May 13, 1910] 



SCIENCE 



751 



The hope of continuing the banana industry 

 successfully in the affected districts lies in the 

 substitution of an immune variety. This the 

 writer has found in a Chinese banana now occa- 

 sionally grown in Central America. This sort is 

 easily grown, yields good fruit, and has been 

 found entirely resistant. The plantain is slightly 

 but not seriously affected by the blight. The red 

 banana is also subject to this blight, but less than 

 the common yellow (Martinique) variety. 



Notes on some Diseases of Trees in our National 

 Forests: Dr. George Grant Hedgcock, Bureau 

 of Plant Industry. (Read by C. J. Humphrey.) 

 Notes were given on the occurrence and dis- 

 tribution on a large number of hosts of the fol- 

 lowing wound parasites attacking forest trees: 

 Polyporus dryophilus Berk. ( ?), P. ohtusus Berk., 

 P. sulphureus Fr., P. schweintzii Fr., Fames ig- 

 niarius Gill., F. applanatus (Pers. ) Gill., F. lari- 

 ■cis (Jacq.) Murr., Trametes pini (Brot.) Fr., and 

 Echinodontium tinctorium E. & E. Many new 

 hosts for several of these species were named. 



The more injurious species of mistletoe in our 

 coniferous forests are RazoumofsJcya douglasii 

 (Eng.) Kunze, on Pseudotsuga taarifoUa (Poir.) 

 Britt., R. cryptopoda (Eng.) Coville, on Pinus 

 ponderosa Laws., R. americana (Nutt.) Kunze 

 on Pinus murrayana " Oreg. Conn.," and R. oyano- 

 oarpa A. Nels. on Pinus flexilis James. 



Of the species of Peridermium attacking trees 

 in the same area, Peridermium coloradense (Diet.) 

 Arth. & Kern on Picea engelmanni Eng., and 

 Peridermium- elatimtm (A. & S.) Kunze on spe- 

 cies of Abies are the more injurious. 



Successful inoculations were made with the 

 iiredospores of Cronartiuni quercuum (Brond.) 

 Arth. on oak leaves of a number of species for the 

 first time, and with the teliospores of the same 

 fungus, producing galls on the twigs of young 

 trees of Pinus virginiana Mill. 



Potato Wilt and Dry Rot [Fusarium oxy- 



sporium ) .■ Mr. W. A. Obion, Bureau of Plant 



Industry. 



This disease described by Smith and Swingle 

 in Bulletin 55 of the Bureau of Plant Industry 

 in 1905 is now coming into prominence as one 

 of the most wide-spread and destructive maladies 

 ■of this crop. It appears to occur throughout the 

 United States, but is more injurious in the irri- 

 gated sections of the west and in the southern 

 half of the potato belt. 



Three types of injury occur. The most serious 

 and least recognized is a wilting and premature 



ripening of the plant due to infection of the stem 

 and underground portions. The second is a dry 

 rot beginning at the stem, which develops most 

 rapidly in warm temperatures. Finally, the dis- 

 ease is responsible for a portion of the trouble 

 experienced from poor germination in the spring. 

 Of methods of control at present available 

 rotation of crops appears most effective. Seed 

 selection through discarding diseased portions of 

 tubers has been proved helpful. A thin slice 

 across the stem end affords a simple test, the 

 vascular ring being brown where the fungus is 

 present. There are indications that resistance 

 can be bred, though no existing varieties are very 

 promising in this regard. 



The Double Blossom: Dr. Mel. T. Cook, Dela- 

 ware Agricultural Experiment Station. 

 This is a disease of the genus Rubtis originally 

 attributed to Fusarium rubi Winter. It is very 

 abundant on the Delaware-Maryland Peninsula, 

 where it is destructive to the Lucretia and Rath- 

 bone dewberries. It is due to a fungus which 

 appears to be a Fusarium. The fungus winters 

 in the buds and the spores are formed in the open 

 blossom. The effect of the disease is the forma- 

 tion of a witches broom, deformity of the blos- 

 soms and atrophy of the berries. Late blossoms 

 are very abundant in the fields where the disease 

 is present and also occur one year in advance of 

 the witches brooms. These late blossoms also 

 contain spores. 



The Toxic Properties of Ta/imin: Dr. Mel. T. 

 Cook, Delaware Agricultural Experiment Sta- 

 tion. 



Since the preliminary report given a year ago 

 at the Baltimore meeting, work has been con- 

 tinued along the same lines and considerable addi- 

 tional information gained. None of the species of 

 Glceosporium or Colletotrichum gave maximum 

 growths on media containing more than two fifths 

 of one per cent., and the majority gave best 

 growths on media without tannin. Fusarium was 

 much more resistant to low percentages, but none 

 gave maximum growths above three fifths per 

 cent, tannin. 



Neocosmospora, Cladosporium, Sphceropsis, 

 Sclerotinia and Phoma were more resistant than 

 Glceosporium, but none gave maximum growths 

 on media containing more than three fifths per 

 cent, of tannin. 



The species of Penicillium were retarded at 

 first, but had a tendency to overcome the toxic 

 action of the tannin. 



