62 VOL. 2, N.4, CAN. PLANT DIS. SURV. DEC., 7972 STEM RUST OF WHEAT, BARLEY, AND RYE IN CANADA IN 972' G. J. Green Prevalence and importance in Western Canada Stem rust spores (Puccinia raminis Pers.) were found in spore aps in b Manitoba and Saskatchewan during May and early June. Apparently the spores were carried into Western Canada earlier than usual because stem rust was more widespread in the United States than in the preceding 8 years. Despite the early presence of inoculum, stem rust was not found in Manitoba until July 7, about 2 weeks later than usual. Development was slow, but before the end of the growing season stem rust (p. raminis Pers. f. sp. itici Eriks. and E. b w a s present on susceptible wheat varieties (Triticum aestivum L.) and wj Id barley (Hordeum jubatkiiacross Western Canada. w e r it was not observed on resistant commercial varieties that occupy most of the wheat acreage in the rust area, and losses were insignificant. The bread wheat varieties Manitou, Neepawa, and Selkirk, the utility wheat variety Glenlea, and the durum wheats (x. durum Desf.) Stewart 63, Hercules, and Wascana continue to show good resistance. The Mexican variety Pitic 62, which was severely attacked by stem rust in 97 and 97, was moderately infected in test plots. Stem rust of rust nurseries wheat, barley, and rye in the Uniform rust nurseries were planted by cooperators at 29 locations across Canada in 972. The wheat varieties grown included the Table. Percentage infection of stem rust (Puccinia graminis f. sp. itici) on 8 wheat varieties in uniform rust nurseries at 6 locations in Canada in 972 Common wheat Durum wheat Creston, B.C. Edmonton, Alta. Lacombe, Alta. Scott, Sask. Melfort, Sask. Indian Head, Sask. Brandon, Man. Durban, Man. Morden, Man. Glenlea, Man. Thunder Bay, Ont. New Liskeard, Ont. Guelph, Ont. Appleton, Ont. Ottawa, Ont. Kentville, N.S. 3 4 4 2 3 2 7 2 t r O O O O O O O t r t r O O O O t r O t r O t r O t r O t r t r 4 2 3 t r O t r O t r O t r O O O O O O O No rust was observed in nurseries at 3 locations: Agassiz, B.C.; Beaverlodge and Lethbridge, Alta.; Kemptville and Vineland, Ont.; La Pocatihe, Quebec, Macdonald College and Normandin, Quebec; Truro, N.S.; Fredericton, N.B.; Charlottetown, P.E.I.;and St. John's West, Nfld. = ace. susceptible Red Bobs and Mindum; Lee, which 'Conibution No. 64, Research Station, is Selective for all sains of the Agriculture Canada, Winnipeg, Manitoba R3T "standard" race B (c9, c, ell, c8, C26, 2M9. C33, C38, C44, C46, C47, C48, and C); Pitic 62, which is selective for certain sains in Plant Pathologist the "standard" race group -32-3 (C3,
VOL.2, N.4, CAN. PLANT DIS. SURV. DEC., 972 63 C4, C, and C2); the resistant commercial varieties Selkirk, Manitou, Neepawa, Napayo, Glenlea, Stewart 63, Hercules, and Wascana; and the resistant test varieties Kenya Farmer and D.T. 36. The cooperators harvested the nurseries at an appropriate time and sent the sheaves to Winnipeg where rust infection was assessed and collections were made for race identification. Wheat stem rust was more widespread and infections were more severe than