Hilgardia
Hilgardia
Hilgardia
University of California
Hilgardia

Pythiaceous fungi and plant-parasitic nematodes in California pear orchards: I. Occurrence and pathogenicity of pythiaceous fungi in orchard soils

Authors

Carl W. Nichols
S. M. Garnsey
R. L. Rackham
S. M. Gotan
C. N. Mahannah

Authors Affiliations

Carl W. Nichols was Plant Pathologist and Program Supervisor of Special Projects, Bureau of Plant Pathology, California Department of Agriculture, Sacramento; S. M. Garnsey was formerly Research Assistant, Department of Plant Pathology, Davis, and is now Plant Pathologist at the Horticultural Field Station, U.S. Department of Agriculture, Orlando, Florida; R. L. Rackham was formerly Extension Technologist in the Agricultural Extension Service, Davis, and is now a University of California Farm Advisor in the Agricultural Extension Service, San Bernardino County; S. M. Gotan was Plant Pathologist, Bureau of Plant Pathology, California Department of Agriculture, Sacramento; C. N. Mahannah was Research Assistant, Department of Irrigation, Davis.

Publication Information

Hilgardia 35(21):577-602. DOI:10.3733/hilg.v35n21p577. October 1964.

PDF of full article, Cite this article

Abstract

Pythiaceous Fungi and Plant-Parasitic Nematodes in California Pear Orchards

I. During a year’s survey of 126 California pear orchards with varying degrees of pear-decline damage, a total of 3,586 isolates of soil-borne fungi of the genera Phytophthora and Pythium were recovered, and, where possible, identified as to species.

A direct relationship was found between the severity of pear-decline damage in an orchard and the percentage of isolates from the orchard that were Pythium spp.; and a corresponding inverse relationship between pear-decline damage severity and the percentage of isolates that were Phytophthora spp.

Isolates of Phytophthora cactorum and P. cryptogea were found to be pathogenic on Pyrus communis L. hort. var. Winter Nelis and Pyrus serotina Rehd. seedlings. These pathogens were found infrequently, and it was concluded that pythiaceous fungi were not the primary cause of pear decline.

Pear fruit and pear and apple seedlings trapped more Pythium spp. than the fruit of apple, lemon, and avocado, while few Phytophthora spp. were trapped in seedlings. Phytophthora spp. isolates were trapped most often in pear and apple fruit. Lemon and avocado fruit yielded a fair number of both genera.

Literature Cited

Anderson E. J. A simple method for detecting the presence of Phytophthora cinnamomi Rands in soil. Phytopathology. 1951. 41:187-89.

Anderson E. J. Distribution maps of plant diseases 1942-1963. Anonymous Commonwealth Mycological Institute Map Nos. 35, 47, 70, 157, 174, 203, 280, 281, and 302.

Anderson E. J. Index of plant diseases in the United States 1960. p.531. Anonymous U. S. Dept. Agr., Agr. Handbook No. 165.

Baldacci E., Catoni G., Ciferri R., Marimpietri L., Refatti E. Relazione sui dati e le esperienze circa la “Moria” del peronella Venezia Tridentina (Trentino ed Alto Adige) 1949. p.51. Notizario Sulle Malattie Delle Piante. No. 4 (Sept. 1949)

Blackwell Elizabeth M. Terminology in Phytophthora. 1949. Commonw. Mycol. Inst. 24p. Mycol. Papers, No. 30.

Cameron H. Ronald. Infection of pear roots with Phytophthora cinnamomi. (Abstr.). Phytopathology. 1960. 50:630

Cameron H. Ronald. Susceptibility of pear roots to Phytophthora. Phytopathology. 1962. 52:1295-97.

Campbell W. A. Phytophthora cinnamomi associated with the roots of littleleaf-diseased shortleaf pine. Plant Disease Rptr. 1948. 32:472

Campbell W. A. A method of isolating Phytophthora cinnamomi directly from soil. Plant Disease Rptr. 1949. 33:134-35.

Chiarappa Luigi. The root rot complex of Vitis vinifera in California. Phytopathology. 1959. 49:670-74.

