148 EXPERIMENT STATION EECOED. 



with a coarse bagging, wuich is considered to be au important factor in con- 

 trolling temperature nnrt reducing the amount of loss. 



A bacterial disease of fruit blossom, B. T. P. Barker and O. Grove (Univ. 

 Bristol, Ann. Ri)t. A(i>: and Hart. Research Sta., 1913, pp. '76-79).— This is a 

 detailed account of investigations, a preliminary account of which has been 

 noted elsewhere (E. S. R., 32, p. 148). 



For several seasons, according to the authors, pear trees have been subject 

 to a disease which 'is first characterized either by the tips of the sepals turning 

 gray and later blackening, or by the appearance of small black dots on the 

 rec-eptncle of the flower. Occasionally the stigma and style of the pistil of 

 the flower are first attacked, and sometimes the attack occurs on the petals. 

 Occasionally the leaves are attacked, the disea.se appearing on them in the form 

 of small blackened areas which eventually dry up and fall away. 



The organism which is believed to be the cause of this trouble has been 

 isolated and appears to be a species of Pseudomonas which has not been identi- 

 fied with any other form previously described. In addition to occurring in 

 pear flowers, it has been isolated from apple, plum, and cherry flowers. In- 

 oculations have been made on young shoots of apples, pears, plums, and goose- 

 berries by means of needle punctures, but without causing any serious injury 

 to the surrounding tissues. 



Infection and immunity studies on the apple and pear scab fungi, S. P. 

 Wiltshire {Ann. AppJ. Biol., 1 (1915), Xo. 3--}, pp. 3S5-350, pis. ^). — This is a 

 study of the method by which Yenturia incequalis and Y. pirina attack their 

 hosts, and the history of the parasite after penetration, in order to investigate 

 eventually the question of relative immunity. 



The facts as noted seem to show that the appressorium penetrates the cuticle, 

 upon which it feeds, and reaches its normal habitat between the cuticle and 

 epidermis, where it flourishes if the attacked variety is susceptible. Immunity 

 apparently does not depend upon any protection afforded by the cuticle, and 

 indications are noted which suggest a general antagonism of the cell sap for 

 the fungus. 



Wind scorch, of apple foliage, B. T. P. Barker and C. T. Gimingham (Univ. 

 Bristol, A7in. Rpt. Agr. and Uort. Research Sta., 1913, pp. 67, 68). — For several 

 seasons attention has been paid to a severe scorching of the foliage of apple 

 trees, and the possibility of the trouble's being due to a fungus or to spray 

 injury was considered. 



It was also suggested that wind might be resi^onsible for the trouble by 

 causing a constant rubbing of adjacent leaves on each other, and a careful 

 exainination has shown that this is the cause of the injury, the rough edge of 

 one leaf irritating the cells of another at points of contact, finally resulting in 

 the development of a slightly purplish coloration suggesting a slight bruise. 

 Later these discolored patches begin to turn brown, dry up, and present the 

 typical scorched character. It is thought probable that much of the injury 

 that has been attributed to sj-iray mixtures may really be due to the action 

 of wind. 



Sources of the early infections of apple bitter rot, J. W. Roberts (17. S. 

 Dcpt. Agr., Jour. Agr. Research, Jf (1915), No. 1, pp. 59-6.',, pi. 1).—As a result 

 of studies made in the Ozark region of Arkansas, the author has shown that 

 in apple orchards where infections had been severe the fungus Glomerella 

 cingulata may winter over on almost any cankered or dead parts of the tree, 

 including the canker due to X ton miliaria disereta, dead tips of fruit spurs, dead 

 parts of limbs due to injury by freezing or to death of roots, branches injured 

 by mechanical means, cankers caused by the pear blight organism, and twig 

 cankers due to PhyUosticta solitaria. 



