Evaluation of resistance of Phytophthora spp. And Rhizoctonia solani in stone fruit rootstocks

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1 Evaluation of resistance of Phytophthora spp. And Rhizoctonia solani in stone fruit rootstocks Stylianides D.K., Chitzanidis A., Theochari I. GREMPA, colloque 198 Paris : CIHEAM Options Méditerranéennes : Série Etudes; n. 198I 198 pages 778 Article available on line / Article disponible en ligne à l adresse : To cite this article / Pour citer cet article Stylianides D.K., Chitzanidis A., Theochari I. Evaluation of resistance of Phytophthora spp. And Rhizoctonia solani in stone fruit rootstocks. GREMPA, colloque 198. Paris : CIHEAM, 198. p (Options Méditerranéennes : Série Etudes; n. 198I)

2 7 Evaluation of resistance to Phytophthora spp. andrhizoctoniasolani I instone fruitrootstocks D. C. STYLIANIDES' A. CHITZANIDISz I. THEOCHARIATHANASS10U l Pomology Institute, Naoussa 2 Benaki Phitopathological Institute, Kifissia, Athens Plant Protection Institute, Patras (Greece) words : Phytophthora. Rhizoctonia. Susceptibiiity. Almond. Almond X peach hybrid Plum. RESUME EVALUATION DE LA RESISTANCE DE PO,RTEGREFFES DE FRUITS A NOYAU A PHYTOPHTHORA SPP. ET.RHIZOCTONIA SOLANI Le niveau de resistance des portegreffes de fruits à noyau au Phytophthora a été évalué sur de jeunes arbres inocul6s artificiellement en verger. Les amandiers et Pêcher X Amandier sont très sensibles à Phytophthora syringae et P. citrophtora. Les Pêchers sont moins sensibles que les Amandiers à P. syringae et moyennement sensibles à P. citrophtora.'le, Prunier Marianna est assez r6sistant à P. citrophtora. P. cactorum est moins pathogène que P. syringae et P. citrophtora. P. citrophtora et P. cactorum s'attaquent aux arbres fruitiers à noyau au printemps et en automme. Une resistance differentielle à Rhizoctonia solani a été observée sur des portegreffes d'amandiers dans une phpinière... ABSTRACT The relative resistance of stone fruit rootstocks to Phytophthora collar w,as rot tested on young artificially in the field. Almonds and almond X peach hybrids were very susceptible to Phytophthora syringae and P. citrophthora. es were less susceptible than almonds P. to syringae and showed a medium susceptibility to P. citrophthora. The plum Marianna was somehow resistant to P. citrophthora. P. cactorum was less pathogenic than P. syringae and P. citrophthora. P. citrophthora and P. cactorum infected stone fruit in spring and autumn. Differential resistance Rhizoctonia solani was observed in almond rootstocks'in a nursery. tamz p/l

