AGRONOMJAS VESTS (Latvian Jurnal f Agrnmy) NO. 7 LLU 04 NCDENCE AND SEVERTY OF LEAF SPOTTNG DSEASES OF WNTER WHEAT N LTHUANA Rma Semaskiene, Antanas Rnis Department f Plant Pathlgy and Prtectin, Lithuanian nstitute f Agriculture, nstitut at. 1, LT 58344, Akademija, Kedainiai d., Lithuania, email: rma@lzi.lt Abstract Residuebrne pathgens that cause leaf sptting diseases f wheat have becme increasingly imprtant in Lithuania because mre grwers are adpting reduced tillage, which leaves crp residue n the sil surface cmpared with cnventinal tillage. The bjective f this study was t investigate differences in susceptibility t leaf infectin by Drechslera triticirepentis and septria leaf spt cmplex (Septria tritici and Stagnspra ndrum) amng sme f the currently registered winter wheat cultivars. We als examined the influence f primary field infectin n the develpment f leaf sptting diseases during the whle grwing seasn. The experiments were cnducted during the tw grwing seasns (0203 and 0304) at the Lithuanian nstitute f Agriculture in Dtnuva, Kedainiai district. Three winter wheat cultivars Arn, Hereward and Tauras were swn. The field trials were made n tw backgrunds: sil surface was cvered with naturally infected straw in autumn and natural field infectin withut straw. Observatins f disease severity were made apprximately every 7 days n each plt starting at the beginning f stem elngatin and cntinuing thrugh the late milk stage. Results shwed that the mst cmmn disease in winter wheat during the grwing seasns 0203 and 03 04 in ur experiment was tan spt. Septria leaf spt cmplex was less prevalent. At the beginning f stem elngatin in inculated with straw and in naturally infected plts the severity f tan spt was similar fr all cultivars. Until winter wheat flwering stage, n significant differences between the severity f tan spt in inculated and naturally infested wheat were fund in bth years. At late grwth stages straw n sil surface had a significant effect n tan spt severity increase. The reactin f test cultivars t leaf sptting disease was different and depended n grwing cnditins (with r withut straw) and grwing seasn. Key wrds: winter wheat, tan spt, septria leaf spt cmplex, disease severity. ntrductin \ Residuebrne pathgens that cause leaf sptting diseases f wheat have becme increasingly imprtant in Lithuania because mre grwers are adpting reduced tillage, which leaves crp residue n the sil surface cmpared with cnventinal tillage. The pathgens which cause leafsptting disease n wheat include Pyrenphra triticirepentis (Died.) Drechs. (anamrph Drechslera triticirepentis (Died.) Shemaker) which causes tan spt, and the septria leaf spt cmplex, which includes Phaesphaeria ndrum (E. MUlier) Hedjarude (syn. Leptsphaeria ndrum E. MUller, anamrph Stagnspra ndrum ([Berk.] Berk. in Berk. and Brme) and Mycsphaerella graminicla (FUckel) Schreter (anamrph Septria tritici Rb. ex Desm.). Airbrne ascspres discharged frm mature pseudthecia serve as an effective surce f primary inculum fr S tritici and. S ndrum. Hwever, there are many instances where the sexual stage was nt fund and it is, therefre, assumed that infected wheat debris and rain splashed pycnidispras serve as a primary surce f inculum (Eyal, 1999). nvestigatins n epidemilgy f tan spt indicate that the main surce f primary infectin is ascspres prduced in pseudthecia develping n dead leaves, leaf sheaths and culms (Maraite et at., 1992; Zamrski and Schllenberg, 1994). Currently D. tritici repentis is ne f the mst imprtant wheat leaves sptting pathgens in many Eurpean cuntries (Bankina, 02; Gustssn and Berg, 03 ; Jrgensen and Jensen, 03; Sarva et a., 02; Zamrski and Schllenberg, 1994) and in Lithuania t. Tan spt as winter wheat disease was first reprted in Lithuania in 1995. The bjective f this study was t investigate differences in susceptibility t leaf infectin by D. triticirepentis and septria leaf spt cmplex (S tritici and S ndrum) amng sme f the currently registered winter wheat cultivars. We als examined the influence f primary field infectin n the develpment f leaf sptting diseases during the whle grwing seasn. Materials and Methds The investigatins were cnducted during the tw grwing seasns (02 03 and 0304) at the Lithuanian nstitute f Agriculture in Dtnuva, Kedainiai district. Three winter wheat cultivars Arn, Hereward and Tauras were swn. A plt size f 300 m 2 was inculated fr each cultivar. A surce f inculum was prvided by wheat straw, spread ver plants in late autumn. Straw was cllected after harvest frm the winter wheat field. t was naturally infested with D. triticirepentis and ther residue brne