THE ASPARAGUS RUST. 



141 



300 times are shown by 

 Fig. 2038. 



In the Wheat Rust the 

 uredospores are multiplied 

 rapidly, by reproduction of 

 the same torm many times, 

 until near the time of ripen- 

 ing of the grain ; then the 





Fig. 2035. 



Fig. 2036. 



fungus plants, apparently aware of the neces- 

 sity of prov^iding a thicker walled spore for 

 the winter, cease to grow uredospores and 

 instead produces a crop of teleutospores. 

 In the Asparagus Rust the uredospores are 

 not multiplied by reproduction ; that is, they 

 do not become plants producing more rust, 

 more uredospores, but, shortly after the 

 yellow rust appears on the stalks, the black 

 teleutospores are to be found in the same 

 pustules, thus completing the cycle. 



What this parasite accomplishes in the 

 way ot mischief is done by the power of 



Fig. 2037. 



numbers. Shall we count the spores to be 

 found on a piece of asparagus stalk not more 

 than three inches long as presented in Fig. 

 2035 ^"'^ interpreted by Fig. 2037, and tell 

 how many they be ? Such is the host with 

 which we have to contend now on the war 

 path : infinitesimal in size, infinite in num- 

 ber, "horsed upon the sightless couriers of 

 the air" it comes as destructive, if not as 

 " terrible as an army w'ith banners," and we 

 are powerless to stay its coming. Spraying 

 with fungicides is in this instance of doubt- 

 ful utility, for such is the foliage and smooth- 

 ness of the epidermis of asparagus that it is 

 well nigh impossible for the fungicide to 

 effect a lodgement. Nevertheless we should 

 be able to stamp out the enemy by united 

 action of asparagus growers in cutting off 

 at the ground every afi^ected 

 stalk, as soon as, by its 

 change of color it is shown 

 to be no longer of service 

 to the plant, and burning 

 them forthwith ; for, if the 

 teleutospores are destroyed 

 before they are dislodged 

 from the stocks where they are formed, then 

 there can be no sporidia in the spring to breed 

 Rust. The importance of united action 

 should be apparent to all, and the import- 

 ance of burning the teleutospores while yet 

 in the stalk will be seen when it is under- 

 stood that the teleutospores produce sporidia 

 without reference to any particular place, 

 but do so wherever they chance to be if only 

 there be the requisite atmospheric conditions. 

 The writer desires to acknowledge his in- 

 debtedness to Professor Byron D. Halsted, 

 of the New Jersey Experiment Station, 

 whose valuable paper on the Rusts of Horti- 

 cultural Plants has been largely drawn upon, 

 as published in the Transactions of the 

 Massachusetts Horticultural Society for 

 1900, and the accompanying figures copied 

 to illustrate this paper. 



D. W. Beadle. 

 207 Givens Street, Toronto. 



Fig. 2038. 



