12 1 2 DISEASES OF VARIOUS CROPS 



ter Tannenzapfen ", " Vater Rhein " and " Wohlgeschmack ". Part of 

 the varieties were slightly attacked and part strongly (more than 50 % of 

 the tubers) . The soil of the plots was no doubt less infected by the parasite 

 than that of the plots used for the disinfection tests. This year, the experi- 

 ments will be repeated on a larger scale with those kinds which were found 

 immune in 191 5. 



III. — Vitality of the dormant spores of the fungus in the soil when the 

 host is not cultivated thereon. — Previous observ^ations have shown that 

 the dormant spores of Chrysophlyctis endohiotica Schilb. retain their germina- 

 tion capacity in the soil for 6 years. By way of checking this observation, 

 the Writers acquired from the town of Kronenberg a field which was greatly 

 over-run b)- the parasite, and which for that reason had not been cultivated 

 from the end of the 1907 growing period till the spring of 1915. Two plots 

 of the field were ploughed, situate at two separate points, and in the 15th 

 April 1915 they were planted with the " Industrie " potato variety. On 

 gathering the crop, a very strong infection was found on both plots. It clearly 

 follows from this that the dormant spores may retain their vitality in the 

 soil for 7 5'ears. This 3^ear other plots in the field will be planted with po- 

 tatoes, and the operation will be repeated subsequently in order to deter- 

 mine the time the dormant spores retain their vitality. 



For practical agricultural purposes, it follows from these experiments 

 that fields invaded b}' the parasite should not be put°down to potatoes be- 

 fore thefexpiry of a period of 7-8 years, and it is even probable that the 

 vitality of the parasite lasts still longer. 



DISEASES 9.^4 - Phytophthora sp. Injurious to Oats in America. mc murphy j.ames, in 



OF VARIOUS Science, New Series, Vol. Xlylll, No. I\', p. 534. I^ancaster, Pa., 1916. 



CROPS Specimens of oats attacked by an unidentified species of Phytoph- 



thora were discovered in the vicinity of the University of Stanford and near 

 Ma>^eld in California. Symptoms of the disease : spots and stripes of 

 different sizes along the edges, or a long stripe running along the central 

 Hne of the leaf. The parts attacked are first yellow, then whitish (when the 

 conidia are abundant) ; finally they become brown, dry and break up. 



The conidiophores, which are short and simple, emerge through the 

 opening of the stomata and generally carry a single conidium. Chlaniy- 

 do.spores and oospores were likewise found in abundance on the infested 

 parts. 



In regard to these characters, this Phytophthora approximates to P. 

 Colocasiae a parasite of " taro " {Colocasia esculenta), in Java, India and 

 Formosa. 



940 - Potato Diseases in the Dutch East Indies. — westerdi jk j . , in Tcysmannia, 



XVIIlh Year, Isl ami Ilnd Parts, pp. 1-15, I PI. Batavia, ioi6- 



The Writer was able, during his sta}' in the Dutch East Indies, to 

 study the cultivation of potatoes in Java, where it is carried on in the mount- 

 ains, at an altitude of 1300 to 6500 feet. 



While the few F,uropean growers devote all the necessary care to this 

 cultivation, the nati\'es use seed potatoes, too small in size to be of any value 



