

342 



[Vol. 9 



GARDEN 



Artificial inoculations clearly indicate that the pathogen enters 

 by means of the natural openings, the stomata and the water- 

 pores. Material fixed in chrom-acetic acid, imbedded in paraffin, 

 sectioned, and stained with carbol-fuchsin has shown substo- 

 matal cavities full of bacteria, which in later stages of infection 

 are surrounded by cells and intercellular spaces which are also 

 full of bacteria (pi. 27, fig. 1). Regarding infection through 

 water-pores it was noted that under certain conditions in the 

 greenhouse, which included an extreme dryness of the atmos- 

 phere, resulting in an incipient wilting accompanied by a clos- 

 ing of the stomata, the few infections obtained occurred at the 

 tips of the leaves, indicating entrance by means of the apical 

 hydathode. This is of interest since it indicates that under nat- 

 ural conditions when stomata are closed, as at night, infection 

 may take place through the water-pores. 



HOSTS AND EXTENT OF INJURY 



Thus far, foxtail is the only grass that has been found infected 

 under natural conditions. This statement may not be of much 

 significance, as the time spent in looking for the disease on other 

 hosts was, by force of circumstance, very limited. The ease with 

 which artificial infections are obtained on a number of wild and 

 cultivated grasses indicates that the pathogen may be looked 

 for on all the common cereals, particularly in the southern states. 

 The following species representing 5 different tribes are suscep- 

 tible, as proved by artificial inoculations: Avcna saliva, Chaeto- 

 chloa geniculates, Chaetochloa italica, Chaetochloa lutescens, Hol- 

 cus Sorghum (Andropogon Sorghum), Holcus Sorghum sudanen- 

 sis, Hordeum vulgarc, Secale cereale, Triticum sativum, and Zea 

 Mays. 



A sufficient number of artificial inoculations and of reisolations 

 have not been conducted with red top (Agrostis palustris) and 

 with goose-grass (Elcusine indica) to warrant any definite state- 

 ment, but preliminary tests would seem to show that these also 

 are susceptible. 



fol 



Chaetochloa 



dis, Festuca elatior, Oryza sativa, and Phleum pratense. 



The disease on foxtail has now been observed in northwest 

 Arkansas for four successive seasons. Specimens have also been 

 obtained from other portions of the state, indicating that the 



