584 ANNUAL REPORT OF THE Off. Doc. 



spray applications are timed according to the frequent swelling 

 of the moistened spore masses, the treatment will prove costly, and 

 cannot be carried out during periods of continuous moisture. 



It is also difficult to apply promptly enough to be effective when 

 the danger is greatest. Where such procedure has been most care- 

 fully tried, using Bordeaux mixture, the rust was diminished on the 

 sprayed trees, but not satisfactorily controlled. 



We ought to know whether apple leaves and fruit are susceptible 

 equally at all stages of development, or whether the period of sus- 

 ceptibility is somewhat restricted. The constant occurrence of rust 

 spots at the flower end of the fruit is suggestive; although this may 

 simply mean that spores lodge here more securely and have more 

 moisture for germination. 



It may be that the disappointing results from spraying are due 

 to the use of fungicides that are less effective against this fungus 

 than against others; for we know some fungi may be controlled 

 by preparations that are ineffective for others. Several corraspon- 

 dents have noted some reduction in rust from the routine use of 

 Bordeaux mixture or Pyrox; but I have received only one report of 

 pronounced success. I wrote again asking for further information 

 on several points, but in the absence of a reply, I simply quote from 

 the first letter: "York Imperial jdeld is cut 90 per cent, the first 

 100 feet (from the red cedars) ; and about 75 per cent, the second 

 100 feet; and about 50 per cent, for the next 500 feet. We sprayed 

 with lime-sulphur solution, Bordeaux, self-boiled, lime-sulphur, and 

 atomic sulphur. All the other ,sprays failed except atomic sulphur, 

 which finished up a crop of very fancy York Imperial Apples worth 

 ten dollars per tree within 100 feet of red cedars on my neighbor's 

 land, where the unsprayed trees were not worth picking. Our ob- 

 servation is that no fungicide applied after May 15th will do any 

 good toward controlling cedar rust." I simply pass on to you this 

 bit of experience as it was reported to me, and leave you to judge 

 its merits. 



Serious outbreaks of cedar rust are sporadic and so have been 

 the attempts to devise reliable methods of control. In the east and 

 south and middle west there is the constant possibility of an epi- 

 demic, and hardly a season passes without the report of serious loss 

 from some apple growing district. We need to have at our com- 

 mand a knowledge of means of control that can be relied upon in 

 such emergencies. 



APPLE BLIGHTS 



By PROF. H. R. FULTON. 



It has been suggested that this Association might be interested 

 in a discussion of apple blights; and by the plural form of the word 

 I understand to be meant mainly the various forms of the bacterial 



