180 DISEASES OF TROPICAL PLANTS CH . 



Loranthus. This plant has been reported as severe 

 in the gardens in India. Its general character, behaviour, 

 and the results of its attacks are very similar to the 

 mistletoe. The diseased branches should be cut off and 

 the wounds painted. 



Lichens and Mosses. These are very troublesome 

 where the drainage is poor and the shade too dense. 

 They not only interfere with the growth of the plants, 

 but furnish a harbour for insects. The gardens should 

 be carefully drained, and the plants so cared for as to 

 give free circulation of air. 



Nematodes. These pests attack the tea and are 

 very destructive, especially on the seedlings. The 

 nature of the disease is practically the same as that on 

 other plants. 



CACAO 



Brown Rot. This disease has been attributed to a 

 number of organisms, but according to the latest 

 authority it is due to Thyridaria tarda, 1 Bancroft. 

 It originates as a circular brown patch on the pod, 

 usually at the ends or along one of the grooves, but 

 most frequently at the basal end. It spreads rapidly, 

 and the pod turns brown and rots. The rapidity of the 

 spread depends on the ripeness of the fruit, which 

 usually falls in from six to ten days from date of the 

 first attack. When the spots are about the size of a 

 penny, small circular wounds are seen near the centre 

 which give rise to the greyish brown mycelium. 



The fungus enters wounds with great readiness, and 

 bruised fruits are much more susceptible than the 

 healthy ones. It is usually very abundant on the old 



1 Botryodiplodia theobromae, Pat. (1892) ; Macrophoma vestita, Prill et Del. 

 (1894) ; Diplodia cacaoicola, P. Henn. (1895) ; Lasiodiplodia nigra, Appel and 

 Laub. (1896); Lasiodiplodia theobromae, (Pat.) Grill and Maubl. (1909); 

 Diplodia rapax, Massee (1909) ; Botryodiplodia elasticae, Petch (1910) ; Thyri- 

 daria tarda, Bancroft (1911). 



Jonge and Drost report that this organism in culture produces Diplodia, 

 Lasiodiplodia, or Chaetodiplodia characters, dependent upon circumstances, and 

 conclude that the generic name Diplodia should be maintained. 



According to Bancroft, the ascigerous stage which occurs on dead wood 

 determines the fungus as Thyridaria tarda, and the two pycnidial stages should 

 be known as Diplodia and Cytospora. 



