CLUB-ROOT IN TURNIPS.

Southland Times, Issue 19546, 9 May 1925, Page 14

CLUB-ROOT IN TURNIPS.

“ Disease-Resistant” l Varieties.

Trials in Southland. (By R. B. Tennent, M.D.D., Instructor of Agriculture.) During the season 19’23-24 field trials of several varieties of turnips claimed to be highly resistant to club-root were conducted in Otago and Southland. In the present article a brief description of the economic importance of this disease is given, together with a record of the observations made in connection with the trials. The occurrence of dry-rot disease in the same plots is also recorded incidentally. Where (he general term “turnip” is used it is intended to include both soft and swede varieties. The turnip crop may be regarded as the most important cultivated crop, apart from grass, grown in Otago and Southland, approximately 205,000 acres having been grown there during the season 1923-24. The value of the crop to the southern farmer lies in the comparative ease with whieh it may be grown, coupled with its relatively high yield and great utility as a winter feed for stock. Such features give it a leading place in the farming practice of the South rivalled by no other crop. Consequently, when weather conditions, or the incidence of certain bacterial or fungoid diseases, or the attack of insects, are such as to reduce the yield per acre, such a visitation is a most serious one for the farmer, seeing that the successful wintering of his stock is to a large measure regulated by the success or failure of his turnips. Turnip-growihg was introduced into Otago and Southland by the early Scottish farmers who settled in that part of the Dominion. With increased settlement turnip-growing also increased, and each succeeding year saw larger areas laid down. With the increased acreages shorter rotations between crops were evolved, this to a large measure accounting for the spread of various diseases. Also the common practice of purchasing turnips —a large portion of whieh are often infected with club-root—-and feeding such roots on clean land is a common means whereby disease is spread from farm to farm. It is only by a realisation of the danger of carrying out this practice that the farmer ean hope to prevent the introduction of disease on his property. The position to-day is that in certain localities of Otago and Southland turnip-growing is, to say the best, a most precarious undertaking. A large number of farmers find that they can only grow turnips with great difficulty, that failure is more often likely to accrue than success, and, in short, that they have been forced to abandon turnip-growing as a reliable farm practice, thus being forced into growing less satisfactory substitutes. The two chief diseases to which the turnip is susceptive in Otago and Southland are club-root or finger-and-toe (Plasnridophora brassicae) and dry-rot (Phoma napo brassicae). In this article, however, only minor reference is made to the latter disease, the main observations being concerned with club-root. No definite figures are available in regard to the annual loss experienced by farmers as a result of club-root infection, and it will be realised that such pecuniary loss will vary considerably with the seasons, being lower in a dry and higher in a wet one. Estimating the average yield of turnips over all classes of country in Otago and Southland as about 15 tons per acre, and giving those turnips a value of £1 per ton, it then follows that the gross value per acre works out at £l5. According to official statistics 205,000 acres of turnips were grown in 1923-24 in those districts, thus representing a monetary value of approximately £3,075,000. Making a deduction from this sum of 15 per cent., estimated as the loss incurred by club-root infection—namely, £461,250—it can at once be realised of what importance is the finding of some means of counteracting this disease. Including resultant losses directly due to the primary loss just indicated, the total amount would probably be brought well up to the million sterling mark. PLAN OF THE EXPERIMENTS. Seeds of the following varieties were submitted for trial: (1) Irvipe’s Purple-top swede, (2) Irvine’s Green-top Yellow turnip, (3) Sutton’s Hardy White (swede), (4) Mein’s Purple-top swede, (5) Mein’s Green-top Yellow turnip, (6) Mein’s Purple-top Yellow turnip, (7) Bangholm swede. In planning the experiments it was realised that, as the infection of the different fields varied considerably, an endeavour would have to be made to obtain the same intensity of infection by sowing the trial seed along with a control in various portions of the fields. Accordingly the ordinary turnip-ridger was employed, each drill of the ridger sowing different seed. For example, one drill would sow Bangholm seed, and the other a commercial strain of turnip similar in qualities to Bangholm swede. When the drilling was completed the field consisted of alternate rows of Bangholm and commercial swede, so that the variety under trial 'and the control were as nearly as practicable subjected to similar conditions in so far as soil infection was concerned. This method was adopted in the case of each variety of seed under trial, commercial seed being used as a control, this being selected to conform as nearly as possible with the type of turnip under trial. The fields selected for trial were known to he infected with club-root. When the crops were matured J-chain strips of adjacent rows of trial and control turnips were examined microscopically for club-root and dry-rot. These I-chain rows were also weighed. Double rows were taken in this manner at varying places of the fields. The results obtained from this preliminary investigation are given below, a commentary being made on each result: — IRVINES’S PURPLE-TOP SWEDE. Three trials of this variety were carried out, two at Gore Experimental Area and one. on the property of Mr W. Scott, Mataura. TRIAL 1. GORE EXPERIMENTAL AREA.

