1900.] PUBLIC DOCUMENT — Xo. 33. 59 



The Chrysanthemum Rust. 

 This disease, which we first reported in 1897, appears to 

 be on the decline in Massachusetts. It has been quite com- 

 mon the past season in various places, but in most cases has 

 caused no apparent damage. 



Some Experiments in growing Violets in Sterilized 



Soil. 



Some experiments have been made this last year with 

 violets, for the purpose of determining the relation be- 

 tween the production of flowers and the occurrence of leaf 

 spots in sterilized and unsterilized soil respectively. For 

 this purpose cuttings were made in the spring from mature 

 plants and put into sterilized sand, after which they were 

 transplanted into sterilized soil and removed out of doors, 

 where they remained during the summer. In the fall they 

 were transferred to the house and planted in a bed divided 

 equally into two sections, each of which consisted of garden 

 soil of good quality. One section of the bed was sterilized 

 and the other section was not, and, in addition to this, the 

 latter was inoculated with the parasitic nematode Heterodera. 

 It should be stated, however, that the nematodes were not 

 abundant enough in the inoculated soil to do any harm, as 

 the bed was inoculated some time previous to setting out 

 the violet plants, and, as no host plants were present, they 

 died, or at least they did not gain any foothold upon the 

 violets. The experiment is therefore largely one between 

 sterilized and unsterilized soils. 



Sterilizing the soil alone gives rise to beneficial results in 

 the growth of a crop, a fact which we have already called 

 attention to in Bulletin 55, issued from this station, and 

 various experiments on different crops since has demon- 

 strated the same thing. 



Both of the beds were under tolerably equal conditions, 

 at least so far as light and moisture were concerned ; but a 

 ventilator made some difference in the growth of a few plants 

 in each section. The total number of plants employed in 

 this experiment was fifty-four, and were of the variety known 



