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Resistance of Rootstocks to Phytophthoracitrophthora During Winter Dormancy

0. TUZCU, Associate Professor, Department of Horticulture, University of Qukurova; A. QINAR, Professor, Department of Protection, University of Qukurova; M. 0. GOKSEDEF, Research Plant Pathologist, Regional Plant Protection Institute; M. OZSAN, Professor, Department of Horticulture, University of Qukurova; and M. Bii•iC, Teaching Research Assistant, Department of Plant Protection, University of Qukurova, Adana, Turkey Use of resistant rootstocks has ABSTRACT provided partial success in preventing Tuzcu, 0., Qlnar, A., Gbksedef, M. 0., Ozsan, M., and Bicici, M. 1984. Resistance of citrus gummosis in Turkey. , although rootstocks to citrophthoraduring winter dormancy. Plant Disease 68:502-505. grafted on resistant sour stocks, show high incidence of infection in the Resistance of 70 citrus genera, species, and to Phytophthora citrophthora was eastern Mediterranean area. This paper investigated during winter dormancy. Aeglopsis chevalieri; Citrus yatsushiro; C. sulcata; C. reports a study of the relative resistance aurantium 'Alibert'and 'Granito'; C. reshni'Kibris';Poncirus trifoliata'Yerli,'"Jacobson,'"SEAB,' of various citrus rootstocks to root rot 'Luisi,'" Rubidoux,' 'Benecke,' 'Rich,' 'Ferme Blanche,' 'Troyer' , and C. ampullaceae were and canker caused by P. citrophihor found to be very resistant. Citrus celebica; C. aurantium 'Cardosi,' 'Santucci,' and 'Curagao'; C. pennivesiculata'CRC'; C. depressa 'CRC'; Carrizo citrange, C. trifoliata 'Menager'; C. wilsonii; and C. webberi 'SRA' were resistant. C. keraji; C. nobilis; C. aurantium 'Azaguie'; C. trifoliata MATERIALS AND METHODS 'Christian,' 'Town,' and 'Yamagushi'; C. assamensis;and C. were very susceptible. C. Two-year-old seedlings of 70 varieties aurantium 'Yerli' showed medium resistance and 'Okan' was susceptible. Among the citrus and selections of citrus and related genera rootstocks used widely, C. taiwanica, C. macrophylla, C. aurantium 'Brazilian,' and C.junos were were used. These were obtained from ranked as susceptible to P. citrophthora. various research institutes in the United States, France, Cyprus, and Turkey and are listed in Table 1. There is a great potential for citrus Mexican , , and Inoculum was prepared as follows: P. culture in Turkey, where the citrus were intermediate (1,3,6,10,11,17,20). citrophthora was grown on 2% potato- industry has been developing rapidly. Rough , lime, all dextrose agar at 26 C for 7 days, anddisks Eighty-seven percent of the total citrus, except Carrizo and Troyer, 6, 8, and 10 mm in diameter were cut and and 93% of the lemons are produced near Madame Vinous orange, , transferred into 250-ml flasks containing the Mediterranean Coast. Although the and lemons were susceptible (6,7,10, sterilized distilled water. After being eastern Mediterranean area provides the 18,22,26). incubated for 24 hr at 18 C, the disks were most suitable growing conditions for lemon trees, its culture has been threatened by Phytophthora.It has been Table 1. The resistance of various varieties and selections of Citrus and related genera to Phytophthora reported that 7.8% of lemon trees had citrophthora trunk infections and 65% of the citrus Mean orchard soils were contaminated by Contributing lesion Phytophthora in Turkey (10,15). P. Botanical name Common name instituteY Origin indexz citrophthora(Sm. & Sm.) Leon., which Aeglopsis chevalieri Swing. IFAS Florida 0.00 a incites gummosis or foot rot, is widely Citropsisgilletiana Swing. IFAS Florida 