VJT2 DISEASES OF VARIOUS CROPS 



\ili- Fusarium oxysporum and F. tricoihecioides in their Relation to 



Txiber-rot in Potatoes. — I^ink, G. K. K., in The Botanical Gazette, Vol. I^XII, Xo I, 

 pp. 169-209,, Fg. 1-13. Chicago, 111., September 1916. 



Fusarium oxysporum Wilcox and lyink is identical with F. tricho- 

 thecioides Woll. 



Tuber-rot and decay of the whole plant are produced by F. oxysporum 

 in the same way as by F. trichothecioides. The withering of the haulm 

 is due to the destruction of the roots and the blocking of the xylem ele- 

 ments in the stem; in mild cases the disease is characterised by such sj^mp- 

 toms as discolouration and drooping of the leaves and by the appearance 

 of aerial tubers. 



In the conditions that one meets with in the field and in stores F. 

 oxysporum seems to be more definitely the cause of decay than is F. tri- 

 chothecioides, while the latter appears to be responsible for rot in the tubers. 

 The optimum and maximum temperatures for F. oxysporum are higher 

 than those for F. trichothecioides which develops well from 8° to 10° C. 

 These facts can in part explain the different effects of the two fungi. F. 

 oxysporum increases and spreads more rapidly than F. trichothecioides, 

 a circumstance which can be correlated with the greater need for oxygen 

 shown by F. oxysporum, and which explains why the fungus invades the 

 xylem elements. 



The two species both possess marked powers of utilising organic mat- 

 ter of all kinds in their metabolism. F. oxysporum has this faculty in the 

 greater degree and can make use of more varied substances than can F. 

 trichothecioides , but the destruction of the organic matter is not so complete. 



The growth in F. oxysporum is less readily arrested than is the case 

 in F. trichothecioides. Solanine is not toxic to either species, although in 

 the case of F. trichothecioides it seems to check the growth. 



1233 - Urophlyctis Alfaltae on Lucarne ("tumeurs marbrees") in France. — 



Armaud, G., in Journal d'A'^riculture pratique, Year 80, N. S., Vol. 29, N. 17, pp. 291-292, 

 fig. 58. Paris, August 1916. 



The Station of Plant Pathology in Paris received specimens of lucerne 

 from Villepreux (Seine-et-Oise) which were attacked by Urophlyctis Al- 

 jalfae at the base of the stems. 



The soil of the fields from which the specimens were taken was dry 

 and permeable and cv.ing to the lack of water was not really suitable 

 for lucerne. The disc:..:e had developed irregularly. To check the disease 

 it is best to plough up the lucerne in infected fields and replace it by some 

 oilier crop. 



12^^ -Sti/be/Ia Meveae and Ustulina zonata,?ests on Rubber in Sumatra. — 



Vriens, J. (;. 0.,in Medcdeclin;en van ilen Adviseur der A. ]'. R. O. S., No. 5, pp. 66-68. 

 Medan, 1916. 



The mycelium of Stilbclla Heveae spreads out into fine wliite threads 

 over the young shoots and leaves of the rubber tree. Soon the leaves which 

 have been attacked lose their colour and die, and are left hanging on to 

 the branches by threads of the m^'celium. 



The writer has been able to show that the disease can be stamped out 



