8 



In place of the hedge of coffee bushes constantly sprinkled with tobacco water, fences of other 

 bushes may be used and of these none are more suitable than Annatto (Bixa Orel/ana), a plant which 

 grows very rapidly and has the advantage also of being a valuable dye producer, the demand for which 

 in the European market is increasing, or a fence may be made of pepper-vines cultivated upon Kapok 

 trees {Eriodendron anfractuosum) these if planted close together forming a very impenetrable hedge.* 

 In using these hedges it is to be remembered that the spores which are carried by the wind upon the 

 leaves are not necessarily destroyed as in the previous case, but the chances of life are against them, 

 as the spores are likely 10 be washed down by the rain or killed by the light, before they have drifted 

 off again upon the coffee leaves. 



It seems remarkable that the danger from allowing the plants to be so distant that the wind can 

 freely penetrate the plantation and bring with it the spores has been so long overlooked. It was 

 observed that the edges of plantations were more severely attacked than the interior but this was attri- 

 buted to insufficient shading. Professor Marshall "Ward, however, knew well the influence of the wind 

 on the disease and mentions plantations free of disease on account of their being protected by strips of 

 forest land, and recommends the separations of plantations by the culture of other plants or of forest 

 ground. 



Duration of Protection of Leaves by Tobacco-water. 



This depends much on two factors fist) the frequency of rains, and (2nd) the chance of infection. 

 The latter depends very much upon the distance from diseased plants and on the direction of winds. 



That the danger of infection diminishes with the increase of distance from a diseased garden is 

 obvious, but the spores are so very light that the wind can carry them to enormous distances. Thus 

 the hemileia which appeared in Ceylon in 1869 was blown over to Sumatra where it first bppeared in 

 the Padang uplands. Thence it was carried to Java where it appeared in 1876 in the Botanic Garden 

 at Buitenzorg. After which it spread over the whole of West, Middle and East Java. 



In order to find exact data for the effective duration of the tobacco water, plants in pots were 

 placed among some very badly diseased ones in the nursery grounds and were allowed to remain there 

 from March 16th to April 16th in the time of heavy daily rain, and every two days were sprinkled 

 with tobacco water, and in spite of the air being saturated with disease, they were unharmed. A si- 

 milar batch similarly placed were then treated twice a week only with tobacco water, i.e., every three 

 and four days alternately. These became attacked but not so badly as a similar lot which were not 

 treated at all. 



The tobacco water must, in any case, give protection for forty-eight hours. For, suppose the 

 leaves are sprinkled in the morning, during the day while the sun is out the liquid is protecting the 

 leaf and has already killed all the seeds which fell on it before. The rain of the afternoon or evening 

 will wash off the tobacco, so that next day they are quite unprotected again. Directly after the rain 

 falls there is again the chance of infection, principally in the early morning hours, when the young 

 leaves are still wet with rain and dew-drops. The fungus can then begin to germinate, and a few hours 

 after will begin to enter the pore. It can go on growing till the morning of the next day when it is 

 again sprinkled. By this time though the tube has entered a short way into the stoma of the leaf, it 

 is not yet free of the seed, but is still drawing nourishment from it, and it is only when this food is 

 done that it is independent of the seed, and before this, it is again sprinkled and the seed killed. Thus 

 absolute security can only be obtained by treatment every two days. Some nursery plants standing 

 a few yards away from badly diseased plants were treated during the first months of the rainy mon- 

 soon, viz., November to February, only once a week, and notwithstanding remained free of disease, but 

 perhaps that was because there were fewer wet days than usual then Later the remedy was applied 

 twice a week, but whether it is necessary to do it quite as often as this, is still doubtful. The planter 

 is, however, recommended not to be too sparing where the disease is rampant and increasing every 

 year. This abundant treatment is more adapted for nurseries and young plantations and for pro- 

 tection hedges. 



Summary. 



Any planter can keep his nurseries free of disease at a little expense by sprinkling them with 

 tobacco water and so start the plants in life in a healthy state. Young plantations can be similarly 

 treated and any spots arising from insufficient wetting of the leaf can be cut out with the scissors or 

 burnt out with sulphuric acid as described above. In fruiting plantations heavy attacks can be pre- 

 vented by enclosing the gardens by hedges which can be composed either of coffee trees kept free of 

 disease by tobacco water, or of annatto or some such shrub, Teosinte grass or of trellises with creepers. 

 If these attempts to arrest and prevent the disease are carried out by all cultivators, it is by no means 

 improbable that the disease will be so reduced that it can never form any obstacle to culture and loss 

 from it will always be a negligible quantity. 



Dr. Burck has here shewn that it is by no means impossible to cope with the disease as was stated 

 no great time ago, and that it is a mere question of beginning the struggle early enough. Further 

 experiments may simplify the methods of contending with the disease, but at present this plan is com- 

 paratively inexpensive and has proved decidedly successful. 



Notes on the Foregoing. 

 The abstract of Dr. Burck's works I have made is very much eondensed from the original. The 

 substance has, however, been reproduced, but I have eknitted portions which have no bearing upon 

 cultivation in the Straits Settlements. The whole system of cultivation differs considerably in the two 



* Another plan is to make hedges or fences of sticks covered with creepers sueh as Antigonon leptopus, Ipomeas, or 

 ' wnbergias, or again, Teosinte grasB {EwchoUna luxurians) , or maizo may be planted in rows, or raised banks. 



