Vol. XI V No. 337. 



Tin; AGRICl LTUBAL NEWS. 





lative ground. The subject i> a • - complex one and 



rather negl larh ds fungi. Ii is 



probable thai man} of the old established maladies 



iduced with the plants and animals commonly 



id. On ' hand, indigenous, or at least 



alized species of insects and fungi may have 



gradually become parasitic after the introduction "l 



particular cultivated plant or animal. It maybe 



menti our views as to wh a pa 



is. haveoflate years undergone a We now 



a hich is nol highly specialized 



to a saprophytic life, is liable bo bi a parasite, the 



rning factors being principally the activity of the 



natural enemies of the species, and the extenl of its 



I supply. 



h is possible, however, ho pro luce several definite 

 examples of introduced pests and diseases. Among 



cale insects al leasl twenty-five species havi been 



introduced from outside the West Indies. Among 



boring insects there are several notable cases. The 



borer of the sugar-cane (Diatreu saccharalis) 



is probabty a native of Smith rica, whilst 



the giant moth borer (Castnia licus) was certainly 

 introduced from that country. The longicorn beetle 

 which was observed two years ago boring in mango 

 and Avocado pear trees in Trinidad and St. ( 'mix was 

 identified as Bartocera rubus, which is a native of 

 Asia and Easl Africa, 



As regards natural enemies, an interesting intro- 

 duction is the Mexican predaceous bug (Gastolus sp.), 

 which was brought to Trinidad as an enemy of the 

 froghopper. 



Turning to fungoid diseases, it is possible to give 

 only two examples with am degree of certainty, 

 because our knowledge of the exact distribution oi 

 -is so imperfect. It is likely that the fungus 

 Colleiotrichum falcatum, which causes Red rot of the 

 sugar-cane, was imported from the East to the West 

 Indies in cane cuttings. The principal reason for 

 holding this view is that the disease broke out more 

 or less suddenly long after sugar-cane had been grown 

 in these islands as a principal crop. Another example 

 of a still more definite kind is that of the Panama 

 banana which occurs in Jamaica and Cuba. 

 This is caused by a fungus (Fusarium sp.) which was 

 cert < introduced from ( 



1 »n the basis of this information it will be evid- 

 ent that we have no reason to think thai all our introduc- 

 tion- concerning plants and anin been entireh 



icial. When we comi more 



insidious and fatal disea.- > of man and the don 

 animals yellon fevei ira pyroplasmosis i 



wi see that all the causative organisms must have 

 introduced in the blood of emigrants. Further- 

 more m the c ■■ II",. fever 1 1. >• ars to be 



evidence to show that the transmitter, the mosquito 

 (Stegomyia fasciata), is nol indigenous to Centra! 

 America al ill, but was 'nought over with the slaves 

 from W. st Atiica. 



CACAO MANURIAL EXPERIMENTS, 

 TRINIDAD. 



The results of three years' trials on eight different esl 

 have just been issued in tabular form by the Trinidad 1 1 

 men! oi Agriculture in their Bulletin, Vol. XIV, Pari I (1915). 

 The results recorded are of considerable interest, especially 



when considered in i nexion with the Dominica experiments 



(see West Inditn Bulletin, Vol. XIV). The weather condi- 

 tions were very favourable forlasl year's trial, for although the 

 rainfall was less than in the previous year, the precipitations 

 wen more evenly distributed, and the dry season preceding 

 the crop-was comparatively mild. All the plots -h iwed a large 

 increase over previous years, and the fundamental importance 



of a favourable season is seen at a glance at 3t of the 



ins facing the tables. This is obvious from the fact 

 that the increase in crop over that of last year was in several 

 cases as great in the no-manure or control plots as in those 

 which had been treated with artifical fertilizers. 



The diagrams indicate the average yield of pods pei 

 tree on twelve different plots each receiving different treat- 

 ment, at least two being controls. In diagram I. it is seen 

 that basic slag and sulphate of potash: and hone meal, sulphate 

 of potash, sulphate of ammonia, and pen manure, gave the 

 greatest return for 1913-14. In diagram II, which illustrates. 

 the experiments on Esperanto estate, bone meal, sulphate of 

 potash and sulphate of ammonia produced the greatest effect. 

 According to diagram III, the increases were more even in 

 the case of all the treated plots with the exception of that 

 receiving nitrogen only. In diagram IV the greatest return 

 is shown to have been got from the application of bone meal 

 and nitrate of soda. The next plate shows a very high all- 

 round increase from manures. Diagram VI indicates the 

 usefulness of superphosphate, sulphate >f potash and nitrate 

 of soda. The results on Santa Isabella estate, plotted in 

 diagram VII, indicate clearly (the increased yields produced 

 1>\ the application of mulch in connexion with potash. In 

 the next diagram, No. VIII, sulphate of potash and sulphate 

 of ammonia produced the greatest return. 



Summarizing these observations, it wouldappear evident 

 that the full effect of manurial treatment is nevet obtained 

 unless the rainfall is favourable. The importance oi 

 nitrogenous and phosphatic manuringapp indicated, 



and there is reason to b thai in Trini lad as well as in 



Dominica the greatest benefit is obtained by the employment 

 of mulch in conjunction with mineral manures. 



In ci, elusion we may compliment the department on 

 the clear way in which the} h; , ed bj means of 



diagrams the results of their experiments for the years under 



review, and there ca ■ no doubt that the report which 



form- ii ; of this brief review will be found oi 



and value to in Triuid.ul. bul 



also in i hi '•'< e lly. 