0.00 a distributed in Mediterranean citrus areas & M. Kell. (27). It was found that 24.0% of the citrus Citrusyatsushiro ATAE Japan 0.00 a ( Hort. ex Tan. trees is Igel, and 22.4% in Adana C. sulcata Tak. ATAE Japan 0.00a provinces, based on fruit infection, were C.aurantium L.'Alibert' Sour orange SRA Tunisia 0.00 a contaminated by P. citrophthora(12). C. cxreshni Tan. Hort.'Kibris' Cyprusmandarin Cleopatra Giizelyurt Cyprus 0.00 a Use of resistant rootstocks offers an Poncirus trifoliata (L.) QUZF CRC 0.00 a excellent means of reducing the damage Raf. 'Yerli' caused by P. citrophthora. Resistant P. trifoliata 'Jacobson' Trifoliate orange SRA CRC 0.00 a citrus species and varieties have been P. trifoliata'SEAB' Trifoliate orange SRA Algeria 0.00 a reported from many parts of the world. P. trifotiata 'Luisi' Trifoliate orange SRA (oFarik) .0 Although variations exist among the (Corsica) selections, trifoliate orange, sour orange, P. trifoliata 'Rubidoux' Trifoliate orange (•UZF CRC 0.00 a Cleopatra mandarin, Taiwanica, Cit- P. trifoliata 'Benecke' Trifoliate orange (QUZF CRC 0.01 a C. siniensis Osb. X Citrange QU[ZF CRC 0.03 a remon, Carrizo and Troyer citranges, P.trifoliata 'Troyer' Macrophylla, Siamelo, and Volkameriana P. trifoliata'Rich' Trifoliate orange SRA CRC 0.06 ab were reported resistant (2,5,6,11,12,15-19, P. trifoliata 'Ferme Blanche' Trifoliate orange SRA France 0.12 abc SomesouC. mpulacae orages Hrt.cx Tn. TAE(Perr~gaux) 2 1,23,25,26,28,30). Soesu rne, c mulca ot xTn TE Japan 0.14 abcd mandarin, trifoliate oranges, oranges, C. aurantium 'Granito' Sour orange SRA Algeria 0.16 abcd (Boufarik) Accepted for publication 16 December 1983. C. celebica Koord. CRC CRC 0.18 abed C. aurantium 'Santucci' Sour orange SRA France 0.19 abed (Corsica) The publication costs of this article were defrayed in part C. aurantium 'Cardosi' Sour orange SRA CRC 0.21 abed by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 C. pennivesiculata (Lush.) SRA CRC 0.21 abed U.S.C. § 1734 solely to indicate this fact. Tan. 'CRC' C. depressa Hay. 'CRC' CRC CRC 0.23 abedef ©1984 The American Phytopathological Society (continued on next page) 502 Plant Disease/Vol. 68 No. 6 Table 1. (continuedfrom precedingpage) inoculated rootstocks were cut 25-30 cm and Mean above and below the inoculation site Contributing lesion brought to laboratory. Infected bark was Botanical name Common name institutey Origin index z removed carefully and the lesion areas on C. aurantium 'Curarao' Sour orange SRA CRC 0.24 abcdef the cambium were traced on translucent C. depressa 'Florida' IFAS Florida 0.25 abcdef paper and measured with an Automatic C. sinensis Osb. X Citrange QUZF Turkey 0.26 abcdef Area Meter Type AAM-5. Stem diameter P. trifoliata Raf. 'Carrizo' (Adana) at the lesion site was also measured. C. jambhiri Lush. tCDZF Turkey 0.27 abcdefg D i m se mentete rnal aearanc (Adana) During measurement, external appearance P. trifoliata 'Menager' Trifoliate orange SRA France 0.29 abcdefgh of the lesion site and gummosis under the (Carcans) bark were recorded. Results were C. wilsonii Tan. Ichang lemon SRA CRC 0.31 abcdefgh luated after C. webberi Wester 'SRA' SRA CRC 0.31 abcdefgh eva ransforming the measure- C. parasidiX P. trifoliata CUZF CRC 0.32 abcdefghi ments to lesion index (I) according to 'CRC 1452' Qinar and Tuzcu (11): C. aurantium 'Vallauris' Sour orange SRA France 0.34 abcdefghi (Corsica) C. reshni Hort. Cleopatra ATAE CRC 0.34 abcdefghi L A Tan. 