1897.] PUBLIC DOCUMENT — No. 33. 50 



in heat, light, moisture and iu the soil conditions. It is 

 therefore the proper application of these factors which the 

 practical grower has to take into consideration, and his suc- 

 cess in plant growing will depend largely upon his skill in 

 dealing with them. The minute details connected with the 

 application of light, heat and moisture, the judicious use of 

 fertilizers and the bringing of the soil into proper mechani- 

 cal condition, are matters which are now commencing to re- 

 ceive some of the attention which they deserve. 



Diseases entirely or partially due to Parasitic Or- 

 ganisms. 



A Bacterial Disease of the Strawberry (^Micrococcus sp. ?). 



During a hot sultry period which occurred in the month of 

 May, 1895, some diseased strawberry plants of the varieties 

 known as the Sharpless and the Belmont were sent to the 

 botanical department from Fitchburg, Mass., for the purpose 

 of determining the nature of the disease and the remedies for 

 the same. The freshly gathered plants showed by their dark- 

 colored, shrivelled leaves that they had been killed outright 

 in the tield by some unknown cause. 



A careful microscopic examination of the plant proved that 

 there was nothing of an insect or fungous nature to which the 

 trouble could be attributed ; but by making more careful ob- 

 servations of the cell contents of the roots and leaf petioles, 

 numerous bacteria (micrococci) were found, which at least in- 

 dicated a possible cause of the disease. 



At about the same time these specimens were received, 

 the disease made its appearance on many of the strawberry 

 plants in the college plats, resulting fatally to the plants in 

 numerous instances, besides leaving others in a dilapidated 

 condition. The variety which suffered the most in the college 

 plats was the Marshall. 



In order to ascertain whether the two diseases were identi- 

 cal, and whether the bacteria were the specific cause of the 

 disorder, the organisms were isolated, and a number of pure 

 cultures made in the ordinary sterilized nutrient gelatine. 

 In this medium the bacteria developed quite readily, ]iroduc- 

 ing a white, liocculent mass at the bottom of the tul)e. Its 