in 97. It was found in 6 nurseries in 972 (Table ) and in in 97. Evidently, severe infections would have developed in Western Canada if commercial varieties had been susceptible to the prevalent races. The nurseries also included the barley (Hordeum vul are L.) variety Montcalm, which i-e+ to wheat stem rust and rye stem rust (P. raminis Pers. f. sp. secalis Eriks. and- E? Henn.); the barley varieties Parkland and C.I.644, and the rye (Secale cereale L.) variety Prolific, whicltzfz resistant to wheat stem rust and susceptible to rye stem rust. These differences in reaction and the early maturity of barley compared with rye, account for the different amounts of rust on the barley and rye in the nurseries (Table 2). Table 2. Percentage infection of stem rust (Puccinia graminis) on three varieties of barley and one variety of rye in uniform rust nurseries at locations in Canada in 972 Barley We C.I. Location Montcalm Parkland 644 Prolific Agassiz, B.C. 2 Creston, B.C. 4 2 8 Brandon, Man. 7 Durban, Man. 2 Morden, Man. 6 Thunder Bay, Ont. Kemptville, Ont. Guelph, Ont. 2 Appleton, Ont. 4 2 7 Ottawa, Ont. 4 Kentville, N.S. No rust was observed in nurseries at 8 locations: Edmonton, Beaverlodge, Lacornbe and Lethbridge, Alta.; Scott, Melfort and Indian Head, Sask.; Glenlea, Man.; New Liskeard and Vineland, Ont.; La Pocatigre, Quebec, Macdonald College and Normandin, Que.; Truro, N.S.; Fredericton, N.B.; Charlottetown, P.E.I.; and St. John' s West, Nf Id. = ace. Rye stem rust has become prevalent in recent years but it was less prevalent in 972 ( nurseries) than in 97 (4 nurseries). It was present in all Manitoba nurseries but not in Saskatchewan nurseries. Presumably it was carried into Manitoba by southerly winds but developed too slowly to infect rye in Saskatchewan. Physiologic races Physiologic races were identified by six "standard" differential hosts (T. aestivum 'Marquis' and 'Reliance'; ;. durg 'Arnautka' and 'Mindum'; T. monococcum L. 'Einkorn', and; ;. dicocc6 Schrank 'Vernal') and by the formula method. The formulas were determined using the identified resistance genes Sr, Sr6, Sr7a, Sr8, Srga, Sr9b, Sr9d, w, S m, Sr3,and thathadenbackcrossedmo lines of Marauis. Marauis is known to carrv at least three resistarke genes, the main on; for Canadian races being Sr7b. The variety Norka carries Sr, butthere was evidence for a second g e n z this variety. A line of Chinese Spring carrying Sr6 from Thatcher and a selection of Renown carrying Sr7 were also used. Both lines are believe- carry additional resistance genes. The additional genes complicate race identification but they do not appear to cause important errors. Several cultures identified in earlier years were retested and the genes found in recent years were placed in their formulas (Table 3). Eight new virulence combinations ((24 to C2) were described in 972 (Table 3). Formula C4 is for the old race 6A that differs from race C7(6) by being virulent on Sr6. Formula C is for the old race B- (can.) that is virulent on both Sr6 and Golden Ball. Races 6A and B- have not been found in the field for many years but they