Leaflet Now 20. Beas * SeaLE HAYNE AGRICULTURAL COLLEGE. i 22%, NEWTON ABBOT. DEVON. AGRICULTURAL DEPARTMENT. POTATO VARIETY TRIALS, 1926. The potato variety trials carried out previously in 1922, 1924 and 1925 were continued in 1926 with modifications as follows : (a). Since it was considered from previous years’ experience that first earlies were not an economical proposition as a farm crop in the district, owing mainly to the difficulty of getting them in early enough to give a good crop, it was felt that no useful object was being served by including them any longer in the trials. The varie- ties were therefore confined to Second Earlies and Main Crops. (b). Certain of the Second Earlies and Main Crops had yielded so poorly in all three of the previous seasons that their inclusion in the trials was no longer warranted. The tested varieties for 1926 were as fol]ows :— Second Earlies. Main Crop. Great Scot. Rhoderic Dhu. Ally. Majestic. Arran Comrade. *Arran Chief. Tinwald Perfection. Bishop. Ker’s Pink. *Up-to-date. *Field Marshal. Crusader. *King Edward. *Susceptible to Wart Disease. SOURCE OF SEED. The seed was obtained, as in previous years, fresh from Scotland, all the varieties being obtained from one district to avoid any variation likely to occur from that source. It was found that the size of the seed varied a good deal from variety to variety, Majestic being of noticeably larger size than the rest, a common failing with this variety, meaning that a bulk of seed will not plant as large an acreage as the same bulk of another variety. Varieties such as Rhoderic Dhu, Bishop, Crusader, and Ker’s Pink, were on the other hand small sized. In judging results from the economic standpoint, a very considerable difference in cost of planting must therefore be considered. ARRANGEMENT OF PLOTS. Varieties were planted according to the plan published in the Guide to Field Trials, 1926, each being replicated three times. Plots were one-thirteenth of an acre in size, consisting of four rows, 24 inches apart, the two middle rows being planted in all cases with 350 tubers. These latter constituted the plot proper, the two outside rows being discarded at harvest. DETAILS OF CULTIVATION, PLANTING AND MANURING. The crop was taken on land which had grown sugar beet in 1925, so that it was in good condition as regards cleanliness and manuring. All the sugar beet, however, could not be removed till late in the year, after the weather had broken, causing ploughing to be delayed. This fact, combined with the somewhat heavy soil and wet winter that followed, caused great difficulty in the spring cultivations and the potatoes had to be planted in a bad tilth. | The potatoes were planted on April Ist in the ridge on top of a dressing of Farmyard Manure about Io tons to the acre in triplicate plots as indicated. Thirteen or fourteen inches were left between the sets in the row, after which the ridges were split back, and the following artificials sown by hand on top of the ridge: | 22 cwts. Dissolved Bone Compound per acre. 2 +) Kainit ’) 9) Later a dressing of i cwt. Sulphate of Potash per acre. 2 cwts. x of Ammonia 3) 3) was applied. The usual after-cultivations of horse and hand-hoeing and remoulding were carried out later. SEASONAL AND GENERAL NOTES. A very dry unfavourable season was experienced all through ; a comparison of the rainfall for the growing period of the two seasons 1925 and 1926 will serve largely to show the reason for the very much lower general yield obtained in 1926, as compared with 1925. Month. 1925 1926 PSOE hee bak. ees 2O2 IS Over ee 2.32 ins. Mayer eee AOD Lee ache a ee 0:07 way p| Tithe ene eae: NGL Agee eee 3:32am july tee a ZOO see ttre meee 0.00 3 PUCUSU soy ous, 237 | cs9 hie ORs tere 1:37 Bs september 2 9 (02) te net ear T1338 15 50. 0.00 43 The lack of rain, however, had beneficial effects in three ways i— (a). Much less secondary growth was apparent than in 1925. (b). There was comparatively little disease on the crop.in general. (c). The percentage dry matter in all varieties was greater than in previous seasons. 