The Soil and Health by Albert Howard

Author:Albert Howard
Language: eng
Format: epub
Publisher: The University Press of Kentucky
Published: 2011-03-18T16:00:00+00:00

TOBACCO

One of the crops understudy at Pusa between the years 1905 and 1923 was tobacco grown for leaf and also for seed. Only one disease, which resulted in malformed dwarf plants, was met with during these nineteen years. This trouble has since been proved to be due to virus. Such affected plants were quite common in the various cultures for the first two years, then they became fewer and by 1910 had disappeared altogether. Similar diseased plants occurred in the neighbourhood in the fields of the cultivators from whom a portion of the labour force was obtained. At no period were any steps taken to control this disease or to regulate the movements of the labourers. Nevertheless, no infection was spread or was carried once correct methods of growing tobacco were adopted. These consisted in raising the seed on humus-filled soil, careful attention to the surface drainage, and organic manuring of the nurseries, the production of well-grown material for transplanting, and the growth of the leaf tobacco on soil fertilized by various organic manures including farmyard manure. At no period in these nineteen years was the soil of the tobacco nurseries sterilized nor were artificials or spraying machines used. My tobacco cultures, which always earned the respect of all who saw them, were examples of organic farming pure and simple. Once the details of tobacco growing were mastered there was no disease of any kind: the plants protected themselves against every form of parasite as well as virus.

Captain Moubray informs me that similar results are now being obtained in Southern Rhodesia, where tobacco is an important commercial crop. The replacement of artificials by freshly prepared compost in the nurseries and in the tobacco fields was at once followed by a very marked diminution of virus trouble.

That the other tobacco diseases which of late years have begun to trouble the farmers in Rhodesia are due to an impoverished soil is suggested by the appearance of eelworm in this crop. This disease and its prevention are referred to in the Rhodesia Herald of 4th September 1942 as follows:

“At Darwendale, Mr. O. C. Rawson has applied five tons of compost per acre to infested tobacco land. In the first year there was a reduction of eelworm, and in the second year, without a further application, the eelworm disappeared. Other tobacco farmers began to report similar experiences. The compost, of course, was applied for its fertilizing value and the consequences on the eelworm population were a surprise/’

Tobacco has not proved to be an exception to the long list of crops which are mycorrhiza formers. Samples of the surface roots of Rhodesia tobacco, taken from plants grown by means of freshly prepared humus, exhibit, as was expected, this very significant symbiosis. It is more than probable that quality in this crop will be found to depend, among other factors, on the efficiency of the mycorrhizal association. If this proves to be the case, the restoration of high quality in the cured product in places like Cuba will not be a very difficult matter once properly made humus replaces artificial manures.

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