ESTIMATION OF LILIUM RESISTANCE AGAINST GREY MOLD (BOTRYTIS MICHELI ex FR.)

Transcription

1 AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy l. No. 7 LLU 2004 Geographic distribution and epidemiology of diseases and pests ESTIMATION OF LILIUM RESISTANCE AGAINST GREY MOLD (BOTRYTIS MICHELI ex FR.) * Antra Balode, Ina Belicka *Latvian University of Agriculture, Department of Horticulture, Liela 2, Jelgava, LV 3000, antra@ram.lv Abstract Grey mold, caused by fungus Botrytis Micheli ex Fr., is especially destructive to lilies (Lilium L.) in the second half of summer. It attacks the leaves, flower buds and flowers; in the result lilies loose their general attractiveness. In lily breeding the current activities are directed towards development of disease resistant cultivars to avoid the use of chemical plant protection, to make the growing economically sound and ecologically safe. Resistance to grey mold (Botrytis elliptica (Berk.) Cooke) in 7 species and 75 cultivars of lilies was tested visually on natural and artificial infection backgrounds according to method of S. Sidorova and V. Popov in grades 0 to 4 (0 healthy; 4 very heavy susceptible). The 10 lily plants selected from each spec ies and cultivars were estimated for their resistance to diseases and the average index of morbidity was caiculated. The obtained results show no differences when testing lilies for grey mold resistance under field conditions ( ) and utilizing leaf segments under laboratory conditions. Cultivars of different levels of resistance to diseases were included in our trial. Estimation of parent plants and the produced hybrids was done. The obtained hybrids were resistant to grey mold if parents crossings were resistant to this disease agent. When crossing cultivars susceptible to grey mold with cultivars resistant to this disease agent, the obtained hybrids were either intermediate by this trait or susceptibility to this disease was dominant. 10 perspective hybrids were tested under field conditions by resistance to grey mold ( ). No significant differences were found between the two years results. Key words: Botrytis, estimation, inoculation, fungi, lilies. lntroduction In moderate c1imate one of most widely spread diseases of lilies is grey mold, caused by fungus Botrytis spp. mold infects various vegetative organs Ieaves, flower buds, flowers, stems and seed pods of lilies. Various wild plants and cultivars infect about 50 spec ies of the genus Botrytis Micheli ex Fr. that differ by specialization of host plants. The most important are: c10ver flowers (B. anthophila Bond.) (Van der Plank, 1963), leaves and bulbs of tulips (B. tulipae (Lib.) Lind.) (Koster and Meer, 1993), gladioluses (B. cinerea Pers.) (Van den Ende, 1996). The grey mold is caused in lilies (Lilium L.) by two species of Botrytis: mainly B. elliptica (Berk.) Cooke and B. cinerea Pers (McRae, 1987; Lawson and Hsu, 1996), seldom B. tulipae (Lib.) Lind (Doss et ai., 1988; Van Aa.1rijk, 1996). The conidia spores germinate and enter leaves through the epidermal stomates. The first evidence of the disease appears as reddishbrown oval spots on the leaves. During wet weather the spots eventually coalesce and the whole leaf collapses and decays (McRae, 1987). The conidia of the genus Botrytis germinates on the plant only if there is sufficient moist environment with drops of water. Injury to the plants, especially frost or mechanical damage, will always make it easier for Botrytis spores to enter the leaf. The fungus formed on died tissue smaii, black sclerotia and over winter in soil (Lawson and Hsu, 1996). These sclerotia produce spores in the next vegetation season, which spread by the wind and are splashed by rain onto the new foliage. Even if fungus B. cinerea Pers. has a lot of food plants, it is possible to establish varieties and races that differ by morphological and biological traits (by form and measure of conidia spores, measure of sclerotia and its formation, virulence to individual