3 These three factors combined to give a very satisfactory sample of ware potato, and for the best varieties an excellent price was obtained. A good deal of trouble was experienced from the ravages of rooks, and in spite of the use of an automatic shot gun during the early part of the growing period, a large amount of damage was done to the seed. HARVESTING. Lifting started with the second Earlies on August 31st. The two middle rows of each plot were lifted and sorted by hand into ware, seed, chats, and diseased. The outside discarded rows were lifted by machine and were not weighed, but the varieties were still kept separate for selling purposes. During lifting the weather was exceptionally fine, no rain falling at all, so that all varieties were harvested clean and dry. The order of ripening was as follows :— Second Earlies. Ally, Arran Comrade, and Great Scot were all ready together. Main Crops. 1. Crusader. 6. Up-to-date. 2. King Edward. Ze airane niet. 3. Bishop. 8. Field Marshal. 4. Majestic. g. Ker’s Pink. 5. Tinwald Perfection. © to. Rhoderic Dhu. ‘* This order was the same as in 1925, except in the case of Field Marshal, which was slightly later in 19206. TABLE OF YIELDS. SERIES I, SERIES II. Series III. AVERAGE. VARIETY. . per acre. ~ Tons ewts. ibs. | Tons ewts. lbs. |Tons ewts. lbs. | Tons. ewts lbs. 2nd Earlies : Great Scot 6 10 0 5 0 32 5 9 .12 sy Wit Veh Arran Comrade 5 2 68 38 19 44 A Y D4 A, 9 82 alii SAL: CLASS A 6 40 A 1 80 A, 8 %6 4 om G5 ~ Main Crops: f Field Marshal .. 8 ll 48 9 6 46 Vp AT ways °F 0 11 Arran Chief .... W)) 72" 58 6 16 56 SIS 72 7 14 24 Tinwald Perfec- TOI cidtezee 6 11 96 8 4 14 7.28 ..535 Ts Se Lo Ker’s Pink 6 13 44 7 17. 44 7 0 102 ri 3 101 * Rhoderic Dhu 6 17 96 on Oe ee ge aR 7 $8 26 Up-to-date .... 7 AS 1-6 6 4 "TA PULLS ait SG Crusader ...... 6°17. B4 Gaekb21B6 7246 26 G 18:45 Majestic a. 5A~.+ 6 11 44 Gs OF 54 6 2 90 6 4100 King Edward .. Gay our 5 10 108 G6 ;-2..86 Gy wie, 47 ~~ Basliopy skis «s 2 AB als a? ye ie 8 °8 106 Ly Sl ANALYSIS OF YIELDS. Percentage Ware. VARIETY. Series Series Series Average. 1 2 3 Second Earlies : 7.10 Uh gia tT ONE Aaa Ok 5A 57 57 56 22.20 Great Scot ........ 56 55 54, 55 24.60 Arran Comrade .... 39 32 33 34 26.11 Main Crops: t MMAIESHICE f.0 bs sx sls oie 81 85 83 83 24.34 Field Marshal ...... 75 81 78 78 23.81 Up-to-date 24.25. TA, (Ped 76 T4 23.45 Arran-Chief-:. 2554.6 TA 70 73 72, 22.63 Kers Pinks). oas 68 73 74 71 24.74 King Edward Be re! Wes 67 71 - 24.37 Rhoderiec Dhu ee 57 69 70 68 26.13 Crusader’ so. bec 67 63 59 63 26.63 Tinwald Perfection .. 63 64 60 62 26.36 Bishop '.% ... eRe ar AT A5 AT 46 24.85 REMARKS ON YIELDS. The varieties having been grown in triplicate, three weighings were available for comparison, and these were examined in the light of experimental error. This examination showed an error of 3.75%, so that a differ- ence of 9 cwts. approximately can be considered as significant. This should therefore be borne in mind in reviewing the results. SECOND EARLIKES. The second earlies as a whole were a most disappointing crop. No growth was apparent from the beginning of the season. The tops were always poor in appearance and the expectation of a poor crop was borne out in the subsequent weighing. Compara- tive results give Great Scot as the best in a poor season, the average result being borne out in each of the three individual series. Between Ally and Arran Comrade there was no significant difference. MAIN CROPS. Taking into consideration the dry season, the main crops as a whole may be considered as satisfactory, and as a class as very much better than the second earlies. | A review of the individual results brings forward the follows ing points as worthy of special note :— (a).. Field Marshal, a variety being tried for the second year, has given an exceptionally good result, over a ton more than any other variety. Field Marshal is a potato very similar in type to the older Up-to-date, of a good saleable appearance, a large ware percentage and not an exces- sive amount of disease, so that on the whole it may be considered as the best of this year’s main crops. (b). Ker’s Pink has upheld its reputation as a good yielder, though not heading the list as in other