: PART IV.
probable that Colletotrichum coffeanum had become parasitic on coffee
branches in this country and in both these cases there were special
conditions favouring the fungus. In these instances ‘the attack
occurred on isolated twigs and the branches died not from their tips
but from the actual point of attack. The name anthracnose is better
suited to this disease than ‘‘ dieback,”’ to which actually it bears no
relation.
One other malady which may be confused with dieback should
also be mentioned. This is known in Kenya as ‘‘ black tip,” and
occurs almost exclusively at altitudes above 6,000 feet. It appears to
be due in part to the scorching effect of the sun’s rays acting through
drops of rain or dew and in part to too rapid changes of temperature
in the plantation. The operation of these factors causes the deaths
of the main growing points of the branches and the consequent
stimulation into activity of numerous auxillary buds, so that the
production of a bushy growth of secondary shoots behind the tips of
the primaries results. The actual killing of the tissues is confined to
the ends of the branches, and once the difference is realised there is
no difficulty in distinguishing between black tip and dieback proper.
REFERENCES :
(1) Small, W. Dieback of Coffea arabica in Uganda. Circular No.
4, Uganda Department of Agriculture, 1920.
(2) Small, W. The Diseases of Coffea arabica in Uganda. Circular
No. 9, Uganda Department of Agriculture, 1925.
(3) McDonald, J. Fungoid Diseases of Coffee in Kenya Colony.
Bulletin No. 3, Kenya Department of Agriculture,
1925. ;
"Mr. RITCHIE said that in his experience, dieback was less
frequent if the long top or multiple stem system was adopted, i.e.,
when the balance between crop and foliage is more evenly maintained.
Mr. TRENCH observed that dieback was the result of a
combination of causes. Pruning on the single stem requires expert
knowledge, and dieback may be caused by bad pruning. The
multiple stem system does not require so much pruning, and so 1s
probably to be recommended in order to minimize the incidence of
dieback.
In reply to Mr. Ritchie, Mr. Trench stated that dieback was not
usually serious at the higher altitudes, where growth is sturdy and
crops not very heavy.
MetHODS OF COMBATTING COFFEE STEM BORER.
Mr. WILKINSON said that the only stem borer in Kenya was
Apate—the black borer; this was easily combatted by injecting Carbon
bi-sulphide or petrol into the hole in the stem.
Mr. RITCHIE said that in Tanganyika, the white coffee borer
(Anthores leuconotus Pasc.) is controlled by hand-picking out of the
grubs by means of a wire with a hook attached. Where conditions
are suitable for coffee, and it is subjected to no set back by overbearing,
 leaf disease, etc., borer is easily kept in check. Correct
coffee culture to maintain the sap flow and steady growth of the
tree is the main essential in borer control. The yellow borer ( Dirphya
sp.) and the bostrychid borer (Apate monacha) are not of any
considerable importance in coffee culture in Tanganyika.

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