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THE AGRICULTURAL NEWS 



NOVEMBEE L-*, 1916. 



PLANT DISEASES. 



HOSELLINIA ROOT DISEASES IN THE 



LESSER ANTILLES. 



The following is a sunun;iry of an important paper by 

 IVIr. W. Nowell, D.I.C, Mycologist to this Department, oil 

 Rosellinia root diseases, which appears in the current number 

 of the West Indian Bulletin (Vol. XVI, No. 1): — 



Several species of the genus Rosellinia give rise to a 

 well-defined type of root disease in numerous countries of the 

 world, temperate and tropical. The fungus kills out 

 cultivated trees or shrubs in patches, and often infests the 

 .soil and destroys practically all vegetation with which it 

 comes into contact. 



In the Lesser Antilles, Rosellinia diseases occur in 

 ' >uadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, 

 and Grenada: the)' are unknown in the remaining islands of 

 the group, which have drier climates. 



The range of hosts is an exceedingly wide one, 

 embracing pract.ically all the impgrtant cultivated and semi- 

 cultivated plants, but the cultivations most affected are those 

 of cacao (in all the islands), coffee (in Guadeloupe and 

 Martinique), limes (on new clearings in Dominica), and 

 arrowroot (in the interior districts of St. A''incent). 



The disease on cacao is usually caused by the species 

 Jiosellinia I'epo, and in most cases at the present time, the 

 fields being well established, is communicated from the roots 

 of dead or dying shade trees, especially breadfruit, avocado 

 pear, and pois-doux. Another species as yet unidentified, 

 is believed to attack cacao in certain localities. 



The disease on limes and coffee is caused by E. Pepo or 

 R. bunodes, indifferently. 



The first cases in new clearings are usuallj' as.sociated 

 with forest .stumps left to decay, especially those of certain 

 special trees. Subsequent cases arise from the spread of the 

 fungus from tree to tree along the roots, or by infection 

 from surface soil rich in decaying vegetable matter, which 

 readily becomes infested in damp and shaded situations. 



An infested tree may be killed gradually by the pro- 

 gressive investment of the roots, or rather quickly by the 

 destruction of the bark around the collar. The fungus 

 enetrates both bark and wood. Cpnidia are produced with 

 great readiness wherever the mycelium emerges into the open; 

 jierithecia occur later, and especiajly in the case of R. Pepo 

 their formation may he. long delayed. 



Much can be done to prevent outbreaks of the disease by 

 measures directed towards exposing to wind and sun the soil, 

 the bases of the trees, and any logs or other dead material 

 lying about. Cases which arise may be restricted by these 

 measures and by the provision of a close system of trenches 

 to prevent root contact. 



Treatment by excision and exposure is successful in the 

 early .stages of infection, but in practice these are hardly ever 

 detected. I'eriodical surveys would ."^ave many trees. 



Infested trees should be flamed and then promptly 

 removed, all roots dug out and burnt, the .soil limed, and the 

 .situation exposed as much as possible. All adjacent trees 

 should be isolated from each other by trenches. 



DOWN THE ISLANDS. 



ITEMS OF LOCAL INTEREST. 



ST. Luci.v. Mr. A. J. Brooks's report for October states 

 that the rainfall at the Botanic Gardens, Castries, was 2 1 -82 

 inches. The maximun fall was 3'34 inches on the 21st 

 while rain fell on twenty-six days. The rainfall at the 

 Agricultural and Botanic Station, Choiseul, was 11-3.5. 

 Work in the Experiment Station has included the planting 

 of lime seedlings for 1917, the budding of oranges, and the 

 planting of ])rovision crops. In the Botanic Garden.s, work 

 was retarded by the heavy rainfall. Ob.servations relatincf to 

 the staple crops show that at the time of writing there was 

 a good cacao crop but this was late in some districts. The 

 lime crop slackened during the month Extension in lime 

 planting continues. As regards sugar, it is stated that the 

 canes are now arrowing and there is a good stand through- 

 out the island. Thirteen casks of concentrated lime juice 

 were prepared at the Government Factory during the month 

 and 1 1 carboys of distilled oil await shipment. The new 

 Crossley .5i h.p. oil engine gave every satisfaction during its 

 trial run. Further, .soil shrinkage tests have been made in 

 connexion with cacao cultivation 



A meeting of, the Good Shepherd Catholic Friendly 

 Society was held in Castries on October 22, attended b}' the 

 Inspector of Agricultural Credit Societies. It was decided to 

 form an agricultural credit society, limited to members of the 

 former society, and to advance money for agricultural purposes 

 to its members from its surplus funds. The agricultural 

 officers in St. Lucia devoted special attention during October 

 to peasant cultivation.^, urging the planting of ground 

 provi-sions. 



ST. KITTS. In Mr. Shepherds report for October it is 

 stated that work in the Experiment Station largely consisted 

 in planting provision crops and. in j)icking cotton from .selected 

 plants and from the manurial plots. During the month 

 12,000 sweet j)otito cuttings were distributed. The Garden 

 suffered -severely from the strong southerly gale of October 

 9 and 10. On the estates the more advanced sugar-canes 

 suffered worst, B. 117 being the variety damaged most. This 

 variety seems very susceptible to damage owing to its vioorous 

 growth. In some instances the damaged canes have been 

 used for planting purpoje.s. Generally speaking, however 

 the heavy rainfall for the month (1")'59 inches in the Valley 

 district and 190 inches in the Northern District) has done 

 much good, and the present condition of the cano crop is 

 all that can be desired. It appears that cotton sutlercd much 

 more than the cane, particularly along the coast. Appended 

 to Mr. Shepherd's oWrvations is a summary of the work 

 conducted during October at the Government Chemical 

 Laboratory. This included the examination of eighty- 

 one samples of cotton lint, the partial analysis of 

 three samples of soil, and the analysis of seventeen 

 samples of milk from the Inspector of Police. On sixty-one- 

 of the cotton samples, lint length, available fibre, and ginning 

 out-turn were determined; on the other twenty samples 

 lint length and ginning out-turn only, were a.scertained. 



