POTATO DISEASE EXPERIMENTS IN 1894.

New Zealand Mail, Issue 1196, 1 February 1895, Page 6

POTATO DISEASE EXPERIMENTS IN 1894.

(Agricultural Gazette.) During .the last three weeks the results of experiments for the prevention of potato disease have been sent to us from different, quarters, and we notice that-they have proved more uniformly successful than in any preceding season,■'-.■■ prjobably because the dressing was more needed. In previous years the Bordeaux mixture was found to have done more harm than good in many cases where disease had not attacked the crop at all, and partly for that reason, and partly on account of the expense, we have always demurred at. the suggestion that all potatoes should be dressed, whether in a season or oh-soil pai ticularly liable to disease or not; Some months ago, however, when the wet summer had set in, we.pointed out that the circumstances were such as to render a general attack of potato disease almost certain, and recommended the general dressing of the crops with the Bordeaux mixture. In the accounts before us the gain of sound tubers through the use of the dressing is very striking, as was to be expected disease was in strong forced It nijay now be considered settled, indeed, that the remedy is an effectual one, and that experiments with it in, the common form are no longer necessary. There is scope, however, for experiments to determine certain points not yet fully settled. In most cases the original proportion of 201 b of sulphate of copper* 101 bof quicklime, and 100 gallons of are still used, although authpritfeßthstibhe quantities of copper and lime should be equal, in order to be certain/that the, acid is neutralised. Unless our;~ : merhory is at fault M. Oirard's best results have been obtained with a mixturiß of 201 b of sulphate of copper and' 20lb of quicklime to 100 gallons of water. It seems desirable, tbeny to, test,.thoroughly the proportions of liuxture in future experiments. /Another point which has aot been sufficiently tested is the comparative ad vatitages of one dressing or two or even three dressinga Again, the plan, o.f dressing immediately after the 'firstsign" of has not been well tried against' that of applying the mixture before there is any disease. This is a point of great importaiiee, -because if satisfactory results can be attained by the former method, a great saving can be effected. If it be safe to wait for the first sign of disease, it is a mistake to dress a crop before there is any such sign, unless, as in the past season," there is every reason to expect an attack. Some enthusiasts for dressing will probably be impatient with this statement, as they are in favour of dressing every acre of potatoes every Season. We cannot forget, however, that hi past seasons a great many cases of diminished yield where the Bordeaux mixture has been I applied unnecessarily have been recorded..; V

Last week we gave a brief report of the Wiltshire experiments, of which the most remarkable feature is the great yield reported, .though it is not equal to the declared results of la3t year. The conductors of the experi- j ments would rendef a service to persons who are astonished at yields of 15 to over 18J tons, an acre if they would state whether there is anything special in the soil of the fields on which the potatoes are grown, or whether they attribute their great results to the manure which they use. At the same time they might state the proportions of the mixture. The quantities per acre of that mixture, consisting of nitrate of soda, superphosphate, and kainit, were given in the i*eport we received, but not the proportions. It is clear that a great deal depends upon the variety, as the highest yield was more than double that of the lowest ‘ } but, with one exception, every variety is represented as haying produced XO|l tons or moi ) u.l all but three out of twenty-four as having produced 11 tons or more, and all but six over 12 tons j and there is nothing special in some of the varieties.

In some , experiments carried out on the K.ent County Asylum Farm, at Maidstone, six varieties of potatoes were tried, two of them being sprayed once, three, twice, and one thrice The yield of the sprayed plots ranged from 4 tons 16 cwt to 9 tons 15 \ cwt, the greatest being that *of the Bruce, sprayed three times; Jeanie Deans came second with 7 tons 18 cwt, and Abundance third with 7 tons 5 cwt, both being sprayed twice; but Satisfaction, sprayed twice, yielded only 4 tons 16 cwt, whereas Puritan, sprayed

once, gave 6 tons cwt. To be of any real use, the different number of spraying* should have been tried on the same variety. As it is, there is no proof that it was the increased number of sprayings which gave the greater yield to the potatoes dressed more than once, as the extra productiveness may have been due to the varieties. The increase over the uhsprayed lots ranged from 9 cwt 2 qrs to 3 tons 2 cwt 2 qrs per acre, which is very satisfactory. It will be noticed that the yield at Maidstone was very much smaller —not more than half on the average—than at Warminster (Wilts). Yet the Mailstone plots were dressed with the heavy allowance of 25 tons of farmyard manure. Now, at Warminster, it is stated, four plots were dressed with the same kind of manure, and yet they yielded 2 cwt 2 qrs 1 lb per perch, or nearly 18 tons 3 cwt per acre, the i variety being Blue G-iant, only fourth in the list of producers on the average when all were tried. This yield was much more than double the Maidstone average, which, however, was not at all a. low one. We notice that two varieties, the Bruce and Satisfaction, were used in both trials. The former at Maidstone gave 9 tons 15 cwt 2 qrs, after being sprayed thrice, while at Warminster it yielded 14 tons 2 cwt. The latter produced 4 tons 16 cwt at Maidstone and 10 tons 15 cwt at Warminster.

A third set of experiments, of which we have received a report, was carried out in Ireland at the instigation of the Royal Dublin Society, though the grant of LIOO given by the Society in 1893 was not repeated, only L 8 for sulphate of copper being offered to experimenters, who were not much benefited by it after all, apparently, as the sulphate was not' sent to them till after the disease had appeared. The results are given too irregularly for quotation, most of those who made the trial having only sent rough estimates of the results, which were tabulated in only three or four cases—and in those irregularly—the most important table showing the yield per plot of a certain number of feet and inches. In most cases, though not in all, the use of the dressings increased die yield of sound tubei’s.

Four hundred tons of butter and fortythousand frozen rabbits were shipped to London from Melbourne last Saturday.