DISESE-RESISTING VRIETIES OF POTATOES.

Otago Witness, Issue 2745, 24 October 1906, Page 4

DISESE-RESISTING V RIETIES OF POTATOES.

The information which the American investigator, Dr Jones, obtained in Europe regarding the nature of resistance towaids potato late-blight, and the character of tha varieties exhibiting thi.s quality, is formulated tentatively as follows — (1) Disease resistance in potatoes Ls relative, not absoluto, no vaiiety being wholly proof against late-blight and rot. (2) Resistance seems related to general vegetative vigour, and is, thorelore, in a measure dependent upon cultural developmental aonditions, and tends to decrease with the age of the variety. (3) It can be restored by originating new Vdiieticb from seed, e-pecially of hybrid origin. Not all &eedhua;s show superior •ditcd&e icsi-t.ince. <4) The we of othtr .sp< j ciL\» -of tubur-bearing Solanums for hybridising offei.- iome promise, but no practical results have yt't been iecured. (5) I'osMbly tli," dVeniP resistance in established vauetit* can be improved by solcct'on, but this ha** not been proved. (6) Early \ ax-ieti'-s may escape the dibe..=o by maturing bcfoie it becomes epidemic, but when suinLii'v exposed thi-v are, as a Hiif- 1 -, !f -b rc.-ifataiu than late vdiieties. (7) The tauico of feed tubeis is a matter of importance, northern -41 own .scrd giving plunts of superior disease ros-iatanee in luiropc. Seed from a ci>jp that was not too highly f-crtilibcd is probably piofeiablo. l ) os < -iblv tubors aie bettor for sc-od purpocos if dug before the}- n.acli full maturity. (8) High fciUiibation, especially with nitrogenous manures, lowers the power of the plant to rtbKt both blight and rot. (9; Vaiictii.-> ld.itivrly 1 ich in starch are more r<bistiUil f< > rot; tlio>e richer in protein, are more "-u-teptiblp to it. (10) So far as f-kin cbarditiii rip an index, tLo red. vari^tu-, with tbitk ar.d rough fckin seem moie roMaut ,ib a class than the thinbk.inr.cd vluto vai it-tit's. (11) So far as stem .md foliage < haracti r.s are concerned, the evulence favours the sttm that Ls hard, lough, and 1 ttlif" woody at the ba-o, and the leaf that i-. •jinall. .-omc^hat rou»h ; ,tnd

dark-coloure<s. The varieties stated bj» - Dr Joaes to be rated highest as to disease resistance are, in England, Evergood, Discovery, Royal Kidney, Northern Star, Sip John" Llewellyn, King Edward VII, Eldorado, and Factor (all these varieties, it will h», noted, are well known in New Zealand ; four of them were raised by Findlay). la Germany ,and Holland the best types are represented by Mohort, Irene, Geneimrat Thiel, Professor Wohltniann, Boncza, Eigenheimer, and Paul Krager. In Belgium and France there is no improvement " upon fclie best English and 1 German, kinds. In America no one vaiiety is pre-eminent, but kinds selected as deserving mention are Dakota Red, RnstprooT, Irish Cobbler, Sir Walter Raleigh, Doe's Pride, and Whita Beauty (incst or all of which are known here) ; several new sorts of reputed disease resistance are mentioned as being under observation, some of them giving muclu promise. It is remarked that most of the vaiieties which have proved strongly esistant to late-blight have also showed great resistance to early-blight, -scab, and bacterial blight.