19181 DISEASES OP PLANTS. 449 



show that the best avera^o results, considering both freedom from bunt and 

 geruiinabillty, are obtained by dipping the seed grain into 1.5 per cent copper 

 sulphate for 3 minutes and then for an equal period of time into limewater. 

 This is considered the standard remedy to be employed for protection from 

 bunt. Formalin lowered the germination percentage. Experiments under con- 

 ditions of heavy infection of the check plats at Cowra in 1915 and 1916 and at 

 Wagga In 1915 gave, however, better results from dry copper cai'bonate (2 oz. 

 per bushel) than from the standard method above noted. The use of gaseous 

 formaldehyde gave unsatisfactory results during its year of trial, and the tests 

 are to be repeated with modifications. 



Pod blight of the Lima bean caused by Diaporthe phaseolonim, L. L. Hab- 

 TEB (U. S. Dept. Agr., Jour. Agr. Research, 11 (1911), No. 10, pp. 473-504, pis. 2, 

 figs. 11). — An account is given of an investigation of pod blight of Lima beans, 

 which was first reported in this country by the botanist of the New .Jersey Sta- 

 tion (E. S. R., 4, p. 52). 



The disease is characterized by circular brown spots on the leaves and large 

 unsightly spots on the nearly mature pods and stems. As a result of a study 

 of the disease and the literature pertaining to it, the author concludes that 

 it is due to D. phaseolorum. In addition to its occurrence on the Lime bean, 

 the fungus was found to fruit well on stems of Melilotus alba, rice, corn 

 meal, and other starch media. Dilute solutions of formaldehyde, copper sul- 

 phate, and mercuric chlorid proved toxic to the spores. 



For the control of the pod blight, the author recommends the selection of 

 clean seed which should be disinfected in mercuric chlorid, formalin, or copper 

 sulphate. The plants in the field should be sprayed from the time they are 

 1 to 2 ft. tall sufiiciently often to keep the foliage covered with a copper 

 fungicide. 



Cucumber scab caused by Cladosporium cucumerinum, S. P. Doolittle 

 (Rpt. Mich. Acad. Sci., 17 (1015), pp. 87-116).— The injury associated with 

 cucumber scab, which is said to have been very severe during the past two 

 seasons in Michigan, Indiana, and Wisconsin, is due partly to the soft rots 

 which gain access through the scab lesions. The author gives an account of a 

 somewhat extended study of the disease, its distribution, effects, and control. 



The chief difficulty in the control of this disease lies in the rapid growth of 

 the cucumber plant and fruit and in the rapid development and spread of the 

 fungus. Measures recommended include rotation, destruction of trash and 

 vines, drainage, drilling in rows of ample width, airing and sunning the vines 

 after showers, and frequent spraying coordinated with the weather changes. 



Flax wilt: A study of the nature and inheritance of wilt resistance, W. H. 

 TiSDALE (U. S. Dept. Agr., Jour. Agr. Research, 11 (1917), No. 11, pp. 573-606, 

 pis. 3, figs. 8). — In a contribution from the Wisconsin Experiment Station, the 

 author gives the results of investigations carried on as to the nature and in- 

 heritance of wilt resistance. For the purpose of this study, flax was chosen 

 on account of the ease with which it may be gi'own, its short growing season, 

 the availability of resistant and susceptible strains, the ease with which the 

 strains are crossed, etc. The wilt, which is due to Fusarium lini, was studied 

 at great length. 



The fungus was found to penetrate the flax plant through root hairs, young 

 epidermal cells, stomata of seedlings, and perhaps through wounds, invading 

 the tissues of susceptible plants and causing the wilt. No considerable clog- 

 ging of vessels was observed, and the wilting is believed to be due to several 

 factors, such as the destruction of the young active root system, which partly 

 cuts off the food and water supply of the plant; use of the food and water 



