414 



THE AGRICULTURAL NEWS. 



December 24, 1910. 



FUNGUS NOTES. 



SUMMARY OF INFORMATION GIVEN 

 DURING THE YEAR. 



A very short summary is given lielow of the informa- 

 tion contained in the various articles published under the 

 heading Fungus Notes in the volume of the Agricultural 

 Nev's that is concluded by this number. The informa- 

 tion is divided up, with a view to making the sum- 

 mary as clear as possil)le, and references are given in each 

 case to the pages on which the different .subjects have been 

 discussed. 



CACAO. Two important publications on cacao canker 

 have been dealt with during the year. The first, by Mrs. 

 A. E. van Hall, in Surinam, attributes the disease in that 

 country to Sijicnria rolontus, though infection e.xperiments 

 with the fungus were unsucce.ssful (p. 46). The second, by 

 Rorer, in Trinidad, proved that in that island the disease is 

 due to a species of the genus Phytophtliora, which is also res- 

 ponsible for black rot of the pods (p. 222). This information 

 is somewhat contradictory; but, at any rate, both authors 

 agree that all the species of Nectria which have l>een found 

 on canker wounds are almost certainly purely saprophytic. 

 An interesting point of local interest that has been noted is 

 the susceptibility of the grafted Alligator and Criollo cacaos 

 to this disease in Dominica (p. 222). 



Information on the subject of die-liack disease is given 

 on pp. 46, 270, and 382. It has been shown that the 

 causative fungus is the same in Surinam as in the West 

 Indies; and it is almost certain that the allied fungi described 

 on cacao from different parts of the tropics are in reality 

 identical with one another, and with that found in these 

 islands. The present tendency appears to be to adopt the 

 name L'Xsio'Jiplodia tlieoliromac to indicate them all. This 

 fungus also causes brown rot of cacao pods, and is believed 

 to be identical with that causing die-back of Hevea in Ceylon, 

 namel}', BotryvdiiA'<dia elasticae. Evidence is accumulating 

 which tends to prove that Lasiodiplodia theobroniae can live 

 as a saprophyte on a very large number of other plants, and 

 can act as a partial parasite on several, under the right con- 

 ditions. (See p. 254.) Recent investigations, conducted 

 locally, have indicated that the fungus causing root disease 

 of cacao may also attack limes. A full list of its hosts, and 

 an account of its appearance, are given on p. 366. Some 

 notes on pink disease {Corticiina lilac i no- fusrum) are given 

 on pp. 286 and 382, where its occurrence on pigeon peas is 

 also recorded. On p. 238 appears an account of some 

 experiments conducted in Trinidad by Rorer, to test the effect 

 of spraying cacao systematically with Bordeaux mixture. The 

 experiments indicate that this course is highly remunerative. 



RUBBEi!. A general summary of the diseases of rubber 

 is given on pp. 302, 318 and 334; while a description of 

 pink disease appears on p. 286, and information on die-back 

 on pp. 270 and 382. Rink disease, in Ceylon, is due to 

 Corticium javiinicum; the causative fungus in the Straits 

 Settlements was identified as C calccum. It is possible that the 

 two fungi are identical in Ceylon and in the Straits. Both are 

 closely related to C lilaciito-fusrum. Die-back, in Ceylon, is 

 caused by Boiri/cjdiplodia elasticae following the attacks of 

 Gloeosporiuiii nlhorubrum; in the Straits it is caused by 

 a fungus which has been identified as Diplodia rapnj'. There 

 is evidence to suggest that Di2'lodia rajjax and Botryodip- 

 lodia elastic'ie are the same; and Fetch is of the opinion 

 that the latter is identical with Lasiodiplodia theohromae. 

 A new fungus, found recently on Hevea, is Eutyprt caidivora; 



its parasitism is, however, somewhat doubtful. It is of 

 interest, since it is closely related to E. erunipens — a wound 

 parasite of trees in the West Indies. 



COCOA-NUTS. A short review of some recently published 

 work on well known diseases of this host is given on 

 p. 254; it includes bud rot, root disease and stem bleeding 

 di-sease: the two former from Ceylon and Trinidad, the latter 

 from Ceylon alone. The root disease in Ceylon has been 

 found by Fetch to be due to Fumes lucid us, which is often 

 associated with Botrt/odiplodia elasticae, the last mentioned 

 being saprophytic on the dead roots. In Trinidad, there seems 

 to be a possibility that both bud rot and root disease are of 

 bacterial origin, and due to the same organism; the matter, 

 however, requires further attention. 



LIMES. There appear to be several forms of root disease 

 attacking this host plant in the islands of St. Lucia, Dominica, 

 Montserrat and Antigua; one only has been dealt with — that 

 apparently due to the fungus that causes root disease 

 of cacao. (See p. 366.) The other forms are still under 

 investigation. Another fungus, TItclephorapediccllata, allied 

 to Corticium lilaciiio-fuscuni, has lieen described as forming 

 superficial, violet-grey, waxy patches on the branches of limes 

 in St. Lucia. (See p. 286.) It may be controlled by use of 

 measures similar to those employed tor pink disease of cacao. 



ENTOMOGENOua FUNGI. A general article on this subject 

 appeared on p. 30. An interesting point contained in it 

 is the discovery of Botrytis eriopihyes as a parasite on the 

 black currant mite, Eviaphyes ribis, in England. This 

 suggests the possibility that a similar parasite may occur on 

 the leaf-blister mite of cotton, Eriopliyes (/oisypii, which 

 could be used as a partial means of control. Metarrhi:iurii 

 anisopliae has been found to occur on the frog-hopper 

 Tomaspis piostica in Trinidad, and Rorer and LTrich are at 

 present engaged in conducting experiments to test its value 

 as an effective control of these insects (p. 350). 



SMUT FUNGI. An account of three members of the group 

 Ustilagineae, which contains all the fungi causing smuts of 

 many cereals and other grasses, appears on pp. 59 and 

 398. These are Ustihujo maydis on Indian corn, Ustilago 

 saccliari on sugar-cane, and Ihtilaijo son/In on various 

 Sorghums. 



CHiKF (;roups of fungi. A series of eight articles has 

 been written, giving some idea of the various characters 

 that serve to mark off the main classes of fungi from one 

 another, and of the different types of reproductive structures 

 found among these plants. The series commences on 

 p. 78, and is continued in the seven following numbers. It 

 concludes with a tabular diagram on p. 190, summarizing 

 the information given. 



MISCELLANEOUS. Various fungi of local interest have 

 been described, or referred to, from time to time. The econo- 

 mic importance of these species is very variable, but the 

 record of their occurrence, and advice as to their control, were 

 thought to be of interest to readers for various reasons. One 

 of these is an unidentified root fungus found on many differ- 

 ent host plants, including ground nuts, egg plants and 

 toinatos It is mentioned on p. 11, and also in Vol. VIII, 

 p. 347. Thread blight of nutmegs in Grenada is described 

 on p. 206, and die back of mangos on p. 270. Some 

 account of loaf spot of beet, due to Cercospora hcticola, and 

 rust of grape vines, caused by Uredo viti.t, is given on 

 p. 398. Finally, the results of experiments on disinfect- 

 ing Indian corn seed with corrosive sublimate appear on 

 p. 350. These show clearly that disinfection has a decid- 

 edly beneficial effect on germination, since it increases 

 the percentage of seeds that grow, and also causes them to 

 germinate more nearly simultaneously. 