pathgens and stred under natural cnditins. At 0 m distance frm the inculated plt we marked plts fr leaf sptting disease assessments.in winter wheat grwn n natural field infectin backgrund. The develpment f diseases was mnitred by sampling fur replicatins f 15 plants per plts. Randm tillers were selected and the tp three leaves were scred fr disease severity by using th e 00% scale (Guidelines..., 1999). Observatins f disease severity were made apprximately every 7 days n each plt starting at the beginning f stem elngatin and cntinuing thrugh the late milk stage. Grwth stage was recrded when disease severity was assessed (Meier, 1997). Temperature, relative humidity (RH) and rainfall were recrded frm May t July. The data were analysed by Duncan's multiple range test and significance is reprted at P < 0.05. 98
AGRONOMJAS VESTS (Latvian Jurnal f Agrnmy) NO. 7 LLU 04 Results and Discussin n Dtnuva, the winter wheat grwing seasn was little drier in 03 than in 04. The ttal rainfall frm 1 51 May befre last assessment in July in 03 was 5 mm, in 04 122 mm. Frequent rainfall, higher relative humidity in July resulted in mre severe infectin f leaf sptting diseases in 04. Results shwed that the mst cmmn disease in winter wheat during the grwing seasns 0203 and 03 04 in ur experiment was tan spt (P. triticirepentis) (Table 1). Septria leaf spt cmplex was less prevalent. Table 1 Leaf sptting disease severity n flag leaf at late milk develpment in different cultivars f winter wheat in Dtnuva, 0304 Cultivar 03 04 Tan spt Septria leaf spt cmplex Tan spt Septria leaf spt cmplex Natural field infectin Arn 12.42a* 0.08 9.75a 14.55c Hereward 13.67a 0 19.58b Oa Tauras 11.58a 0 8.77a 3.40b Sil surface inculated with straw Arn 25.17c 0.13 7.75a 0 Hereward 14.08b 0 65.00c 0 Tauras 7.a 0 59.58c 0 * d nt differ (P = 0.05) by the same letter accrding t Duncan' s multiple range test. At the beginning f stem elngatin, the severity f tan spt was similar fr all cultivars in inculated with straw and in naturally infected plts (Figures 1 3). Until winter wheat flwering stage, n significant differences between severity f tan spt in inculated and naturally infested wheat were fund in bth years. Tan spt severity in 03 began t increase at the beginning f ripening (BBCH 71 milk ripening). Mre intensive develpment f tan spt in inculated plts in 03 was recrded in cvs. Hereward and Arn cmpared with naturally infected wheat. n the middle f milk develpment, the severity ftan spt in the tw cultivars in inculated with straw plts was significantly higher than that in naturally infected plts. n cv. Tauras, significant differences between tan spt severity in inculated and natural infected plts were nt fund. When the weather cnditins were mre cnducive t tan spt develpment (in 04) the disease severity began t increase at heading. An increase in tan spt severity was fund in bth inculated and nt inculated plts. n winter wheat cv. Arn, develpment f tan spt was n a similar level in inculated with straw and naturally infected plts. Significant differences were nt fund. 99
AGRONOMJAS VESTS (Latvian Jurnal f Agrnmy) NO.7 LLU 04 03 ;:J? 'E 40 > 30 if) Date BBCH 0 / A.... A. 1405 22 05 2905 06 16 06 30 06 07 07 14 07 31 32 33 41 55 69 71 73 75 04 40.;:: 30 r/) Date BSCH A........... ::y. 04 05 11 05 18 05 25 05 0 06 08 06 18 06 22 06 30 06 06 07 13 07 07 31 32 37 37 39 47 59 65 69 73 75 77 41 61. nculated with straw... Natural field infectin Fig. 1. Tan spt (Drechslera triticirepentis) prgress curves f winter wheat cv. Arn in Dtnuva, 03 04 n winter wheat cvs. Hereward and Tauras, tan spt develped mre intensively in inculated with straw plts. An extremely severe attack f this disease was recrded at milk grwth stage. Our experimental results shwed that the mst rapid develpment f tan spt in bth years was at late grwth stages fr all cultivars. We can assume that the severe attack depended nt nly n the level f primary infectin and gentype, but als n the age f plants, t, because lder leaves have been fund t be mre susceptible t tan spt than yunger leaves (Cx and Hsfrd, 1987). Tan spt severity in cvs. Hereward and Arn at the end f milk develpment was significantly higher in inculated with straw plts cmpared with the plt withut inculatin. Sme authrs have reprted that retentin f wheat residue n the sil surface generally results in increased tan spt severity, while the incrpratin f wheat debris reduces severity (Bckus and Claassen, 1992; Stver et a., 1996; Duveiler et a., 02). 0
