diseased plants 

 are suggested as control measures. — C. L. Shear. 



2044. Foex, Et. Quelques remarques au sujet de la presence de peritheces de Phyllac- 

 tinia corylea sur des feuilles de Chene atteintes de "Blanc." [ Note on the presence of peri- 

 thecia of Phyllactinia corylea on oak leaves affected with powdery mildew.] Bull. Soc. Path. 

 Veg. France 6: 161-166. 1919.— Oak leaves having all the appearance of the mildew attributed 

 to Microsphaeria quercina were found to bear perithecia of Phyllactinia. Certain peculiari- 

 ties of the walls of the hyphae of the mildew on the leaves known to occur in Microsphaeria 

 but not in Phyllactinia lead the author to believe that the perithecia found were not pro- 

 duced on the oak leaves but blown there from some other host. — C. L. Shear. 



2045. Greene, Latjrenz, and I. E. Melhus. The effect of crown gall upon a young apple 

 orchard. Iowa Agric. Exp. Sta, Res. Bull. 59: 147-176. 8 pi, 3 fig. 1919.— This bulletin 

 deals with the effect of crown gall on a young orchard up until the bearing age. Infected 

 trees were selected and planted on a modified Missouri loess type of soil. The observations 

 extended over a five years period. Crown gall effects were determined by measurements of 

 the trunk diameter, and by consideration of the twigs, their number, length, thickness and 

 weight. The large galls were more injurious than the small ones and those on the stock and 

 union were more harmful than those on the secondary growth. — /. E. Melhus. 



