O22 REPORT OF THE HARVARD AFRICAN EXPEDITION 
ring disease (p. 389 of this Report). This find is of exceptional interest, since 
heretofore, the disease has been reported only from the American tropics. T he 
writer has seen its effects in Trinidad and British Guiana, although it is also 
known from Tobago, Grenada, British Honduras, Panama, and Venezuela, and 
then only on Cocos nucifera and in one case on an undescribed species of Cocos, 
not on other palms. The parasite has been described by Cobb 1 as Aphelenchus 
cocophilus. Since the symptoms of the disease are the same and since only the 
coconut appears to be attacked, it seemed quite possible that the nematode was 
the same as that found in the Western Hemisphere, and that the organism might 
have been transplanted by its eggs on imported seeds. If, however, the species 
proves on more careful study to be endemic, then an interesting field of investi- 
gation is open to the plant pathologist to determine whether the organism is as 
specific as is indicated, and if not, what other hosts are infested. 
At all events the symptoms of the disease in the two regions appear to be 
much the same. The trees so infested are characterized by a yellowing of the 
older fronds which progresses until all but the youngest ones are involved, and 
these eventually succumb. The trees at an advanced stage of infection become 
rich yellow and then a rich golden brown. The internal symptoms are quite 
decisive. A zone, one to two inches wide, at first dingy-yellow, then dull-red, is 
formed one or two inches from the periphery, and extends up the tree a distance 
that varies with the age of the infection. Root infection, in the case of T'ylenchus 
cocophilus, according to Nowell,? the discoverer of the nature of the disease, 
is confined to the cortex between the horny hypoderm and the central wood 
strand. 
The mode of infection is not definitely known, although Nowell * considers 
it possible that the worms ascend from the soil by way of the surface of the stems 
and gain entrance at the base of the leaves in the same manner that rice and 
black currants are known to be infected. Just as the exact mode of infection is 
uncertain, so too is the method of control. In view of the fact that when the 
trees die the soil becomes heavily infested, it is obviously a good practice to cut 
the trees into convenient lengths and then to burn them thoroughly, since charred 
parts may still harbor the parasites. Furthermore the roots should also be ex- 
cavated and burned with the trunk and leaves, the incineration being performed 
over the excavated area formerly occupied by the trees. This is done in order to 
bake the soil. 
. A Visit TO THE RUBBER PLANTATION AT Mt. BaRcLAyY 
While in Monrovia awaiting completion of arrangements necessary for the 
subsequent expedition into the interior, the writer, through the courtesy of the 
Firestone Plantations Company, was afforded the privilege of visiting one of their 
stations. The first impression one receives is the park-like appearance of the 
plantation. The undergrowth, because of the frequent removal is almost en- 
1 Cobb: West Indian Bull., 1919, Vol. 17, p. 208. 
2 Nowell, W.: West Indian Bull. 17:189. 1919; 18:73. 1920. 
3 [bid.: Diseases of crop-plants in the lesser Antilles, pp. 177-182. West India Committee, London. 
1924. 
