Vol. XI. No. 278. 



THE AGRICULTURAL NEWS. 



415 



FRHiT DISEASES. Under the title The Panama Disease 

 of Bananas, on pages 126 and 142, is summarized the 

 literature dealing with those diseases of bananas and 

 plantains characterized by the progressive destruction of the 

 water-conducting tissue of the roots, bulbs and leaf sheaths. 

 The tentative conclusion is reached that three different 

 diseases of this nature must probably be recognized: the 

 'Moko' disease of plantains described by Korer from Trinidad' 

 caused by BadUus musae; the Surinam Panama disease prin- 

 cipally confined to the Gros Michel banana, described by 

 Drost and attributed to a fungus Leptosphaeria musae, while 

 possibly incompletely described forms of disease in Trinidad 

 and Cuba may be identical with this, as well as a disease 

 with similar symptoms in Bengal: and the true Panama 

 disease of uncertain origin found in Central America. 

 Diseases of avocado pear, mango and bread-fruit, of which 

 the first two are due to species of Gloeosporium, while the 

 third may also be caused by a species of that genus, receive 

 attention on page 334. The first two may be successfully 

 controlled by spraying the young fruits with Bordeaux mixture 

 as shown by Piorer in Trinidad; and Stockdale has found the 

 same treatment efi'ective in the case of the bread-fruit in 

 British Guiana. 



ENTOMOGENOIJS FOXGi. In a note on page 270 the occur- 

 rence of the white-headed fungus of scale insects, Ophionectria 

 coccicola, is recorded in St. Lucia on lime scales, and a hint is 

 given as to the best course to follow in making artificial 

 inoculations with it. The presence of Aschersonia turbinata 

 on the mango shield scale in the same island is also reported. 



MISCELLANEOUS DISEASES. A soft rot of ginger in Bengal, 

 with its cause and remedy, receives attention on page 46. 

 The investigation was conducted by McRae and the disease is 

 attributed to a fungus, Pythiwti gtacile, which infects the 

 parts below ground, entering from the soil and eventually trans- 

 forming the rhizomes into a wet, rotten mass. The well-known 

 mildew of roses is the subject of a short note on page 174, on 

 which a canker of the immortel shade tree found in St. Lucia 

 is also considered; its cause has not yet been definitely ascer- 

 tained. Some further notes on the distribution and host 

 plants of the black root disease (Jiosellmm spp.) are given on 

 page 270. 



GENERAL ARTICLES. Four articles of a general nature 

 have appeared in this volume. A summary of experiments 

 on the control of leaf rust of ground nuts appears on page 14, 

 and the conclusion is reached that the disease does not inflict 

 sufficient damage in most cases to justify the use of spraying. 

 On page 30 is an article entitled Iteports on Fungus Diseases 

 during the years 1910 and 1911. This is a summary 

 of a fuller paper by the Mycologist to this Department read at 

 the Agricultural Conference held this year in Trinidad and 

 published in full in the West Indian Bulletin, Vol. XII, 

 p. 425. The third is an article on the General Treatment of 

 Boot Diseases of Permanent Crops, which appears on page 190; 

 while the last is entitled Crown Gall of Plants and its Rela- 

 tion to Animal Cancer, and appears on page 318. This last 

 presents a short summary of the work of ^rwin Smith and his 

 collaborators on this subject, and of the reasons he gives for 

 considering the plant galls as analogous to human cancers. 

 Since the galls have been shown to be due to the presence in 

 their cells of a bacterium, Bacillus tuiaefaciens, it seems 

 possible from the anology and from the peculiar relation 

 found to e.xist between the host and the parasite in the plant 

 disease that cancer in animals is due also to a bacterium 

 which has been overlooked 



PALMS FOR DECORATIVE PURPOSES. 



The information below is taken from an article 

 giving general suggestions regarding plants for tropical 

 landscapes, in the Philippine Agricidtural Reiiew 

 for September 1912:— 



According to their habit and behaviour the palms may 

 be used in a variety of ways for decorative purposes. 

 Because of their slow growth and comparatively small spread 

 ef crown which gives but little shade, they are not as fre- 

 quently planted for street trees as they deserve from a purely 

 ornamental point of view. This is a matter for much regret 

 because no shade tree can approach a well-developed palm of 

 certain species in clean cut knightlj' beauty. A tree may be 

 the most majestic or the most graceful, but the palm is, 

 nevertheless, distinctly in a class by itself. 'The princes of 

 the vegetable kingdom', so were the palms termed by the 

 great Linnaeus, and there seems to be no reason for a revi ion 

 of that expression. And yet Linnaeus received his impres- 

 sions of the palms from descriptions by others, from herba- 

 rium specimens, and from what must have been but poor 

 specimens found in the crudely constructed greenhouses of 

 his day. We can but conjecture his expression if he had 

 seen the palms in their native habitat. One cannot but 

 regret that the great plant lover and botanist never saw the 

 real Tropics— but to return to our subject. If palms are 

 unsuited to line the wider streets and thoroughfares of a city 

 or the country, they should be planted along paths and 

 walks in the park and plazas whenever this can be done so 

 as to conform to the general design. 



For avenue purposes only, species having a straight 

 trunk and a fairly well developed crown should be chosen, 

 such as the Canary Island date (Phoenix canariensis), the 

 royal palm (Roystonea regia), the California fan palm ( Wash- 

 ingtonia rof'usta), Cocos plumosa, Buri, Corypha elata, etc.; 

 the date {Phoenix dactyUjera) makes a very satisfactory 

 avenue true; though it has a rather 'stiff and ungraceful 

 appearance; for narrow walks and the 'patio' the 'Bonga de 

 China' (Normanbya merrilli) is excellent. As an all-round 

 avenue tree, perhaps no species surpasses the Canary Island 

 date. The royal palm is indeed excellent when from 5 to 

 10 metres tall, but it unfortunately grows so rapidly as 

 to lose its greatest charm while it is still compar- 

 atively young. For the best effect palms should never be 

 planted so close in the avenue that the leaves interlace. For 

 massing, as solitary specimens on the lawn, or in the shrub- 

 bery, all palms may be utilized more or less. For a 'grove', 

 particularly near water, none is more appropriate than the 

 coconut palm. In planting a 'grove' for ornamental pur- 

 poses be sure not to plant an 'orchard' or else much of the 

 charm will be lost. 



A paper in the Annates du Jardin Botanique de Buiten- 

 zorg, 1910, describes an investigation which shows that the 

 latex in plants may contain a reserve of plant food as starch. 

 An abstract of the paper in the Gardeners' Chronicle for 

 October 26, 1912, states: 'By cultivating laticiferous plants 

 in an atmosphere containing no carbon dioxide the formation 

 of sugars is suppressed and the starved plants utilize the 

 starch grain* suspended in the latex. At all events, these 

 grains become corroded just as they do when they are acted 

 on by a diastatic enzyme in the normal course of the "diges- 

 tion" of starch, that is, the conversion of starch to sugar.' 



