Vol. IX. No. 226. 



THE AGRICULTURAL NEWS. 



405 



with the previous one. On the heavier soils, the disc ha now 

 does not work so well, and the iilougli is used almost entirely. 



After turning under a green manure, the land is kept 

 well cultivated the remainder of the year. 



For obtaining the best results, a green manure cro[) 

 should be turned under early enough in the season to allow 

 perfect decomposition. 



RESULTS OF USING GREEN MAXUKKs. There have been nr) 

 definite tests made in California to determine the results in 

 an increased yield of fruit or improved quality of the same 

 from the use of green manures. The only evidence available 

 is that of general observation and the e.xperience of the 

 orcharHists 



While orchardists differ to some extent in conclusions, 

 they generally are favourable to the practice, as its continued 

 and growing use attests. Careful observations also show the 

 beneficial results of green manure crops in a more thrifty 

 appearance of the trees, the improved condition of the soil, 

 and a better quality of the fruit. The belief is quite gener- 

 al that the yield also is increased. Orchards in which a few 

 ye;irs ago there were unthrifty trees with yellowish-coloured 

 leaves, now, after several years' use of green manure crops, 

 show a decided improvement in colour and general appear- 

 ance. The work of the California E.xperiment Station has 

 demonstrated that gummosis of citrus trees is brought on by 

 unfavourable soil conditions, and that in remedying sucli 

 conditions green manures serve a very useful purpose. 

 Orchards in which green manures have been used for a long 

 time are but little affected by this disease. 



The improved condition of the soil, when green manures 

 have been used for some time, has been readily noticeable to 

 those handling an orchard. The heavier soils have become 

 quite open and friable, and the sandier soils more loamy. 

 Beneficial results in the conserving of rainfall and the pre- 

 Tention of washing of the soil have also been very api)arent. 

 Most soils that wash badly do so because they are deficient 

 in organic matter. Oreen manuring, b)' the improvement of 

 the mechanical condition of the soil, not only prevents wa.sh- 

 ing, but the presence of the growing crop on the land pre- 

 vents gullying during the rainy season. This is of particular 

 importance on sloping lands. 



DOMINICA EXHIBITS AT THE COLONIAL 



FRUIT SHOW. 



According to the Dominica Chronicle for November 26, 

 1910, 33 packages of exhibits were sent, under the auspices 

 of the Dominica Permanent Exhibition Committee, on 

 November 1.3, 1910, to the Colonial Fruit Show to be held 

 in London. 



Below is a list of the various exhibits and exhibitois: — 



Castle Comfort estate, limes; Wall House estate, limes; 

 Gleau Manioc e.state, limes; Everton estate, cacao, nutmeg.s, 

 nutmegs in shell with mace, essential oil of limes, limes, 

 oranges; Sylvania, oranges; Coron.i, oranges; St. Aroment, 

 lime juice, essential oil of lime.s, otto of limes, lime.s, nutmegs 

 in shell with mace; Ancaster Park, limes; La Haut, limes; 

 Permanent Exhibition Committe, limes, shaddocks, oranges, 

 essential oil of limes; Dominica Fruit C4rowers' Association, 

 limes; Botanic Station, oranges, grape fruit, citron, lemon.s, 

 bread nut fruit, bread fruit, nutmeg fruits, nutmegs in .shell 

 with mace, nutmegs, kola nuts. 



THE NATURAL ENEMIES OF MILLIONS. 



References to the natural eneniie.softhc niosiiuito- 

 destroyiiig fish, nnWioDS (Girardin im 2)w^iloides), have 

 been made recently in the Agricidtural NeivsiVol.IX, 

 ])]). oL") and 3.5.5). Further information in regard tothe 

 matter has been kindly supplied by Dr. Lucius Nicholls, 

 of ,St. Lncia, whose rejiort as medical officer of District 

 I II of that island was reviewed on page 'M^ of this 

 \(ilume of the Agricultural News. 



As destroyers of mosquito larvae the 'Millions' fish when 

 thoroughly exploited, are proving themselves to be of great 

 value in anti-malarial work. The correct method of viewing 

 the natural enemies of these is to consider them with all 

 circumstances that are adverse to the little fish. For the fact 

 that some rare water creature occasionlly devours a small fish, 

 though worthy of mention, may practically be of little or no 

 moment. 



I have performed many experiments with these fish, and 

 have placed them under a great variety of surroundings. 

 Circumstances that are detrimental to them may be considered 

 under two headings: — 



(1) Adverse physical conditions. 



(2) Natural enemies. 



In the first grou[i are included conditions external to 

 the water, such as, heat, cold and solar radiations, and water 

 condition.% as bracki.sh water, water in iron tanks, etc. To 

 a certain extent, lish can be gradually immunized to all these 

 circumstances except .solar radiations. If they are placed 

 in shallow water with a total absence of shade, the exposure 

 to the sun by day and the rapid cooling at night invariably 

 kill them. Fortunately, there are very few natural breeding 

 places of anophelines in which the fish will be unable to find 

 ample shelter from the solar rays. 



The second part of the subject may be likewise 

 divided into classes: (1) that concerned with enemies 

 which destroy sufficiently large numbers to affect their 

 establishment in the same situation: among these are the 

 larger fish, mullets, loaches and eels, in large collections of 

 water, and dragon-fly larvae, which are very common in 

 tropical countries in small collections of water: secondly, that 

 having relation to enemies which destroy a few, but practi- 

 cally never exterminate them: these include water-fowl, 

 (ducks, craneSjetc.), crustaceans (crayfish), predaceous neurop- 

 terous larvae, excluding those of the dragon-fly larvae, and 

 coleopterous larvae; in the case of the Dytiscidae, the adult 

 beetles as well as the larvae prey upon the fish. Fortunately, 

 water beetles are much more common in temperate than in 

 tropical climates. 



Despite this array of natural enemies, millions will 

 survive in more than 90 per cent, of the surroundings in 

 which mosquito larvae are found. In many localitie.s, it is 

 not difficult to get rid of the other inhabitants of the water. 



These little fi.sh have not yet received the general research 

 and attention that they deserve. Anyone working with them, 

 who will make use of them with tlioroughnes.s, and who will 

 reason upon his successes and failures, will find them an 

 addition of great value in liis work against that terril)le 

 in.sect pest---the mosquito. 