'Antalya' mandarin C. webberi 'CRC' Kalpi papeda SRA CRC 0.35 abcdefghi D C. aurantium 'Genest' Sour orange SRA Spain 0.38 abcdefghi 2 C. aurantium 'Yellow fruited' Sour orange Giizelyurt Cyprus 0.39 abcdefghi where LA = lesion area (mm ) and D = C. sinensis X P trifoliata Citrange tUZF Turkey 0.40 abcdefghi mean diameter of the stem (mm). '8A-34/ 5' (Adana) Differences among the lesion indices were C. aurantium 'Yerli' Sour orange QUZF Turkey 0.45 abcdefghi tested statistically ( 13). (Adana) C. reshni 'SRA' Cleopatra SRA CRC 0.47 abcdefghij mandarin RESULTS AND-DISCUSSION C. aurantium'Tulear' Sour orange SRA Madagascar 0.49 abcdefghij The degree of resistance of each C. taiwanica Tan. & Shim. Taiwanica QUUZF CRC, 0.54 abcdefghij C. limon (L.) Burm. F. SRA Morocco 0.54 abcdefghij rootstock to P. citrophthorais indicated 'Borneo' by its mean lesion index (Table 1). The P. trifoliata 'Dwarf' Trifoliate orange SRA CRC 0.54 abcdefghij degree of resistance varied greatly among C. aurantium 'Australian' Sour orange SRA CRC 0.54 abcdefghij the rootstocks during their dormancy. C. latipes (Swing.) Tan. QDZF CRC 0.55 abcdefghij Aeglopsis chevalieri, Citropsisgilletiana, C. aurantium 'Brazil' Sour orange SRA Brazil 0.59 abcdefghij C. aurantium 'Okan' Sour orange Ulucinar Turkey 0.62 abcdefghij Citrusyatsushiro, C. sulcata, Alibert sour (Hatay) orange, Kibris Cleopatra mandarin; C. aurantium 'Brazilian' Sour orange CRC CRC 0.62 abcdefghij Yerli, Jacobson, SEAB, Luisi, Rubidoux, C. macrophylla Wester Macrophylla QUZF CRC 0.66 abcdefghijk C. madurensis Lour. 'CRC' Calamondin CRC CRC 0.68 abcdefghijk and Benecke trifoliate oranges and C. aurantium'Red fruited' Sour orange Giizelyurt Cyprus 0.69 abcdefghijk Troyer citrange were highly resistant. C. mitis Blanco'Antalya' Calamondin ATAE CRC 0.74 abcdefghijkl Rich and Ferme Blanche trifoliate C. aurantium'Luisi' Sour orange SRA France 0.76 abcdefghijk oranges, C. ampullaceae, and Granito (Corsica) C. obovoidea Hort. ex Tak. ATAE Japan 0.77 abcdefghijk sour orange also showed resistance to the C. tachibana (Mak.) Tan. CRC CRC 0.79 abcdefghijk pathogen. These results are in agreement C. sinensis'Madam Vinous' Sweet orange ATAE CRC 0.84 bcdefghijkl with results obtained by Carpenter and C. aurantium Sour orange SRA France 0.84 bcdefghijkl Furr (8), Klotz (20), and Laville and 'Ruche Fonciere' (Corsica) C. pennivesiculata'SRA' CRC CRC 0.86 cdefghijkl Blondel (24). Although they are wound- C. natsudaidaiHay. ATAE CRC 0.86 cdefghijkl resistant, A. chevalieri and Citropsis C. junos Sieb. ex Tan. QUZF Turkey 0.92 defghijkl gilletianacannot be recommended to the (Adana) growers at this stage because of their C. keraji Hort. ex Tan. ATAE Japan 1.01 efghijkl growrat t ita causevofithei C. volkameriana (Pasq.) Tan. Volkameriana t•UZF CRC 1.02 fghijkl incompatibility with citrus varieties C. limonia Osbeck Rangpur lime QUZF CRC 1.05 ghijkl compared with other citrus rootstocks C. intermedia Hort. ex Tan. CRC CRC 1.08 hijkl (1). However, these two species might be C. nobilis Lour. King mandarin ATAE CRC 1.11 ijkl chosen as parent lines for hybridization C. aurantium 'Azaguie' Sour orange SRA Ivory Coast "1.26 jklm to obtain resistant rootstocks. P. trifoliata 'Christian' Trifoliate orange SRA CRC 1.42 klm P. trifoliata 'Town' Trifoliate orange SRA CRC 1.44 klm C. yatsushiro, C. sulcata, and C. c. assamensis Dutta & Bhatt. CRC CRC 1.63 lm amp ullaceae are considered different P. trifoliata 'Yamagushi' Trifoliate orange SRA CRC 1.96 mn species by Tanaka, but in Swingle's C. micrantha Wester CRC CRC 2.73 n sseC assioi lcdi D 0.01 0.79 mandarin and C. sulcata and C. YATAE = Citrus Research Institute, Antalya, Turkey; CRC = Citrus Research Center, Riverside, CA; QUIZF = ampullaceae are placed in grapefruit. University of t•ukurova, Faculty of Agriculture, Adana, Turkey; IFAS = Institute of Food and Agricultural Because of their Far Eastern origin and Sciences, Gia~esville, FL; and SRA = Citrus Research Institute, Corsica, France. their nonacceptance as separate species 'Lesion index = ei~aeam + stem diameter at lesion site (mm); meansof 10replicates per plant species under Swingle's taxonomic system, very or . Means followed by the same letter are not significantly different (P =0.01) according to Tukey's limited studies have been made on the procedure. resistance of these rootstocks to P.

citrophthora. Detailed studies on the used as inoculum. sterile water, then covered with aluminum rootstock characters and resistance of Disks of bark 6, 8, and 10 mm in foil and polyethylene. Inoculations were these three species may reveal useful diameter were cut with acork borer 30-35 made on 19 November 1981 and the traits. The high resistance of C. cm above the ground from the trunks of wrappings were removed on 25 November yatsushiro in this study and its suitability rootstocks. An inoculum disk of the same 1981. Ten of each type were as a rootstock for orange and mandarin size was inserted mycelial face inward inoculated. During the period of lesion make it a promising rootstock for these into each of the holes where cambium had development, the mean temperature was species. C. sulcata and C. ampullaceae been exposed and was covered with the 13.5 C, with 9.5 C mean minimum and also possess good possibilities as lemon disk of bark. The inoculation site was 23.1 C mean maximum. rootstocks because they both showed wrapped with cotton moistened with Thirty-five days after inoculation, the resistant reactions to the pathogen and

Plant Disease/June 1984 503 grapefruit is known as the best rootstock trifoliate orange rootstocks, which were ranking system. In general ranking, Yerli for lemon (31). The varieties of some evaluated separately (Table 2), showed sour orange was intermediate and Okan species did not differ from each other varying reactions to the pathogen. was susceptible. Therefore, the suscept- significantly (eg, Citrus webberi var. Cleopatra mandarin and C. pennivesi- ibility of the varieties and possible SRA and var. CRC [CRC and Antalya culata also showed varying reactions. hybrids of sour orange to P.citrophthora calamondin]), but sour orange and Rootstocks were ranked as follows: should be investigated in detail. Among those having lesion index values up to the sour oranges studied, Alibert was Table 2. Resistance of various cultivars of Citrus 0. 15 highly resistant, those between 0.15 highly resistant and Granito, Santucci, aurantium, C. taiwanica, and C. intermedia to and 0.30 resistant, those between 0.30 and and Curagao were resistant. C. taiwanica Phytophthoracitrophthora 0.50 intermediate, those between 0.50 and was ranked as susceptible (Table 2). 1.00 susceptible, and those higher than Azagui& sour orange was highly Species lesionMean 1.00 highly susceptible. In general, the susceptible. This varying reaction of the Cuitivar Source indexz rankings presented here are in agreement sour oranges indicates the importance with those given by Carpenter and Furr and necessity of studying the various Citrus aurantium (8), Frossard (14), Laville and Blondel properties of each variety or selection. An Granito Algeria 0.16 ab (24), Grimm and Timmer (17), and investigation of the reactions of 29 clones Santucci Corsica 0.19 ab Carpenter et al (7). However, some selected by Tuzcu (29) from the eastern Cardosi