DISEASES OF PLANTS. 843 



descriptions are given of the root knot of vnrious plants due to Ilcterodera 

 radicicola and suggestions for its control. 



The means of control consist principally in the growtli of resistant i)lants. 

 lists of wliioli are given. In orchards and ornamental gardens no very.sati.s- 

 factory uietliods of control Lave been determined. In greenhouses and seed 

 beds steam fumigation is recommended, and for field purposes rotation of 

 croiis is the most practical method known. 



The conidial fomi of Ophiobolus herpotrichus, E. Voces {Ccntbl. Bakt. 

 [etc.], 2. Abt., 42 {WIJ,), No. l-.'f, pp. //.'M)V/, figs, il).— The author, referring to 

 work previously noted (E. S. R., 29, p. 244; 31, p. 542), now states that an 

 Acremonium (.1. alteniatum). and not a Fusarium, is found to be the conidial 

 form of O. herpotrichus. Among the forms present in the fungal complex 

 characterizing stalk disease of cereals, F. riibiffinosiiin, Jlcndersonia hcrpotricha, 

 Mucor ruceiiiosus, Lcpiosphwria tritici, Chidosporiiiiu licrharu/ii, Altcrnaria 

 tenuis, Ascochijta sp., and Heptoria sp. have been identified. 



Control of stem rust of rye, II. C. JMiJXLER and E. Molz {Landio. Weh^ischr. 

 Sachsen, 16 (VJH), No. 7, pp. 60, 61; abs. in Ztschr. Landw. Versuchsw. Osterr., 

 17 (191J,), No. 6-7, pp. 647, 6V/8).— Experimentation showed that Vrocystis 

 occulta on rye is easily controlled by steeping the seed in 0.5 per cent copper 

 sulphate for HG hours, in 0.25 per cent commercial formaldehyde for 15 minutes, 

 or in water at 20° C. for 15 hours or at 30° C. for 4 to G hours. The two last- 

 named treatments were followed respectively by steeping in water at 50° C. for 

 10 minutes or at 52° C. for 5 to 10 minutes without very serious imiiairment 

 of germinability. 



Leaf spot of beans, O. Appel (Mitt. Deut. Landw. Gesell., 29 (1914), ^^0. 18, 

 pp. 249-251, figs. S; ahs. in Ztschr. Landw. Versuchsw. Osterr., 17 (1914), No. 

 6-7, p. 648). — ^An unusually threatening recent increase of infection of beans 

 by Gleposporium (Collciotriehuin) lindemiitlriunHm is noted. The remedies 

 available are careful seed selection, destruction of all infected plants, employ- 

 ment of open ground for planting, and spraying with 0.5 per cent Bordeaux mix- 

 »ure once or twice before the blooms open. 



Eggplant rots, F. A. Wolf (Mycol. Ccntbl., 4 (1914), ^^0. 6, pp. 278-287, 

 figs. 4)- — A detailed account of a study already noted (E. S. R., 31, p. 344).- 



Further studies on the spread and control of hop mildew, F. M. Blodgett 

 (Neic York Htatc ^ta. But. 395 (1915), pp. 29-80, pis. 2, figs. 2; abs. in Phi/to- 

 pathology, 4 (1914), No. 6, pp. 4OO, 401). — In continuation of studies of the hop 

 mil<lew (E. S. R.. 20. p. 34G) the author gives the results of three years' ex- 

 periments on control, together with further observations on the life history of 

 the fungus, relation of tlie weather to the spread of the epidemic, etc. 



The perithecia or winter fruit bodies of the fungus have been found to reach 

 maturity in March and have been shown capable of causing infection in the 

 greenhouse at that time of the year. Artificial inoculations in the field indi- 

 cated that the period of incubation is about ten days. 



In the experiments on the control of the disease, flowers of sulphur, heavy 

 flour sulphur, and fine flour sulphur have been compared, and also the effect 

 of lime used in conjunction wnth suljihur. Flowers of sulphur have been found 

 variable in mechanical condition, and it was impossible to apply satisfactorily 

 some forms. It was also determined that injury following the use of this 

 form of sulphur was due to the presence of considerable amounts of sulphui'ic 

 acid. Extremely fine flour sulphur also pi'oved difficult to apply, and flour 

 sulphur of a medium degree of fineness seemed to be most efficient, easiest to 

 handle, and the cheapest of the fungicides tested. Sulphur and lime mixture 

 proved less effective than sulphur alone. 



