414 



THE AGRICULTURAL NEWS. 



December 21, 1912. 



FUNGUS NOTES. 



SUMMARY OF THE INFORMATION GIVEN 



DURING THE YEAR. 



In this concluding number of the current volume of the 

 Agriiidtiiral Neii'^ a summary will be given of the informa- 

 tion that has been published during the year on the subject 

 of plant disease, in continuation of the course adopted in 

 Volumes IX and X. As on previous occasions the major 

 portion of the information deals with investigations that 

 have been conducted in other parts of the world, principally 

 in the tropics, or in the larger islands of the West Indies 

 such as Trinidad and Porto Rico. Certain of the articles, 

 however, as for example the following: that dealing with the 

 prevalence of plant diseases in 1910 and 1911, on page 30, 

 that on the general treatment of root diseases of permanent 

 crops, p. 190, as well as others, have been the outcome of 

 observations made either by the agricultural officers in the 

 various islands of the Windward and Leeward Colonies, or 

 by the Mycologist on the Staff of this Department. The 

 information is here classified under various headings in order 

 to facilitate reference. 



!<UGAE-CANE, There have been three articles dealing with 

 diseases of this host plant in various parts of the world. The 

 first appeared on page 78, and was entitled Red Rot Disease 

 of the Sugarcane in Louisiana It contains an account of 

 Edgerton's observations on the symptoms of the disease as 

 found in that State, and of his successful inoculation experi- 

 ments with Colletotrichum fahatum, the causative fungus. 

 The disease appears in its most typical form and causes much 

 damage to the juice of the cane, which it enters principally 

 through moth borer tunnels. In Louisiana the fungus does 

 not appear to spread into the shoots from infected cuttings as 

 it is reported to do in other parts of the world, notably in 

 India. Its presence in the cane stem is often attended by red 

 spots on the leaves believed to be of the same origin. In the 

 course of the inoculation experiments, the seedlinas D.74 and 

 D.9.5 were found to be more immune than the local varieties. 

 Inoculations with two other fungi very similar to that caus- 

 ing red rot gave no very definite results. In the article 

 on page 366 entitled Iliau- A Cane Disease of Hawaii, 

 a summary is given of Lyon's work on a serious disease of 

 cane, confined to Hawaii. This was shown to be due to 

 a fungus previously undescribed and called by him Gwymonia 

 iliau. It has a Melanconium stage similar to that of the 

 fungu.s found so very commonly on dying canes in the West 

 Indies. The disease is mainly i onfined to the young shoots, 

 which it kills by encasing them in a wrapper of leafsheaths, 

 closely cemented together by mycelium. The growth of the 

 fungus is much favoured by cool, damp weather, which checks 

 that of the cane; while in its partial parasitism dependent on 

 the reduced vitality of its host, as well as in the fact that it is 

 a soil organism, it resembles Marasmius mcchari, one of the 

 local root disease organic ms, and the treatment for the two is 

 consequently also similar. Johnston's work on sugarcane 

 diseases in Porto Rico is summarized on page 482. The 

 most important is root disease which is due to at least two 

 different kinds of fungi, one M<trasmius sacc/uiri and possibly 

 other species of Marasmias, the other unidentified, but caused 

 by a fungus with a mycelium characterized by the presence of 

 stellate crystals. This latter fungus has been found on other 

 grasses, especially guinea grass. In dealing with rind disease 

 the influence of climatic conditions and of the attacks of 

 moth borer on its virulence are noted, as well as other points 



of considerable interest. Experiments showed that the red 

 spot of the leaf sheath due to Cenvspora vaginae did not 

 appear to cause much damage to the cane, and the same was 

 true of the red rot of the leaf sheath due to Sderotium sp., 

 though other observers have recorded it as inflicting serious 

 harm in some cases. It is further noted that the question of 

 other native host plants for the sugar-cane parasites is 

 receiving attention. 



COCONUT p.\L.M. On pages 94 and 110 is given a .sum- 

 mary of Johnston's work on the bud rot of this plant as 

 it occurs in the West Indies. The symptoms, distribution, 

 cause and treatment of the disease, with the means of spread 

 of the infection, are discussedat some length. The causative 

 organism is believed to be a bacterium or strains of bacteria, 

 known as Bacillus coli which is found in the human colon'. 

 This is an important instance of a plant disea.se attributed to 

 an organism best known in connexion with animals. The 

 symptoms of the disease are numerous and rather various, and 

 the rate at which it induces death depends very largely, as 

 do the symptoms exhibited, on the original point of infection. 

 The destruction of the diseased trees is believed to be the best 

 remedy. Another form of bud rot disease, due to a fungus 

 Pythium palmivorum and described from Mexico by the late 

 Olsen-Sefier is dealt with on page 238. This is the same 

 disease as that found in India by Butler, of which an account 

 was given in the Agricultural News, Vol. X, pp. 14 and 30. 

 Finally, part of Freeman's report on Diseases of Coco-nut 

 Palms in Tobago is reproduced on page 398. The diseases dealt 

 with are root disease and one possessing somewhat different 

 symptoms that may be due to other causes. It is stated that 

 the incidence of root disease is independent of soil conditions, 

 while the peculiar fact is noted that only the more superficial 

 roots are diseased in some cases. 



CITRUS. In two articles, one entitled Gummosis of 

 Prunus aud Citrus on page 206, and the other Exanthema and 

 Squamosis of Citrus on page 222, the result of Butler's work 

 on these diseases is summarized. It was found that all three 

 are physiological and are not occasioned by any definite 

 organism, but depend on the incidence of a free supply 

 of moisture at a time of active growth The young 

 newly, formed elements of the wood which are still in 

 a more or less embryonic state break down and form 

 gum, which in gummosis swells out the bark tissues 

 and then breaks through them, forming drops which 

 harden on the outside. Certain varieties of Citrus are 

 very resistent to gummosis and may be u.sed as stocks, 

 while applications of .salt are suggested as preventive of this 

 disease. The occurrence of an alga, Cepheleuros sp., on lime 

 leaves is noted on page 270. On page 350 is a summary of 

 an account of a knot disease of limes found in Jamaica and 

 investigated by Florence Hedges and L. S. Tenney. The 

 disease is characterized by the presence of 1\rge galls on the 

 branches and even on the main stem. Tlieoe when old, girdle 

 the stem and cause the death of the parts above them. The 

 cause is a fungus Sphaei-ojms tumefaciens of which the 

 mycelial characters are somewhat similar to those of 

 Thyridaria tarda and of Diplodia natalensis. The disease 

 may be controlled by the destruction of badly damaged trees, 

 and by heavy pruning of those less affected. 



PARA RUBBER. A short article dealing with investiga- 

 tions by Bancroft on the cause of spotting of prepared sheets 

 of rubber appears on page 62, while on page 158 attention is 

 drawn to Hevea stumps as possible carriers of disease, 

 especially that due to Thyridaria tarda, and Stockdale's 

 advocacy of Government control of their importation into 

 British Guiana is recorded. 