years. AL (c). Majestic has taken a surprisingly low position, being née 3 tons below Field Marshal. As the saleable sampls was badly marked with disease and irregular in shape it must be considered as one of the worst varieties of the year in spite @f its high ware percentage. (d). Bishop was a complete failure, bearing out results obtained with regard to this variety in previous seasons. (e). Of the other varieties, Tinwald Perfection, Arran Chief, Up-to-date, and Rhoderic Dhu all upheld their reputa- tion as good croppers, King Edward was moderate, whilst Crusader was not up to the standard that it had set in 1924 and 1925. GERMINATION. It is necessary to qualify the results set out in the table of yields, by comparing these with the number of plants, from which the yields were obtained. It has been pointed out that plots were set with 350 tubers of each variety, and during the season the number of plants in each plot were carefully recorded. The following table shows the actual number of plants in the plots on July 22nd :— SERIES I. | Serres II.|SeErtiEs III.| AVERAGE. Rhoderic Dhu. .......... 308 326 304 313 Tinwald Perfection 300 310 308 306 1G) co oa ee 302 307 304 2010) a ee 267 306 337 301 ioe echo OV eV igen 282 293 295 290 Field Marshal ........... 287 291 289 289 LS SC Sea 275 300 265 280 Draiestiow: sn Se s., 268 253 269 263 RUE EOROA LET cite ry 261 245 249 252 King Edward. .......... 266 243 BAT 252 The number of tubers actually giving plants varied widely ; in the case of Rhoderic Dhu 90% and in King Edward 72% only of the tubers planted germinated. GENERAL REMARKS. (x). As usual, all varieties were tested for dry matter, and exceptionally high results were obtained in every case, ranging from 22 to over 26%. These results were not surprising in view of the very dry season that was experienced, the driest since Ig2I. As had been noted in previous years, the percentage dry matter varied roughly inversely as the percentage ware, showing that the smaller the tuber the higher the dry matter that might be expected. (2). The percentage ware in all varieties, except Bishop and Ally, was good, and in nearly every case larger than in previous years. As usual, Majestic headed the list in this respect, but was not so far ahead of the others as previously, Field Marshal and Up-to-date ranking very high. (3). The dry season kept most.warieties fairly free fro: Pdisease. Ally and Arran Comrade of the second earlies, and Kin Edward, Bishop, Tinwald Perfection, and Ker’s Pink of the main crops gave nearly clean tubers. Of the others, Crusader, Majestic, and Up-to-date were all scabbed, which, though having very little effect on the yield, tended to give a badly marked sample of ware for sale. In the case of Great Scot, Arran Chief, Rhoderic Dhu, and Field Marshal scab was apparent in patches and more at one side of the field than the other, whilst Majestic and Field Marshal — showed a small amount of blight, in the case of Field Marshal very ~~ slight. Tinwald Perfection, as in previous years, showed most | tendency to contract the virus diseases, leaf-curl and mosaic, though not sufficiently to cause any apparent effect on the yield. (4). Secondary growth was not bad except in the case of - Ker’s Pink, Rhoderic Dhu and Arran Chief. In these three cases, in the order given, it was bad enough to have a very considerable effect on the appearance of the ware sample. The other main crops gave a good clean sample from this point of view, the earlier ripening and earlier harvested ones being the best, 7.e., Crusader, King Edward, Bishop and Tinwald Perfection.. The second earlies were completely free from secondary growth. (5). Note was taken of the appearance of the tubers fron the point of view of regularity of shape and trueness to type and good results were obtained in most cases. Of the second earlies, Arran Comrade was not up to the standard of the other two. Of the main crops, three, Rhoderic Dhu, Up-to-date and Majestic, may be picked out as bad in this respect; King Edward, Field Marshal, Bishop, Crusader, and Arran Chief were all good, whilst Tinwald Perfection and Ker’s Pink were moderate.