Part I.] STATE NURSERY INSPECTOR. 87 



follow the valleys where they occur and its direction of spread 

 is probably determined to a large extent by the wind currents. 

 The spraying of Ribes for this fungus is not practicable. It has 

 been discussed in other bulletins on the subject and need not 

 be taken up here. Mountains appear to form a partial, local 

 barrier to the disease depending on flora, height, etc. 



General results seem to indicate that the spores produced on 

 pines may spread some distance to currants; that the spores 

 produced on the currants during the summer are capable of 

 being carried several miles in each generation, and that the 

 spread of fall currant spores to pine is effective for a com- 

 paratively short distance only. 



In 1916 the earliest date on which the summer stage of the 

 blister rust was found on currant leaves was June 5. The fall 

 stage was first found upon the currant on June 23. This dis- 

 covery of the early formation of the teliospores shows that 

 pines might have become infected this year at any time after 

 June 23 until the leaves fall from the currants and gooseberries. 



During the scouting it was learned that wild Ribes were ex- 

 tremely plentiful in many parts of Berkshire and Essex counties. 

 In some cases as many as 5,000 were removed from a single 

 estate. In central and southeastern Massachusetts they were 

 very scarce except, perhaps, in spots here and there. These data 

 should prove of great value in attempting further work in the 

 control of this disease. 



Throughout the State during the past year many pine trees 

 have been seriously troubled by a gradual browning, and some- 

 times the ultimate dying of the needles. Many specimens and 

 inquiries have come in, asking if this trouble was caused by the 

 blister rust. In this connection it is well to remember that the 

 latter is strictly a bark disease which girdles the limb or tree 

 affected, finally killing it, and does not directly affect the 

 needles. It is difficult to say exactly what causes the brown- 

 ing and dying of the needles, but it is generally agreed to be of 

 a physiological nature and is probably due to a combination of 

 causes. One explanation is that weather conditions the past 

 year were of such a nature as to produce rapid but soft and 

 tender growth. As a result the delicate young needles of many 

 trees were burned by the intense rays of the sun. Where this 