3 7L INTRODUCTION seedlings were very susceptible to P. syringae and P. citrophthora (Tables 1, 2, and 4) and less so to P. Collar rot of stone frui caused by Phytophthora cactorum (Table 4). The seedlings of the crossing Marspp. a common disease in Greece (, ). Several cona X Pangrati showed a medium susceptibility to P. species of Phytophtora have been isolated from insyringae and P. citrophthora (Tables 1 and ) whereas fected (4). The most common ones are P. sythe seedlings 9/1/77 and 10/9/77 showed an increasringae and P. citrophthora and to a lesser extent P. caced resistance to P. syringae (Table ). These two seedtorurn. Trees attacked by P. syringae show the symplings come from open pollination of the hybrid Martoms of the disease in late winter or early spring, while cona X Pangrati. It should be noted, however, that this those attacked by P. citrophthora and P. cactorurn exresistance might be due to the growth conditions of hibit symptoms on the hot summer months (2). In a the at inoculation time; it has been proved, that field experiment it was shown, that differential suscepthe resistance of to P. syringae increases after tibility to P. syringae does exist among stone fruit dormancy (6). Although the appeared as dormant species (). This observation was the starting point for at the time of inoculation, further tests are necessary the testing of stone fruit rootstocks to Phytophthora to make sure, that their resistance is intrinsic. collar rot. At the Pomology Institute Naoussa a research program is being carried out on the selection seedlings were less susceptible than almonds to and creation management of stone fruit rootstocks ap P. syringae (Tables 1 and ). This is an agreement with propriate for the greek conditions. This paper presents the results of experiments conducted over a four year the results of Kouyeas (). Siberian C (Table ) was an exception showing a high degree of susceptibility. period to investigate the relative resistance of This can be attributed to the fact that Siberian C, berootstocks produced in this program to infections by ing a slow growing tree, had a very thin trunk com Phytophthora spp. In addition some observations on pared to the other seedlings and thus it was completely the relative resistance of almond seedlings to Rhizoc girdled by the pathogen and finally died by the time tonia solani are included. records were taken. Compared to P. syringae the other Phytophthora spp. were less pathogenic to peach MATERIAL AND METHODS seedlings (Table ). The experiments were carried out at the experimental fields of the Pomology Institute Naoussa (nothern Greece), at the Benaki Phytopathological Institute in Athens and at the Plant Protection Institute Patras (Peloponnesus). The were two to three years old and planted in the field. All the inoculations were made on 'the trunk 101 cm above soil level. The Phytophthora isolates were obtained from naturally infected in the orchard. The inoculum, consisting of a mm in diameter disc from a five days old culture of the fungi on cornmeal agar was inserted under the bark of the. The wound was covered with vaseline and bound with adhesive tape. Inoculations with P. syringae were done in late winter when were still dormant. Those with P. citrophthora and P. cactorurn were made in spring and autumn. For rating the severiof the disease Fitzpatrik's et al (1) arbitrary scale was adapted as follows: not infected were graded as O; with lesions less than cm in length as 1; with lesions 8 cm in length as 2; with lesions over 8 cm in length as ; killed as 4. The final rating of the disease was obtained as a percentage of the highest sum had all the been killed. Observations on the differential resistance of almond seedlings to Rhizoctonia solani were made on naturally infected in a nursery at the Pomology Institute Naoussa. RESULTS. AND DISCUSSION The results of the inoculation tests are summarised in Tables 16. It can be seen, that most of the almond Almond X peach hybrids were very susceptible both to P. syringae and to P. citrophthora (Table 6). It seems that the susceptibility of almond parents is transmitted to their progenies. The rootstock GF 677 was less susceptible than other hybrids tested. Nevertheless, collar rot is common on GF 677 in the field. This rootstock because of its cultural suitability has replaced in northern Greece the more resistant wild peach seedlings and this resulted in a serious Phytophthora collar rot problem. Nemagard X Italian 2 was also less susceptible than the other rootstocks. This hybrid is resistant to mematods. The plum Marianna was relatively resistant to P. citrophthora in spring and in autumn inoculations (Table The capability of P. citrophthora and P. cactorurn to infect in spring and autumn was also noticed on almonds and peaches (Tables 4, and 6). This result should be taken into account when Bordeaux paste is applied on the trunk of the to prevent Phytophthora infections (2). In Table 7 it can be seen that large differences existed in the behaviour of almond seedlings to infections by Rhizoctonia solani. The peach Nemaguard seemed to be immune as it was not infected. The hybrid Marcona X Pangrati showed a relatively high resistance. It must be added, that in an orchard with heavy soil, where several almond hybrids were grown for eight years, 6.8% of the Marcona X Pangrati hybrids died, while the death rate of the other hybrids was much higher (Retsou X Ferragnes70 %, Retsou X Phyllis42 %, Fer YI

4 7 ragnes X Phyllis. %). It is not known if the death of the was due to attacks by Phytophthora spp. or other causes. This resistance of the Marcona X Pangrati hybrid in addition to its other characteristics (uniformity, drought resistance, adaptability to heavy soils) qualify it as promising rootstock for almonds. According to Ch. Gasselly (personal communication), that can withstand heavy soils are also resitant to Phytophthora collar rot. The most effective measure to control Phytophthora collar rot is the use of resistant rootstocks. None of the stone fruit rootstocks tested in this work were resistant to Phytophthora artificial inoculations. Nevertheless, it is important to know the degree of susceptibility of a given rootstock in order to apply the appropriate control measures. Evaluation of disease resistance of rootstocks by artificial inoculation of young is not enough. This is a method for an initial screening of rootstock material. The resistance will be assessed after growing the for several years in the field.: i Table 9 Evaluation of almond and peach seedlings with respect to their susceptibility to Phytophthora syringae. Trees were artificially on Feb. 2, Records were taken on July 20, 1981 Almond seedlings seedlings Ferragnes, open pollination Pangrati X Marcona Xirolimni X Italian 79 Italian X Xirolimni 8 78 Marcona, open pollination 2 7 Ferrgagnes X Retsou Marcona X Pangrati 0 62 Marcona X 67" 7 2 Wild GF 0 ID 2b S 7 Wild MG Nemaguard a O=all uninfected, l00=all killed (details are given in Materials and Methods). seedlings selected from local population of wild. c greek._ Table 2 Evaluation of stone fruit seedlings with respect to their susceptibility to Phytophthora citrophthora. Trees were artificially Almonds Seedlings Retsou X Ferragnes' Ferragnes X Retsou Ferragnes X AI X Italian Marcona, open pollination Marcona X Pangrati Retsou, open pollination ID 2b Wild MG Wild MZ Number of on 14.1V on 7.V.82 9 'I O a O =all uninfected, 100= all killed (details are given in Materials and Methods).. seedlings selected from local population of wild. " greek hybrid

