40 MASSACHUSETTS HORTICULTURAL SOCIETY. 



and destroy them. The fungus is carried over by the common 

 round-leaf mallow so it is desirable to eradicate all these plants 

 in the vicinity. 



Treatment of soil to eliminate disease germs. Steam steriliza- 

 tion of the soil has given good results in the destruction of disease 

 germs and injurious insects. Also the use of formalin can be 

 recommended; one part to one hundred, sprayed on with a sprink- 

 ling can, a gallon to the square foot. Carbon bi-sulfide kills 

 insects in the soil, but formalin seems to be as effective as anything 

 against fungi. 



