October i, 1882.] 



THE TROPICAL AGRICULTURIST. 



301 



being burnt on the sides of tbe estate roads. But 

 even this disaster is better b(irne than tlie leaf-disease, 

 whicli subtle pest spreads and spreads and cannot be 

 overcome but with vigorous measures applied quirkly 

 and in time to the borer, its increase is greatly chockfd. 

 Moreover, I saw an estate last month in good con- 

 dition, and bearing a virgin crop from iis young trees, 

 which had been replanted where the borer had de- 

 stroyed the coffee six years ago. Of leaf-di.sease its 

 attitude is highly paciflc, and where a system of 

 high cultivation is followed, as is the case in the 

 majiirity of coffee estates, the evil effect is almost 

 nil, and it is only upon the early ghat or lore>t clear- 

 ing, whire the pioneer coffee planters firut emb.irked 

 their euterpriz-, that the bad consequences are felt fr.rhere 

 all nutrition has long since gone ; the top substance 

 being exposed to the tun and made friaMe, has 

 been waslied away in impetuous monsoons, causing 

 the trees easily to succumb: so that from this ex- 

 perience, now all new coffee clearings nre planted 

 largely with coeval surface root feeding shade trees, 

 which afford protection doublefold. — A/orfras Standard. 



THE BLUE UUM LEAF DISEASE. 

 Of the disease in the leaves of Eucalyptus ytobtdus, 

 and of its effects not only on the trees them- 

 selves but on neighbouring vegetation, we have 

 frequently wi-itten in these columns since the disease 

 was first noticed about tlu'ee years ago. It took 

 the form of spots resembling smallpox on the 

 leaves, and similar spots, more injurious than the 

 originals in then- results, spread to ledgerianas which 

 it was hoped would have benefited by shelter instead 

 of suffering from contagion by being planted close 

 under the lee (the opposite side to that whence the 

 south-west monsoon blows) of the Australian ti'ees. 

 Beyond loss of foliage the gums did not, at first, 

 seem to sufi'er, and, although contiguous cinchonas and 

 rose bushes were more injuriously affected, a few 

 spots on the leaves of tea plants were reckoned of 

 but little account. We referred specimens of affected 

 leaves to Dr. Thwaites, C. M. G., who told us to look 

 out for a "bug." But the presence of diurnal or 

 noctximal insect we have never been able to trace. 

 Still stranger, Mr. S. Green, so well qualified as a 

 naturalist and microscopist, has never been able to 

 find on the affected leaves any specific fungus or the 

 certain action of an insect. Leaves were sent to Mr. 

 Marshall Ward by Mr. A. M. Ferguson, junr., and 

 tbe Government mycologist merely replied that leaves 

 of trees were frequently so spotted ! He suggested 

 neither cause nor remedy. Our own crude tlieory of 

 the disease is, that it is a chemical change of an iu- 

 iurious nature in the juices and tissues of the leaves, 

 owing to change of habitat in the tree from warm 

 and dry to cold and wet. Until quite recently the 

 affection was confined to trees on Abbotsford above the 

 elevation of .5,000 feet. Now, we fear, it is spread- 

 ing downwards, but for information on this head 

 we wait. Before the writer left Abbotsford at the 

 end of July, he felt anxious about the condition and 

 effects of trees which it had cost him so much to 

 establish as drainers of the soil and shelterers of other 

 vegetation, and the introduction of which, he had, 

 through the press, so earnestly (and honestly) urged 

 on his brother planters. We left, hoping that as the 

 disease had abated in previous years, without doing 

 serious damage, so it would in the present season. 



But the heavy and long-continued wet of this monsoon 

 brought matters to a crisis, and the conviction, which 

 cost us many a pang, was forced on us by the re- 

 ports which reached us, that, to save not only the 

 cinchonas which we had left looking so healthy and 

 luxuriant but even the much hardier tea bushes, 

 we must consent to sacrifice the blue gums, at least 

 to the coppicmg of them. The trees were not only 

 themselves dying but were spreading infection and de- 

 nudation of leaf, canker of stems (in the case of cin- 

 chonas), and in some cases death all around them. 

 From the tops do^^^lwards the cinchonas died off • 

 a hedge of roses was left utterly leafless, and patches 

 of tea bushes (for the first time seriously affected 

 by the pest) were reduced to the same condition. 

 "Wattles," never before shewing a trace of disease, 

 were infected by neighbouring gums and killed, and 

 the infection spread to rare Australian plants, around 

 the bungalow, which had been sent to us by Dr. 

 Bennett and Mr. Moore of Sydney. Our latest ac- 

 count of the disease is that it was down and doing 

 damage at 4,900 feet above sea level, and our fear 

 is that it may prevail even at lower elevations. 

 Planters naturally, especially m these hard times, 

 do not care to mention the appearance of pests, new 

 or old, and we kept saying : " Surely this disease 

 cannot be confined to Abbotsford. What about the 

 gums on Oliphant at an average of nearly 7,000 feet • 

 and what, especially, about those fine shelter rows 

 of gums in the Lover's Leap cinchona plantation at 

 the Kandapola end of Nuwara Eliya ? " A visiting 

 agent assured us recently that there was no sign of 

 the disease on the Uva side of Nuwara Eliya, and, 

 until our attention was called to a paragi'aph in 

 the local "Times" indicating the presence of the 

 disease in Dikoya, we had never heard of it beyond 

 the limits of the property in which we were interested. 

 We fear we shall now hear too much of it. If com- 

 pelled to abandon the cultivation of blue gums, we 

 trust we may be able to say that GreviUca rohiiata 

 retains all its favourable characteristics. The great 

 advantage of the blue gums was their exceedingly 

 rapid growth and the prospect of good timber from 

 them at ten years old. The GreriUea also grows 

 quickly, and gives better shelter and timber than the 

 Eucalyptun. We have abeady stated in the Obsenyr 

 that we saw square miles of Eucalyptus in Gippsland, 

 bare of foliage and dead. But the cause of the de- 

 struction was a ravenous moth. Of fungus or chemical 

 leaf disease we have never heard, as afiecting the 

 Australian trees, which, after all, attam their gi-eatest 

 perfection on such wet ranges as those above Fern- 

 shaw in Victoria, the scene of the growth of the highest 

 trees in the world. These are E. amaijilylina, to 

 which E. i/tofjidiix is only second in height. In the 

 " Tea Eiicyclo/iLrdia" there are illustrations of diseased 

 tea leaves, somewhat resembling in appearance those 

 affected by the gum leaf disease, but below each 

 drawdng is the description "pierced" by the immature 

 or mature insect. But in our case there are no 

 marks of piercing. The "tea bug" or "mosquito 

 blight " of India is undoubtedly Helopelth theirora, 

 a name changed by Mr. Moens in his later accounts 

 of its deadly doings on cinchona and t a in .Java to 

 Heloj/<:ltis Anfoiiii. If bad in India, this insect seems 

 to be worse in Java. We said to our good host 

 Mr. Kerkhoven of Siuagar : "Why, may I ask, ha\e 

 yo\i pruned your fine tea so uimiercifully : down al- 

 most to the gi'ouud ':" ' Sorely against my will," he 

 replied, " but the remedy was rendered absolutely 

 necessary by the ravages of HclojKltis." We took 

 away a glass bottle in which specimens of these destruc- 

 tive insects, resembling large mosquitoes, were preserA-ed 

 in spirits, and which we handed to Mr. Green. But he 

 has seen no sign of the bisect, mature or iimnature, on the 

 leaves we have submitted to him. In only one case did 



