Parasitic Fungi of Illinois. 



395 



roses, hops, gooseberries, raspberries, grapes,* and of many 

 ornamental plants and trees, is caused by different species of 

 this family. As their development is superficial, they are 

 easily reached by remedial agents. Sulphur has long been 

 successfully used to check the ravages of the grape mildew, 

 and as a^ remedy for rose mildew in greenhouses. Its use is 

 often indiscriminately recommended for any and all of these 

 diseases, but the caution should be added, that, in some cases, 

 the host plant suffers more from the sulphur, as usually 

 applied, than from the parasite. The fact is, that each case 

 needs careful practical study before a remedy can be safely 

 recommended. More recently sulphate of copper has come 

 into extended use for the destruction of various fungous 

 parasites. The crystals may be dissolved in water — one pound 

 to two gallons — and used as a spray. Or the mixture may be 

 improved by the addition of lime slacked in water, — the 

 whole so diluted that it can be easily applied with a broom or 

 whisk. As the copper sulphate is poisonous,, care must be 

 exercised in handling and applying. The remedy appears to be 

 serviceable against the Peronospora of the vine as well as for 

 the special fungi to which attention is herein directed. 



Illustkation's op the Gekeka. 



Figure 3. Sphssrotheca 

 Castagnei, L6v. : a, perithe- 

 cium with b appendages, — 

 magnified 90 times ; c, fer- 

 tile hypha or conidiophore, 

 bearing six conidia which 

 readily separate at the con- 

 strictions, — magnified 190 

 times; d, the single ascus 

 with eight spores, — magni- 

 fied 250 times. 



*The commonest " grape mildew "in this country is caused by a 

 very diflferent fungus, 'Peronospora viticola, B.&C. 



