44 SPICES 



CHAP. 



and figured by Massee in the Kew Bulletin (1892), 

 p. 110, as Calospora Vanillae, Massee. 



This disease seems to have been noticed first in the 

 Seychelles in 1887, when it was found that hundreds 

 of pods were damping off, and it was observed that 

 the finest and plumpest pods went first. They turned 

 black at the end or in the middle, and in the course of 

 a day or two fell off. 



The fungus which causes this is a minute species 

 belonging to the group Peronosporeae, which attacks 

 the leaves and stem of the plant. It appears as ex- 

 tremely minute, dull red or amber coloured pustules 

 springing in small groups from discoloured patches. 

 These were found on both surfaces of the leaf, but 

 for the most part on the upper side. This form of the 

 fungus is known as the Hainsea form. Its mycelium 

 spreading through the leaf destroys the tissue and 

 causes the death of the plant by destroying the organs 

 on which the plant depends for its food and for the 

 regulation of its water supply. In such a case the 

 youngest parts, farthest from the food supply, namely 

 the young fruit and the aerial roots, show the first 

 symptoms of disease, the fruit turning black and falling 

 off, as described. 



When the leaf has become yellow and is dying from 

 the attack of the fungus in this stage, a second form of 

 the fungus appears in the form of yellow waxy masses, 

 the Cytospora form, eventually presenting a blackened 

 appearance, and finally a third form when the leaf is 

 dead, the Calospora form. This form produces spores 

 which enter the stomata of the leaves and develop into 

 the mycelium of the Hainsea form. 



The Hainsea form in the diseased leaves cannot re- 

 produce itself, but from its mycelium, when the leaf is 

 dead, are produced the Calospora spores, which can 

 attack healthy leaves and cause the death of the plant. 

 It therefore follows that if all dead and dying leaves 

 of the vanilla are rigorously destroyed by burning, 

 the disease may be checked or exterminated. The 



