192 PATHOLOGY [Bot. Absts., Vol. IV,. 



1262. Butler, O. R. Field control of the snapdragon rust. — Florists' Exchange 48: 951. 

 1919. — Many practical tests lead to the conclusion that finely powdered sulfur or sublimed 

 sulfur is the only known fungicide that affords adequate protection against the snapdragon 

 rust so long as conditions are favorable for its action. The temperature most favorable for 

 the germination of spores of Puccinia antirrhini is 50°F. In order that sulfur shall afford full 

 protection, the day temperature must remain for several hours at 70°F. or above. It is only 

 at this higher temperature and in the immediate neighborhood of the sulfur particles that pro- 

 tection is afforded. If all infected plants in a block are not treated, the spores produced on 

 a non-sulfured plant are not affected by the presence of sulfur on neighboring plants, and if 

 blown onto sulfured snapdragons under conditions favorable for germination and at a pre- 

 vailing temperature too low for the sulfur to be active, will cause infection and the sulfuring 

 will appear less beneficial than it really is. — L. A. Minns. 



1263. Byars, L. P. Experiments on the control of the root-knot nematode, Heterodera 

 radicicola (Greef) Mueller. I. The use of hydrocyanic-acid gas in loam soil in the field. Phy- 

 topath. 9: 93-103. 1919. — Results secured in 1916 and 1917 as a result of treatimg loam soil 

 in Florida in 1916 with hydrocyanic acid for the control of nematodes are presented in tabular 

 form. Carefully isolated small plots were treated at the rate of 600 to 3600 pounds of sodium 

 cyanide per acre in conjunction with 900 to 5400 pounds of ammonium sulphate. The dasheen 

 (Colocasia esculenta) was used as a test crop. The higher applications checked the infections 

 and lower amounts reduced the infection the first year. The nematodes were not entirely 

 destroyed at the highest application as shown by infection the following year. The cost of 

 application is considered too high to render the use of this method practical except on a small 

 scale. — J. Johnson. 



1264. Byars, L. P., A. G. Johnson, and R. W. Leukel. The wheat nematode, Tylenchus 

 tritici, attacking rye, oats, spelt and emmer. Phytopath. 9: 283-284. 1919. — Experiments- 

 were conducted to show the host range of the parasite. This is the first report of the parasite 

 on emmer (Triticum dicoccum) and the first record in this country of its attacking rye, oats, 

 and spelt (T. spelta). No infections were noted on barley. — C. S. Reddy. 



1265. Carpenter, C. W. Preliminary report on root rot in Hawaii (Lahaina cane deter- 

 ioration, pineapple "wilt," taro rot, rice root rot, banana root rot). Hawaii Agric. Exp. Sta. 

 Press Bull. 54. 9 p. PI. 1-8. 1919. — Studies indicate that the Lahaina disease (root rot) 

 of sugar cane, pineapple "wilt," taro rot, banana center leaf necrosis (root rot), and a root rot 

 of rice appear to be caused by a parasitic fungus with a definite mycelium and of the Pythium 

 dcbaryanum type. This root rot fungus is tentatively considered as identical with Pythium 

 debaryanum. Characteristic symptoms of the disease were developed in sugar cane by inocu- 

 lation with pure cultures of the fungus under observation. — /. M. Westgate. 



1266. Carsner, Eubanks. Susceptibility of various plants to curly-top of sugar beet. 

 Phytopath. 9: 413^121. 7 fig. 1919. — Chenopodium murale and Rumex crispus, being non- 

 susceptible to curly-top, make excellent food plants for rearing non-virulent leaf hoppers 

 (Eutettix tenella), while the chickweed (Stellaria media), being very susceptible, is the most 

 suitable for rearing virulent hoppers. The disease has been produced on 14 species of plants 

 included in eight different families and has been crossed back from 12 of these to healthy beets. 

 Hoppers retained virulence after being kept on non-susceptible plants 111 days. Diseased 

 plants of the red-stem filaree (Erodium cicutarnim), which is a common California winter 

 plant and a food plant of the hopper, have been found in or near beet fields in late summer, 

 fall, and early spring. This species probably plays an important role in overwintering the 

 virus and in furnishing a source of the same to the brood of hoppers attacking beets in the 

 spring. — J. C. Walker. 



1267. Chandler, W. H. The effect of cold winter of 1917-18 on the fruit industry. Trans. 

 Indiana Hortic. Soc. 1918: 91-103. 1 pi. 1919.— See Bot. Absts. 4, Entry 90S. 



