I04 Journal of Agricultural Research voi. xix.no. 3 



the College of Agriculture, however, where many kinds of cereal, forage, 

 and cane crops were grown under conditions favoring infection, the downy 

 mildew was found also to attack teosinte {Euchlaena luxurians Schrad.) 

 and sorghum (Andropogon sorghum (Linn.) Brot.). 



With teosinte, the percentage of infection and resulting loss is not quite 

 so great as with maize, and the symptoms are less pronounced (PI. 22, C), 

 since the attacked individuals, especially those showing the disease late 

 in their development, are much less conspicuously marked and are very 

 seldom appreciably deformed, while the conidiophores are more scattered 

 and more scantily produced. 



As might be expected, hybrids resulting from the crossing of maize 

 atid teosinte are also susceptible to the disease, the degree of suscep- 

 tibility and the effect on the plants attacked being intermediate between 

 those shown by the two ancestors. 



In sorghum the percentage of infection is very low, and the few plants 

 infected are easily overlooked, because they turn pale when still very 

 young (PI. 22, B), bear but few conidiophores, and wither and die after a 

 brief period of weak, stunted growth. No cases of individuals more con- 

 spicuously marked or deformed, in which the disease appeared later, 

 were ever seen; and the loss was limited to the destruction of the few 

 attacked plants. 



Cross-inoculation experiments and the biometric study of spores and 

 conidiophores show that the same causal fungus is involved in all these 

 cases. 



In view of this condition, it would naturally be suspected that other 

 members of the Maydeae and Andropogoneae might also prove sus- 

 ceptible to the disease. So far, however, in spite of extensive search, no 

 such Sclerospora, characterized by a conspicuous and rapidly spreading 

 conidial stage, has been found in this region under natural conditions on 

 the many wild grasses related to maize. However, the writer has found 

 on Saccharum spontaneum L., a very common wild grass here, a Sclero- 

 spora which although of very frequent and widespread occurrence 

 produces only the characteristic thick-walled resting spores. Further 

 description of this Sclerospora will be given in a later paper, but it should 

 be said at this point that this oogonial form on wild grass does not appear 

 to be connected with the conidial form growing on cultivated maize, 

 sorghum, and teosinte. 



Moreover, inoculations such as were successful in the case of maize, 

 sorghum, and teosinte have so far failed to accomplish the transfer of 

 the disease to other related Gramineae — namely, Coix lachryma-jobi L., 

 Philippine, United States, and Hawaiian strains; Coix ma yuen, Philip- 

 pine and United States strains ; several varieties of sugar cane {Saccharum 

 officinarum L.), uba or Japanese cane (Saccharum sp.), and the native 

 grasses, cogon (Imperata cylindracea L.), anias {Andropogon sorghum, 

 var, halepense L.), and aguingay {Rottboellia exaltata L.)- In view of the 



