362 



THE AGRICULTURAL NEWS. 



November 17, 1906. 



INSECT NOTES. 



The Use of Paris Green. 



Previous to the revival of cotton cultivation in the 

 West Indies only five years ago, very little Paris green 

 was used in these islands. At the present time the 

 amount used in a year is, in comparison, enormous. 



In a recent number of the Agrladtural Xews (Vol. V, 

 p. 346) reference was made to the great amount of waste in 

 the use of Paris green. ];i the present article the use of 

 different machines and appli.uices for distributing Paris green 

 in the cotton field is discussed. 



The cloth bag is a simple, effective, cheap, and, if 

 properly used, economical device for distributing Paris green. 

 The bag should be made of ticklinburg, and not of ordinary 

 burlap, such as is used for bags for feeding stuffs and artificial 

 manures. A bag of tickjinburg can be used in such a way 

 that i fli. of Paris green and 3 lb. of lime can be applied in 

 a thorough dusting of an acre of young cotton ; or 1 i Di. of 

 Paris green and 9 lb. of lime for an acre of full-grown cotton. 



The Acme powder bellows is also cheap and effective. 

 This machine can be imported at a cost of about 3s., and 

 with it a labourer can cover thoroughly a somewhat larger 

 area of cotton than with the bag. 



The Champion powder gun is a larger and more com- 

 plicated machine than the Acme bellows, the cost being about 

 $7-.50 in Barbados. With this machine, the labourer can do 

 more work than with any of the other devices, doing it very 

 well and without waste of material. 



In certain of the West India Islands, tin shakers or 

 dusters are in use. These are made in different sizes and 

 shapes, varying in cost from Is. to 3s. They are made with 

 the Ijottom perforated with fine holes, or the bottom of fine- 

 mesh wire gauze. Very few of them are economical of 

 material, as it is almost impossible to get the perforations 

 sufficiently small or the gauze fine enough to prevent the 

 escape of more Paris green and lime than is needed. Many- 

 planters who had these tins made have found that, by using 

 a ticklinburg bag inside the shaker, it has been possible to 

 use the correct amount of material. 



In applying Paris green, it is desirable that the poison 

 mixture .should be distributed evenly and lif/htly over the 

 leaves of the cotton plant. It is always a mistake to apply 

 so much that the leaf shows a solid white surface. It must 

 be remembered that very little poison is required to kill 

 a cotton worm. 



When a field of cotton has received more than li Itj. of 

 Paris green per acre in a single application, it may safely be 

 assumed that there has been a waste, no matter what 

 proportion of lime has been used ; and when the amount used 

 runs to 4 IT), or 5 lb. of Paris green, then the waste is 

 enormous. This is a matter which recpiires more attention 

 from cotton planters. Most planters now recognize the 

 necessity of using Paris green to check the ravages of the 

 cotton worm ; but many are not awake to the necessity of 

 using it in a careful n:anner, and in such a way as to get the 

 greatest good from the expenditure involved. 



FUNGUS DISEASES OF PLANTS IN 



CEYLON. 



As some of' the information about fungus diseases 

 of plants contained in the report of the Government 

 Mycologist for Ceylon, for 190.5, is likely to be of 

 interest to jjlanters in the West Indies, a few short 

 extracts have been made : — ■ 



Para rubber [Uevni branlienah) has received consider- 

 able attention, and records show various diseases of leaf, stem, 

 root, and fruit. The canker disease of the stem, caused by 

 Nectria diversispora, has diminished in e.xtent. It is stated 

 that, ' with regard to canker, the outlook is decidedly 

 improved. E.xcision of diseased tissue has in all cases 

 proved efficacious, without injuring the subsecpient growth of 

 the tree.' Further it is urged that periodic inspection of 

 trees should be continued, for the disease may easily be kept 

 in check if the first stages are noted, but that neglect results 

 in the death of the tree. 



A decay of the fruits of Hevta brasiliensis occasioned 

 serious loss during the year. It is caused by a species of 

 Pliytopldliora, very similar to that found on cacao pods in 

 Trinidad, 8t. Lucia, and probably British Guiana, and it is 

 advised that all diseased fruits should be collected and burnt, 

 so as to prevent any possibility of further spread of the 

 disease. 



The Central American rubber tree (Castilloa clasfica) 

 is sometimes attacked by a wound parasite, Botryodiplodia 

 elasticae, nov. sp., 'jvhich gains an entrance through a previous 

 injury and converts the bark of the tree into a soft, rotting 

 mass. Excision of all diseased tissue will save a tree, if it 

 be done before the fungal mycelium has spread into the 

 deeper tissues 



The fungus diseases of tea have been cla.ssed under 

 leaf, root, and stem diseases. Work with root diseases 

 has been directed towards the separation of the different 

 fungi, so as to be able to suggest methods of prevention 

 to suit each individual case. The horse-hair blight is similar 

 to the thread disease of cacao that has been reported from 

 St. Lucia and Dominica. It spreads over the bush in all 

 directions ; it is therefore advised that all attacked trees should 

 be pruned, and all the diseased prunings collected and burnt. 



Cotton is reported to be free from serious fungus 

 diseases, but ' rust,' produced by Uredo gossypjii, has been 

 found on a native variety, while the roots of the Caravonica 

 variety have suffered from a species of Uyiiwnochoeic. 



Cacao has suffered from a root parasite in a few 

 instances, and Collelotrlchuni incarnatinn has been found on 

 ' brown ' pods. Canker is now kept well in hand, and ' the 

 value of canker excision and the spraying of pods is now 

 proved beyond dispute by the results obtained at the Experi- 

 ment Station and elsewhere.' It is pointed out that 

 attention should now be directed to the possibility of 

 reducing the cost of spraying by the adoption of more 

 modern appliances. 



Ground nuts have suffered from a leaf disease, which 

 usually appears when the plants are about a month old. 

 Infection exiieriments have been conducted with this disease 

 and they show that the fungus (Septoijloeum arachidis) ' may 

 be transfei-red to a succeeding croj) by means of the dead 

 leaves in the soil ; that the disease spreads rapidly after the 

 plants are about a month old ; and that it might have been 

 prevented by disinfecting the nuts.' 



On the whole, cultivated products appear to be com- 

 paratively free from disease, which may be accounted for by 

 the prom]jt attention given by planters to diseases and by 

 the systematic destruction of diseased material. 



