NOTES AND ABSTRACTS. 



665 



Root-Knot and its Control. By Ernst A. Bessey {U.S.A. Dep. 



Agr., Bur. PI. hid., Bull. 217; 1911).— The writer describes the life- 

 history of the nematode Heterodera radicicola which causes root-knot 

 in. a very large number of different plants. Lists of the susceptible 

 and immune plants are given, the former largely outnumbering the 

 latter. 



Heterodera radicicola is distinct from Tylenchus tritici, T. dipsacii, 

 &G. Its larva is susceptible to adverse conditions and cannot stand 

 desiccation like the other nematodes mentioned. Also it cannot remain 

 alive very long in water. A large number of experiments for the control 

 of root-knot are recorded. 



The soil was treated with various chemicals and artificial manures 

 none of which proved effective except on a small scale, some on the 

 ground of expense, others on the ground of ineffectiveness. The 

 rotation of immune crops for several years on infected land proved 

 to be the most successful means of controlling this pest. Many of 

 the common weeds are highly susceptible and must be kept down 

 rigorously and the crop sown so thickly as to effectually choke 

 out the weeds. The nematode travels slowly through the soil, but 

 can be widely distributed by nursery stock, cultural implements, &c., 

 and by torrential rains which wash infected soil on to lower non- 

 infected land. 



Some of the resistant plants belong to the Leguminio'Sae, such as 

 Oowpea (iron variety) and hence if grown enrich the soil besides 

 keeping down Heterodera radicicola. The author points out the 

 necessity of raising immune varieties of the susceptible plants. 



Probably the most satisfactory method of destroying the root-knot 

 in greenhouses and seed-beds is the use of live steam under considerable 

 pressure. 



The length of time varies according to the pressure of steam, 

 depth of bed, &c., but a sure test as to whether the steam has passed 

 long enough is to bury potatos in the soil, and when they are thoroughly 

 cooked the steam can be safely turned off. 



Special boilers at fairly high pressure are to be recommended, 

 with the pipes attached to them running through the soil. A formalin 

 drench of one part commercial formalin (40 per cent.) in 100 parts 

 water is effectual, applied at the rate of 1-1^ gallons (rather more in 

 the case of absorbent soils) to the square yard. 



An interval of ten days should elapse before planting. Good 

 plates and au extensive bibliography are given. — D. M. G. 



Rose, A New Climbing- {Bev. Hort. Beige, p. 241; Aug. 1, 

 1911 ; coloured plate). — The new Wichuraiana rose * Aviateur Bleriot ' 

 is said to be a valuable new climbing variety introduced by M. A. 

 Braechman, of Wetteren. In colour it is saffron-yellow with a golden- 

 yellow centre. — M. L. H. 



Rose *Wichm0SS.' By E. Barbier {Rev. Hort. Beige, p. 317; 

 Oct. 1, 1911). — A hybrid rose of which the origin is Wichuraiana x 