Corsica 0.21 ab rootstocks showed different susceptibility Mediterranean area but not included in Curacao South America 0.24 abc than reported previously. Other workers this study may reveal some highly Vallauris France (Nice) 0.34 abed Genest Spain 0.38 abcd have also reported conflicting information resistant rootstocks and could be Yellow Fruited Cyprus 0.39 abcd about clones or varieties of same species beneficial for Turkey's citrus culture. (Giizelyurt) (4,5,18,32). As seen in Table 3, Yerli, Jacobson, Yera Turkey 0.45 abcd Although Taiwanica, Macrophylla, SEAB, Luisi, Rubidoux, Benecke, Rich, Tulear Madagascar 0.49 abcd Yuzu, and Volkameriana have recently and Ferme Blanche trifoliate oranges and Australian Australia 0.55 bcde been accepted as promising rootstocks, Troyer citrange were highly resistant; Brasil Brazil 0.59 bcde they did not show resistance to winter Citrumelo CRC 1452 and citrange 8A- Okan Turkey 0.62 bcde infections of P. citrophthora (Table 1). 34/5 were resistant. Dwarf trifoliate (Ulu~inar) Brazilian Brazil 0.62 bcde The other interesting result was that orange was susceptible, and Christian, Red Fruited Cyprus 0.69 bcde Yamagushi, Town, and Christian trifoliate Town, and Yamagushi trifoliate oranges (Giizelyurt) oranges and Azaguie sour orange and were highly susceptible. These results are, Luisi Corsica 0.76 cdef King mandarin were more susceptible in general, in accordance with Laville and Ruche Fonci're Corsica 0.84 def Azaguie Ivory Coast 1.26f than Rangpur lime. Some trifoliate Blondel (24); however, those authors C. taiwanica United States 0.54 abcde orange selections have been reported as reported SEAB and Ferme Blanche C. intermedia United States 1.08 ef highly resistant and some selections of trifoliate oranges as susceptible. Carpenter D 0.01 0.54 sour orange as resistant. The relative and Furr (8) found that Rich and Benecke Although 'Lesion index = -,1lesion area (mm +stem diameter susceptibility of the trifoliates and some trifoliates were resistant. at lesion site (mm); means of 10 replicates per plant sour oranges obtained in this study may Yamagushi trifoliate orange was species or cultivar. Means followed by the same be due to different genetical makeup determined resistant by Hutchinson and letter are not significantly different (P = 0.01) existing among the clones or varieties. Grimm (19) and Vanderweyen (30), it according to Tukey's procedure. Although not investigated thoroughly, showed a susceptible reaction in this , C. obovoidea, C. tachibana, study (Table 3). Our results support the Table 3. Resistance of various trifoliate oranges and C. natsudaidai, C. intermedia, C. suggestion by various authors (4,9,18, citranges and their hybrids to Phytophthora assamensis, and C. micranthawere found 20,24) that resistance of rootstocks to P. citrophthora susceptible and could not be recommended citrophthora should be investigated at Lesion as rootstocks for Turkish conditions, varietal or even clonal levels instead of Species index except for specific purposes. species level. Otherwise, ranking the Cultivar Source meanz The susceptibility of sour oranges with rootstocks at species level may create Poncirus different origins varied greatly (Table 2). discrepancies. The reactions of Cleopatra trifoliata Sour orange has been accepted as a mandarins with different origins provide Yerli Turkey (Rize) 0.00 a resistant rootstock and used widely in an example (Table 4). Kibris Cleopatra Jacobson United States 0.00 a Turkey without looking into varietal mandarin was highly resistant and SEAB Algeria 0.00 a Luisi