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virgins and, if feasible, to give an application also to the third or fourth ratoons. Purchased fertilisers are also used freely, mainly sulphate of ammonia, sulphate of potash and guano phosphate, the last having been found more effective than super- phosphates. Green manuring with cowpeas (Vigna sinensis), sword beans (Canavalia- ensiformis) or Stizolobium spp. is practised on many of the estates as a crop of a few months duration before replanting, while the first-named is often also interplanted with the virgin cane. The former practice of burning the trash has been given up, only a few estates retaining it still. Virgin canes run as a rule for 18 to 22 months ("grand saison ") but in the lowlands a number of estates plant also one year virgins (" petit saison "). The number of ratoons taken is on an average five, but on the deeper, well-manured lands, they may go to seven or eight and are now almost invariably reaped in one year. Mr. J. de Speville, in a communication to the Sugar Technologists' Conference in Java (1929), has stated that about 83 per cent. of the estate cultivation is reaped annually as against 50 per cent. in Hawaii where both ratoons and virgins go for two years. Although the tonnage reaped in Hawaii is higher, the annual yield from a given estate area in Mauritius is as great. About 44 per cent. of the total area in canes in the Island is grown by small culti- vators independent, or tenants, of the estates, who sell their canes to the factories; the yields obtained are substantially less than on the estates as little manure is used. The La Ferme reservoir is able to furnish water to irrigate some 2 to 3,000 arpents (an arpent is about 1.04 acres) in the driest district (Black River) in a year of good rainfall, and a dam is now under construction which, it is hoped, will im- pound some 500 acres of water and furnish enough to irrigate the greater part of the two northern districts. Cultivation has had to be adapted to the stony character of the land and the depth of the top soil over a large area so that implemental tillage is more or less restricted.

Chemical control is employed in all factories; detailed returns are furnished monthly to the Sugar Technologist of the Department, who makes them available for inspection by the Société des Chimistes; it is understood that the returns compare favourably with those of factories of similar capacity elsewhere.

Recommendations.

I. It is highly desirable that the Sugar Industry in Mauritius be in possession of all available knowledge concerning, and effective means of controlling, the major diseases, especially Gumming Disease and Leaf Scald. I recommend, therefore, that the Botanist and Mycologist, Mr. Shepherd, be sent to Australia to examine the control methods which are now being employed there against those diseases, particu- larly such as are now in operation against Gumming and Leaf Scald under the direction of Mr. D. S. North, Senior Pathologist to the Colonial Sugar Refining Company in northern New South Wales, resulting from his long and unique ex- perience, in Australia and Fiji, of a number of the most serious diseases of the sugar cane. Mr. Shepherd would, in addition, be able to study at first hand the degrees of resistance of a number of varieties to Gumming and Leaf Scald and the probable commercial significance of such resistance; and be able at the same time to identify certain kinds, the behaviour of which is already known in Australia, with some of those now widely cultivated in Mauritius. It is also desirable, in connexion with the introduction of foreign kinds and the breeding of seedlings, that he should have & first-hand knowledge of the other known serious diseases not at present in Mauritius. Among these may be mentioned in particular, Mosaic, Sereh, Fiji Disease, Leaf Stripe, and Red Stripe. It is suggested, therefore, that after spending some weeks with Mr. North, presumably with headquarters at Broadwater, Richmond River, New South Wales, he go to Queensland and get in touch with the Department of Agriculture and its mycologists and return by way of Java, visiting the Sugar Planters East Java Station at Pasoeroean and the sub-station at Cheribon. He might also find it useful to visit the Tobacco Station in Java. The tour might cover a period of three to four months at a cost probably not exceeding £350.

2. At present the staff of the Botanical Division is restricted to two officers- the Botanist and Mycologist and the Plant Inspector. (The Botanist and Mycolo- gist is required to give a general course in Botany and special lectures on Mycology and Plant Pathology to students of the College of Agriculture; the preparation necessary occupies an appreciable part of his time.)

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In consideration of the important work it performs in connexion with the investigation, inspection and control of plant diseases, and the greater amount of work of the same kind it will certainly have to perform in the near future, this Division urgently needs strengthening by the addition of another officer. It is recom. mended that Mr. G. Orian the Inspector, who has been on the temporary staff of the Department for over five years, be appointed Scientific Assistant on the perman- ent staff at a commensurate pay. Apart from his regular plant disease inspection work on the estates and the very important work of inspection of the small farmers' cultivations which must be continued, he has been able to carry out some original research on certain sugar-cane diseases and to acquire a good laboratory technique of which I had proof during my visit.

A third officer will be needed, therefore, to fill the post of Inspector and his appointment should be made as early as possible so that he may receive the neces- sary training in the field work. With this increase it will be feasible for the work of the Division to maintaip its continuity during the temporary absence of its Head. 3. The space allotted to the Botanical Division at the Headquarters of the Department is at present inadequate (one room of moderate size has to serve as office and laboratory for both Botanist and Inspector). Following the appoint- ment of a Scientific Assistant more space will be essential.

