30 



THE AGRICULTURAL NEWS. 



Januaey 20. 1912. 



FUNGUS NOTES. 



A REPORT ON FUNGUS DISEASES 

 DURING THE YEARS 1910 AND 1911. 



In the Wtst Indian Bulletin, Vol. XI, p. 73, appeared 

 an account of the prevalence of some fungus diseases during 

 the years 1909-10. This report dealt with observations up 

 to June 1910, and the.se were communicated on forms, con- 

 taining a list of the commoner diseases, sent out from the 

 Head Office. In order to bring the information up to date 

 for the forthcoming Agricultural Conference in Trinidad, 

 similar forms were again sent to the various agricultural 

 officers in the different islands, with a request that they would 

 fill them in, as before. On this occasion two forms were sup- 

 [ilied to each Department. The first related to a period from 

 June 1910 to March 1911, and the second to one commencing 

 in April 1911, and closing at the beginning of December of 

 that year. The first period will lie referred to as period A, 

 and the second as period B. The information thus obtained 

 is abstracted in this article. A further account of it will be 

 published in a forthcoming number of the Wciit Indian Hid- 

 lefin, containing papers presented before the Agricultural 

 Conference. It may be noted that no reports were obtained 

 from Grenada and St. Lucia for period A. 



sLTGAR-c.iXE. The root disease of this crop occurs in all 

 the islands of the Windward and Leeward groups where 

 sugar cane is grown, with the po.ssible exception of the Virgin 

 Islands, in which its effect, if any, is negligible. In Antigua 

 it was very noticeable in both periods, particularly in dry 

 months and on ratoon canes in heavy .soils. In St. Kitts it 

 was more in evidence in period B, which was dry, and it was 

 noted that the variety B.208 was particularly affected, in 

 certain districts. 



The common rind fungus, Melanconium sacc/iari, was 

 not more in evidence than usual during either period. In 

 St. Vincent it is mainly confined to the Bourbon cane, while 

 in St. Kitts 6.208 is believed to be susceptible to the disease. 

 In Antigua, in period B, it was common on overripe canes, 

 and on canes attacked by root disease. The distinction bet- 

 ween this and the red rot is not well recognized in many of 

 the islands, but a disease was recorded from St. Lucia in 

 period B which agreed with typical red rot in its symptoms, 

 while material examined by the Mycologist showed the fruc- 

 tifications of Colletotpchum falcatum, to which true red rot 

 is due. 



COTTON. Anthracnose {Colletotrichum gossypii) was fairly 

 prevalent in the wetter districts of St. Vincent, in period A, 

 and throughout the i.sland in the wet season of period B. 

 Reports from Nevis emphasize its occurrence in damp districts 

 only, while in Montserrat it is not clearly recognized as 

 a disease of any importance, and is probably of quite rare 

 occurrence. It was found to be causing some damage on 

 a field in a newly started cotton cultivation in Grenada. Bac- 

 terial boll disease, together with angular leaf spot and black 

 arm — which are believed to be of similar origin — was fairly 

 prevalent in St. Vincent and St. Kitts in period A, when its 

 spread was apparently encouraged by wet weather. This 

 was noted as occurring in St. Vincent in September and 

 October, but the dates of the heavy rains are not recorded in 

 St. Kitts. It was also found in Montserrat to some extent 

 in the same period, while black arm appeared at the end of 

 the season. In period B, it caused much damage during the 

 abnormally wet season in St. Vincent. In Montserrat, 



St. Kitts and Nevis the season was very dry up to the begin- 

 ning of September, and the various forms of the disease were 

 not much in evidence. A few cases of angular leaf spot 

 were seen in St. Kitts, and of this and black arm in Nevis; 

 but in the latter island no boll disease was noted. 



The West Indian leaf mildew was fairly prevalent in 

 St. Vincent, in October and November 1910; that is in 

 period A. It was also fairly common in Antigua, while in 

 Montserrat it was more noticeable than in previous seasons, 

 and one field which was attacked early in the season was, by 

 October, rendered leafless; in spite of this, it gave a good 

 crop. The mildew was not observed at all in Nevis, in 

 either period, nor in St. Kitts in period B. In St. Vincent, 

 however, in the latter, it was prevalent after October owing 

 to the wet weather, while it was also fairly common on fields 

 of older cotton in Antigua. In Montserrat it was not much 

 in evidence. 



Certain miscellaneous diseases were also reported, of 

 whicli the most important, from Montserrat, is a disease of 

 liolls borne on branches near the ground. The infected tissues 

 exhibit a soft rot, and a species of Pythium or Phytophthora 

 occurs on them. The disease is responsible for some loss, 

 and will receive further investigation. 



CAC.io. Root disease occurred in damp situations in 

 Grenada, in peri(jd B, when it was also found to be fairly 

 common in St. Lucia Of the other diseases canker and 

 black rot of pods, both due to Phi/tophthora Faheri, are the 

 most important. In Dominica, canker occurred on delicate 

 varieties of cacao in both periods, while in the second it was 

 found to be always associated with pod disease; in St. Kitts, 

 a few cases that occurred in [leriods A and B were successfully 

 treated. Die-back, due to Thyridaria tarda, is known to 

 occur throughout St. Lucia, but no special outbreak was 

 recorded. In all the islands, increa.sed attention to proper 

 sanitation is resulting in keeping under adequate control both 

 this disease and brown rot of pods due to the same fungus. 

 None of the other cacao diseases were at all in evidence, 

 except that in Grenada an outbreak of thread and horse-hair 

 blights occurred on nutmegs in one district, and in a few 

 instances individual cacao trees were infected. 



LIMES. Black root disease {Rosellinia sp.) occurred on 

 limes, cacao, and pois doux in sporadic instances, on estates 

 in the interior of Dominica, while red root disease of limes 

 (Sjiharrostilbf sp.) was also observed to be present in the 

 same way in a similar locality. These diseases have only 

 recently been described, so that they are not recorded 

 previous to period B. (See Agricul/ural News, Vol. X, 

 pp. 366 and 382.) 



A peculiar form of root disease, sometimes associated 

 with the presence of the brackets of Fames lucidus, occurred 

 in IMontserrat and Antigua in both periods, but in the latter 

 island it was not spreading at all rapidlj-. 



The only other disease noted was Melanose of lime-', seen 

 in Montserrat and Antigua, in period B. 



ELiBBEE-PRODUCixi; PLANTS. A disease of Hevea seed- 

 lings appeared in the nurseries of the Dominica Botanic Gar- 

 dens in period A, and at one time assumed threatening pro- 

 portions. This wasj however, controlled by sprajlng the plants 

 with Bordeaux mixture, and by the use of a mixture of lime 

 and sulphur. The exact cause was not determined. It did not 

 re-appear in period B. 



A disease believed to be identical with the black root 

 disease of limes, and in any case due to a species of Rosellinia, 

 was found on young Castilloa trees in Grenada, in period B. 

 In St. Lucia, one instance of the disease was noted; while in 

 Dominica it only occurred where Castilloa was grown under 

 unsuitable conditions. Both these records apply to period B. 