Corsica 0.001a differences. Although two local sour Antalya and SRA Cleopatra mandarin Rubidoux United States 0.00 a oranges, Yerli and Okan, showed no were intermediate. Although Cleopatra Benecke United States 0.00 a statistical differences, they showed mandarin was reported as intermediate in Troyer different susceptibility according to our resistance by Blondel (3), it was found citrange United States 0.03 a Rich United States 0.06 ab susceptible by Vanderweyen (30), Ferme Frossard (14), and Grimm and Timmer Blanche Algeria 0.12 ab Table 4. Resistance of Cleopatra mandarin cultivars (17). Our results indicate that Kibris Carrizo obtained from different sources to Phytophthora Cleopatra mandarin could be ranked as citrange United States 0.26 ab citrophthora highly resistant to P. citrophthora Menager France 0.29 abce ______1452 Mean infections during dormancy. citrumelo United States 0.32 abc Species lesion 8A-34/5~ Cultivar Source indexi ACKNOWLEDGMENTS citrange United States 0.40 bc We thank the Turkish Scientific and Technical Dwarf United States 0.54 c Council (TUBITAK) for financial support and E. Christian South Africa 1.42 d Kibris Cyprus 0.00 a •ekero~lu for his valuable assistance in preparation Town United States 1.44 d Antalya Antalya 0.34 b of the manuscript. Yamagushi United States 1.96 e SRA Corsica 0.47 b D 0.01 0.35 D 0.01 0.16 LTRTR IE ______1. Bitters, W. P., Cole, D. A., and McCarty, C. D. ______2 'Lesion index = xlesion area (mm ): stem diameter ' Lesion index = xlesion area (mm ) + stem diameter 1977. Citrus relatives are not irrelevant as dwarf at lesion site (mm); means of 10 replicates per plant at lesion site (mm); means of 10 replicates per plant stocks or interstocks for citrus. Proc. Int. Soc. species or cultivar. Means followed by the same species or cultivar. Means followed by the same Citricult. 2:561-567. letter are not significantly different (P = 0.01) letter are not significantly different (P = 0.01) 2. Blondel, L. 1969. Research on citrus rootstocks according to Tukey's procedure. according to Tukey's procedure, in Corsica. Proc. Int. Citrus Symp. 1:367-371. 504 Plant Disease/Vol. 68 No. 6 3. Blondel, L. 1973. Les porte-greffe des agrumes en Turk. Phytopathol. 5:49-59. Stn. Circ. 369. 26 pp. Corse. Somivac. 68:41-48. 13. Diizgiine§, 0. 1963. Bilimsel ara~tirmalarda 23. Klotz, L. J., Dewolfe, T. A., and Baines, R. C. 4. Boccas, B., and Laville, E. 1978. Les maladies 'a istatistik prensipleri ve metotlari. Ege Universitesi 1969. Resistance of trifoliate orange stocks to Phytophthorades agrumes. SETCO-IRRA, Matbaasi. Izmir. 375 pp. gummosis. Citrograph 54:259-260. Paris. 162 pp. 14. Frossard, R., 1978. Lutte contre la gommose des 24. Laville, E., and Blondel, L. 1979. Comportement 5. Broadbent, P. 1973. Phytophthora disease of agrumes en C te dIvoire. Fruits 33:889-891. de diff~rents clones de Poncirus trifoliata aux citrus. A review. Proc. Int. Soc. Citricult. 15. Giksedef, M. 0. 1980. Akdeniz b~lgesi attaques racinaires A Phytophthora sp. Fruits 3:986-992. limonlarinda gtvde zamklanma etmeni 34:175-178. 6. Broadbent, P., Fraser, L. R., and Waterworth, Phytophthora citrophthora (Smith and Smith) 25. Newcomb, D. A. 1978. Rootstocks and nursery Y. 1971. The reaction of seedlings of Citrus spp. Leonian'in yayiliýi, bazi biyolojik 8zellikleri ve practice. Proc. Int. Soc. Citricult. 