In this trial, as will be noted, the infection of club-root in the ground was high. In the case of Plots A, B, and C, Irvine’s seed showed superiority in club-root resistance over the commercial swede. In Plot D the position, however, was reversed. The infection of the swedes by dry-rot was slight, being about equal in both varieties. 2. GORE EXPERIMENTAL AREA. No. No. of Roots Per cent, of Roots of Roots infected with infected with Weight , Plot. Variety. ex- Club- Dry- Club- Dry- of Roots amined. root. rot. root. rot. examined.

In this ease, as in’ Trial 1, Irvine’s swede showed superiority in regard to club-root resistance over the commercial strain in all but Plot F. Here the position was entirely reversed. On the whole, Irvine’s was less infected with dry-rot than the commercial strain. 3. T. SCOTT’S FARM, MATAURA.

Average ' x Yield per Acre. Averages of Plots. I Tons cwt. Irvine’s Purple-top : 221 148 67 7 4 Commercial 120 84 1 70 0.8 4 13 In Plots A, B, and E the commercial swede used showed less infection than Irvine’s. This piece of ground was very badly infected with club-root, and a large number of misses occurred in the i-chain lengths. Whether those misses were accountable to club-root or not is problematical, but it would appear that in the majority of instances such was the case. If* so, a different result would most likely have been obtained, for it is noticeable that in the ease of each plot a larger number of Irvine’s than commercial swedes were examined, thus rendering Irvine s more likely of showing a higher percentage of infection. This crop was remarkably free from dry-rot infection. SUMMARY. As a result of this trial, and taking into account the remarks made in -connection with Trial 3 of this series, it would appear that Irvine s Purple-top swede shows a higher capability of resisting clubrroot than the commercial strains used. The same conclusion is arrived at in regard to its resistance to dry-rot. IRVINE’S GREEN-TOP YELLOW TURNIP. Three trials of this variety of soft turnip were made, two at, Gore Experimental Area and one on Mr Raynbird’s farm, Otago Peninsula. 4. GORE EXPERIMENTAL AREA.

The infection with club-root was very light in all plots but A. In the case of Plots A and D the infection with dry-rot was greater than on the other plots. As will be noted, Plots A and B showed the greater percentage of infection with Irvine’s turnip. The reverse was the case in Plots C and D. The averages show a higher percentage of club-root infection in the commercial turnip over Irvine’s turnip. This also is the case in regard to dry-rot infection. It should be noted that the commercial turnips, despite the heavier infection, gave a heavier yield per acre. 5. GORE EXPERIMENTAL AREA.

In this case Irvine’s turnip showed a decided superiority in regard to dub-root resistance, particularly where the incidence of infection in the soil was high. This also applies in the ease of those turnips infected with dry-rot. with the exception of Plot F. As was the case in Trial 4, the commercial turnip gave the heavier yield per acre, notwithstanding its greater degree of infection. As will be seen in the averages, the incidence of disease in this was comparatively slight. 6. MR RAYNBIRD’S FARM, OTAGO PENINSULA. .

