SCHIZOMYCETES. BACTERIA m 



alkaline agar (22 Fuller's scale) colonies are circular, pale to wax 

 yellow in color, margin entire. On potato there is a copious, flood- 

 ing growth, with no browning of the substratum, and no odor. No 

 acid is produced. All liquid cultures become gradually alkaline. 



The optimum growth is believed to be at 25 to 30 C., and 

 growth is feeble at 5 and 7 C. and at 37 and 38 C. It is killed 

 by an exposure of ten minutes at 51 C. It differs from Pseudo- 

 monas Hyacinthi, to which it is related. 



It is believed that this organism is able to pass the winter in 

 the soil of fields in which it has been abundant. The suggestion 

 has also been made that it may be disseminated through compost 

 when cabbage refuse has contributed to the compost heap. Re- 

 cently it has been demonstrated that some of these germs are able 

 to live over on the seed for at least a year. 



Control measures. The most dangerous sources of infection are 

 the infested fields and the seed beds. Seed beds should be watched 

 carefully, and no suspicious plants used. A rotation of crops is 

 the sole means of eradicating the organism from a field once in- 

 fested. Insects, snails, etc., may spread the disease to some extent. 

 When leaves only have become infected, picking these and burn- 

 ing them may be of service, although in most instances this method 

 has proved a failure. Seed treatment (mercuric bichlorid I to 1000, 

 fifteen minutes ; or formalin I to 200, twenty minutes) is advised. 



III. WILT OF SWEET CORN 

 Pseudomonas Stewarti Erw. Smith 



STEWART, F. C. A Bacterial Disease of Sweet Corn. N. Y. Agl. Exp. Sta. 



Built. 130: 401-412. pis. 1-4. 1897. 

 SMITH, ERW. F. Notes on Stewart's Sweet-Corn Germ (Pseudomonas steivarti 



n. sp.). Proc. Am. Assoc. Adv. of Sci. 47: 422-426. 1898. 

 SMITH, ERW. F. U. S. Dept. Agl., Div. Veg. Phys. and Path. Built. 28: i- 



153. 1901. 



This disease was first discovered in the market gardens of Long 

 Island, where much damage was done to sweet corn, Zea mays. 

 It has since been found in Iowa and reported from parts of New 

 York, so that it is doubtless widely spread. It is entirely distinct 

 from the disease of field corn described by Burrill. 1 



1 Burrill, T. J. A Bacterial Disease of Corn. 111. Agl. Exp. Sta. Built. 6 : 

 165-176. 1889. 