are used often in experimental work at Winnipeg. Five interesting new races (C46, C47, C48, C49, and C) were discovered in 972. Race C2(32-3), called C3"S" in 97, is like C3 but is virulent on Renown and Selkirk. (m) Most of the resistance genes used are good differentials but Sr and Sr6 have serious disadvantages. T t h are influenced greatly by temperature and possibly by other environmental factors. Their resistance breaks down completely at times making differentiation between certain races possible only when the environment is favorable. At Winnipeg, the difficulties occur mainly during late spring, summer, and early fall when, despite evaporative cooling, greenhouse temperatures may be high. The resistant reactions are usually distinct at temperatures about 2 O C (7'F). Norka (Sr) produced infection type 2+ or 3- with cares of race C4 (38) instead of the usual ; to 2 or X- that resemble the resistant reaction described by Watson
64 VOL.2, N.4, CAN. PLANT DIS. SURV. DEC., 972 Table 3. Formula (physiologic race) numbers, virulence formulas, and infection types produced on four wheat varieties by stem rust races found in Canada to 972 Virulence formula Infection type on Formula and (race) number Effective genes Ineffective genes Sk Mit Np Ptc62 Cl(7) C2 (7A) C3 (29-4) C4 (23) C (29-) C6(29-2) c7 (48) C8 (48A) C9 (B-L) ClO(B-) Cll(B-4) c2 () C3 (32,3) C4 (4,38) C(,32,3) C6 (39) C7 (,6) C8 (B-L) c9 (,38 C2 (,87) C2(32) C22 (32) C23 (38) C24 (7) C2 (38) C26 (B-4) C27(33,9) C28 (8,4 C29 (7) C3 (29) C3(27) C32 (32) C33 (B-L) C34 (32) C3 (32-3) C36 (48) C37 () C38 (B-lL) C39 (32-3) C4 (32-3) C4(32-3) C42 (),6,7a,9a,9b,,3,6,9a,,6,,7,9a,9b,9d,,6,9a,9b,ll,GB,, GB,,6 6,7a,8,9a,9b,,3, 6,7a, 8, GB 6,7a,8 6,7a,9a,9b,, 6,7a,9d,,,3 6,7a,,,,6 6,7a, 6,7a, 6,8,9a,9b,9d,,3,7 6,8,9a,9b,3,,7 6,9d,, 7a,8,9d,,3 9a,ll 9a, 9d, 3,6 6,7a,8,9b,3, 6,,7 6,8,9b,9dlll,6,7a,9a,9d,, 9a, 9b, 9d,6,7a,, 9a,9b,9d,ll 6,9a,9b,3,,7 6,7a,9a,9b,9d,ll 9d,,,3,7,6,7a,,6 6,8,9a,9b,,3 6,8,9a,9b,3,7 6,98,,3,7 6,9d,,3,7 9d,,3,37 6,8,9a,9b,,3,,7 8,,4,,6 7a,8,9b, 7a,,6 6,7a,8,,3,4,,7,GB 6,7a,8, 6,7a 6,7a,,GB,9d,,4,6,9a,9b,9d,,,3,4,,6,7,9a,9b,9d,,,3,4,,6,7,GB t8,8,9a,9b,4,,6,8,9a,9b,ll,,,6,7a,,4,,6,7a,9d,,,4,6,7a,,6,6,9a,9b,,4,,6,7,6,7a,8,9b,,6,7a,8,9b,,,4,,7,6,7a,,,6 6,8,,6,7a,,,,9a,9d,,,4,6,7a,,,6,7a,9a, 8,9b,6,7a,8,, 3.t ; 2 3+ 2 2 2 3+ 23 2 2 2 3t 3f 2 i2 ; 3i 3f 3+ 2 2,; i 3f 23 3+
VOL. 2, N.4, CAN. PLANT DIS. SURV. DEC., 972 6 Table 3 (ctd.) Virulence formula Infection type on Formula and (race) number Effective genes Ineffective genes Sk M i t Np Ptc62 C43 (32) 6,7a,8,9d,,6,9aI9b,,3,4, i ; C44 (B-lL) 6,9a,9b,3,7,7a,8,9d,,,4,,6 ; i 2 C4 (6A) 8,9a,9b,9d,lI3,7,6,7a,,4,,6 ; ; C46 (B-L) 6,8,9a,9b,3,,7a,9d,,,4,6,7 ;2 C47 (B-lL) 6,9a,9b,,3,7,7a,8,9d,,4,,6 i ; C48 (B-lL) 6,8,9a,9b,7,7a,9d,,,3,4,,6 ; ; 2 C49 () 6,9a,9b,,3,,7,7a,8,9d,,4,6 ; ; C (B-) 7a.8,6,9a,9b,9d,,,3,4,,6,7 4 ; x- + C(32-3) 9d,,3,6,7a,8,9a,9b,,4,,6,7 3+ 23 23 3+ C2(32-3) 9d,,,3,6,7a,8,9a,9b,4,,6,7 3+ 3f 3f 3+ Sk = Selkirk, M i t = Manitou, Np = Neepawa, Ptc62 = Pitic 62, GB = Golden Ball. and Luig (). Norka seems to carry a of race B-IL than to earlier