Phytophthora faberi Maubl. a, 

 Chlamydospores (X 325) from 

 pure culture ; 6, conidium ( X 

 325 ) from pure culture ; c, 

 conidia (X 325) from surface 

 of diseased fruit. 



244 '^he Philippine Journal of Science isis 



THEOBROMA CACAO LINN. CACAO 

 BLACK ROT OF PODS: PHYTOPHTHORA FABERI MAUBLANC 



Symptoms. — This destructive disease causes a loss of one-half 

 of the cacao fruit in certain sections of the Philippines. The 



fungus attacks the fruit at any 

 stage during its growth; how- 

 ever, the greatest damage is 

 done to the young fruits. At 

 the point of entrance of the fun- 

 gus a minute black spot is first 

 developed. This spot gradually 

 enlarges, until the entire pod 

 becomes blackened. At this 

 stage, during damp weather, a 

 dense mass of mycelium is 

 formed on the surface, the 

 latter producing conidiophores 

 and conidia (Plate XIX, fig. 4). 

 A section of diseased fruit 

 shows that the mycelium invades the rind, passing into the 

 seed. Finally both rind and seed become rotted with a more 

 or less dry rot. The diseased pods may fall or remain upon 

 the tree, drying up and be- 

 coming mummified. Flowers 

 and stems also may be attacked 

 and killed by the fungus. 



Cattsal organism. — The oval, 

 hyaline, much-granular conidia 

 are produced in abundance from 

 the conidiophores (fig. 33). 

 These spores are produced on 

 the surface of the fruit, whence 

 they are blown to other fruits, 

 causing new infection. Micros- 

 copic examination of the inte- 

 rior of diseased pods shows an 

 abundance of mycelium and 

 chlamydospores (fig. 33). An- 



theridia and oogonia have not been observed. The chlamydo- 

 spores are resting spores and are capable of producing disease 

 after the pod disintegrates. The fungus grows well in pure 

 culture, producing a white, downy growth. Inoculation experi- 



^^ 



Fig. 34. Fusariuyn 

 Strunk. 



theobromae App. et 

 a, portion of conidio- 

 phore (X 315) ; 6, microconi- 

 dia (X 316) ; c, macroconidia 

 (X 315). 



