754 EXPERIMENT STATION EECOKD. 



woiiuds which reached to the wood of the tree. From the investigations on 

 Para rubber and cacao it is claimed that the life history of the die-bacli organ- 

 ism consists of 3 forms, viz, the Diplodia stage for rapid reproduction, a Cyto- 

 spora form which develops on the plant some time after it has died, and the 

 Thyridaria stage which appears later, and which can infect the living plant with 

 the production of the Diplodia form. The fungus must commence its existence 

 on dead tissue, and having accumulated a mass of mycelium spreads to healthy 

 parts of the attacked plant. The damage done by the fungus is closely related 

 to the condition of health of the plant, and this is more evident in the case of 

 older plants. 



The occurrence of burs on the trunk of Hevea brasiliensis, K. Bancroft 

 (Agr. Bill. tStraits and Fed. Malay mates, 10 (1911), No. J, pp. ISS-U/l).— 

 Attention is called to the occurrence of excrescences or burs on the trunli of 

 H. hrasiliensis in the Federated Malay States. These burs are referable 

 to 2 distinct sources. One type occurs on untapped trees as well as tapped, 

 while the other type is distinctly the result of wounding by tapping. 



The burs of the first type originate as small structures, raising the outer 

 surface of the bark in lumps and in this condition they are known as the " pea 

 disease." Arising in the cortex they have at first no connection with the main 

 wood of the plant, but by continual growth and fusion with each other large 

 structures are produced of irregular shapes, often several feet in size. At first 

 these are superficial to the latex layer, but by further growth they fuse with 

 the main wood and the intervening latex and cambium layers are squeezed 

 out of existence. Each nodule possesses a central woody core composed of 

 vessels which are for the most part irregularly arranged ; outside the core is a 

 layer of cambium which produces a slow growth by the addition of wood to 

 the central woody mass. The commonest cause of the production of burs of 

 this type is the wounding of the cortex, such as by the grazing of a cart wheel. 

 Also many of them in their nature and mode of origin seem to be buds which 

 have failed to develop into shoots. 



The second type of burs is apparently caused by the tapping knife severing 

 tlie cambium and wounding the wood. 



Nut diseases; with special referen-ce to the pecan, M. B. Waite {Proc. Amer. 

 I'oniol. Soc, 1911, pp. 182-190). — In addition to a general discussion of the 

 diseases of the pecan, the author notes a disease of the English walnut 

 (Pseudomonas jtigJandis), almond leaf-blight (Cytospora circumcissa) , the 

 gumming fungus (Coryneum hcyerinckU) , the crown-gall {Bacterium tume- 

 faciens), and the chestnut disease {Diaporthe parasitica). The following 

 pecan diseases are noted, their charateristics given, and methods for their 

 control suggested: Pecan scab {Fiisicladium effusuin), the most serious disease 

 of pecans in the Southeastern States (E. S. R., 24, p. 452), pecan rust (Helmin- 

 thosporium ardusciila). mildew {Microsphwra alni), leaf blotch (Cercospora 

 halstedii), root rot {Fiisarium sp.). pecan rosette, winter kill, and pecan drop, 

 which is characterized by the shedding of nuts of various sizes, due apparently 

 to a physiological cause. 



Notes on fungus diseases, L. H. Pammel (Abs. in Science, n. ser., 33 {1911), 

 No. 862, p. 28). — At the April meeting of the Iowa Academy of Sciences atten- 

 tion was called to a very destructive Exoascus on the hard maple in the Rocky 

 Mountains, an Exoascus on the oak. Fames iyniariits on the quaking aspen in 

 the Wasatch Mountains in Utah, and a Pleurotus on box-elder and other 

 deciduous trees in Iowa. 



Zythia resinae as an injurious timber fungus, C. Brick {Stat. Pflanzen- 

 si-lnitz Ilamhurg [Ber.^, 12 {1909-10), pp. [25-32]: Jahresbcr. Ver. Aiigetv. 

 Hot., 8 {1910), pp. IGJi-nO). — Attention is called to a staining of structural 



