DISEASES OF PLANTS. 855 



The wet rot of cliesnut roots, J. ua Camaiia Testana (liul. Nor. Porliigaiae 

 tici. Nat., J (11)07), No. 2, pi). Ho-l'O, pis. .i ; liol. It. Assoc. Cent. Agr. I'orliigncsn, 

 9 (1907), No. 12, pp. 686-702, pis. 2).— Thin disease of cliestnut trees the author 

 says has beeu known hi Europe for fully half a century and has been attributed 

 to various causes. After a review of some of the literature relating to the 

 disease, the author gives an account of his observations on it. 



The disease seems to attack wild and cultivated trees in almost every soil 

 and under every system of cultivation. The diseased trees are late in doveloi*- 

 ing their leaves, the leaves are abnormal in color, and the terminal twigs are 

 often stunted. The fruit may fall prematurely or it may hang on the tree for a 

 year. The whole tree after a time presents an abnormal appearance and sooner 

 or later dies. 



An examination of the tissues of the aerial parts of the tree failed to reveal 

 any abnormal character, but the finer roots were found to be darkened and 

 often black. The cortex was easily removed, the tissues were soft and they 

 exuded a black liquid which gave off an odor of tannin. When examined under 

 the microscope a zone of the root between the sound part and that sbowing the 

 above described characters was found to be infested with bacteria and mycelial 

 strands. The latter api)ear to be connected with the mycorrhiza wliich normally 

 occur on chestnut roots, and the author believes that the disease is due to the 

 bacteria and to the mycorrhiza fungus having become parasitic in habit through 

 a lack of nitrification in the soil. 



Investigations on timber dry rot, A. Moller (Hausschwammforsehungen. 

 Jena, 1907, pt. 1, pp. IV+1')4, pis. 5). — This is an advisory report by the author 

 and others to a commission of the German ministry appointed to investigate 

 the causes of dry rot of timber, effect of the rot on health, means for prevent- 

 ing attacks of fungi, etc. In the different papers the literature of the subject 

 is reviewed, the morphology, anatomy, physiology, and biology of the different 

 fungi described, and suggestions given for preventing their attacks. 



The bud rot of carnations, F. D. Heald (Nebraska Sta. Bui. 103, pp. 1-2.^, 

 pis. 6; ahs. in Science, n. scr., 27 (1908), No. 68.'i, p. 211). — During the past few 

 years a troublesome and destructive disease of carnations has been under ob- 

 servation. The disease was first reported in 1J»05 from a greenhouse in Ne- 

 l)raska, and a study of the material showed that the bud rot produces effects 

 which show externally, the character depending upon the extent and severity 

 of the infection. The most striking external condition is the failure of the 

 affected buds to expand into perfect flowers. xVll affected buds show on close 

 examination that all or part of the flower parts included within the calyx are 

 affected with a rot which causes a brown coloration and a softening of the 

 tissues. 



The immediate cause of this disease is said to be Uporotrichum anthophilum, 

 and it is associated constantly with a species of mite, which is described else- 

 where (see p. 8()0). 



The first and i)erhaps the most important factor influencing the develop- 

 ment of this disease is the water relation, the bud rot being m(»st prevalent 

 where the air and soil have been kept too damp. Different varieties seem 

 unequally subject to the attack of this fungus, the variety Lawson suffering 

 more than any other, so far as the author's observations have gone. 



For preventing this disease the measures recommended are clean culture, 

 the reduction of the moisture to a minimum necessary for the healthy growth 

 of the plants, and the i)icking of all infected l)n(ls as soon as they a|»i)ear. 

 rhes(> should i»e burned and under iid conditions allowed to remain about the 

 benches, 



