EXrElUMi:XT STATION KEPOHT. 527 



upon mulberry only, one upon the vines, American ivy and grape, 

 two others upon the hackberry only, and the most common species 

 of all {Uucinida Salicis DC.) is limited to poplars and willows. 



Remedies for the Pow^dery Milde^irs. 



The powdery mildews were among the first economic fungi to be 

 systematically combated by substances inimical to them. 



Until 1880 sulphur was the substance that was used for this pur- 

 pose and with good results, particularly for the mildew of the vine, 

 then known as Oidiiun Tucheri, and of the rose and other susceptible 

 plants under glass. The sulphur was applied as a powder, dusted 

 in various ways upon the plants, and by means of the fumes which 

 slowly arose the mildew was checked in its growth or killed. The 

 methods of application are many. Professor Maynard* uses '"evapo- 

 rated sulphur," as follows: "A small kerosene stove, with a thin, 

 iron kettle was used, and the sulphur kept boiling two or three hours 

 thrice each week, when the house was kept closed. Care must be 

 taken that only enough heat is used to boil the sulphur and that it 

 is not set on fire." 



It is thought by many to be more convenient to apply the remedy 

 as a spray, and for this purpose any of the standard fungicides may 

 1)6 employed. The Bordeaux mixture, while effective, is not to be 

 recommended for indoor plants like roses, as it leaves a discoloration 

 of lime that is objectionable. 



During the past two winters the experiments with kerosene emul- 

 sion indicate that this compound is effective and at the same time 

 does not leave any stain upon the treated plants. A statement of 

 these results is given in a recent buUetinf from this department. 



As an illustration of the susceptibility of the powdery mildews to 

 the toxic effects of fungicides, the following experiment is cited : The 

 plants involved in the trial consisted of twelve seedlings of the Drum- 

 mond phlox, each in a separate flower-pot. Six of these, six plants 

 in every way as nearly equal as possible to the other six, w'ere sub- 

 jected to treatment, while the duplicate half dozen were placed along- 

 side and subjected to all surrounding conditions, oxce])ting the single 

 one, of the spraying the first six received. 



♦Treatment of Mildews upon Plants Under Glass, .Journal Mycology, Volume 

 VI., pages 16-17. 1891. 



t No. 157. Some of the Newer Fungicides, June, 1903. 



