348. Kbport of the Horticultural Department of thb 



experiment of this Ivind, since old infections cannot be cured and 

 new ones are not rapidly formed. 



Another year's observation confirms the recommendations 

 made last year in regard to spraying with Bordeaux mixtuie, 

 with good orchard sanitation, as a preventive of apple-tree 

 canker. The presence of this disease in aeglected orchards and 

 its absence in orchards that have been well sprayed and well 

 cared for in general, is strong evidence that with most varieties 

 the disease may be easily controlled; but with some of the more 

 susceptible kinds as the Esopus and the Twenty Ounce it is quite 

 probable that the conditions known as sun-scald and sun-burn 

 must be overcome before the canker fungus will be successfully 

 combated. 



Another point of practical importance not mentioned in the 

 former bulletin is the method that some orchardists have 

 adopted for saving the larger diseased limbs. This is done by 

 sawing the limb off just back of the diseased area and then 

 inserting cions of the same variety. 



MACROPHOMA AKD APPLE-TREE CANKER. 



In Bulletin 163, page 203, Macrophoma malorum (Berk.) Berl. 

 et Vogl,, is mentioned in connection with the body blight of the 

 pear. This fungus is very common on both apple and pear trees 

 and during the past season a number of cankered apple-tree 

 limbs were found on which the injuries were evidently due to its 

 attack. 



Vfter repeated trials the fungus was finally induced to grow 

 luxuriantly in test tube cultures where it fruited abundantly. 

 The spores germinate readily in potato agar, but make very little 

 growth. When transferred to sugar beet plugs they made bet- 

 ter growth, but produced no spores. The method finally adopted 

 was to make plate cultures of the spores when they were located 

 under the microscope, then transfer to sterilized bean stems in 

 test tubes. 