Darley Ellis F., Wilbur Wesley D. Phytophthora rot of Washington palms. Phytopathology. 1953. 43:469-70.

Eckert J. W., Tsao P. H. A preliminary report on the use of pimaricin in the isolation of Phytophthora spp from root tissues. Plant Disease Rptr. 1960. 44:660-61.

Eckert J. W., Tsao P. H. A selective antibiotic medium for isolation of Phytophthora and Pythium from plant roots. Phytopathology. 1962. 52:771-77.

Fawcett H. S. Two fungi as causal agents in gummosis of lemon in California. Calif. State Commr. Hort. Mon. Bul. 1913. 2(8):601-17.

Fawcett H. S. The known distribution of Pythiacystis citrophthora and its probable relationship to Mal da Gumma of citrus. Phytopathology. 1915. 5:66-67.

Fawcett H. S. A Pythiacystis on avocado trees. Phytopathology. 1916. 6:433-35.

Fawcett H. S. Pythiacystis and Phytophthora. Phytopathology. 1920. 10:397-99.

Fawcett H. S. Citrus diseases and their control. 1936. New York, N.Y.: McGraw-Hill Book Co., Inc. 656p.

French A. M., Lownsbery B. F., Ayoub S. M., Weiner A. C., El-Gholl N. Pythiaceous fungi and plant-parasitic nematodes in California pear orchards. II: Incidence and distribution of parasitic nematodes in orchard soils. Hilgardia. 1964. 35(21):603-10.

Hoagland D. R., Arnon D. I. The water culture method for growing plants without soil. Calif. Agr. Expt. Stat. Circ. 1950. 347(Revised):32

Hunt T. Francis. Pythiacystis “brown rot” affecting deciduous trees. Calif. Dept. Agr. Monthly Bul. 1921. 10(4):143-45.

Klotz L. J., DeWolfe T. A. Techniques for isolating Phytophthora spp which attack citrus. Plant Disease Rptr. 1958. 42:675-76.

Klotz L. J., DeWolfe T. A. The production and use of zoospore suspensions of Phytophthora spp for investigations on diseases of citrus. Plant Disease Rptr. 1960. 44:572-73.

Klotz L. J., DeWolfe T. A., Wong Po-Ping. Decay of fibrous roots of citrus. Phytopathology. 1958. 48:616-22.

Klotz L. J., Sokoloff V. P. The possible relation of injury and death of small roots to decline and collapse of citrus and avocado. Calif. Citrog. 1943. 28:86-87.

Lindner R. C., Burts E. C., Benson N. R. A decline condition in pears induced by pear psylla. Plant Disease Rptr. 1962. 46:59-60.

Lownsbery B. F., Mitchell J. T., Paracer S. M. Pythiaceous fungi and plant-parasitic nematodes in California pear orchards. III: Effect of reduction in nematode populations by soil fumigation on subsequent growth of pear seedlings. Hligardia. 1964. 35(21):611-14.

McIntosh D. L. The infection of pear rootlets by Phytophthora cactorum. Plant Disease Reptr. 1960. 44:262-64.

Middleton John T. The taxonomy, host range and geographic distribution of the genus Pythium. Mem. Torrey Bot. Club. 1943. 20(1):1-171.

Middleton John T. Generic concepts in the Pythiaceae. Tijdschrift over Plantenziekten. 1952. 58:226-35.

Miller P. A. Phytophthora crown rot of loquat. Phytopathology. 1942. 32:404-09.

Newhook F. J. A Pythium disease of pear trees. New Zealand Jour. Sci. and Technol. 1957. 38:533-38.

Newhook F. J. The association of Phytophthora spp. with the mortality of Pinus radiata and other conifers: I. Symptoms and epidemiology in shelterbelts. New Zealand Jour. Agr. Res. 1959. 2(4):808-43. DOI: 10.1080/00288233.1959.10422840 [CrossRef]

Nichols Carl W., Schneider Henry, O’Reilly H. J., Shalla Thomas A., Griggs W. H. Pear decline in California. Calif. Dept. of Agr. Bul. 1960. 49:186-92.