food plants). It is observed that these parasites have biological specialization to substrates and biotopical diversity (Py.u.aKoB, 1959). The breeding of the fungus resistant varieties of lilies can help to solve the Botrytis problems. Resistant cultivars can play an important role in the control of this disease. Using resistant genotypes as parents give the highest chance of a resistant progeny. Chemical treatment is not always adequate and it pollutes the environment. In Latvia, lilies are mainly grown under field conditions and in nature flowers are pollinated by usefui insects: bees, bumblebees, nightmoths, ants, etc. The 'goal of research was to estimate resistance to grey mold in lilies originated from different countries and hybrids in field and laboratory trials for recommendations to variety resistance, to make hybrid selection and evaluation of the perspective hybrids in field trials. Up to now no research on distribution of grey mold and evaluation of resistance of lilies has been done, Materials and Methods In autumn 1996, a field trial was established in Saulkrasti of the Riga region. The soil was well cultivated, ph KCI 6,7, P 2 0 S 850 mg kg', K mg kg' (determined by EgnerRiehm), Ca 1388 mg kg', Mg 219 mg kg" (determined by photometry method), Organic matter content 4,6 g kg" (by Tyurin' s method), Between 1997 and 1998, 7 species of lilies, 75 different cultivars of lilies were evaluated for resistance to grey mold (B. elliptica (Berk,) Cooke). Initial material was obtained in the following way: a lily bulb was vegetatively propagated from bulb scales, and 10 bulbs of the same age (twoyear old) from each spec ies and cultivars, cm in diameter, were included in the trial. The seedbed was prepared in early September prior to planting of bulbs, The 25 varieties of parent plants varying in resistance to grey mold were included in 14 cross combinations. The 10 bulbs of 134

2 AGRONOMIJAS VESTIS (Latvian.Journal of Agronomy) No. 7 LLU 2004 Geographic distribution and epidemiology of diseases and pests each parent plant and hybrid bulbs were planted in l m wide beds; the planting depth was 10 cm, the distance between rows 20 cm. Two free rows separated parent plants from hybrid populations. Bulbs were grown in the same site for two years. The level of grey mold resistance of plants was rated visually on natural and artificial backgrounds according to method of S. Sidorova and V. Popov in grades 0 to 4: 0 healthy, resistant, free from any grey mold symptoms; 1 slightly susceptible, individual spots are detected on plant leaves, injury of leaves below 25%; 2 moderately susceptible, injury of1eaves below 50%; 3 heavy susceptible, leaf damage below 75%; 4 very heavy susceptible, leaf damage exceeds 75% or spots are spreading over the whole leaves. The 10 perspective lily hybrids selected from 14 cross combinations were estimated for resistance to grey mold under field conditions and the average index of morbidity was calculated ( ). No chemicals were used in the trial. The resistance test of lily varieties was determined using the artificial infection with application of conidia suspension of B. e/liptica. The segments of lily leaves grown in a glasshouse were used. Five leave segments from each variety were selected at random. Isolates of B. e/liplica was obtained from infected leaves of Asiatic lily variety ' Roma' collected from a field. The segments of lily leaves were put in Petri dishes on potatodextrose agar with spore suspension and kept for 48 h, at 22 C, with moisture present (Doss et ai., 1984). After this incubation, Petri dishes with segments of lily leaves were transferred to a growing chamber (12 h day, light 3000 Ix, 18 C, 70% moisture). Segments of lily leaves were examined 6 days after inoculation according to 04 grades: 0 healthy; 4 very heavy susceptible. The obtained data were analyzed by heterogeneous complex dispersion method; the hybrids produced were compared to parent plants using Fisher's criterion (F); phenotypic variabijity of the studied traits was characterized by the coefficient of variation (V %) according to method of 1. Guzov: < 10% low, % medium, > 20.1 % high. Meteorological conditions The April and May of 1997, 1999 and 2000 were mostly cold, with often frosts and heavy downpours. The development of lilies was slow. Fast development of lilies was observed in the third decade of May, when air temperature increased. The weather was warm in June with abundant rainfall, speeding up the development of lilies. July was hot, sunny and dry, which intluenced the development of lilies and did not promote Botrytis Micheli ex Fr. development. The April of 1998 was cold and c10udy with precipitation in the first half, and warm and sunny in the second phase, favouring fast development of lilies. The first two tenday periods in May were very warm and sunny, but the third tenday period in May and June was cold with abundant rainfall slowing down the development of lilies. Jul y was hot and sunny in the first tenday peri od, but in the second half of the month it was c10udy with much rainfall and cold nights. The parasitic fungus Botrytis damaged the leaves and tlowers of lilies. The trial years were characterized by contrasting meteorological conditions. Due to sunny and dry July, the years 1997 and 1999 were most favourable for lily breeding. More unfavourable weather conditions occurred in 1998 and 2000 when lily plants were frostdamaged (2000) and severely attacked by grey mold (1998). Results and Discussion Assessment of lily Botrvtis e/liptica (Berk.) Cooke resistance Resistance to grey mold (Botrytis e/liptica) in 7 spec ies and 75 cultivars of lilies included in the collection was tested on natural infection background during (Table 1). As healthy (grade 0) were assessed 23 (28%) plants of the collection, including 6 spec ies of lilies. 27 (33%) varieties were assessed as slightly susceptible (grade 1) to grey mold. Disease ratings in grades 0 and 1 were given to 24% of lily cultivars from Latvia, 10% from USA, 7% from Canada, and to 6%, 4% and 2% of cultivars coming from Holland, Russia and Germany, respectively. As moderately susceptible to grey mold (grade 2) were assessed 20 (24%) cultivars, including 9% of cultivars selected in Latvia, 9% in Holland, 5% in Russia, 1% in USA, and martagonlilies (L. martagon var. album West.). 9 (11 %) varieties were assessed as heavy susceptible (grade 3), including ' ČaČaČa ' developed in Latvia. As very heavy susceptible (grade 4) to grey mold were recognized 3 (4%) varieties of the collection. Disease ratings in grades 3 and 4 were given to 12% of lily cultivars from Holland, 1 % from both USA and Russia, respectively, and 1% from Latvia. The obtained results show no differences when testing lilies for Botrytis elliptica resistance under field conditions and utilizing leaf segments under laboratory conditions. Disease resistance test on leaf segment of lilies is recommended for assessment of the initial breeding material and hybrid material to obtain precise results in a comparatively short peri od of time. Results of resistance testing of different lily groups suggest that the level of infection in tested cultivars varied. The cultivars of Oriental lilies and Trumpet IiI ies were healthy (grade 0) and slightly susceptible (grade 1) to grey mold but in Asiatic lilies the infection level varied (grade 0 to 4). All species of lilies included in the trial were healthy, except Lilium martagon var. album West., which was moderately susceptible to grey mold (grade 2). Basing on the trial results, initial material was selected including varieties with different infection level (grade 0 to 3). 135

