no 



THE AGRICULTURAL NEWS. 



Al'EIL 1, 1911. 



FUNGUS NOTES. 



SOME DISEASES OF THE BANANA. 



During the last few months considerable interest has 

 been shown in the diseases of the banana, particularlj- on 

 account of the destruction wrought in Panama, Costa Rica 

 and Surinam. Consequently, it is thought that a short 

 account of some of these diseases, and of the protective legis- 

 lation which they have called forth in the West Indies, may 

 not be without interest. 



COSTA Ric.v AND PANAMA. A disease of bananas which 

 has now assumed very serious dimensions has been known for 

 several years in these countries, having been observed as early 

 as 1890, in isolated spots. In 1904, a .scientific investigation 

 of the trouble was commenced by Dr. McKenny, who publish- 

 ed a preliminary paper on the subject in Science, Vol. XXXI, 

 p. 750. This author refers to the disease as the Central 

 American banana blight, and states that, according to report, 

 it is not limited to the countries mentioned, but occurs also 

 on the Atlantic side of Nicaragua. Honduras and Guatemala. 



The external symptoms of the disease are briefly as 

 follows. One or more of the leaves turn yellow rapidly, then 

 become brown, and wilt. Sometimes the terminal part of the 

 leaf turns yellow and is noticeably curved, while the remainder 

 is green. Subsequentlj', all the leaves die and fall back 

 against the trunk, and a crop of suckers is left. These in 

 turn die, leaving still weaker shoots which are also killed. 



The internal symptoms of the disease are particularly 

 noticeable in the vascular bundles. When the bases of the 

 leaves which compose the pseudo-stem are cut longitudinally, 

 it is seen that the bundles have a yellow discoloration which 

 becomes red lov^er down, and is almost black near the root- 

 stock. Even in an early stage of the disease, when the vas- 

 cular bundles in the upper part of the stalk appear healthy, 

 those near the root-stock are always coloured. When leaf- 

 stalks which have been afTected for some time are cut open, 

 a nauseating smell is often given off, although there may be 

 no sign of rotting in the trunk. Fruits produced on diseased 

 plants seldom mature, and even when they do so are worth- 

 less, having a Ijlotched and somewhat shrivelled surface and 

 a dry, pithy interior 



The disease is not due to excessive moisture or drought, 

 nor to general conditions of agriculture; though the plants 

 succumb most easily during the period of active growth from 

 April to July. The common yellow, or Martinique, variety 

 is the most susceptible; the red variety is also attack- 

 ed. A new Chinese variety introduced by Dr. McKenny 

 was found to be immune — at any rate temporarily. 



A fungus and a bacteria occurred in the diseased tissues, 

 but McKenny was unable to say definitely which was the 

 cause of the disease, confining himself to the statement that 

 it is evidently produced by a vegetable parasite which makes 

 its entrance into the plant through the rhi/.ome or roots. 



No remedial measures beyond the planting of an 

 immune variety have as yet been devised, aUhongh several 

 have been tried. Some of these are given in a paper b}' 

 Mr. H. C^. Levy, Agricultural Instructor in .Jamaica, in the 

 Journal ot the Jamaica Aiiricxiltnrnl Societi/, \o\. XIV, 

 p. 241. 



CUBA. A similar disease has been reported from Cuba 

 by Dr. Erwin F. Smith, whose paper on the subject appeared 

 in the number of Science cited above. This author remarks 

 that he and McKenny are of the oj)inion that this is probably 

 the same as the Panama disease, though in Cuba a species of 

 .Fusarium was found in the discoloured vascular bundles. 



Inoculation experiments with this fungus showed that it was 

 capable of living as a parasite on the banana, but did not 

 prove conclusively that it was the cause of the disease. 

 Additional experiments are in progress to determine this 

 point 



TKiNiDAD. Bananas and plantains in this island are 

 attacked by two stem diseases and a root disease. The stem 

 diseases are the 'moko disease', .shown by Eorer to be of 

 bacterial origin, and the Panama disease. This last was 

 found on the Gros Michel variety of banana, and liorei- 

 succeeded in isolating a species of Fusarium from the diseased 

 tissues, though the results of inoculations with this fungus 

 were inconclusive. (See Animal Report of the Mycolorjist, 

 Trinidad, 1909-10.) The moko disease is characterized by .symp- 

 toms very similar to those described for the Panama disease, 

 but has been proved by Korer to be definitely of bacterial 

 origin. The plants attacked were the ' Moko Fig ' variety of 

 banana and the French plantain. In considering other 

 accounts of diseases of bananas attributed to bacteria, liorer 

 mentions one described by Earle from Jamaica in 1903, and 

 another from Porto Rico in 1904. (Earle, Journal of the New 

 York Botanic Garden, Vol. 4, p. 37, reprinted in the Went 

 Indian Bulletin. Vol IV, p. 6, and Annual Report of the 

 Porto Rico Ayricidtural Experiment Station, 1904.) These 

 are the only two that Rorer was able to find. The first is 

 not considered by him to be identical with the moko disease, 

 but is mentioned by Smith as being possibly the same as the 

 Panama disease. It would seem, however, that possibl}- the 

 moko and the Panama disease are the same, unless, as Rorer 

 remarks, it is definitely proved that one is due to a bacter- 

 ium and the other to a species of Fusarium. According to 

 Earle's account, the Jamaica disease differs somewhat in 

 symptoms from either of the two referred to above. It may 

 be worthy of note that a rot of plantains is also recorded 

 from British Guiana, though the cause is not given {Journal 

 of the Board of Agriculture, British Guiana, A'ol. Ill, ]i. 90). 

 The third disease in Trinidad is the root disease due to 

 a species of Marasmius, probably Marasmius semiustus, which 

 was reported as being severe on the red banana. 



.SURINAM. The Panama disease has been very destruc- 

 tive to the banana industry in this country, being especially 

 prevalent on the Gros Michel variety, which is that chiefly 

 cultivated. 



The problem here has been investigated by Essed, who 

 published a preliminary note on the subject in the Annah of 

 Botany, Vol. XXIV, p. 488. In this note the author attri- 

 butes the disease to a member of the Ustilagineae, probably 

 in connexion with orie of the primitive group Chytridineae. 

 Subsequently, however, in a letter to this Department, he 

 stated that it is due to a fungus named by him Usti/ae/inoi- 

 della musaeperda, related to the genus Ustilaginoidea, one of 

 the Hypocreales, the family to which the genus Xectria with 

 its conidial stage Fusarium belongs. An attempt was made 

 to overcome the damage due to this disease by planting 

 bananas of the Congo variety. This at first appeared to be 

 successful, but later reports state that the new variety is also 

 becoming att'ected. 



Another disease known as Elephantiasis or 'Bigge Foote' 

 also occurs in Surinam. In this case, the sheathing petioles 

 of the leaves that form the pseudo stem begin to rot at the 

 base. The outer leaves die and fall away, leaving a slender 

 pseudo-stem springing from a large bulb at the base. (Stock- 

 dale, Joxrnal of the Board of Ar/ricultuiv, British Guiana, 

 Vol. IV, p. 18.) This disease is also under investigation by 

 Essed. It may be controlled by digging out and destroying 

 infested plants, as soon as they are observed. 



