226 EXPERIMENT STATION RECORD. 



"(2) Tliere is iio evidence tu show that the second kind of wheat rust, T'uccima 

 gram'iulu, survives the; winter here, either in the mycelial condition or in the uredo 

 stag(!, thougli it may do so further south. 



" (8) A series of inoculation experiments shows that both wheat and oats are easily 

 infected by rust from the same kind of grain, but not by the same kind of rust from 

 other grains; e. g., wheat is infected 1)y rust from wlieat, but not by rust from oats, 

 corn, or blue grass. Hence there is little danger of infection from one kind of grain 

 to. another. 



"(4) The spraying experiments show that certain fungicides, as potassium bichro- 

 mate and ferric chlorid, are effective in jjreventing rust, but that with our present 

 knowledge concerning methods of spraying it seems impossible to sufficiently cover 

 the foliage. For this reason, although the rust can be largely decreased, we can not 

 attain prevention, as is done in such diseases as the grape mildew. Furthermore, it 

 is extremely doubtful if spraying of wheat or oats would pay, even if effective. 



"A more promising plan is the breeding of varieties of grain which shall be rust 

 resisting — the so-called ' rust-])roof ' varieties." 



A new disease of wheat, A. Pbunet {Gompt. Rend., 119 [1894), 

 No. 1, pp. 108-110). — In certain districts in southwestern France tliere 

 lias appeared a formidable disease of wlieat causing very serious loss, 

 tlie complete measure of which can not be estimated even at harvest 

 time. The disease is characterized by a checked growth, and after 

 some time the upper leaves turn yellow and dry up. The growth 

 becomes irregular and one may lind in the same field diseased culms 

 10 to 12 cm. high among normal ones. The yellowish or dried culms 

 are more or less stunted, forming patches of greater or less extent 

 in the fields. The disease is caused by a parasitic fungas of the fiimily 

 Chi/triiUacece. The zoospores, as in all members of this group, are 

 motile and penetrate the tissues of the wheat, piercing the walls of the 

 surrounding cells. Upon germination they produce a branched inter- 

 cellular mycelium composed of very delicate filaments of pure proto- 

 plasm, spreading widely, and difficult to distinguish. Here and there 

 the filament swells, forming a terminal or intercalary sphere furnished 

 with a nucleus and representing a zoosporangium. After having been 

 formed the zoosporangia are surrounded by a thin membrane, growing 

 within which are the spores, ordinarily ovoid or pyriform according to 

 the walls of the cells containing them. The mycelium usually disap- 

 pears before the zoospores attain their full growth. The mature spo- 

 rangia are 15 to 50 pi in diameter. The zoospores which are at first 

 angular, become spherical, furnished with a refractive nucleus and a 

 ciliuin. The average diameter of the sj^ores is about 3 //. After the 

 zoospore has become attached to a cell wall it develops a filament 

 which penetrates the neighboring cells, spreading to form new zoiispo- 

 rangia. The generations of the fungus increase rapidly in all parts of 

 the plant, root, stem, leaves, and fiowers. In the ovules its presence 

 causes a more or less complete abortion of the ovule. The number of 

 the zoosi)orangia contained in a cell is variable, although very numer- 

 ous, 19 having been c(muted in a single cell. They are found in all 

 tissues, even in the thick- walled sclerenchyma, or on the epidermis, 

 where the zoospores spread the disease. 