3 AGRONOMIJAS YĒSTIS (Latvian Journal of Agronomy) No. 7 LLU 2004 Gco!!raphic distribution and epidcl1liology of diseases and pests Results oftesting resistance against Botrytis elliptica in lilies on natural infection background (on average, ) Table I Levelof Lily species and varieties infection by Num Botrytis elliptica ber (grades 04) % Name 0 healthy ' Baltais Lacis', ' Eksotika', ' FlamingGiant', ' Herrold', ' Jumprava', 'Leslie Woodriff, ' My Joann', 'Olga', 'Orfejs', ' Red Carpet', 'Solstice', 'Teika', 'Tirrol', 'Pārgalvīgā', ' Višenka', ' White Henryi', 'Tetra Oriental' L. henryi Bak., L. henryi var. citrinum hort., L. monadelphum Bieb., L. kesselringianum Miscz., L. szovitsianum Fisch. et Ave Lall., L.martagon L. 'Alisa', 'Banga', 'Apricot Supreme', 'Compass', 'Connecticut King', 1slightly 'Gardenia', 'Gran Paradiso', ' Honey Pink', 'Liesma', 'Līksna', 'Marsha',,.,,., susceptible 27.J.J 'Marco Polo', 'Mona', 'Miss Alice ', ' Nākotne ', ' Otello', ' Paija', 'Patrīcija', 'Peachblush', 'Saule', ' Saules Meita', 'Skrīveri ', ' Veltījums', Venta', 'Tokyo', 'Zemgale', ' Yellow Blaze' 'Arabeska', 'Brushstroke', ' Corsica', ' Dzintars', ' Evrika', H792, 2 moderately 'Jolanda', ' Lastočka', ' Lolly', 'Nakts Tango', 'Nepal ', ' Magic Eye', susceptible 'Rotala', ' Rosita ', 'Sally Girl ', 'Saulstarīte', ' Shirley', ' Swing', ' Virineja', L.martagon var. album West. 'Aristo', ' Chinook', ' Č a ČaČa', ' Nočka', 'Moneymaker', 'Montreux', 3 heavy 9 11 ' Parisienne', ' Sirocco', Tirreno' susceptible 4 very heavy susceptible 3 4 'Monte Rosa', ' Mont Blanc', 'Roma' Total Assessment of hybrid resistance to grey mold CBotrvtis elliptica) Grey mold, caused by fungus Botrytis elliptica, tends to show up in lily plantings in the second half of summer. It attacks the leaves, flower buds and flowers at the result of which plants loose their general attractiveness. Making selections of disease resistant plants was one of the most significant aims of the breeding program. Cultivars with different levels of resistance to diseases were included in the trial. Assessment of parent plants and produced hybrids was done (Table 2). The result of a cross between resistant cultivars chosen as parents (K7, K13, K14), were hybrids resistant to this disease agent. The produced hybrids didn 't show significant differences compared to parent plants (F rakt < F O.05) ' However, in one case (K7) there was detected increased susceptibility to the disease (F rakt > F O. 05 ) suggesting that in chosen parents gene interaction was of specific character resulting in hybrids with partial immunity to grey mold. However, resistant initial material L. henryi var. citrinum hort. has contributed to the development of more resistant hybrids with perfectly healthy plants among them. This is in agreement with Iiterature findings on the use of this lily spec ies as a resistance donor in lily breeding (Kroell, 1991). The increase in susceptibility to grey mold was observed in reciprocal crossing between slightly susceptible cultivars (K8). Reciprocal crossing between moderately and moderately heavy susceptible cultivars (Kl, K2, K4, 3 rd group) produced hybrids which got infected by the fungus as heavy susceptible parents (Kl, K4), or by susceptibility to the disease the produced hybrids were in medium position between their parent plants (K2). In these cases, proportion of the effect of combinations accollnted for %. The major factor that caused variability was the environment. Parent plants contrasting in susceptibility to disease agent (4'h, 5'h groups) had greater effect on the degree of infection in hybrids. In crosses between resistant and slightly susceptible (K5, K1 2, KI 0) parents and vice versa (K9), the proportion of the effect of combinations accollnted for %. There exist significant differences (F rak, > F oo5 ) between the average indices of variants (PI, P 2, FI). In hybrids, susceptibility to grey mold was dominant (K5) or prevalent (K9, KIO, K12). 136