Club-root infection in this trial, also dry-rot infection, were distinctly more pronounced in the case of the commercial turnip. Again, however, it is noticeable that the recorded yield per acre of commercial turnips was higher than that recorded for Irvine’s. . SUMMARY. From the three trials of this variety distinct indication is given that Irvine’s turnip has a greater degree of resistance to both club-root and dry-rot than the commercial strains used. This is particularly noticeable in the ease of Trials 5 and 6. The yield per acre of Irvine’s turnips was lower in each case when contrasted with the commercial turnip, but as the value of a turnip is to a large measure regulated by its keeping quality it would appear that the disadvantage of a comparatively low yield in the case of Irvine’s is more than compensated by the lesser percentage of infection throughout the crop. SUTTON’S HARDY WHITE SWEDE. Two trials of this variety were conducted, one at Gore Experimental Area, and the other on Mr Raynbird’s farm, Otago Peninsula. 7. GORE EXPERIMENTAL AREA.

In all plots but one, Sutton’s seed here showed a slight superiority over the commercial seed in so far as club-root infection was concerned. The reverse was the case in regard to dry-rot infection. Both varieties were badly infected by club-root and showed little resistance to the disease. 8. MR RAYNBIRD’S FARM, OTAGO PENINSULA.

As in Trial 7, both varieties were heavily infected with club-root, Sutton’s swede, if anything, the more so. The percentage of dry-rot present was comparatively low, showing in favour of Sutton’s swede. The yield per acre in this case was practically equal for both varieties. SUMMARY. On viewing the results of this trial one is forced to conclude that Sutton’s variety has no claim to be resistant to club-root disease. Plot B of Trial 8 showed that where the disease was severe in the field this swede became badly infected.

MEIN’S PURPLE-TOP SWEDE. One trial only was made with this variety —namely, at Gore Experiments Area, as follows: — 9. GORE EXPERIMENTAL AREA.

Mein’s seed showed a superiority in regard to disease-resistance in so far as club-root disease was concerned. In regard to dry-rot the results were variable, in some instances the control swedes proving superior. Neither variety showed a 'high degree of resistance, and the claim made in connection with Mein’s seed cannot be regarded as fully substantiated from the observations made in this trial. MEIN’S GREEN-TOP YELLOW TURNIP. - A single trial of this variety was conducted on Mr Irvine Martin’s farm, Gore, results being as follows: , ' MR IRVINE MARTIN’S FARM, GORE.

. As will be noted, Mein’s turnip showed no superiority over the commercial variety. The percentage of club-root infection in the field was low, and consequently the information tabulated is a poor index of the probability of this turnip’s disease-resistant properties. It is particularly to be noted that none of the commercial turnips was infected with club-rot, whereas 6.1 per cent, of Mein’s showed infection. In regard to dry-rot resistance both varieties showed equal infection. MEIN’S PURPLE-TOP YELLOW TURNIP. This variety was tested at the Gore Experimental Area, with results as tabulated:— 11. GORE EXPERIMENTAL AREA.

The commercial strain in this trial showed superiority in regard to club-root and dry-rot disease resistance. BANGHOLM SWEDE. A trial of Bangholm swede was conducted at Gore Experimental Area on land known to be heavily infected with club-root. Three years previous to this trial the land had been limed with different quantities of burnt lime per acre, one strip being left as a control. Previous observations made on this block had indicated that as a means of control lime was of no great value. The following information is consequently of value not only in indicating the club-root resistant properties of Bangholm swede, but also in showing the effect of lime in relation to the disease. The tabulated statements explain the scheme of laying out the plots. 12. GORE EXPERIMENTAL AREA.

It will be noted that Bangholm swede showed a fair degree of diseaseresistance in contrast. with the commercial variety. The effect of the various applications of burnt lime appears to be negligible, and only emphasises the fact, as already stated in previous reports, that lime is not an efficacious remedy for the control of club-root. GENERAL SUMMARY OF TRIALS. (1) The results so far obtained serve to pave the way for further experimentation, and indicate that where this class of work is being performed a large number of observations will have to be made to obviate the great variations which occur. (2) Insufficient roots were examined to eliminate any probable error in regard to the experiments. (3) Of the turnips submitted for trial none were immune to club-root disease. (4) Although a number of varieties showed a higher degree of resistance to club-root and dry-rot than the commercial varieties with which they were compared, it cannot be claimed that these varieties warrant the name of “disease-resistant”—all being fairly heavily infected. (5) Two varieties showed promise of being worthy of further trial under more exacting conditions, these being Bangholm swede and Irvine’s Green-top Yellow turnip.

