ACKNOWLEDGMENTS 4. BOTHAST, R. J., and D. I. FENNELL. 1974. A purpose medium for fungi and bacteria. We wish to thank E. B. Lillehoj and his staff at the medium for rapid identification and enumeration Phytopathology 45:461-462. Northern Regional Research Center, SEA-USDA, of Aspergillus flavus and related organisms. 9. RAMBO, G. W., J. TUITE, and P. CRANE. Peoria, Mycologia IL, for aflatoxin analyses of these five 66:365-369. 1974. Preharvest inoculation and infection of 5. CHRISTENSEN, Aspergillus cultures. C. M., and H. H. KAUFMANN. dent corn ears with Aspergillus flavus and 1965. Deterioration of stored grains by fungi. Aspergillus parasiticus. Phytopathology Annu. Rev. Phytopathol. 3:69-84. 64:797-800. 6. LILLEHOJ, LITERATURE CITED E. B., D. I. FENNELL, and W. F. 10. SHOTWELL, 0. L., M. L. GOULDEN, and C. KWOLEK. 1976. Aspergillus flavus and W. HESSELTINE. 1974. Aflatoxin: 1. ANDERSON, H. W., E. W. NEHRING, and W. Distribu- aflatoxin in Iowa corn before harvest. Science tion in contaminated R. WICHSER. 1975. Aflatoxin contamination corn. Cereal Chem. 193:495-496. 51:492-499. of corn in the field. J. Agric. Food Chem. 7. LILLEHOJ, E. B., W. F. KWOLEK, E. E. 11. TAUBENHAUS, 23:775-782. J. J. 1920. A study of the black VANDERGRAF, M. S. ZUBER, 0. H. and the yellow molds of ear 2. ANONYMOUS. 1972. Changes in official corn. Tex. Agric. CALVERT, N. WIDSTROM, M. C. FUTRELL, Exp. Stn. Bull. 270. method of analysis. Natural Poisons 26. B01-26. and A. J. BOCKHOLT. 1975. Aflatoxin 12. ZUBER, M. S., 0. B03. J. Assoc. Off. Anal. Chem. 55:426-433. H. CALVERT, W. F. production in Aspergillusflavus inoculated ears KWOLEK, E. B. LILLEHOJ, and M. 3. BOOTH, C. 1971. Fungal Culture Media. Page S. KANG. of corn grown at diverse locations. Crop Sci. 1978. Aflatoxin B, production in an eight line 77 in: C. Booth, ed. Methods in Microbiology. 15:267-270. Vol. 4. Academic Press, New York. 795 pp. diallel of Zea mays infected with Aspergillus 8. MILLER, P. M. 1955. V-8juiceagarasa general flavus. Phytopathology 68:1346-1349.

Occurrence and Distribution of Stem Pitting of Sweet Cherry Trees in Washington

G. I. MINK, Professor of Plant Pathology, and W. E. HOWELL, Agricultural Research Technologist III, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350