4 AGRONOMIJAS VESTIS (Latvian Journal of Agronomy) No. 7 LLU 2004 Geographic distribution and epidemiology of diseases and pests Estimation of hybrid resistance to grey mold (Botrytis e/liptica) Table 2 Level of infection in grades, on average Intluence of variants Level of significance Cross Parents (0 healthy; 11 2 % 4 very heavy susceptible) Parents Hybrids Group 1 (Healthy / healthy) K7 'Herrold' * F fakl = 4.32 > F O. 05 = ' Solstice' 0.2 K13 'Zemgale' F fa kl = 0.93 < F O.05 = ' White 0.2 Henryi ' K 14 ' Eksotika' 0.4 L. henryi F f.kl = 2.70 < F O.05 = var. citrinum hort. Group 2 (Slightly susceptible / slightly susceptible) K8 ' Compass' F f.k, = 2.0 < F O.05 = ' Gran 1.2 Paradiso' Group 3 (Moderately susceptible / heavy susceptible) KI ' Nakts F fakl = 0.48 < F O.05 = Tango' H K2 'Nakts * F fakl = 4.29 > F O.05 = Tango' 'Ca CaČa ' 2.7 K4 ' CaCaČa' F fakl = 2.94 < F O.05 = ' Sally Girl' 2.1 Group 4 (Healthv / slighth susceptible) and on the contrarv K5 ' Baltais * F fakl = > F O.05 = Lācis ' 'Shirley' 1.5 K \O ' Patncija' * F fa kl = lo.52 > Fo. 05 = ' Magic 1.7 Eye' K12 ' Olga' * F f.kl = 8.82 > F O.05 = , Arabeska' 1.4 K9 'Nepal' 1.6 l..) "* F fakl = 4.72 > F O.05 = ' Alisa' 0.7 Group 5 (Healthy / very heavy susceptible) and on the contrary KII ' Orfejs' * F fakl = > F O.05 = 'Aristo' 2.5 K3 ' CaCaČa ' * F fakl = > F O. 05 = ' My Joann' 0.5 K6 ' Tirreno' * F fakl = > F O.05 = ' Honey 0.2 Pink' * Di fference is signiticant at P 0.05' 137

5 AGRONOMIJAS VESTIS (Latvian Journal of Agronomy) No. 7 LLU 2004 Geographic distribution and epidemiology of diseases and pests The result of crossings between cultivars susceptible to this disease agent, such as 'ČaČaČa' (K3) and 'Tirreno' (K6) and resistant varieties ('My Joann', ' Honey Pink'), were the hybrids being an intermediate (K3) by this trait, or susceptibility was dominant (K6). In one case (K11 ), resistant to grey mold variety 'Orfejs' crossed with susceptible variety ' Aristo' resulted in resistant hybrids (grade 01). It suggests that, genetically, variety 'Orfejs' could be used in breeding for disease resistance. Significance of the obtained results is confirmed by the results of mathematical analysis (F rakt > F005); the noted influence of variants (1']2) is %. Within the hybrid populations, selection of resistant forms is possible in each individual combination thus promoting the development of immune cllltivars. The hybrids produced were estimated in 1998 too (Fig.). On average, the level of infection was somewhat increased due to the periods of excessive rainfall in July, thus contributing too rapid spread of infection. This disease was greatly favoured by the density of a twoyear o ld plantation. There exist c10se correlation between twoyear (1997, 1998) estimation results (r = 0.873, ro.05 = 0.532, ro.oi = 0.661) and between these results no significant differences have been found (F rakt = 3.76 < F005 = 3.86). The research reslllts indicate that the rejection of heavy sllsceptible genotypes collld be realized considering oneyear testing reslllts.... '" ~ '" "'0 E 3.5 ;.c "" c.;: 3.0 " :i 2.5 li Q. 0 0 E..:.:... >. r I(~ 2.0 r '<1 li.; Q. ~ \ : = I~ r I '~ la '" 1* 1'liIII1998. '"... ~ I ~ g,.c c 1.0 \:: ~. J I IA,... ļ t 1p Ht "~.~ '" 0.5 t. " m t;: c ~ '" li. ~ ~ <'..' 111mB co c 0.0 K I K2 K3 K4 K5 K6 K7 K8 K9 K K K K K 10 II Crosses Fig. The level ofinfection ofhybrids (in grades 04) with grey mold (Botrytis elliptica) in Evaluation ofperspective hybrids (in grades 04) to resistance to grey mold 10 perspective hybrids were selected from 14 crosses (Table 3). In both years high level of resistance was shown by the following hybrids: ' Resista 1', ' Arfa', ' Aurēlija ', ' Vārsma '. These hybrids come from crosses K7, KII, K13, K14 in which one or both parent plants were detected as healthy to disease ('Herrold ', 'Solstice', ' Orfejs', ' Eksotika', ' Zemgale', ' White Henryi ', L. henryi var. citrinum). From cross KII was selected hybrid 'Arfa' wh ich showed resistance. As father plant was lised variety ' Aristo' originating from Holland and showing very heavy sllsceptibility to grey mold, which agrees with data in literatllre on sllsceptibility of this variety (Ooss, 1986). From cross K2, hybrid 'Maksis' was selected and assessed as moderately susceptible. The mother plant 'Nakts