AGRONOM.JAS VESTS (Latvian Jurnal f Agrnmy) NO.7 LLU 04 03,. l C 40. 30 V) l i...! Date 14 05 22 05 29 05 06 06 12 06 06 30 06 07 07 14 07 BBCH 31 3132 32 37 47 65 71 73 75 F C 40.;: > 30 V) 04,! /! /! i r!.:! A.. * _..L, 0 04 05 11 05 18 05 25 05 01 06 08 06 18 06 22 06 30 06 06 07 13 07 07 Date 31 32 32 37 41 47 59 65 69 73 75 77 BBCH 61 71 + nculated with straw A Natural field infectin Fig. 2. Tan spt (Drechslera triticirepentis) prgress curves f winter wheat Hereward in Dtnuva, 0304 n ur study we fund that nt nly straw residues but als the gentype had significant effect n tan spt severity increase. The susceptibility t tan spt at a late milk grwth stage f test winter wheat cultivars is presented in Table 1. The leaf area affected by tan spt and septria leaf spt cmplex at this grwth stage was estimated n flag leaves because lwer leaves had died. Under less favurable weather cnditins fr leaf sptting develpment in 03, tan spt severity in naturally infected plts was n the same level. Any significant differences were nt fund. n inculated with straw plts the highest severity at milk develpment was fr cv. Arn. This cultivar was significantly mre susceptible than ther test cultivars. Cv. Tauras was significantly less susceptible t tan spt cmpared with cvs. Arn and Hereward. n 04, when mre favurable weather cnditins fr leaf sptting diseases prevailed, significantly highest susceptibility t tan spt was exhibited by cv. Hereward in naturally infected plts. When sil surface was inculated with straw, in 04 significantly lesser tan spt severity was fr cv. Arn. Susceptibly f cvs. Arn and Tauras t tan spt was fund t differ between the years. This suggests that different race f tan spt might have prevailed in 03 and 04. Eight races have been identified in the fungal ppulatin based n their ability t prduce necrsis and chlrsis symptms n apprpriate wheat differentials (Ali and Francl, 02). Unfrtunately, race ppulatins in Lithuania have nt been identified yet. 1
AGRONOMJAS VESTS (Latvian Jurnal f Agrnmy) NO.7 LLU 04 03 " 40.;:: <U 30 C) Date 140531 25 290532 06 1647066530067773140775 BBCH 3132 3739 04 Date BBCH O 7 / 7 ]................:... T 04 05 05 18 05 25 05 0 06 08 06 18 06 22 06 30 06 06 07 13 07 07 31 32 32 3739 41 47 5961 65 6971 73 75 77 +nculated with straw.t Natural field infectin Fig. 3. Tan spt (Drechslera triticirepentis) prgress curves f winter wheat Tauras in Dtnuva, 0304 The results presented in this paper highlight the imprtance f primary infectin f sil surface n tan spt develpment during the grwth seasns and gentype respnse t pathgens in different envirnmental cnditins. The cnclusins and assumptins made in this study prvide a base fr further research. References 1. Ali, S., Franci, L.J. 02. Aggressiveness variatin within race and 2 islates f Pyrenphra triticirepentis. 4th nternatinal Wheat Tan Spt and spt Bltch Wrkshp, p. 5. 2. Bankina, B. 02. Tan spt develpment peculiarities in Latvia. Plant Prtectin Science, vl. 2, 381383. 3. Bckus, W. W., Claassen, M. M. 1992. Effect f crp rtatin and residue management practices n severity f tan spt f winter wheat. Plant disease, vl. 76, 633636. 4. Cx, D. J., Hsfrd, R. M. 1987. Resistant winter wheats cmpared at differing grwth stages and leaf psitin fr tan spt secerity. Plant diseases, vl. 71, 883886. 5. Duveiller, E., Garcia, A, Fisher, R. A, Budhathki, C. 02. Effect f crp rtatin and residue management n tan spt in the sub humid trpical highlands. 4th nternatinal Wheat Tan Spt and spt Bltch Wrkshp, p. 12. 6. Eyal, Z. 1999. Septria and Stagsnspra Diseases f Cereals: A Cmparative Perspective. n: Septria and Stagnspra Diseases f Cereals, 125. 7. Jrgensen, L. N., Jensen, K. F. 03. Hvedebladplet Resultater med fungicidbekremppelse i Danmark. DJF Rapprt nr 89, 329336. 8. Guidelines fr the efficacy evaluatin f plant prtectin prducts. 1997. PP126(3) Fliar diseases n cereals. Vl., 187195. 9. Gustssn, G., Berg, G. 03. Vetets bladtlacksjuka (DTR) erfarenheter fran Sverige. DJF Rapprt nr 89, 337346.. Maraite, H., Berny, J.F., Gffin, A 1992. Epidemilgy f tan spt in Belgium. Advantages in tan spt research. Prceeding f the Secnd nternatinal Tan Spt Wrkshp, 7379. 11. Meier, U. (ed.) 1997. Grwth Stages f Mn and Dictylednus Plants. BBCHMngraph, 5 17, 569572. 12. Sarva, J., Hanzalva, A, Barts, P. 02. Pyrenphra tritici repentis ne f the mst imprtant leaf spt pathgens in the Czech Republic. 4th nternatinal Wheat Tan Spt and spt Bltch Wrkshp, p. 26. 13. Stwer, R. W., Franci, L. 1., Jrdahl, J. G. 1996. Tillage and fungicide management f fliar diseases in a spring wheat mnculture. J. Prductin Agriculture, vl. 9,261265. 14. Zamrski, Cz., Schllenberger, M. 1994. The ccurrence f tan spt n wheat and triticale in Pland. Genetic Plish, ser. B, vl. 35,375378. 2