cultures. resistance gene in addition to Sr that confers moderate resistance. When zctive, The onlv races virulent on the important - Sr6 produces a 3- infection type. Thatcher de;ivatives Manitou and Neepawa (Table 3) are the rare race C2(38) and The varieties Selkirk, Planitou, Neepawa, certain members of the standard race -32- and Pitic 62 are important commercial 3 complex (c2, c22, c3, c4, c). They varieties in Western Canada and their have not attacked these varieties in the infection types with most races are recorded L 4.- u, in Table 3. The variety Yuma is not shown although it has been a helpful differential. St is resistant to all races excepting Seventeen races were identified in 972, cultures of race B designated B-IL. In when rust was relatively prevalent, compared recent years, its reaction to certain races with 2 in 97, when rust was not prevalent. has been obscure and variable. It is more There were no important changes in race resistant to the recently occurring sains disibution in 972 (Table 4). Race C33 Table 4. Disibution by provinces of physrologic races of Puccinia graminis f. sp. itici collected on wheat, barley, and grasses i n 972, and frequency of isolation of P. graminis f. sp. secalis from barley and wild grasses Virulence Virulence formula Number of isolates from: Total Percent formula (effective/ineffective number of of total (race) number host genes) P.E.I. N.S. Oue. Ont. Man. sask. Alta. B.C. isolates isolates C4 (38) 6,7, lo,ll,.6/ 2 9 3 9 2 8.9 C7 (6) 6,8,%,9b,9d,,3,7/,7a,,4,,6 3 3.2 C8 (%-LX) 6,8,Ya,9b,3,,7/,7a,9d,,,4,6 9 7 4 3. C22 (32) 9a,9d,3,6/,6,7a,8,9b,,,4,,7.3 CZ (38) /,6,7a,l, Z.7 C33(B-lL) 6,9a,9b,3,,7/,7a,8,9d,l,,4,6 9 4 8 6 6 7. C3(32-3) 9d,,,3,7/,6,7a,8,9a,9b,4,,6 2 3 3 2.4 C36(48),6,7a,,6/,.3 C4(32-3) C42 () 9d,,3,7/,6,7a,8,9a,9b,l,4,,6 6,8,Ya,9b,,3,,7/,7a,9d,,4,6 2 3.2.3 C44 (%-L) C46(B-lL) 6,9a,9b,3,7/,7a,8,9d,,,4,,6 6,8,9a,9b,3,/,7a,9d,,,4,6,7 3 2.8.8 C47 (B-lL) 6,9a,9b,,3,7/,7a,8,9d,,4,,6.3 C48 (B-lL) 6,8,9a,9b,7/,7a,9d,,,3,4,,6.3.3.3 C2 (32-3) 9d,,,3/,6,7a,8,9a,9b,4,,6,7 2 2.8 Total wheat stem rust isolates 38 69 43 23 2 282. Rye tem rust isolates 3 6 37 2 2
66 VOL. 2, N.4, CAN. PLANT DIS. SURV. DEC., 972 Table. Disibution by provinces of physiologic races of Puccinia graminis f. sp. itici collected on susceptible varieties of wheat and susceptible wild grasses in 972 Virulence Virulence formula Number of isolates from Total Percent formula (effective/ineffective number of of total (race) number host genes) N.S. Ont. Man. Sask. Alta. B.C. isolates isolates C4(38) 6,7a,,,,6/ 3 2 7 4 7.7 C7 (6) 6,8,9a,9b,9d,,3,7/,7a,,4,,6 3 3.6 ClE(B-lLX) 6,8,9a,9b,3,,7/,7a,9d,,,4,6 4 4 2. C33 (B-L) 6,9a,9b,3,,7/,7a,8,9d,lO,ll,l4,6 8 34 66 3 6.7 C3 (32-3) 9d,,,3,7/,6,7a,8,9a,9b,4,,6 3 4 7.8 C36 (48),6,7a,,6/,.6 C4(32-3) 9d,,3,7/,6,7a,8,9a,9b,,4,,6 2. C42 () 6,8,9a,9b,,3,,7/,7a,9d,,4,6.6 C44 (B-lL) 6,9a,9b,3,7/,7a,8,9d,,,4,,6 2 3.6 C46 (B-lL) 6,8,9a,9b,3,/,7a,9d,,,4,6,7 2.8 C48 (B-L) 6,8,9a,9b,7/,7a,9d,,,3,4,,6.6 CSl(32-3) 9d,,3/,6,7a,8,9a,9b,,4,,6,7.6 C2 (32-3) 9d,,,3/,6,7a,8,9a,9b,4,,6,7 2 2 4 2.2 Total isolates 4 3 46 4 2 8. (B-IL) continued