758 EXPERIMENT STATION RECORD. [Vol. 38 



The authors report that the major part of the June drop occurs early in the 

 season and has to do with blossoms and small fruits. It is caused by a stimulus 

 to abscission arising from abnormal water relations within the plant due to 

 peculiar climatic conditions. The major part of the drop of the larger oranges 

 is caused by the fungus A. citri. The drop caused by water relations is consid- 

 ered to bear a definite relation to climatic conditions, and all efforts looking to 

 prevention or control must be either in the nature of modifying environmental 

 conditions or in selection for dry heat resistant strains. Attempts to control 

 the June drop by spraying have not given any promising results. 



Algal disease of cacao, J. B. Rorer {Proc. Agr. Soc. Trinidad and Tobago, 

 17 {1911), No. 9, pp. 345-348). — It is stated that an alga (Cephaleuroa vires- 

 cens) causes a leaf fall and die-back disease of cacao on practically every estate 

 in Trinidad. This disease has been under observation since 1912 and has been 

 described as attacking any cacao tree at any time during the year, but more 

 readily during the last two months of the dry season especially if the trees are 

 not in a good situation or condition. The disease has been called die-back and 

 sun scald, but the author suggests the name of algal disease in order to distin- 

 guish it from true die-back and sun scald, which are said to be caused by a 

 Diplodia. 



Spraying with Bordeaux mixture has been attended by beneficial results, 

 and attention to tillage, drainage, shade, and protection from wind are also 

 considered essential to the complete control of this disease. 



A full report of the disease, with illustrations, is to appear later. 



The diseases ... of the coconut palm, R. M. Richabds {Agr. Bui. Fed. 

 Malay States, 5 {1917), No. S-9, pp. S27S32) .—In the section of this general 

 review of coconut palm diseases and pests here noted the author discusses, 

 together with other diseases in neighboring territory, bleeding di.sease {Thiela- 

 viopsis etJiacetirt(s) . a leaf disease {Pestalozzia palmarum which may be inter- 

 mingled with Helmintliosporium sp. ), a leaf breaking disease, supposedly due to 

 Botryodiplodia sp., though other fungi may be present, bud rot (bacterial), 

 and a sooty leaf fungus {Meliola palmarum) . No root disease of coconut palm 

 has been found in the region covered by this review. 



Leaf bitten diseases of coconuts, S. F. Ashby {Jour. Jamaica Agr. Soc, 21 

 {1917), No. 7, pp. 269-273). — This is a discussion of pineapple leaf bitten dis- 

 ease {Thielaviopsis paradoxa), hard or little leaf bitten disea.se, and Phytoph- 

 thora leaf bitten disease of coconuts as regards their causation, symptoms, 

 and treatment. 



The white pine blister rust in Canada, W. A, McCTJBBnsr {Ann. Rpt. Fruit 

 Growers' Assoc. Ontario, 48 {1916), pp. 81-86). — In a somewhat general dis- 

 cussion of the white pine blister rust situation in Canada it is stated that ob- 

 servations in the Niagara district in 1916 showed that although the fungus may 

 enter the limbs through wounds, the majority of infections seemed to occur by 

 way of the leafshoots. From this point of entry the fungus grows in all direc- 

 tions in the soft bark, killing the tree eventually if it is weakly, otherwise 

 causing a swollen and sickly appearance. A long time is required to kill a 

 large tree, even if a number of infections work in different portions of it. 

 The period between infection and spore formation varies from three to six 

 years or more, but is usually about three and a half years. 



During 1916 data were collected apparently supporting the conclusion that 

 the fungus is able to winter on the currant, and thus live from year to yeai 

 even when the white pine host is absent. Extended surveys in 1915 and 1916 

 .showed that in addition to a large area of infection in the Niagara peninsula, 

 Isolated cases have occurred at Guelph, Brantford, Port Burwell, Button, Oak- 