4. In view of the setting up of a special Research Division and the increased attention which is being given to the raising and testing of new seedlings, the Depart- ment is in immediate need of more land at Reduit. Desirable investigations have had to be curtailed already on that account. The land available at Pamplemousse is believed to be sufficient to meet the requirements of the immediate future. The differences of soil, amount and distribution of rainfall and temperature at the two stations, render a duplication of tests of seedling canes for yield and resistance to diseases and of trials of other crop plants very necessary.

5. It is suggested that the survey of the incidence of diseases, particularly Gumming Disease, Leaf Scald, and Red Rot, which was omitted in 1929, be under- taken again this year and annually hereafter. It might be restricted to the examin- ation of representative samples, at the cane carriers, of the four main varieties and might include also D. 109 in the northern districts, and at certain estates one or more of the newer seedlings already planted to an appreciable extent. An effort should be made, as in 1928, to record Leaf Scald and Gumming Discase separately.

6. It might be of value if the Statistical Division obtained from as many of the estates as possible at the end of the planting season of 1930 a statement of the rela- tive distribution of varieties as virgins alone including those planted in 1929. A full record like those for 1912, 1915, and 1925 might be delayed until 1935.

During my stay I was granted an interview with His Excellency the Governor, and on the 11th December, at the Institute in Port Louis, gave an address to the Society of Arts and Sciences, of which Mr. D'Emmerez is President, on the " Diseases of Sugar-cane in Mauritius" in the presence of Sir Francis Watts and a representative gathering of estate-owners, managers, and administrators.

In writing this report I have been able to make use of Mr. P. de Sornay's valuable book La Canne à Sucre àl'ile Maurice (Paris, 1920), especially the portions dealing with the introductions of foreign varieties and the earlier work with seedling

canes.

It is with great pleasure that I acknowledge the generous facilities for travel afforded by the Governor of the Island. To the Director of Agriculture and Ento- mologist, Mr. D. D'Emmerez de Charmoy, I.S.O., I am much indebted for arranging my itinerary, for provision of an office, for access to the records of the Department, for accompanying me whenever his official duties permitted, and for granting me on all occasions the indefatigable and invaluable services of the Botanist and Mycologist, Mr. E. F. S. Shepherd, I must also acknowledge with gratitude the information so readily accorded by the owners, managers, and administrators of the estates and by the Heads of the other Divisions of the Department,

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APPENDIX I.

Note on Diseases of Tobaseo.

Tobacco is a valuable crop in Mauritius and is becoming rapidly still more important. It is affected by a number of diseases and my attention was drawn to several of these

Botahist and Mycologist.

the Tobacco Officer and the

The finer varieties introduced during recent years appear to be more susceptible to diseases than those which have been long in cultivation. Crossing is being undertaken and it is hoped that more resistant commercially satisfactory strains will be developed.

Mosaic is commonly present and evidence has been obtained that it may be transmitted to healthy plants by the soil from infected debris of a preceding tobacco crop. It is serious only on ratoons which are not usually grown now.

Seed-bed Failure-Damping-off in the instances examined appears to be due to a strain of the Rhizoctonia solani group; it is favoured by overcrowding and too frequent watering, especially in beds made with soil which is not free-draining. Plants set out in the field from infected seed beds are liable to carry an infection which may prove fatal during the early period of growth. Further investigations will probably show that other fungi are concerned besides Rhizoctonia.

Stem Rot.-A wilt disease of larger plants resembling Black 8hank is also of frequent occurrence. A Phytophthora was extracted from the blackened cortex at the base of the stem and crown of an affected plant. The newer varieties appear to be more subject to this disease than those long in cultivation.

Granville Will.-Plants affected by this disease, due to vascular invasion by Bacterium solanacearum E.F.Sm., were shown to me. The bacterium gains entrance from the soil into injured roots; infection is favoured also by preceding nematode infestation. In Sumatra the presence of the bacterium in suspected field soil is detected by transplanting tomato plants from the seed bed into pots of the soil and keeping them well watered. In transplanting the roots are injured and vascular invasion and wilting occur after some days if the soil is infected. A sensitive, high-class variety of tomato should be used for this test. Powdery mildew occurs but is usually restricted to the "sand" leaves of more or less shaded plants. Nematodes.---Some infestation of the roots may occur in localities where the soil is sandy. A second crop of tobacco on the same land is liable to be more severely infested; this applies also to Granville Wift. Rotation of crops is the only effective control for both diseases, and after a bad attack it may not be feasible to grow tobacco again for several years. Corn, sorghum, sugar-cane or other grasses, sweet potatoes and resistant varieties of cowpeas (Iron, Brabham, etc.) may be grown.

The diseases of tobacco in the Island (including troubles during curing) deserve further investigation

and the issue of a departmental bulletin or circular dealing with the more serious troubles would be doubtless of value to planters.