No. of Roots No. of Roots infected with Per cent, of Roo1 infected with is Weight Plot, Variety. examined. Clubroot. Dryrot. Clubroot. Dry- of Roots rot. examined. Ike A Irvine's Purple-top swede - 40 29 72.5 4 10.0 114 Commercial swede - 37 37 100.0 1 2.7 101 B Irvine’s Purple-top - 32 17 53.1 1 3.1 111 Commercial - -- -- -- - - 39 32 82.0 4 10.2 120 c Irvine’s' Purple-top - 35 21 60.0 5 14.3 119 Commercial - 42 32 76.2 4 9.5 112 D Irvine’s Purple-top - 45 19 42.2 2 4.4 111 Commercial Averages of Plots. - 42 11 26.2 2 4.7 89 Average Yield per Acre. Tons cwt. Irvine’s Purple-top - 152 86 12 56.5 7.9 28 13 Commercial — — — — — — — — - 160 112 11 70.0 6.2 26 13

lbs A Irvine’s Purple-top swede 23 11 — 47.8 — 56 Commercial swede ------ 35 24 1 68.5 4.1 85 B Irvine’s Purple top 39 16 2 41.0 5.1 96 Commercial swede ------ 38 23 10 60.5 26.3 60 c Irvine’s Purple-top - - 49 26 2 53.0 4.0 132 Commercial swede 48 33 3 68.7 6.2 115 D Irvine’s Purple top 40 15 1 37.5 2.5 110 Commercial swede 49 29 5 59.0 10.0 106 E Irvine’s Purple-top 38 15 3 39.4 7.8 118 Commercial swede 39 21 2 53.8 5.1 95 F Irvine’s Purple-top 45 22 2 48.8 3.3 108 Commercial swede Averages of Plots. 42 9 2 21.4 4.7 115 Average Yield per Acre. Tons cwt. Irvine s Purple top 234 105 10 44.8 4.2 26 3 Commercial swede 251 139 23 55.3 9.1 23 7

No. No. of Roots Per cent, of Roots Plot. Variety. of Roots infected with infected with ex- Club- Dry- Club- Dryamined. root. rot. root. rot. Weight of Roots examined, lbs ' A Irvine’s Purple—top swede - --47 11 — 23.4 — 32 Commercial * - - 14 3 — 21.4 V— 18 B Irvine’s Purple—top - - 50 35 — 70.0 — — 30 Commercial - - 27 13 — 48.1 —r20 C Irvine’s Purple-top --37 30 — 81.0 — 25 Commercial - - 38 34 1 89.5 2.6 25 D Irvine’s Purple-top - - 42 37 — 88.0 — 30 Commercial - - - 24 23 — 95.8 — 14 E Irvine’s Purple-top ’ - - 45 35 — 77.8 — 26 Commercial - - r 17 11 — 04.7 — 16

No. No. of Roots Per cent. of Roots Plot Variety. of Roots infected with ex- Club- Dryamined. root. rot. infected with Club- Dryroot. rot. Weight of Roots examined, lbs Irvine’s Green-top Yellow turnip 36 17 4 47.2 11.1 69 Commercial ----- - 42 26 8 61.9 19.0 105 B Irvine’s Green-top Yellow - 32 3 — 9.3 — 68 Commercial ----- - 47 2 4 4.2 8.5 121 c Irvine’s Green-top Yellow - - 36 4 6 11.1 16.6 98 Commercial ----- - 36 2 — 5.5 ——— 59 D Irvine’s Green-top Yellow - - 40 — 3 — 7.5 70 Commercial ----- Averages of Plots. - 35 5 14 14.3 20.0 113 Average Yield per Acre. Tons cwt. Irvine’s Green-top Yellow - - 144 24 13 16.6 9.0 19 4 Commercial - - - - - - 160 35 26 21.8 16.2 25 2