ABSTRACT region of central Washington. In MINK, addition, G. I., and W. E. HOWELL. 1980. Occurrence and distribution of stem pitting of sweet we examined all trees in the cherry trees in Washington. Plant Disease 64:551-552. foundation and mother blocks main- tained by the Washington State Nursery Trunk pitting was observed on nearly 20% of 22,586 trees examined in 12 commercial sweet cherry Improvement Program (WSNIP). This (Prunus avium L.) orchards located throughout central Washington. Pitted trees were found report describes the results of this survey. among all varieties examined, but reduced tree vigor was associated with severe pitting symptoms only for trees with Montmorency (P. cerasus L.) interstocks. In five foundation and mother block MATERIALS AND plantings maintained by Washington State Nursery Improvement METHODS Program, only 1.7% of 1,726 The 12 commercial trees exhibited wood pitting. The incidence of pitting was lower orchards were in commercial plantings located throughout established with certified trees than in similar plantings established with uncertified trees. the Yakima Valley and Columbia Basin regions' of central Washington. Orchards were selected on the basis of location, tree age, varieties, Stem pitting diseases of sweet cherry had moderate to severe pitting on the and owner cooperation. Observations (Prunus avium L.) trees have been main trunk near ground level. Occasion- were made by removing reported in British Columbia (2-4), a 7.5-cm ally the bark from a severely pitted tree triangular bark patch from the trunk California (7), Maryland (5), near and was nearly twice as thick as bark from ground level and recording Pennsylvania (8). In each area the degree of the adjacent nonpitted trees and somewhat pitting in the exposed primary symptom was longitudinal woody cylinder. spongy in texture. However, the Pitting was rated as mild (one to three depressions (pits) in the surface of the association of trunk pitting, thick bark small pits), intermediate (up to 15-20 woody cylinder of either the rootstock or and unthrifty tree growth was highly simple pits), or severe (numerous scion variety or both. Other symptoms pits). inconsistent. Various degrees of stem Each tree was also observed for growth such as thick, spongy bark (7), ridges and pitting were frequent on trees that and foliar symptoms. All furrows in the trunk (8), cambial necrosis tree wounds otherwise appeared normal. were sealed with an asphalt (5,6), necrotic streaking in the wood (2,4), paint after To determine the incidence and readings were made. gumming (4), sparse growth (8), and distribution of the trunk pitting symptom, Insofar as could be established, general decline of trees (7,8) have also all trees we surveyed all trees in 12 commercial surveyed were propagated been associated with trunk pitting. In on either orchards located in the cherry-growing Mahaleb (P. mahaleb L.) some (5,7,8) but not all (4) cases, the or Mazzard (P. disease syndrome in sweet cherry trees appeared quite similar to that associated Table 1. Incidence and severity of stem-pitting symptoms in 10 cherry varieties with the stem pitting disease of peach trees (6). Trees Trees Pitted trees (%) In random surveys made during 1975 examined pitted Variety Mild Intermediate Severe and 1976, we observed a few (no.)I I (%) trees in Mild Intermediate Severe Washington sweet cherry orchards that Montmorency (interstock) 946 53 34 23 43 Black Tartarian 229 50 30 20 50 Supported in part by funds provided by the Columbia Rainier 425 22 69 24 River Orchards Foundation, Wenatchee, WA. 7 Bing 16,979 19 81 15 4 Black Republican 1 Washington State University 1,092 19 90 9 College of Agriculture Chinook Research Center, Scientific Paper 5501, Project 1719. 155 15 74 22 4 Lambert 1,131 14 94 4 2 Van 694 11 76 16 8 0191-2917/80/06055102/$03.00/0 Royal Ann (=Napoleon) 791 3.5 86 10 4 1.3 100 ©1980 American Phytopathological Society Hardy Giant 156 0 0 1.3 100 0

