94 MASSACHUSETTS HORTICULTURAL SOCIETY 



Control. 



A. Roses out of doors. The efficiency of sulfur fungicides for 

 the control of rose mildew has long been recognized. Lime-sulfur 

 and other liquid sprays are more or less effective but owing to the 

 time and labor involved in applying spray solutions and to the 

 unsightliness brought about by their use, an efficient dust mixture 

 is preferable. Stewart (11) reports good control of rose mildew 

 by the use of a dust mixture consisting of 90 parts sulfur and 10 

 parts arsenate of lead. A similar mixture was used by the writer 

 in 1917 and it was found to be decidedly more efficient than lime- 

 sulfur solution 1 to 50 or bordeaux mixture 5-5-50. 



A row of Crimson Rambler bushes planted thickly and forming 

 an arbor about five hundred feet in length was divided into four 

 sections of equal length and treated as follows: section 1, sprayed 

 with bordeaux mixture 5-5-50; section 2, sprayed with lime- 

 sulfur solution 1 to 50; section 3, dusted with sulfur 90 parts and 

 arsenate of lead 10 parts; section 4, untreated. 



The first application of dust and spray was made on August 2. 

 Mildew appeared between this date and August 16, when the 

 second application was made. Another application was made on 

 August 25. The experiment was terminated on September 13. 

 On this date the dusted bushes were practically free from mildew, 

 only a few infected shoots being apparent. The bushes treated 

 with bordeaux mixture and lime-sulfur were severely infected and 

 were but slightly less free from the disease than the untreated 

 bushes. Besides its superiority in fungicidal value the dust mix- 

 ture rendered the plants far less unsightly than the bordeaux 

 mixture or the lime-sulfur solution. The latter fungicide appeared 

 to be slightly more efficient than bordeaux mixture. 



B. Under Glass. Florists commonly paint the heating pipes 

 with mixtures of sulfur and lime for the control of mildew, the 

 sulfur being thus evaporated and condensed on the plants where 

 the fungus is killed. Maynard (12) recommends the use of evap- 

 orated sulfur, a small kerosene stove with a thin iron kettle being 

 used and the sulfur kept boiling two or three hours a week in a 

 closed house. Both methods have given good results, the use of a 