5 76 Table Evaluation of stone fruit seedlings with respect to their susceptibility to Phytophthora citrophthora. Trees were artificially Almonds Seedlings Retsou X Ferragnqs Retsou X Ardechoise Ardechoise, open ppllination Xirolimni X Italian Retsou, open pollination Xirolirnni X Retsou ID 20b Nr of on.v.8 ratinga on 2.V S? 8 1 O a Ozal1 uninfected, 100=all killed (details are given in Materials and Methods). seedlings selected from local populgtion of wild. Table 4 Evaluation of almond seedlings with respect to their susceptibility to Phytophthora spp. Trees were artificially in spring and autumn Almond seedlings Retsou X Ferragnes April, 1984' P. citrophthora P. cactorum Inoculation date Retsou X Ardechoise 1 O0 60 Retosu, open pollination Xirolimni X Retsou 1 6 O a Records taken on June 6, Records taken on Dec., c O=all uninfected, 100=all killed (details are given in Materials and Methods). P. citrophthora \umber of October 2, lwb P. cactorum \lumber of tress

6 L.,.. Table c 77 Evaluation of stone fruit rootstocks with respect to their susceptibility to Phytophthora spp. Rootstocks were artificially at different dates P. syringae P. cifrophfhora P. cacrorwn P. cfrrophrhorn P. cacrorurn, 1.'' :,.%.:.c ~ n]umb+ji ofi?'".~,. 1.. >*P! i&ù6bf.of % Rootstock$ Diseere Uisease.... trw.. tries.. yes ' rating. ratillga Inoculated.' o'n 1l.V.84 on.íf1.84 on.v1.84 on on on on..v.84 on 20.1X.M on 2O.IX.M. es......_..i..~..~. _.. _.._I on ll.v.84.., ~, Nemaguard 21 T4, Siberain C... 8 r1 O Rutgers Leaf Db ID ID 0.l2 6 1, ID 9 8 ID ID Almonds 9177~ /9/77" 1 28 L _.. Plum Mariana Almond X GF a O= all uninfected, 100=all killed (details are given in Materials and ID = seedling selected from local population of wild. open c Marcona X Pangrati, Methodsl.._ Table 6 Evaluation of almond X peach hybrid rootstocks with respect to their susceptibility to Trees were artificially Phytophthora spp. Rootstocks (cuttings) Nr. of on P. s yringae P. citrophthora on Nr. of on 20.1X.84 ratinga on 2.V.8 'j AN^ AN AN l O0 AN 1 1 ', :c AN AN AN : :i.,. AN.... ' ' 7 Italian X Nemaguard 1 8.,m92 Italian X Nemaguard 2,: 2 7 GF ',',..i a1nqc:. a O = all uninfected, 100= ill killed' (details are 'given in Materiàls and;méthods). ban = almond X peach hybrid%öm crossing,n6i$%@ijf% S ,..>... ',< :.

7 I.., Table 7, I, \.. \ Behaviour of young stone fruit seedlings to natural infection by Rhizoctonia solani in the nursery Seedlings t Total * number of Dead of dead.. Almond. I Pangrati X Marcona Ferragnes X Phyllis Marcona, open pollination Marcona X Pangrati Troito, self pollination Ferragnes X Retsou Retsou X Ferragnes Retsou X Phyllis 441 1/68" X Retsou A. Webbii open pollination A. Webbii 4, open pollination A. Webbii 1, open pollination A. Webbii 2, open pollination Retsou X 44 /68* r " 1.. 8, S.! ? 26 ' 17 i: , 20t. i i ' ' ' Nemaguard 1 0 O O * Crossing X....i.... BIBLIOGRAPHY.~.. 1. FITZPATRICK, R.E., MELLOR, F.C. and WELSH, M.F Crown rot of apple in British Columbia. Rootstock and. '. scion resistance trials. Scient. Agr., 24 : KOUYEA, HEBE Stone fruit apoplexy caused by Phytophthora collar rot. EPPO Bull. 7: KOUYEAS, HEBE On the apoplexy of stone fruit caused by Phytophthora spp. Annls Inst. phytopath. kenaki, N.S. 10 : l 4. KOUYEA, HEBE and CHITZANIDIS; ANNA Host list of Phytophthora spp. ideqtified in Greece. Phytophthdra Newslet: ter, No 6 ;. SAREJANNI, J.A. 19. L'apoplexie des arbres fruitiers des environs d'athènes. Annls Inst. phytopath. Benaki, : SEWELL, G.W.F. and WILSON, J.F Death of maiden apbie tree$.caused by Ph,ytophthora syringae and a bompari. son of the pathogen with P. cactorum. Annsl appl..biol., : 27280,,,, I,