which secrete " honey-dew." Injury is done to the trees 

 by preventing the leaves from performing their proper 

 functions, and fruit covered by the fungus is frequently 

 rendered unsaleable. The black incrustations occur where- 

 ever the orange is cultivated, and are caused by different 

 species of the genus Meliola in different countries. 



Messrs. Swingle and Webber have demonstrated that 

 resin-wash is effective, since it destroys the " honey-dew " 

 secreting insects. It is important that the spraying should 

 be done when the insect is in the larval stage. Fumiga- 

 gation with hydrocyanic acid gas is also very effective ; 

 the treatment should last for about forty-five minutes, and 

 should be done when the temperature is low. 



SWINGLE and WEBBER : U.S. Dept. Agvic., Div. of 

 Veg.Physiol. and Pat hoi., Bull. No. 8. 



MASSEE : Text-Book of Plant Diseases, p. IOO. 



DIMEROSPORIUM MANGIFERUM, SACC. 



( = CAPNODIUM MANGIFERUM, C. & B.) 



(Black Blight of Mango.) 



This is a black, incrusting, non-parasitic fungus which 

 forms black patches on both sides of the leaves of mango. 

 The fungus spreads somewhat rapidly, and by forming a 

 coating over the leaves prevents them from carrying out 

 their assimilating functions. It is certain that the fungus 

 follows such insects as secrete " honey-dew." The method 

 of treatment is, therefore, similar to that recommended for 

 the sooty mould of orange {Meliola spp). 



Diagnosis : Mycelium incrusted, effuse, sometimes 

 almost covering the entire surface of the leaf, amphigenous, 

 velvety, intensely black ; perithecia globose-pyriform, 

 rounded at apex, mouth absent ; asci obovoid, rounded at 

 apex, 48-50 by 30 microns ; spores 8, hyaline, elliptical, 

 slightly constricted at the septum, 12-15 by 5-6 microns. 



MASSEE : Text Book Plant Dis., p. 103. 



COOKE & BROOME : Grev., IV., p. 117, pi. 63. 



SPHAERIACE^:. 



TRICHOSPHAERIA SACCHARI, MASSEE. 

 (Rind Fungus of Sugar Cane.) 



Attention was first called to the fungus in Trinidad in 

 the year 1893. At the end of the last century the disease 



19 



