72 MASSACHUSETTS HORTICULTURAL SOCIETY 



Another disease which is essentially a reproduction disease 

 is the white-pine blister rust (10, 11). Trees affected with this 

 disease rarely survive the twentieth year and the greatest loss 

 comes in the nursery. This disease is not indigenous to America 

 but has been introduced within the past ten years in nursery 

 stock imported from Europe. Just what this disease will do if 

 allowed to gain a foothold in this country we do not know, and 

 we cannot afford to take the risk of waiting to find out. A dis- 

 ease which effectively prevents the cultivation of white pine in 

 three northern countries of Europe should not be permitted to 

 gain a foothold in this country if we can help it. I believe I 

 am safe in saying that at the present time the white-pine blister 

 rust is under control. We know of no places in America where this 

 disease now exists; but there are many localities where it has been 

 found that must remain under suspicion for years, and there must 

 not be the least relaxation of vigilance in the attempt to stamp out 

 this disease. Fortunately for us, the blister rust has been for fifty 

 years the subject of serious study in Europe. The life history of 

 the parasite was known and many of the biological relations of the 

 disease; hence the great facts regarding its control were perfectly 

 understood when it reached this country. The present control of 

 this disease in America and its ultimate eradication, if we can 

 hope for this, furnish the justification, from the practical man's 

 standpoint, of fifty years scientific research on this disease in 

 Europe. Would that we were as fortunate in the case of the chest- 

 nut bark disease and other epidemic diseases, in having at our 

 disposal the result of years of antecedent research! 



Forest Tree Diseases. 



In the control of such diseases as the heartrots, the mistle- 

 toes of the West, the pin-rots of incense cedar and cypress we 

 have recourse only to slight modifications of silvicultural prac- 

 tice which will enable such diseased trees to be marked for removal 

 when the forest is cut. I can only indicate this procedure thus, 

 in the merest outline. Suffice it to say that these methods are 

 being developed and are in practice, so far as developed, in four 

 of the six districts of the national forests. 



