W. J. DowsoN n 



time. The virulence of the fungus remains the same, the resistance of the 

 host increases. 



Under such conditions, spraying for leaf disease has proved successful 

 at altitudes of 5000 to 7000 feet. Any dilute fungicide has been found by 

 experiment not only to control the disease but, if applied at the right 

 time, to completely eradicate it from plantations. The usual time for 

 spraying is just before the long rains commence, and again at their 

 termination. Reinfection usually takes place in subsequent seasons by 

 reason of wind-blown uredospores from a plantation which has not been 

 sprayed. In the Limuru district the disease does such little damage that 

 spraying, always an expensive business, has not been resorted to. The 

 most popular fungicide, and one easily made up, is known locally as 

 "carbide," and is prepared by adding 12 ozs. of calcium carbide to 

 40 gallons of a solution containing 2 lbs. of copper sulphate in water. 

 At lower altitudes, e.g. between 4000 and 5000 feet, spraying with such 

 dilute fungicides is of no avail; but with a stronger mixture containing 

 4 lbs. of copper sulphate and 24 ozs. of calcium carbide per 40 gallons, 

 the results are much more encouraging, particularly on well-cultivated 

 plantations. At such altitudes it is essential to spray regularly to keep 

 Hcmileia in check, l^elow 4000 feet, if the rainfall is at all suitable for 

 the growing of coffee, the other factor of temperature is so much more 

 favourable to the rapid spread of Hemileia that the disease cannot be 

 controlled by any known method, and on account of this, coffee growing 

 is rendered unprofitable at such altitudes. 



Of other fungous diseases of coffee, mention may be made of the 

 leaf and berry spot due to the attacks of Cercospora cojfeicola B. & Cke. 

 Considerable damage has been caused by this fungus on neglected plan- 

 tations, and cases have occurred in which defoliation has resulted. On 

 the berries it is rather more serious from the planter's point of view, as 

 the affected fruits cannot be pulped clean. This trouble is more prevalent 

 during unusually heavy and prolonged rains but can always be found on 

 ill-cared for plantations either on the leaves at any time, or on the 

 berries as they commence to turn red. The disease is easily controlled 

 by spraying either with the "carbide'' mixture mentioned above, or 

 with Bordeaux mixture containing 2 lbs. of copper sulphate per 40 gallons. 



Quite recently a berry spot has occurred due to infection by a s])ecies 

 of Sepforia, which in its effects on the fruit is similar to that produced 

 by Cercospora cojfeicola, but it is not known whether this species is 

 identical with S. maculosa (Berk.) Cke. recorded on coffee berries from 

 Venezuela. The disease is more common on low lying heavy soil, and is 



