W. J. DowsoN 85 



economic biologist, and to consider each plant or crop in the order which 

 one naturally comes across it when travelling on the Uganda Railway 

 from Mombasa to the Victoria Nyanza. 



The writer wishes to acknowledge his indebtedness to the Entomo- 

 logical Division of the Agricultural Department at Nairobi for the 

 knowledge acquired concerning insect pests. 



II. The Cocoanut Palm. 



The rainfall along the coastal belt is between 60 and 70 inches, but 

 towards the S.E. corner in the neighbourhood of Shimoni the rainfall is 

 greater, and besides such indigenous palms as Hyjjhaene fheboica, Boras- 

 sus fiabellifer and Cocos nucifer, a small patch of the oil palm Elaeis 

 guineensis occurs. The rains are distributed in two seasons, a short one 

 in November and a longer period from April to June. Along this coastal 

 strip and for about 20 miles inland cocoanut palms are grown in planta- 

 tions owned by Swaliilis, Arabs, Indians and Europeans. The palms 

 are subject to numerous diseases and pests, the most important of which 

 are undoubtedly the bud-rot or heart-rot, and the cocoanut beetle 

 {Oryctes monoceros). In the first, the infection can be traced from the 

 upper external portion of the youngest folded leaf, but whether primarily 

 due to Phytophthora palmivora Butl. or to bacteria was not ascertained. 

 The dried and wilted upper portion of the spear contained much mycelium, 

 but towards the actual rotting margin no hyphae were discovered. 



Unlike most countries in which bud-rot has been recorded, the palm 

 in East Africa is attacked at the bearing age, seven years, and very 

 considerable loss is thereby caused to owners of large plantations in 

 which several hundreds of acres have been planted out at one time. To 

 the north of Mombasa, on an extensive plantation in which African and 

 Ceylon nuts had been planted, 60 per cent, of the young Ceylon palms 

 were attacked and killed in three years, and so susceptible did these 

 imported palms prove that the rest were taken out and replaced with 

 sisal hemp. The African palms appeared much more resistant, thus in- 

 dicating that the disease, as it exists in East Africa, is probably native 

 to that country, and has not been imported. Besides the high suscepti- 

 bility of imported palms and the comparative resistance of native palms, 

 three other points are worthy of notice. One is the striking fact that 

 palms are only found in certain places and have never been known to 

 thrive in others. Thus along the coast south of Mombasa on the Clazi 

 Road, palms grow in patches which alternate with strips of country 

 apparently similar in all other respects but upon which there are no palms. 



