Xew Diseases of the White Pine. 



165 



eludes: — "It is impossible to state defin- 

 itely what is the primary cause of the 

 leaf-blight, but it is probably closely 

 connected with extreme chmatic con- 

 ditions which have prevailed during the 

 past few winters." 



The outbreaks usually begin about 

 July 1st and vary in intensity' from 

 year to year. The leaf-blight may 

 cause the death of affected trees occa- 

 sionally in a single season, more often 

 in two or more seasons, but even in the 

 worst affected districts the number of 

 trees killed outright bears a small pro- 

 portion to the total number. No new 

 trees became affected in 1908 and half 

 of those that were affected in 1907 did 

 not have their 1908 leaves touched by 

 the bUght. 



Twig-Blight. 



In 1908 the most common form of 

 disease was a twig-blight. Of this there 

 were three forms found. One form of 

 this injury affected only small trees 

 (usually less than ten to fifteen feet in 

 height) and was common in Maine. In 

 this form the injury was usually con- 

 fined to the northern and western sides 

 of the tree, the opposite sides being un- 

 injured. This was apparently a real 

 winter-injury: during the winter 

 months a great deal of water was evap- 

 orated from the leaves, while the roots 

 were frozen solid in the earth, and so 

 were not able to absorb from the soil 

 moisture to replace that taken from the 

 leaves; hence the trees suffered. A 

 small number of trees died through this 

 winter-killing and others experienced a 

 set-back, amounting to one, or. perhaps, 

 two years' growth. 



Another blight, found in New Hamp- 

 shire and northern Maine, was appar- 

 ently due to insects. Only lateral 

 branches were affected, the leaders 

 almost always escaping injury. 



At Brunswick, Me., and sparingly in 

 a number of other places, a twig-blight, 

 due to a fungus (Lophodermium brachy- 

 sporum) did .some damage. 



The White Pine Blister Rust. 



A more serious disease and one that 

 demands much attention and vigilance 

 for its suppression, is the one just 

 named. 



The White Pine Blister Rust (Peri- 

 dermium strobi) is one of the rust fungi 

 (Uredineae). As is the case with other 

 rusts, part of its development is made 

 on one plant, after which spores are 

 carried to plants of another kind, where 

 the fungus completes its course. The 

 first part of the life of the above rust 

 is passed on the White Pine, after which 

 it passes over to black and red currant 

 plants, sometimes to gooseberries.| 



The period of growth on the currant 

 is much shorter than that on the pine. 

 The spores which are produced here 

 appear in summer and autumn as an 

 orange-colored powder. If these are 

 carried bj' the wind to a white pine tree 

 they may germinate and the plant body 

 (mycelium) of the fungus establishes 

 itself in the soft inner bark of the trees. 

 No sign of the disease is noticeable the 

 following spring, but during the summer 

 after stem and branches often begin to 

 thicken and swell. In the following 

 spring the fungus breaks through the 

 bark, and light orange-colored fruiting 

 bodies (about one-eighth of an inch 

 thick) appear. From these spores are 

 emitted which, on reaching a currant 

 bush, germinate and begin the round 

 again. 



The di.sease was discovered on stock 

 imported by the New York State Forest, 

 Fish and Game Commission from the 

 nursery of J. Heins Sons, Halstenbeck, 

 Germany, and was identified by Dr. 

 Perley Spalding, of the Bureau of Plant 

 Industry, United States Department of 

 Agriculture and, later on, by others. 



It was located in Vermont, Massa- 

 chusetts and Connecticut. 



A meeting of foresters (state and 

 private) and others interested in the 

 matter was held in New York and the 

 problem discussed. It was decided that 

 further importations of German white 

 pine stock^were imdesirable. 



The New York State authorities have 

 adopted the following plan for fighting 

 the disease : — 



All places where it can be ascertained 

 that Heins' white pine stock has gone 

 during the past two years are to be in- 

 spected, and all currant and gooseberr}'- 



