114 



tend to further propagate the fungus. Disease is an extremely 

 complex phenomenon, involving many reactions and interactions 

 between the plant and its evironment and, therefore, every disturb- 

 ance of functional equilibrium has to be carefully considered before 

 any definite conclusions can be arrived at. In this report every 

 consideration has been given to the results of practical experiments 

 and the soil and climatic conditions of the different localities in 

 order that the pros and cons should be carefully weighed before any 

 remedial measures are suggested. 



Section I. — ROOT DISEASE. 



13. An attack of this disease is generally first shown by the 

 leaves. They show a slightly wilted appearance, then turn yellow, 

 first at the tips and then gradually all over the leaflets. These 

 dry up, blacken, hang down from the 'cabbage', and often remain 

 for a considsrable time before they are shed,— a badly attacked 

 palm often being entirely enclosed in numbers of leaves around 

 its trunk. Frequently, however, it is noticed that the leaves do 

 not hang down around the trunk but the petioles break across, 

 leaving the sheathing portion on the trunk, while the foliage 

 portions of the leaves have fallen to the ground. Sometimes the 

 petiole does not completely break and the foliage portion of the 

 leaves hangs vertically downwards, attached to the portion of the 

 petiole that is left attached to the stem. 



The outer leaves are sometimes those that show signs of wilting 

 and yellowing first but this is not always so, for frequently palms 

 may be noticed in which a 'middle' ring of leaves becomes wilted 

 and yellow while rings of green leaves remain above and below. 



After the yellowing of the leaves, trees bearing a good crop of 

 nuts as a rule gradually shed most if not all of them, irrespective 

 of their size and state of development, and the flowers subsequently 

 produced do not set. In fact, it is possible for a person to pick 

 out with certainty trees that are diseased before any yellowing 

 of the leaves is noticed, by carefully looking at the condition of- 

 the leaves and at the latest flowers that are being put forward. 

 Any trees that are diseased can at once be singled out. The local 

 conditions of the soil must be considered before a tree is definitely 

 stated to be diseased as the whole appearance of the diseased trees 

 suggests a lack of water, and therefore may be confused with 

 trees that are suffering from this cause alone in drought-affected 

 areas. 



An increased supply of water, either natural or artificial, will 

 improve the condition of drought-affected trees but the wilted 

 appearance of diseased trees, although it may be slightly less 

 noticeable, is more permanent, and the symptoms do not disappear. 



After a number of the leaves have yellowed and died, it is only 

 a question of time before the terminal bud falls over and becomes 