Rackham R. L., Alderman D. E., O’Reilly H. J., Nichols Carl W. Pear decline incidence and severity in California in 1960, 1961 and 1962. Plant Disease Rptr. 1964. 48:204-05.

Shalla T. A., Chiarappa Luigi, Blodgett E. C., Refatti E., Baldacci E. The probable coidentity of the moria disease of pear trees in Italy and pear decline in North America. Plant Disease Rptr. 1961. 45:912-15.

Shalla T. A., Chiarappa Luigi, Carroll T. W. A graft-transmissible factor associated with pear decline. Phytopathology. 1963. 53:366-67.

Smith C. O., Barrett J. T. Some inoculations with Phytophthora-like fungi. (Abstr.). Phytopathology. 1930. 20:849-50.

Smith Elizabeth H. Pythiacystis infection of deciduous nursery stock. Phytopathology. 1915. 5:317-22.

Smith Ralph E. Diseases of fruits and nuts. Calif. Agr. Ext. Ser. Circ. 1941. 120:168

Smith Ralph E., Smith Elizabeth H. Further studies on Pythiaceous infection of deciduous fruit trees in California. Phytopathology. 1925. 15:389-404.

Sprague Roderick. Fungi isolated from roots and crowns of pear trees. Plant Disease Rptr. 1957. 41:74-76.

Sutherland C. F., Newhook F. J. The association of Phytophthora spp. with mortality of Pinus radiata and other conifers. II. Influence of soil drainage on disease. New Zealand Jour. Agr. Research. 1959. 2:844-58. DOI: 10.1080/00288233.1959.10422841 [CrossRef]

Torgeson D. C. The Phytophthora root rots of Chamaecyparis lawsoniana Parl. (Abstr.). Phytopathology. 1951. 41:944

Torgeson D. C., Young Roy A., Milbrath J. A. Phytophthora root rot diseases of Lawson cypress and other ornamentals. Oregon State College Agr. Expt. Stat. Bul. 1954. 537:11

Tucker C. M. Taxonomy of the genus Phytophthora de Bary. Univ. of Mo., Coll. of Agr., Agr. Expt. Stat. Res. Bul. 1931. 153:208

Tucker C. M. The distribution of the genus Phytophthora. Univ. of Mo., Coll. of Agr., Agr. Expt. Stat. Res. Bul. 1933. 184:80

Tucker C. M., Milbrath J. A. Root rot of Chamaecyparis caused by a species of Phytophthora. Mycologia. 1942. 34:94-103. DOI: 10.2307/3754945 [CrossRef]

Wager Vincent A. Phytophthora cinnamomi and wet soil in relation to the dying-back of avocado trees. Hilgardia. 1942a. 14(9):519-32. DOI: 10.3733/hilg.v14n09p517 [CrossRef]

Wager Vincent A. Pythiaceous fungi on citrus. Hilgardia. 1942b. 14(9):535-48. DOI: 10.3733/hilg.v14n09p533 [CrossRef]

Waterhouse Grace M. The genus Phytophthora. Commonw. Mycol. Inst., Misc. Publ. 1956. 12:120

Waterhouse Grace M., Blackwell Elizabeth M. Key to the species of Phytophthora recorded in the British Isles. Commonw. Mycol. Inst., Mycol. Papers. 1954. 57:9

Woodridge C. G., Blodgett E. C., Diener T. O. Pear decline in the Pacific Northwest. Plant Disease Rptr. 1957. 41:569-72.

Zentmyer George A., Gilpatrick J. D., Thorn W. A. Methods of isolating Phytophthora cinnamomi from soil and host tissue. Phytopathology. 1960. 50:87

Zentmyer George A., Richards Sterling J. Pathogenicity of Phytophthora cinnamomi to avocado trees and the effect of irrigation on disease development. Phytopathology. 1952. 42:35-37.

Nichols C, Garnsey S, Rackham R, Gotan S, Mahannah C. 1964. Pythiaceous fungi and plant-parasitic nematodes in California pear orchards: I. Occurrence and pathogenicity of pythiaceous fungi in orchard soils. Hilgardia 35(21):577-602. DOI:10.3733/hilg.v35n21p577
Webmaster Email: wsuckow@ucanr.edu