NOTES ON RECENT RESEARCH. 



•2-27 



This stage was cultivated artificially on Apple leaf agar and other 

 nutrient media. 



The Vcnturia stage appears on the old leaves which have been infected 

 with scab. The perithecia usually originate in the spongy tissue of the 

 leaf from the mycelial threads which have by this time penetrated more 

 deeply into the dead tissues of the leaf. They appear as small black 

 pustules, scattered as a rule, but frequently in the vicinity of the veins. 

 The author has never found the perithecia on the old fruit and only once 

 on the twigs. In the latter case it is probable that the perithecium had 

 blown into the position taken up. 



The ascospores from the perithecia were cultivated, and produced 

 characteristic Fusicladium colonies and spores on Apple corn meal. 



The Vcnturia stage is identical with V. incequalis (Cke.), Ad. : it is 

 considered distinct from the form on the Pear, which was included by Cooke 

 in his Sphcerclla incequalis (see Seem. Journ. Bot. iv. 18G(), pp. 24H, '249, 

 illus.). The author notes also another ascogenous fungus having perithecia 

 chiefly on the upper surface of the fallen leaves (Splicerella pirina, 

 E. & E.) 



The synonymy and bibliography of the fungus are given in full (pp. 

 124-137). 



In the second pamphlet the author enumerates the various " rots " to 

 which Apples are subject in Illinois. " Fruit burn,'' due to sun heat, 

 mostly attacking fallen Apples ; " brown rot," due to Monilia frucligcna, 

 Pers. ; " soft rot," due to lihizopus nigricans, Ehr., like " brown rot," 

 attacking fallen or mature Apples only as a rule; "fruit blotch," due to 

 Phyllosticta sp., apparently a new disease which the author hopes to 

 investigate next year ; "black rot," due to Sphteropsis malorum, Berk. ; 

 and " bitter rot," which forms the chief subject for consideration in this 

 pamphlet. Other rots due to various causes are incidentally referred to. 

 The bitter-rot fungus attacks both green and ripe fruit, and is widely dis- 

 tributed over the world. It is much more frequent in some seasons than 

 in others, and has been known to cause the destruction of an entire crop. 

 The means of prevention suggested are the thorough removal of all in- 

 fected fruit and spraying at frequent intervals after the disease appears, 

 but experiments along these lines are in progress. 



The rot may spread from many starting points, but generally from one 

 or a few places, and forms a brown rotten area j inch or | inch in 

 diameter. After a time blackish pustules appear at the centre, which under 

 favourable weather conditions burst and set free the pinkish masses of 

 spores. One characteristic feature of this rot is the shrinkage of the 

 tissues, so that a depression is formed, and another is the peculiar bitter 

 flavour of the rotten part. 



Experiments proved that moisture was a necessary condition for the 

 bursting of the pustules and the liberation of the spores. The rot usually 

 appears in July (in Illinois), and the spores, which when moist form a 

 somewhat sticky mass, are carried from tree to tree by small pomaceous 

 flies belonging to the genus Drosophila : they never become so dry as to 

 be blown about by the wind. The spore develops into the Glceosporium 

 stage of the fungus which produces the rot, but during the autumn and 

 the succeeding spring another form of the same fungus develops as a 



