No. 7. DEPARTMENT OF AGRICULTURE. 583 



help to keep up a hotbed of infection ready to extend to neighbor- 

 ing orchards when conditions favor. Such pomaceous plants should 

 be destroyed also. From reports and observations, I have tried to 

 tabulate a number of varieties according to rust susceptibility. In 

 its preparation error may have come from necessary dependence on 

 unaided memory; from the fact that different assortments of va- 

 rieties will show differences in the relative rating of any given 

 variety; from varying local chances of infection; from the biennial 

 fruiting of some varieties ; from the possibility that different ones 

 of the three s})ecies of cedar rust have been involved in different 

 localities; and possibly from differences in individual resistance 

 within the variety. 



For fruit infection, the most susceptible varieties to be York 

 Imperial, Fallawater, Eome Beauty, Smokehouse and Ben Davis. 

 Less susceptible are Eambo, Simth's Cider, Bed Doctor, York Stripe, 

 Summer Queen, Bellflower and Winter Banana; while very slightly 

 affected varieties are Jonathan, Stayman Winesap, Baldwin and 

 Northern Spy. 



Susceptibility of leaves to infection does not follow the same 

 order. York Imperial seems to be undoubtedly most susceptible. 

 Followed at a distance by Ben Davis, Wealthy, Newtown Pippin, 

 Jonathan, Maiden Blush, Gano, Stayman Winesap and Grimes' 

 Golden in descending order of susceptibility. As to resistance suf- 

 ficient to make the variety practically, if not absolutely immune, 

 opinion must be somewhat more guarded. Grimes' Golden is gen- 

 eral choice for first place in resistance. In a second class come, 

 curiously enough, York Imperial and Ben Davis, along with Black 

 Twig. A less number mention York Stripe, Baldwin, Stayman, 

 Winesap, Northern Spy, Dominie, Porter and Strinetown Pippin. 



The effect on yield is variously reported, — from nothing or very 

 little, up to 80 per cent, in one case, and 90 per cent, in another; 

 these figures being for some special tree or group of trees. When 

 leaves are badly infected during a season, the manufacture by them 

 of food for storage and bud formation is interferred with, and a 

 shortage in the next season's crop from such trees is to be looked 

 for. In some instances leaf attack has been severe enough to pre- 

 vent proper maturing of the current crop, notably when rust attack 

 v/as severe enough to cause early defoliation and consequent dwarf- 

 ing of fruit on the trees. The quality of fruit directly attacked is 

 greatly lowered. Many sold such apples for eider this last season; 

 but with strong market prevailing others disposed of theirs as No. 

 2's, or along with the general run of the orchards. Buyers seem 

 not to have been as critical as they may be another season. 



From the habits of the fungus, proper spraying ought to control 

 cedar rust on apple. In practice, in closely watched experimental 

 tests, the results from spraying have varied from success to failure. 

 In the light of last year's experiences it seems that routine spray- 

 ing for scab with Bordeaux, self-boiled lime-sulphur, commericial 

 lime-sulphur and certain proprietary preparations is not a sure and 

 reliable preventative of rust. 



Cedar rust shows considerable seasonal variation in the time of 

 infection spore production ; and these spores are formed in several 

 crops extending over a period of a month or two. If fungicidal 