to predominate at about the same level as in 97. It does not threaten the resistant varieties grown in Western Canada. Three races C4 (38), C8 (B-ILX) and C3 (32-3) were moderately prevalent. Race C4 more than doubled its prevalence in 97; race C8 recovered from near extinction in 97; and race C3 was identified about half as many times as in 97. Race C3 is virulent on Pitic 62 and moderately virulent on seedlings of Manitou and Neepawa. Reduced planting of Pitic 62 probably accounts for its reduced prevalence. Fourteen other races occurred in ace amounts and some are worthy of note. The old and well-known race C7 (6) was found three times in Nova Scotia. It had not been identified in 97, for the first time since 93, but apparently it has persisted in the east although not in Western Canada. The new races (C46, C47, C48, C49, C:l, and C2) are variants in the "standard race complexes IB-IL and -32-3. The disibutions of races isolated from all sources (Table 4) and from susceptible, non-selective, hosts (Table ) are similar. A few rare races (C22, C2, C47,and C49) were obtained only from selective hosts. Changes in the percentage of isolates avirulent on the identified resistance genes were small (Table 6). The avirulence of the rust DoDulation on Sr8 had decreased SharDlv in 77, but genes S&, Sr9a, Sr9b, Srj3 Sr, and Sr7 continue to provide resistance toost isolates. All cultures were bulked to make composite collections which were used to inoculate 26 highly resistant varieties. Varieties resistant to all composite collections were: C.I. 8, St464, WRT 24 (Manitou with rye anslocation), Agent, Tama, Esp. 8/9, Inia 66, Saric ZO, Era, D.T. 332, D.T. 38, D.T. 37, ftewart x R.L. 244, and Marquis x (Stewart x R.L. 244). The last two have resistance from T. monococcum at the teaploid and hexaplord levels, respectively. Important varieties showing susceptible or moderately susceptible type pustules were: Mida-McMurachy-Exchange -47-26, Frontana-K8-Newthatch --7, Chris, Glenlea, Kenya Farmer, C.T. 6, and Timgalen. C.T. indicates a variety from the Western Canadian Cooperative Test; D.T. Table 6. Percent of total isolates avirulent on single identified resistance genes and number of avirulent races in 97 and 972 Number of Resistance Avirulent isolates (%) avirulent races gene 972 (97) 972 (97) Sr.3 (.6) (2) Sr 6 83.2 (68.8) (7) Sr 7a 9.2 (.8) 2 () Sr 7b 9.2 2 Sr 8 4. ( 3.2) (2) Sr 9a 74.3 (6.6) (4) sr 9b 74. (6.6) Sr 9d 7.2 (3.2) Sr 2. (32.) sr 2.2 (3.4) 7 () Sr 3 89.8 (96.8) 3 (7) sr 4. (.) () sr 79.4 (9.2) 6 (2) Sr 6 9. (.) 3 () Sr 7 87.7
I VOL. 2, N.4, CAN. PLANT DIS. SURV. DEC., 972 67 indicates a variety from the Durum Test. No new races were isolated from the susceptible gratefully acknowledged. Mr. J. H. Campbell was responsible for the technical aspects of pustules. the survey. Ac know ledg men ts Literature cited The valuable conibutions of cooperators. Watson, I. A. and N. H. Luig. 966. across Canada who cared or rust nurseries Srl--a new gene for use in the and sent rust samples for identification are classification of Puccinia raminis var. itici. Euphytica :239&