April, 1910.] 



325 



Plant Sanitation, 



investigation of this disease. It is hoped 

 to obtain resistant varieties, but as the 

 plant is a slow growing perennial, 

 results cannot be expected for a long 

 time. 



Investigations have recently been 

 begun by Messrs. Macrae and Anstead, 

 and in a preliminary paper in the 

 " Planters' Chronicle," the latter recom- 

 mends the adoption of following mea- 

 sures, pending the results of experiments 

 which are now being instituted. 



" In the first place pepper cultivations 

 should be well drained so as to keep the 

 bases of the vines free from stagnant 

 water. A system of drains, 18 inches 

 deep, will probably be found beneficial. 



" As a preventative, every vine, heal- 

 thy or diseased, should be sprayed at 

 least once a year with Bordeaux mixture. 

 The bottom three or four feet of the 

 stem should be well drenched with the 

 mixture. This will require about a 

 quart of the mixture for each vine, and 

 it may be applied with a watering can, 

 though it will be found more economical 

 and rapid to spray it on with a Deming 

 Success Knapsack sprayer fitted with a 

 Bordeaux mixture nozzle. 



"As soon as ever a vine begins to 

 show signs of the disease, the area 

 covered by the roots should be given 

 an application of slacked lime, at the 

 rate of about 4 lbs, per vine, broadcasted 

 on the surface, and a trench should be 

 dug round it to a depth of about 2 feet, 

 the soil taken from the treuch beiug 

 thrown inside to cover the lime. 



"Care should be taken about forking 

 round the vines; if done at all it muse 

 be done very lightly so as not to wound 

 the roots and form points of entry for 

 fungus spores. Cattle manure should be 

 applied as a mulch, and covered down 

 with leaves, etc. At the Taliparamba 

 farm leaf-mould is found to be a good 

 fertiliser for pepper. At all times the 

 vines should be kept heavily mulched, 

 and if this is done no forking will be 

 necessary beyond perhaps breaking up 

 the area just beyond the root spread 

 every year, i.e., forking a circle round 

 the vine outside the range of the roots. 



"More care might betaken, I think, 

 with advantage to keep the fields clean. 

 I have already alluded to the im- 

 portance of destroying dead vines ; all 

 diseased plants should be cleaned up and 

 burnt. On one occasion part of a dead 

 vine covered with fungus fructifications 

 was picked up by the roadside, it having 

 evidently been used to tie up a bundle of 

 wood. This serves to show how careful 

 one should be to keep the totes clean, 

 and how easy it is to spread the disease 

 about," 



Mr. Macrae states: "I have been assured 

 that after a diseased stem and the upper 

 parts of the roots to a depth of about 

 one foot have been removed, new 

 cuttings may be planted immediately, 

 and that the percentage of these 

 cuttings that strike is not less than that 

 in places which had not previously sup- 

 ported diseased vines. I was shown 

 such that were five years old and still 

 look healthy. But the reverse is the 

 case in some other instances." 



It would seem preferable to leave the 

 ground vacant, after forking in lime, for 

 about a year, 



CANKER~OP CACAO. 



By A. E. De Jongb. 



[Recueil ties Travaux botaniques Neer- 

 landais., Vol. VI, 1909.] 



This disease had been observed in 

 Surinam for years. In 1891 it was noticed 

 at Dordrecht and since then on several 

 other estates, but up to the present it 

 has only been sporadic, In the summer 

 of 1907, however, the canker became epi- 

 demic on some estates in the Saramacca 

 district. In consequence, an investiga- 

 tion into the disease was undertaken, 

 the results of which are recorded here. 



Cankered trees are first recognized 

 by the occurrence of moist patches on 

 the bark, caused by a liquid oozing 

 out, sometimes in considerable quan- 

 tities. Where it has dried on the bark, 

 this assumes a rusty colour. These 

 places are nearly always found on the 

 trunk and thicker branches ; sometimes 

 the younger branches of a tree also 

 show them- When the bark is cut oft' 

 superficially, it appears to have assumed 

 a claret colour ; this claret patch is 

 surrounded by a narrow black border 

 which marks it off sharply from the 

 surrounding healthy tissue which is of 

 a yellowish red colour. These patches 

 occur in large numbers on the tree ; they 

 may extend over a large area or even 

 encompass the stem or branch. Often 

 two patches unite into a single one, 

 or one first appears under the surface 

 and joins itself on to another, in the 

 latter case the infection must have 

 spread from within to the outside. 

 Even in badly affected trees, spots 

 which may penetrate to the wood are 

 not always a deep claret colour, but 

 often light red. When these light- 

 coloured patches are exposed to the 

 air after cutting, they become dark 

 red. Where the wood is also affected, 

 it sometimes assumes a red, but generally 

 a blackish brown colour, which may 

 penetrate into the wood for some cen- 

 timetres, The dark discolouration of 



