1902.] PUBLIC DOCUMENT — No. 33. 67 



These are the stem rots of the chrysanthemum, carnation and 

 aster, all of comparatively recent occurrence, but becoming 

 more and more serious each year. 



Chrysanthemum Stem Rot. — This disease has been known 

 in Massachusetts only during the past two years, but has 

 rapidly increased, and is considered by many growers as 

 the most serious trouble threatening this important plant. 

 It is characterized by a slow fading and withering of the 

 leaves, beginning towards the bottom and gradually working 

 up the stem. The flower develops poorly or not at all, and 

 the whole plant finally dies prematurely. The cause of the 

 disease is a fungus which grows in the stem and fills up the 

 large ducts or vessels through which the water must pass in 

 coming up from the roots. The development of this fungus 

 has not yet been closely followed ; but, since it is a species 

 of Fusarium, similar forms of which cause like diseases in 

 other plants, there can be but little doubt that the plant is 

 first attacked from the soil, whence the fungus spreads into 

 the stem and on up through it to a considerable height. As 

 the pores become more and more clogged with the fungous 

 growth, the water supply to the leaves is diminished, and 

 consequently they gradually die and wither away. It is 

 noticeable that this disease appears most commonly as a re- 

 sult of conditions favoring "damping off." Where young- 

 plants are crowded in flats or beds, those in the centre are 

 generally the ones to show the trouble. This is likewise 

 true with the other diseases of this class mentioned here, 

 and such conditions should be avoided. The soil is to be 

 looked upon as the chief source of infection in all such 

 troubles. There is no danger of contagion in well-rooted 

 plants by spores in the air, as with rusts, mildews and simi- 

 lar diseases. Healthy propagating stock, fresh soil, or that 

 which has been sterilized,* and hygienic conditions, are the 

 most effectual means of controlling such a trouble as this. 



Carnation Stem Rot. — This disease has been longer and 

 more generally known than that of the chrysanthemum, but 



* One florist who grew 125,000 chrysanthemums sterilized the soil in ten houses, 

 200-300 feet long and 20-30 feet wide. Three and one-half houses, 300 feet long 

 and 18-40 feet wide, in which carnations are growing, were also sterilized. The 

 result of this experiment has not as yet been ascertained. 