1: 117-120. and related genera to Phytophthoracitrophthora. tarimsal savak y~ntemleri ile infeksiyon 26. Roth, G. 1966. The pathogenicity of Diplodia Proc. Linnean Soc. N.S.W. 9:219-227. stiresinde etmene karli farkh duyarhk gtsteren natalensis and Phytophthora citrophthora 7. Carpenter, J. B., Burnis, R. M., and Sedlacek, R. turunigil getitlerindeki dayanikhhk nedenlerinin (Smith and Smith) Leon. to citrus rootstocks. F. 1981. Phytophthora resistant rootstocks for saptanmasi iizerinde arattirmalar (Yayanlan- Phytopathology 57:201-215. Lisbon lemons in California. Citrograph 66:287- mami§) Doktorra Tezi. Adana. 101 pp. 27. Sahh, N. 1974. Adana gevresinde turungvillerde 288, 291-292. 16. Grimm, G. R., and Hutchinson, D. J. 1973. A meyve ve kikbojazi viiriikliijii yapan Phytoph- 8. Carpenter, J. B., and Furr, J. R. 1962. Evaluation procedure for evaluating resistance of citrus thoracitrophthora (Smith and Smith) Leoniana of tolerance to root rot caused by Phytophthora seedlings to Phytophthoraparasitica.Plant Dis. yayilisi ve biyolojisi iizerinde arattirmalar. parasitica in seedlings of citrus and related Rep. 57:669-672. Adana B81. Zir. Miic. Aralt. Enst. Yayin No. 35, genera. Phytopathology 52:1277-1285. 17. Grimm, G. R., and Timmer, W. 1981. Control of Adana. 102 pp. 9. Chapot, H. 1965. Maladies, troubles et ravageurs Phytophthora foot rot and root rot. Citrus Ind. 28. Schneider, H., Platt, R. C., Bitters, W. P. and des agrumes au Maroc. INRA de Maroc. Rabat. 62:34-39. Burns, R. M. 1978. Diseases and incompatibilities 339 pp. 18. Hutchinson, D. C., and Cooper, W. C. 1977. that cause decline in lemons. Citrograph 10. •inar, A. 1976. Ifel ve Adana B8lgesi turunggil Recent advances in the search for improved 63:219-221. agaalarinda Phytophthora citrophthora (Smith citrus rootstocks in Florida. I. Cong. Mundial 29. Tuzcu, 0., Ozsan, M., and Kaplankiran, M. 1983. and Smith) Leonian zarari ve topraklarda Citricult. 2:181-184. Do'u Akdeniz yerli turunglarinin biiyijme hastahik potansiyel indeksinin ara§tirilmasi. Q. 19. Hutchinson, D. J., and Grimm, G. R. 1973. durumlar. Pages 207-227 in: Tubitak-Toag 7. Ziraat Fakiiltesi Yilhi.5:l17-125. Citrus clones resistant to Phytophthora Bilim Kongresi (Bah2e Bitkileri Seksiyonu). 11. Qinar, A., and Tuzcu, 0. 1976. Resistance study parasitica: 1973 screening results. Proc. Fla. Tubitak Yaymi No. 547. Tilbitak Matbaasi, of the citrus rootstocks to Phytophthora State Hortic. Soc. 86:88-91. Akara. pp. No. citrophthora(Smith and Smith) Leonian. II. The 20. Klotz, L. J. 1978. Fungal, bacterial and Ankara. 539 pp. use of new method in selecting resistance citrus nonparasitic diseases. Pages 1-66 in: Citrus 30. Vanderweyen, A. 1973. La gommose a rootstocks to Phytophthoracitrophthora (Smith Industry. Vol. 4. W. Reuther, E. C. Calavan, and Phytophthora des agrumes au Maroc. C. R. and Smith) Leonian. J. Turk. Phytopathol. G.E. Carman, eds. Univ. Calif., Div. Agric. Sci., Acad. Agric. Fr. 59:125-129. 5:98-99. Berkeley. 31. Webber, H. J. 1948. Rootstocks: Their character 12. Qinar, A., Tuzcu, 0., and G~ksedef, M. 0. 1976. 21. Klotz, L. J., Bitters, W. P., Dewolfe, T. A., and and reactions. Pages 69-168 in: Citrus Industry. Resistance study of the citrus rootstocks to Garber, M. J. 1968. Some factors in resistance of Vol. 2. L. D. Batchelor and H. J. Webber, eds. Phytophthora citrophthora (Smith and Smith) Citrus to Phytophthora spp. Plant Dis. Rep. University of California Press, Berkeley. Leonian. I. Research on the resistance of 14 52:952-955. 32. Whiteside, J. 0. 1973. Phytophthora studies on different citrus rootstocks to Phytophthora 22. Klotz, L. J., and Calavan, E. C. 1969. Gum citrus rootstocks. Proc. Int. Citrus Short Course, citrophthora (Smith and Smith) Leonian. J. diseases of citrus in California. Calif. Agric. Exp. Univ. Fla.

Plant Disease/June 1984 505