No. No. of Roots Per cent. - of Roots Plot ; Variety. of Roots infected with ex- Club- Dryamined. root. rot. infected with Club- Dryroot. rot. Weight of Roots examined. lbs A Irvine's Green- top Yellow turnip 40 1 1 2.5 2.5 57 Commercial ----- - 57 2 10 3.5 17.5 106 B Irvine’s Green-top Yellow - - 30 — — — — 74 Commercial ----- - 36 — 7 — 19.4 105 C Irvine’s Green-top Yellow - - 33 3 1 9.1 3.0 50 Commercial ----- - 44 13 4 29.5 9.1 76 D Irvine’s Green-top Yellow - - 35 3 3 8.6 8.6 45 Commercial ----- - 46 10 6 21.7 13.0 90 E Irvine’s Green-top Yellow - - 38 2 — 5.3 — 55 Commercial - - - - - - 41 9 4 22.0 9.7 70 F Irvine’s Green-top Yellow - - 33 1 1 3.0 3.0 32 Commercial ----- Averages of Plots. - 38 9 1 24.0 2.6 98 Average Yield per Acre. Tons cwt. Irvine’s Green-top Yellow - - 209 10 9 43 4.1 13 2 Commercial - - - - - - 262 43 33 16.4 12.6 22 19

No. No. of Roots Per cent. of Roots Plot Variety. of Roots infected with infected with Weight Dryof Roots ammed. root. rot. root. rot. examined. lbs Irvine’s Green-top Yellow turnip 19 — — — — 54 Commercial ------ 36 4 4 11.1 11.1 67 B Irvine’s Green-top Yellow 43 — — — — 53 Commercial ------ 45 2 3 4.4 6.6 59 c Irvine’s Green-top Yellow 41 2 2 4.8 4.8 50 Commercial ------ 26 Averages of Plots. 10 13 38.4 5.0 42 Average Yield per Acre. Tons cwt. Irvine’s Green-top Yellow - - 103 2 2 1.9 1.9 13 2 Commercial ------ 107 16 20 15.0 18.7 14 3

No. No. of Roots Per cent. of Roots Plot , Varietj of Roots infected with ex- Club- Dryamined. root. rot. infected with Club- Dryroot. rot. Weight of Roots examined, lbs A Sutton’s Hardy White swede - 33 11 3 33.3 9.1 53 Commercial ----- - 30 19 — 63.3 — 30 B Sutton’s Hardy White - 31 4 3 12.9 9.7 63 Commercial ----- - 32 22 2 68.7 6.2 67 C Sutton's Hardy White - 35 7 6 20.0 17.1 68 Commercial ----- - 38 27 3 71.0 7.9 72 D Sutton’s Hardy White - 45 38 4 84.4 8.8 60 Commercial ----- - 42 36 3 85.7 7.1 58 E Sutton’s Hardy White - 29 24 3 82.8 10.3 45 Commercial ----- Averages of Plots. - 23 22 4 95.7 17.4 22 Average Yield per Acre. Tons cwt. Sutton’s Hardy White - 173 84 19 48.6 11.0 14 10 Commercial ----- - 163 127 12 77.9 7.3 12 10

No. No. of Roots Per cent. of Roots Ph* Variety. of Roots infected with ex- Club- Dryamined. root. rot. infected with Club- Dryroot. rot. Weight of Roots examined. A Sutton’s Hardy White swede - 30 16 — 53.3 — 50 Commercial ----- - 33 15 1 45.5 3.0 48 B Sutton’s Hardy White - 25 23 1 92.0 4.0 68 Commercial ----- - 27 25 4 92.6 14.4 67 C Sutton's Hardy White - 32 17 2 53.1 6.2 52 Commercial ----- Averages of Plots. - 41 19 6 46.3 14.6 56 Average Yield per Acre. Tons cwt. Sutton’s Hardy White -y - 87 56 3 64.3 4.4 14 5 Commercial -,- - - - - 101 59 11 58.4 10.9 14 8

No. No. of Roots Per cent. of Roots Plot. Variety. of Roots examined. infected with Club- Dryroot. rot. infected with Weight Clubr Dry- of Roots root. rot. examined. IBs A Mein’s Purple-top swede - - - 34 23 4 67.6 11.8 75 Commercial - - 34 30 3 88.2 8.8 72 B Mein’s Purple-top - - 36 19 5 52.7 13.8 Commercial ----- - 35 34 11 97.4 31.4 72 C Mein’s Purple-top - 33 20 6 60.6 18.2 85 Commercial - 41 37 6 90.2 14.9 72 D Mein’s Purple-top - 37 21 2 56.7 5.4 67 Commercial - - - - - - 42 38 4 90.5 9.5 76 E Mein’s Purple-top - 28 16 1 ■57.1 3.5 75 Commercial ----- Averages of Plots. - 31 27 2 87.1 6.4 66 Average Yield per Acre. Tons cwt. Mein’s Purple-top - 168 99 18 58.9 10.7 20 19 Commercial - - - - - - 183 166 26 90.7 14.2 18 1

