454 EXPERIMENT STATION RECORD. [Vol.37 



per acre, according to the depth and nature of the infested soil. On account 

 of the burning effect of the cyanamid, an interval of one to several weeks 

 should intervene between the treatment of the soil and the planting of the 

 seed. The cost of the treatment is such that its use is recommended only on 

 seed beds and truck lands under intensive cultivation, but as cyanamid is an 

 important source of nitrogen its use as a fertilizer shouUl be considered In 

 connection with nematode control. 



Rosellinia root diseases in the Lesser Antilles, W. Nowell (West Indian 

 Bui., 16 {1916), iYo. 1, pp. 31-71, pis. 7, figs. 2).— Rosellinia, several species of 

 which cause root disease in numerous temperate and tropical countries, oc- 

 curs in this relation in the Lesser Antilles, Guadeloupe, Dominica. Mar- 

 tinique, St. Lucia, St. Vincent, and Grenada, but not on the other islands of 

 the group which have drier climates. Though the range of hosts as regards 

 classification is also very wide, the plants most affected in this region are 

 cacao, coffee, limes, and arrowroot. Cacao is attacked usually by R. pepo 

 (possibly in certain localities by another species not yet identified), which 

 spreads from roots of dead or dying shade trees. Limes and coffee plants are 

 attacked by both R. pepo and R. bunodes. 



Infested trees may be killed by the progressive investment of the roots 

 (spreading from roots of other trees) or by the destruction of the bark around 

 the collar. The fungus penetrates quickly both bark and wood, conidia being 

 readily formed where the mycelium is erpo.sed, and perithecia occurring later. 



Preventive measures include periodical inspection, aeration, insulation, dis- 

 "ifection, liming, flaming, and removal of infected wood. 



Observations on a new disease in cotton, M. J.. P.^tel {Poona Agr. Col. Mag., 

 8 (1916), No. 1, pp. ^.5-4<S). — A disease, afferting most of the native varieties 

 of cotton in certain districts, is describo<l. The leaves on some branches turn 

 pinkish yellow just before blooming, the number of blooms is reduced, and the 

 young bolls produced remain small and dry up quickly. 



The trouble, locally termed sterility, was more severe in 1915-16 than in 

 1914-15. It varies somewhat in severity with season, soil, and variety, but it 

 does not appear to be due primarily to diminished water supply or to lack of 

 nutrient material. An observed shortness of the taproot Is thought to be a 

 result, not a cause, of the disease. Belated attacks are less severe. Mites are 

 observed to be more common on affected than on other portion.s of the plant. 

 No disease organism has boon Isolated. The bolls open poorly on affected plants. 

 The seeds are lighter in affected cotton, but the lint is proportionate. y still 

 lighter, as shown by a lowered ginning percentage; also the lint is said to be 

 more brittle In diseased cotton. 



Removal of all affected brunches appears to prevent the disease so far as 

 the individual plant is concerned. 



Studies on clubroot of cruciferous plants, C. Chupp {New York Cornell Sta. 

 Bill ,1S7 {1917), pp. Jtl9-',52, figs. /6).— The author has made a study of the 

 clubroot of cruciferous plants due to Plasmodiophora brassiccr in an attempt 

 to determine the part played by swarm spores In the dissemination of the 

 fungus, spore germination, the manner in which the pathogene enters the host, 

 the distribution of the organism throughout the tissues of the root, the forma- 

 tion and size of the spores, and the reputed relation of bacteria to the normal 

 development of the myxomycete. 



As a result of his investigations he has found that neither the motility of 

 swarm spores nor the action of winds is an important factor In the dissemina- 

 tion of the parasite. Each spore is said to produce one swarm spore which, 

 if not supplied with a host, develops no further. Penetration of the host takes 



