THE BROWN ROT DISEASE OF THE REDWOOD. 



By Hermann von Scheenk, 

 Bureau of Plant Industry. 



The Redwood is one of a g-roup of trees of ancient lineage, all of 

 which are singular!}' free from fungus diseases. A number of parasitic 

 fungi, such as Leptostroma sequoice Cook & Harness., and Stricta versi- 

 color Fr., attack the living leaves and branches; but they occur so 

 rarely, and then only in such small numbers, that they are practically 

 insignilicant. Dr. Farlow states that "more than thirty species have 

 been recorded on Sequoia sempervirensr none of which is known to 

 cause serious disease. In Europe, where the Redwood has been grown 

 for many years as an ornamental tree, a species of Botrytis frequently 

 attacks the young branches. 



Redwood timber possesses lasting qualities scarceh^ equaled by any 

 other wood. Although very light and porous, it has antiseptic prop- 

 erties which prevent the growth of decay-producing fungi. So far 

 as is now known, none of the ordinary wood-rotting fungi gTow in 

 Redwood timber. This is an exceedingly valuable propert}', which 

 should extend the use of the wood for all kinds of construction 

 purposes. 



It is because of its resistance to most forms of decay that the Red- 

 wood reaches such a great age. A remarkable fact to be noted is that 

 the innermost rings of most of the trees are as sound now as when first 

 formed. 



Onh' one disease of the trunk is now known, commonly called butt, 

 brown, or pin rot. The wood at the base of the trunk of diseased 

 trees is filled with many pockets of dark brown, almost black, wood, 

 irregular in form, though usually twice as broad as they are long, and 

 ranging in size from mere specks to masses several inches in diameter 

 (PL XI). They may join at the ends ver}' much as they do at the 

 sides. At first the individual masses of diseased wood are separated 

 from one another by lamellae of sound wood, and the line of division 

 is sharply defined (PL X, fig. 2). In later stages of the disease the 

 dividing lamellae are changed into brown wood, thereby causing two 

 or more masses to unite (PL X. figs. 1 and 2). The bases of the older 

 trunks affected b}' this disease may be masses of brown decayed wood. 



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