DISEASES OF CACAO 85 



Possessed of such measurements it is easily seen that 

 a single drop of water gives them as much room for move- 

 ment, comparatively speaking, as a minnow would have 

 in a mill pond. When the fungus filaments {mycelium 

 or hyphce) have become fully developed, many branches 

 begin to form an oospore or egg-like spore. This spore is 

 formed in a swelling of the free end of a branch of a hypha, 

 and contiguous to it is formed a differentiated branch of 

 the said hyphce, known as an antheridium, and between 

 these two organs fertilisation takes place. It has been 

 noted that some 700,000 oospores may be found on the 

 surface of less than a square inch. The oospores reach 

 the ground in the decomposing part of plants, and it 

 is this fact which has caused us to recommend the 

 entire destruction of all decaying material in so strong 

 a manner from the time the subject was first discussed. 

 Soil containing oospores taken from a diseased seed 

 bed is said to have given rise to the disease four years 

 afterwards, and it is therefore easy to see how readily 

 these spores may be preserved in the decaying masses 

 of broken and empty pods so often seen upon a cacao 

 estate. 



No previous record can be found showing Phytophthora 

 as destroying fruit in the way that it does the cacao pods, 

 its chief ravages having taken place on the leaves of seedling 

 plants. 



With regard to remedial measures, nothing has to be 

 added to, or taken from, the former recommendations 

 made under this head, when attention was first called to 

 the matter, the essential point of which was to destroy 

 all infected material as soon as such comes under the 

 observation of the planter. 



Phytophthora may readily be cultivated in a nutrient 

 fluid, composed of agar-agar and mucilage obtained from 

 a half -grown pod, sterilised and placed in " Petri " dishes, 

 and its growth can easily be studied in an ordinary " drop 

 culture." In the " Petri " dishes it produces a character- 

 istic outcrop, on the surface of the jelly, of small white 