No. No. of Roots Per cent. of Roots Plot , Variety of Roots exinfected with Club- Dryinfected with Club- DryWeight of Roots amined. root. rot. root. rot. examined. lbs A Mein’s Green-top Yellow turnip 44 2 2 4.5 4.5 40 Commercial ------ 43 —— 2 — 4.6 46 B Mein’s Green-top Yellow • 45 6 4 13.3 8.8 36 Commercial ------ *41 — — — — 40 c Mein’s Green-top Yellow 42 2 2 4.7 4.7 28 Commercial ------ 27 — 3 — 11.1 22 D Mein’s Green-top Yellow 48 1 2 2.1 4.2 36 Commercial ------ Averages of Plots. 35 3 8.5 26 Average Yield per Acre. Tons cwt. Mein’s Green-top Yellow 179 11 10 6.1 5.6 8 9 Commercial ------ 146 — 8 — 5.5 8 16

No. No. of S loots Per cent, of Roots Plot Variety, of Roots exinfected with Club- Dryinfected with Club- DryWeight of Roots amined. root. rot. root. rot. examined, lbs A Mein’s Yellow turnip 54 8 5 14.8 9.3 41 Commercial ----- - 37 2 3 5.4 8.1 32 B Mein’s Purple-top Yellow 45 4 1 8.8 2.2 40 Commercial ------ 36 3 1 8.3 2.8 32 c Mein’s Purple-top Yellow 42 8 2 19.0 4.7 32 Commercial ------ 34 — 2 — 5.9 32 D Mein’s Purple-top Yellow 51 6 4 11.7 7.8 41 Commercial ------ Averages of Plots 39 1 1 2.5 2.5 40 Average Yield per Acre. Tons cwt. Mein’s Purple-top Yellow 192 26 12 13.5 6.5 9 14 Commercial ------ 146 6 7 4-.L 4.8 7 19

4 Tons Burnt Lime 8 Tons Burnt Lime Control 16 Tons Burnt Lim 2 Tons' e Burnt Lime Plot. Variety. I >er Acre. per Acre. per Acre. per Acre ClubClub Clubroot. Sound root. Sound root. Sound root Sound root Sound A Bangholm swede — . - 6 15 11 21 13 23 12 23 10 14 Commercial swede 14 1 10 1 31 0 13 4 20 1 B Bangholm - - — 3 18 2 17 4 23 2 26 7 10 Commercial 20 4 16 15 46 0 29 6 24 0 C Bangholm - - — 8 15 18 20 10 19 8 22 10 15 Commercial 24 3 26 5 34 1 29 1 26 1 D Bangholm - - . — 9 21 13 26 14 16 13 27 ‘19 18 Commercial 24 11 25 10 34 10 25 24 26 2 The figures represent numbers of roots, diseased or sound. ' g £ PQ u § © Variety. H g C O .<u £ o 8> "S c 2 o 1 1 S S Q< © O S 3 to HH <J5 o a a .2 a> "a i—< o ’ ® oc aS e 2 a g, o H ® S‘| § *3 t—< o to 08 c 5 O a o Lime per Acre. tage of Infection. O ® .2 § « £ ° o 5 o § Q 2 o $ Ph J} "S = O O £ 11 O ® 02 .2 o o 2 'a s o CO fi 1 8 -A £ 5 rooted. Sound. Percen 2. o o 2 a 5 o co a Bangholm 26 69 27.3 44 84 34.3 41 91 : ?i.o : 15 98 26.3 46 f >7 44.6 32.7 Commercial 82 19 81.9 77 31 71.3 145 11 ! 93.0 1 J6 35 73.3 96 4 96.0 83.1