Tango', included in this cross, was moderately sllsceptible to grey mold but father plant ' Ča ČaČa ' showed heavy susceptibility to grey mold. Reslllts demonstrated that no significant differences were follnd between twoyear estimations. Table 3 The level of infection of perspective hybrids (in grades 04) to resistance to grey mold (Botrylis elliptica) Level of infection Cross. Name of the hybrid Grades To control Grades To control Roma control K 2 Maksis K 5 Balta Brigantma K 6 Menarda K 7 Resista I K 8 Ka lsnava K 9 Šar/ote K lo MēnesnTcas Sonāte K II Arfa K 13 AlIre lij a K 14 Varsma 'y 0.05 = 0.43 'y 0.05 =

6 AGRONOMIJAS v8stis (Latvian Journal of Agronomy) No. 7 LLU 2004 Geographic distribution and epidemiology of diseases and pcsts The obtained hybrids were signitīcantly resistant to grey mold and considerably surpassed control variety 'Roma' in both years: 1999, Ffakl. = > F O.05 = 1.94; 2000, Ffak1 = > F O.05 = No signitīcant differences were found between twoyear results. Estimation of the lily coliection against grey mold in natural and artificial infection backgrounds did not show any significant differences in the obtained results. Resistance rating (grades 04) for grey mold was the foliowing: o healthy with no evidence of the disease, 28%; 1 slightly susceptible, 33%; 2 moderately susceptible, 24%; 3 heavy susceptible, 11 %; 4 very heavy susceptible, 4% of the tested coliectioll material. The foliowing local varieties were assessed as resistant to grey mold infection: 'Baltais Lācis', 'Jumprava', 'Orfejs', 'Teika', 'Venta', 'Eksotika', ' Pārgalvīgā'. The foliowing cultivars coming from Holland were rated as very heavy susceptible to infections: ' Monte Rose', 'Roma', and 'Mont Blanc'. These lily variet ies are not recommended for growing outdoors under conditions of Latvia. The resistance to grey mold characterized the obtained hybrids if parents were resistant to this disease agent. When crossing cultivars susceptible to grey mold with cultivars resistant to this disease agent, the obtained hybrids were intermediate by this trait or susceptibility to this disease was dominant. 10 perspective hybrids showed significant resistance to grey mold and considerably surpassed control variety ' Roma ' in both years of the trial. References 1. Doss, R. P., Chastagner, G., A., Riley, K. L Techniques for inoculum production and inoculation of lily leaves with Botrytis elliptica. Plant Disease, No. 68, Doss, R. P., Chastagner, G. A., Riley, K. L Screening ornamental lilies for resistance to Botrytis e/liptica. Scientia Horticulturae, No. 30, Doss, R. P., Chastagner, G. A., Riley, K. L Summary of Recent Research on Botrytis elliptica. The Lily Yearbook of the North American Lily Society, No. 41, Koster, A.Th.J., Meer, L.J Control of Botrytis ('Fire'). Annual Report. Bulb Research Centre. Lisse, The Neatherlands, Kroell, C The YelIow Henry. The Lily Yearbook of the North American Lily Society, No. 44, Lawson, R.H., Hsu, H.T Lily disease and their control. Acta Horticulturae, No. 414, McRae, E. A Lily disease handbook. The North American Lily Society. Canada, 28 pp. 8. Van Aartrijk, J Department of plant disease and crop protection. Annual Report. Bulb Research Centre. Lisse, The Netherlands, Van den Ende, J. E Towards optimal control of fire (Botrytis spp.) in flower bulbs. Annual Report. Bulb Research Centre. Lisse, The Netherlands, Van der Plank, J Plant diseases epidemics and control. New York and London. Academic Press, 221 pp. II. ry)j{ob, Oynl HCnOJlb30BaHlUI B CeJleKUHH pactehhh 3aKoHoMepHocTeH MO)1.H!ļ>HKaUHoHHoH H3MeH4HBOCTH KOJlH4eCTBeHHhlX nph3hakob. 113BecTHe AH CCCP: cephli 6HOJlOrHH, N 3, PY)1.aKOB, O EHOJlOrHlI H YCJlOBHlI napa3hth3ma rph60b po)1.a Botritis. <1>pYH3e, CHllopoBa, C. <1>., OonoB, B MeTollH4ecKHe YKa3aHHlI no H3Y4eHHIO BepTHUHJlJle3HOrO H!ļ>Y3apH03Horo YBlIllaHHlI OllHOJleTHHX CeJlbCKOX031IHCTBeHHblX pactehhh. 11eHHHrpall, BcecolO3HblH HaY'lHo HCCJlellOBaTeJlhCKHH HHCTHTYT 3all.lHTbl pactehhh, 27 c. 139,