1890.] PUBLIC DOCUMENT — No. 33. 213 



Numerous cases can be cited of common weeds or wild 

 plants, each of which is so closely related to some species 

 of cultivated plants that it is liable to attack by the same 

 fungi that infest its cultivated relative. Where this is true, 

 the wild plant may serve equally with the cultivated one to 

 perpetuate the fungus, and may keep it alive during a time 

 when the latter is not grown, or may become a source of in- 

 fection for a cultivated field, previously free. For example, 

 the "black-knot" fungus grows on our wild cherries, as 

 well as on cultivated cherries and plums ; the lettuce mildew 

 occurs on several species of " wild lettuce ; " and the grape- 

 vine mildew, besides occurring on wild grape vines, has been 

 found on the Virginia creeper. The bearing of these facts 

 on questions of preventing and checking the various diseases 

 is obvious. 



Finally, it is clear that epidemic diseases cannot be suc- 

 cessfully combated without general co-operation throughout 

 an infected region. The attempts of half a dozen intelligent 

 men to protect their crops may be almost of no avail, if one 

 lazy or "conservative" neighbor refuses to join in the 

 attempt, and allows his adjacent field to alford a breeding- 

 place for the very fungus our progressive friends are fighting. 



Successful dealing with diseases caused by parasitic fungi 

 may be said, then, to be based on the following essentials : 

 promptness, thoroughness, cleanliness, intelligent treatment, 

 co-operation. 



The writer wishes to come into much more general com- 

 munication with the farmers, market gai'deners, Jtorticulturists, 

 Jlorists, and all who cultivate plants, in the /State. He es- 

 pecially and urgently requests that specimens be sent him of 

 plants affected hy any disease, not caused by insects, ivhich 

 may come to the attention of any reader of this report. 



Very much aid to a fuller knowledge of many diseases can 

 be afforded if those ivho are the losers by them loill co-operate 

 to render all possible assistance, even to the extent of going to 

 some trouble, to those engaged in their study^ Without 

 • such co-operation and assistance, our work must necessarily 

 be far less effective and our studies far less complete in their 

 results. 



