306 PATHOLOGY [BoT. Absts., Vol. VIII, 



ism, but these have not yet been successful. It is thought that a species of Heterodera is 

 primarily responsible. — C. V. Piper. 



THE PATHOGENE (BIOLOGY, INFECTION PHENOMENA, DISPERSAL) 



2100. Harvey, R. B. Destruction of zoospores of plant disease organisms by natural 

 enemies. Science 52: 84. 1920. — In making motion-picture photomicrographs of the libera- 

 tion of zoospores from the sporangia of Physoderma zeae-maydis, the author observed destruc- 

 tion of the zoospores by certain animalcules which are commonly found in decaying vegetable 

 material. The number of zoospores swallowed by one rotifer (Proales sp.) is very large. 

 In starting with dry material collected from corn stalks infested with Physoderma, the animal- 

 cules appear first, and are on hand for each crop of zoospores. — A. H. Chivers. 



2101. Ravaz, L. Rapport sur le fonctionnement de la station d'avertissements agricoles 

 de Montpellier, en 1918. [Report of the Agricultural Experiment Station of Montpellier, 1918.] 

 Ann. Ecole Nation. Agric. Montpellier 17: 131-167. Fig. 1-27. 1918 [1919].— The main part 

 of the report is devoted to work with grape mildew (Plasmopara viticola). Temperature and 

 humidity are considered the most important factors concerned in the development of this dis- 

 ease, and for this reason meteorological data are reported from various points in the grape- 

 growing section. A minor part of the report consists of observations made on black rot 

 [Guignardia bidwelUi] and insects. A historical review of the station is also given. — F. F. 

 Halma. 



2102. Shunk, I. v., AXD F. A. Wolf. Further studies on bacterial blight of soybean. 

 Phytopath. 11: 18-24. Fig.l. 1921.— A comparison of the pathological symptoms of the bac- 

 terial blight of soybean {Soja vmx) described by Coerper in Wisconsin and that described 

 by Wolf in North Carolina has shown only minor differences in the appearance of the diseased 

 spots; but differences in the reactions and growth characteristics on various culture media 

 were sufficient to prove the causal organisms distinct. The two diseases, one produced by 

 Bacterium glycinum Coerper and the other by B. sojae Wolf, are found in Wisconsin, but only 

 the one produced by the latter organism has been found in North Carolina. — B. B. Higgins. 



2103>. Thomas, H. E. The relation of the host and other factors to infection of Apium 

 graveolens by Septoria apii. Bull. Torrey Bot. Club 48: 1-29. 1921.— The idea of specificity 

 in the relation of plant parasites to their hosts is coming to be one that must be reckoned with ; 

 the obligate parasite is restricted in its host range and a slight change in either host or fungus 

 may completely change the virulence of the parasite or its effect on the host. Data are pre- 

 sented in this paper to show that the infection of Apium graveolens by Septoria apii is favored 

 by conditions which accelerate the growth of the host. Work with many hosts showed a high 

 degree of specialization on the part of the parasite in its inability to cause infection. Experi- 

 ments were conducted on host plants treated with various solutions to produce different 

 degrees of health and vigor. Plants suffering from nematodes, and etiolated plants, were 

 also used. The parasite's development was favored by increased growth in the host and 

 showed a high degree of specialization. This specialization suggests promise for experiments 

 in breeding for resistance. — P. A. Munz. 



THE HOST (RESISTANCE; SUSCEPTIBILITY; MORBID ANATOMY AND 



PHYSIOLOGY) 



2104. ScHLUMBERGER, O. Pflanzenschutz und Sortenfrage im Kartoffelbau. [The ques- 

 tion of varieties and disease resistance in potato culture.] Ftihling's Landw. Zeitg. 69 : 144-149. 

 1920. — A general discussion of the problem of obtaining disease-resistant varieties of potatoes 

 is presented. Pathological investigations of potato diseases and physiological studies of 

 diseased and disease-resistant varieties or individual plants to determine the underlying 

 causes of resistance or susceptibility to disease should be carried on in a systematic way to 



