BLACK STEM RUST OF OATS. 



63 



Tablk 10. — Inoculation experimeHta with Uredo (/raminis avencv — Continued. 



Date 



ofinocii- 



latiun. 



riaco where experi- 

 lueuts were made. 



1897. 

 Sept. 7 



Do... 

 Dec. n 



Orijiin 

 j of inocu- 

 lating 

 material. 



Manhattau, Kaiis . 



do 



I^incoln, Nebr 



Do. 



.do 



VaclyUs 

 glom- 

 erata. 



...do ... 



Arrhen- 

 athc ■ 

 r u tn 

 el al- 

 ius. 



...do ... 



Plant inoculated. 



Period 

 of incu- 

 bation 

 (day.s). 



Oats 



Dactylis glomerata . 

 0at3 



Rye. 



1898. 

 Jan. 5 

 Do... 

 Jan. 24 



Do. 

 Do. 



.do 

 .do 

 .do 



.do 

 .do 



Oafs . 

 ...do 

 ...do 



Oats ... 

 Wheat 

 Data ... 



.do 

 .do 



Wheat 

 Oats .. 



8 

 12 



12 



21 



21 

 12 



12 

 9 



Result. 



Successful. 



Do. 

 Do. 



Negative. 



Successful. 

 Ncnjative. 

 Ouly one or 

 two spots. 

 Negative. 

 Successful. 



Inoculations with this rust were successful on a greater number of 

 hosts than inoculations with any other rust. Of course, as in the case 

 of Uredo coronata, some of the e.xperimeuts might not have proved 

 successful with older plants, but nevertheless a number of inoculations 

 on older jdants also produced infections. On the other hand, in the 

 case of Etampes oats, under date of March 12, 18!)0, and in a few other 

 cases, the plants were inoculatedjust after germination upon damp cot- 

 ton, but evidently were too young to be affected, the germ threads of the 

 spores having ceased to grow before the first leaf was accessible. 



An interesting feature of these experiments is the number of in- 

 fected plants that belong to species of allied genera or to species that 

 are rather similar in structure, and their close correspondence with 

 those infected with Uredo coronata, as shown in Table 6. 



The first forage grass proved to be a host for this rust in this coun- 

 try was Dactylis glomeratct. On account of its susceptibility to infec- 

 tion, both when young and in an advanced stage, the writer for some 

 time believed it to be a host for this rust. On August 2, 1897, both 

 uredospores and teleutospores of the rust were found in great abund- 

 ance on this grass on the grounds of the agricultural college at Still- 

 water, Okla.' A rusted i^lant was transferred from these grounds 

 to the greenhouse of tlie Agricultural College at Manhattan, Kans. 

 Material from this plant easily infected other plants of orchard grass 

 and oats, producing sori on oats more vigorous than those from mate- 

 rial of the same rust taken from oats. The rust was found on Arrhena- 

 theruni elatlus at Lincolu November 16, 1897, and the reverse infectious 

 on oats from this material were produced December 23, 1897. 



On the basis of experiments and observations made so far the follow- 

 ing may be named as well-established hosts for the black stem rust of 



' He had, of course, seen the rust on orchard gra.ss several times before, as it is 

 rather common, but had always supposed it to be e(|uivalent to the form on wheat. 



