MASSACHUSETTS APPLE INDUSTRY. 17 



found (Mass. Agr. Exp. Sta. Bui. No. 207) that it is not safe to spray 

 the apple when the temperature is 90° F. and the relative humidity above 

 67 per cent. It is therefore reasonable to ascribe some of the injury this 

 year to arsenical burning, for this temperature and humidity combination 

 was reached or exceeded during the spraying period in early June. 



Black Rot 



Black rot of the fruit of the apple was not generally serious this year, 

 although certain individual growers considered it more serious than in 

 1924. It was reported on Baldwin, Greening, and Yellow Transparent, and 

 was most common on Baldwin. Black rot was not serious even on fruit 

 which showed severe spray injury. This is of interest since in some sea- 

 sons black rot has been associated with or has followed blossom-end in- 

 jury due to the calyx spray. 



Black rot canker is the most common of the limb cankers, but in most 

 commercial orchards it is not serious. It is often present on old Baldwins, 

 and failure to spray and prune such trees properly results in its rapid in- 

 crease in severity. Occasionally this disease causes serious loss in young and 

 apparently well cared-for orchards, but such a condition is exceptional in 

 this state. 



Cedar Rust of Apple 



This disease was practically absent or existed only in traces (and then 

 on Wealthy) in the Nashoba district. Most orchardists have seen to it 

 that red cedars were removed. There was light infection on Wealthy and 

 Banana in western Massachusetts. The sporidia or spores by which this 

 fungus passes from cedar to apple require water for their dissemination, 

 and during that period in spring when this ordinarily occurs the rainfalt 

 was deficient. 



Sooty-mold and Fly Speck 



This disease was of no great importance this year. It was observed in 

 a few instances on Baldwins and Greenings. It occurred more or less 

 throughout the state, but, except on unsprayed and unpruned trees, it was 

 of no consequence. Ordinarily there is more of this disease in the eastern 

 than in the western part of Massachusetts. It may often be seen on drop 

 ax^ples which have remained long on the ground even when not evident 

 on the fruit on the tree. 



Baldwin-Spot 



This disease, which also goes under the names of stippen or bitter-pit, 

 is well known to orchardists. Unfortunately its cause and control are 

 obscure. 



Baldwin-spot was of somewhat more than average severity this year. 

 In many orchards this was the "off-year" for Baldwins, and the disease 

 was generally associated with a light crop and consequently larger fruit. 

 It was not conspicuous in orchards where the fruit was smaller. The oc- 

 currence of the disease has an evident relation to alternate bearing and 

 to thinning. Baldwin-spot may occur on other varieties, but tills year it 

 was called to our attention only on Baldwin and Stark. 



Fire Blight of Apple and Pear 



In eastern Massachusetts fire blight occurred about as usual in most 

 orchards, alt4iough from a few orchards there were re^iorts ot its being 