Plant Disease/June 1980 551 and severity of stem-pitting symptoms in Bing cherry trees grouped by age and California (7). Stockton Morello (P. Table 2. Incidence a rootstock that exhibited nursery practice cerasus L.), severe wood pitting and necrosis in Trees Trees California and was generally associated examined examiedpittedpttedPitted trees (%) with declining trees, is not used in Age (yr) (no.) (%) Mild Intermediate Severe Washington. Uncertifieda Although there are similarities between 5-12 3,147 15 68 22 10 the stem pitting disorders in Washington 15-25 12,526 21 83 14 3 and California, we observed definite 30-40 409 14 84 12 4 trunk pitting on several Royal Ann (=Napoleon) and Mazzard trees. Certifiedb Napoleon was considered a symptomless 8-10 885 4 70 27 3 carrier of PSP in California, but pitting without regard to known virus content. 'Nursery trees produced on Mazzard in only one bNursery trees produced from virus-tested sources in accordance with regulations promulgated by was observed orchard (7). State Department of Agriculture. Washington An agent associated with PSP in California was graft-transmitted from pitted cherry trees to various Prunus spp. have thus avium L.) rootstocks. Because of For uncertified Bing trees, age had no Graft-inoculation experiments inadequate grower's records or changes apparent influence on either the incidence far failed to demonstrate transmission of trees in in ownership, the specific rootstock for or severity of symptoms (Table 2). The a similar agent from pitted cherry the etiology of every tree could not be determined. incidence of pitting was noticeably less, Washington. Although Preliminary surveys indicated that little if however, in plantings established with this disorder has not yet been established, role of any pitting occurred in the rootstocks and Washington certified nursery trees than it is of interest to note the possible of was generally mild where it occurred. in similar plantings established with the WSNIP in reducing distribution in the Consequently, the data presented are for uncertified trees. Yet, for those trees with stem-pitted trees. All trees derive the scion portions of the trees only. pitting symptoms, the distribution of foundation and mother blocks Where trees contained interstocks, the trees within the severity classes was from source trees that had been indexed then known data are recorded with the appropriate generally the same regardless of certi- 10-12 yr earlier for all viruses variety. fication status (Table 2). to infect sweet cherry trees. Many of these Location of orchards had no influence source trees were obtained from the IR-2 Fruit RESULTS on the incidence and severity of pitting in Interregional Deciduous Tree the transmis- Incidence and distribution of cherry uncertified Bing plantings. Orchard maps Repository (1). Although had not been stem pitting. Pitting was observed on the prepared from survey data showed no sible nature of PSP (7) were trunks of 19.9% of 22,586 trees in apparent pattern to the distribution of demonstrated when these plantings the virus- commercial sweet cherry orchards but in stem pitted trees within orchards. established, apparently most of from the only 1.7% of 1,726 trees in the WSNIP tested source trees were also free foundation and mother blocks. In DISCUSSION PSP agent. The data in Table 2 suggest trees can commercial orchards the incidence of None of the pitted trees exhibited that use of certified nursery incidence trunk pitting and the range of symptom severe branch, leaf, or fruit symptoms substantially reduce the initial severity depended to some extent on the similar to those associated with the graft- of stem pitting. variety (Table 1). Approximately 50% of transmissible xylem aberration disease of sweet cherry trees in British Columbia LITERATURE CITED the Montmorency (P. cerasus L.) 1. FRIDLUND, P. R. 1974. IR-2, the interregional interstocks and the Black Tartarian trees (2-4). Furthermore, none of the trees had deciduous tree fruit repository. In: Virus Diseases had definite pitting; about two-thirds of the severe trunk furrowing, ridging, and and Noninfectious Disorders of Stone Fruits in or severe tree decline associated with stem pitting North America. U.S. Dep. Agric., Agric. these had intermediate Handb. 437. symptoms. At the other extreme, only 2 in Pennsylvania (8). In one of the 12 trees 2. HANSEN, A. J. 1974. Xylem aberration. In: Virus of 156 Hardy Giant trees had pitting; orchards, however, one-third of the Diseases and Noninfectious Disorders of Stone both were rated mild. For the remaining had been propagated with Montmorency Fruits in North America. U.S. Dep. Agric., Agric. seven varieties, the incidence of pitting interstocks. Many of these trees had Handb. 437. pitting and honeycombing in the 3. LOTT, T. B. 1967. Xylem aberration. A ranged from 3.5 to 22%, with a few trees severe Can. Plant this orchard transmissible disease of stone fruits. of each variety expressing severe pitting. Montmorency portion. In Dis. Surv. 47:74-75. In the WSNIP foundation and mother poor tree growth was consistently 4. LOTT, T. B., F. W. KEANE, and J. MAY. 1962. associated with severe pitting of the Gumming, distortion and pitting in cherry and blocks, of 25 seed source trees with mild apricot. Can. Plant Dis. Surv. 42:229-232. wood pitting, 15 were Mazzard and 10 interstock. 5. MIRCETICH, S. M., and H. W. FOGLE. 1969. were Mahaleb. Twenty-four of these trees In 11 of the 12 commercial orchards, Stem pitting in Prunus spp. other than peach. were in one orchard. The five pitted scion trees consisted mainly of scion varieties Plant Dis. Rep. 53:7-11. on either Mazzard or 6. MIRCETICH, S. M., and H. W. FOGLE. 1974. source trees included two Rainier trees propagated and some Peach stem pitting. In: Virus Disease and one tree each of Black Tartarian, Van Mahaleb rootstocks. Although Noninfectious Disorders of Stone Fruits in North and P. serrulataLindl. 'Shogiestsu.' None trees had moderate to severe pitting on America. U.S. Dep. Agric., Agric. Handb. 437. of 112 Bing trees in the WSNIP blocks the trunk of scion varieties, there was no 7. MIRCETICH, S. M., W. J. MOLLER, and G. consistent correlation between the NYLAND. 1977. Prunus stem pitting in sweet exhibited pitting symptoms. cherry and other stone fruit trees in California. Bing is the principal sweet cherry severity of pitting and reduced tree vigor. Plant Dis. Rep. 61:931-935. variety grown throughout central In this respect the stem pitting disorder in 8. STOUFFER, R. F., F. H. LEWIS, and D. M. Washington. Consequently, 75% of the Washington resembled Prunus stem SOULEN. 1969. Stem pitting in commercial pitting (PSP) as described for trees on cherry and plum orchards in Pennsylvania. Plant 22,586 commercial orchard trees Dis. Rep. 53:434-438. examined were of this variety (Table 1). Mazzard and Mahaleb rootstocks in

552 Plant Disease/Vol. 64 No. 6