852 EXPERIMENT STATION RECORD. [Tol. 38 



An epiphytotic of cane disease in Porto Rico, J. A. Stevenson {Phyto- 

 pathology, 1 (Wll), Xo. 6, pp. Jfl8-Jf25, figs. 2). — An account is given of a dis- 

 ease of sugar cane which has been noted elsewhere (E. S. R.. 38, p. 150). 



Tobacco wildfire, F. A. Wolf and A. C. Foster {U. S. Dept. Agr., Jour. Agr. 

 Research, 12 (1918), No. 7, pp. 449-^58, pis. 2, figs. 2).— In this contribution 

 from the ISortli Carolina Experiment Station, the leaf spot of tobacco which 

 has been named wildfire (E. S. R., 38, p. 150) is said to exist in 19 counties of 

 North Carolina and in 3 of Virginia, and also to occur in Wisconsin. It is 

 claimed to be the most destructive disease of tobacco. While the disease origi- 

 nated in the seed bed or plant bed, only negative evidence has been obtained 

 to show that infection occurs through the seed. The organism (Bacterium 

 tahacum), which has an incubation period of about 72 hours, forms large 

 spots within one week on the leaves, to the parenchymal portions of which it 

 is confined. Moisture, especially when accompanied by wind, is of prime im- 

 portance in the rapid spread of the disease. 



Brown rot of fruit. — Investigations in Hawke's Bay, G. Esam (Jour. Agr. 

 [Neny Zeal.], 15 (1911), No. 2, pp. 84-89) .—Brown rot. considered the most 

 destructive of the many pests and diseases attacking fruits and fruit trees 

 in New Zealand, is briefly discussed as causing severe injury in Hawke's Bay 

 and Auckland. A brief account is given of the life history of the disease, and 

 also of investigations. Inoculation tests are described which seem to indicate 

 that the organism is a wound parasite. 



Root knot of fruit trees, J. A. Campbell (Jour. Agr. [New Zeal.'\, 15 (1917), 

 No. 2, pp. 63-68, figs. 5). — Root knot and associated or similar abnormalities due 

 to Bacterium tumefaciens, after being almost totally suppressed in New Zea- 

 land following Government and other action, appeared again in 1915. In 191G 

 a serious situation became evident, this leading to investigations vmder the 

 direction of the minister of agriculture. 



The resulting report states that root knot and hairy root are due to the same 

 organism. Trees from affected nurseries appearing clean when planted may 

 develop galls after 12 months. Root knot is said to be highly detrimental to 

 peach and raspberry, and possibly detrimental also to apple or pear. 



Field experiments with crown gall, 1913-1917, H. Ness (Texas Sta. Bui. 

 211 (1917), pp. 3-21, figs. 7). — The rapid spreading of crown gall in Texas 

 orchards is thought to have had its beginning in the extensive planting of 

 commercial-peach orchards some 25 or 30 years ago. The climate of the 

 Southern States is thought to be favorable to this disease, owing to its humidity 

 and comparative freedom from frost. Absence of noticeable galls is no reliable 

 indication of freedom from infection by the gall organism (Bacterium tume- 

 faciens). Infection may occur through very slight contacts. 



Tests were made with several fungicides of different strengths, and it ap- 

 pears that copper sulphate will prevent the occurrence of crown gall on nur- 

 sery stock, if it is properly used. For sound peach trees 7 oz.. and for apple 

 trees about 1 lb., to 26 gal. of water, with an exposure of two hours in either 

 case, are recommended. Preparation for this treatment includes the cleaning 

 and pruning of the roots and branches and careful examining of the roots. The 

 collar should be several inches below the surface of the disinfecting solution. 

 The tops also should be carefully wetted with the copper solution. 



Black spot of apples [and pears], W. H. Taylor (Jour. Agr. [Neiv Zeal.}, 

 15 (1917), No. 2, pp. 98-100). — Venturia inwqualis (Fusicladium dendriticum) 

 and V. pyrina are discussed in connection with their effects on apple and pear, 

 respectively, and their treatments, the latter being very similar for both species 

 and preferably preventive. 



