Variations of Macro- and Microelements in Yellow-Fleshed Cassava (Manihot esculenta Crantz) Genotypes as a Function of Storage Root Portion, Harvesting Time, and Sampling Method

The correct estimation of the mineral content of cassava (Manihot esculenta) genotypes is vital from a nutritional point of view. This study evaluated the effects of the storage root section, maturity, and sampling method on the macro- and microelements in yellow-fleshed cassava root genotypes. In total, 44 genotypes were grown in replicated field trials of 2 sets (set 25 and set 19) and were harvested at 9 and 12 months after planting. Two sampling methods, sampling with a cork borer (A = proximal, B = middle, C = distal or method 1) and sampling without a cork borer (L = Longitudinal or method 2), were used. The minerals of the samples from the two methods were determined using inductively coupled optical emission spectrometry (ICP-OES). K and Mn were the most abundant minerals, and Na, Mo, and Co were the least abundant. Genotype, method, and maturity had a strong influence on mineral concentrations. Harvesting time affected the concentration level of some macro- and microelements in cassava roots. Additionally, Ca, Mg, K, P, Mn, Cu, Ni, and Zn contents were significantly (p < 0.05) higher in the proximal and middle portions for method 1. K and P and Mn and B were positively correlated, but K and Na and Fe and Ni were negatively associated.

Kaolin/Gum Arabic Nanocomposite as Antifungal agent against Aspergillus Flavus and Saccharomyces cerevisiae

Kaolin/Gum Arabic nanocomposite was cheaply synthesized from Kaolin and Gum Arabic. The Kaolin/Gum Arabic nanocomposite suspension, Gum Arabic extracts and Kaolin suspension were applied as antifungal agents. The antifungal activity was tested using agar well diffusion method where by wells were made on the petri dishes with cork borer 6mm diameter in size and various concentrations (150 µg/L, 200 µg/L, and 250 µg/L) of Gum Arabic ethanol extracts, Gum Arabic /Kaolin nanocomposite, and Kaolin was propelled into the wells with the help of micropipette and the petri dishes were allowed to stand for 30 minutes to ensure proper diffusion before being incubated at 37oC. The results showed that synthesized Kaolin/Gum Arabic nanocomposite and Gum Arabic possess significant antifungal activity against Aspergillus flavus and Saccharomyces cerevisiae. No antifungal activity detected for Kaolin against Aspergillus flavus and Saccharomyces cerevisiae. From the results obtained it could be concluded that the synthesized Kaolin/Gum Arabic nanocomposite and Gum Arabic possess significant antifungal activity against Aspergillus flavus and Saccharomyces cerevisiae.

First Report of Brown Rot of Apricot Caused by Monilia mumecola

In May 2013, apricot (Prunus armeniaca) fruits covered with grayish, conidial masses were collected from an unknown cultivar in an experimental field of Huazhong Agricultural University, Wuhan, Hubei Province. About 3 to 5% of fruit was infected and affected apricots had tan to white zones of sporulation, which resembled brown rot caused by Monilia species. Conidia were harvested from the surface of the sporulating apricot fruit and spread onto shallow potato dextrose agar (PDA) media (about 2 mm in thickness) using sterile cotton swabs. Conidia were lemon-shaped and mean size was 15.7 (10 to 22.5) × 25 (16.25 to 35) μm. Conidia on PDA were incubated at 23°C for 3 h in darkness, then observed under microscope. More than two germ tubes were produced from each conidium, which was the distinctive trait of Monilia mumecola species (2). Single-spore isolates were obtained and 3 isolates were cultured on PDA in petri dishes. Mycelium grew at an average of 15 mm per day, and the colony showed concentric rings of mycelium with lobbed margins at 23°C in darkness. A 712-bp fragment was PCR amplified from β-tubulin gene (TUB2) of all the nine isolates investigated indicative of M. mumecola (2). The ribosomal ITS1-5.8S-ITS2 regions of nine isolates were also PCR-amplified from genomic DNA using primers ITS1 and ITS4 and then sequenced (4). ITS sequences were identical to ITS sequences of M. mumecola from China (HQ908786) and Japan (AB125613, AB125614, and AB125620), but only has 98% and 97% identity with the closest species M. laxa (EU042149) and M. fructicola (HQ908789) according to BLAST search in GenBank. Pathogenicity was confirmed by inoculating mycelial plugs of three isolates into six surface-sterilized apricots wounded with a 6-mm diameter sterile cork borer. Control fruit received plain PDA plugs and was incubated in a moist chamber at 23°C with 12 h light/12 h dark. All inoculated fruit developed typical brown rot symptoms with sporulating areas as described above after 3 days of incubation, while control fruits remained healthy. The developing spores on inoculated fruit were re-isolated and confirmed to be M. mumecola. M. mumecola was first isolated from Prunus mume in Japan in 1982 as an unknown Monilia species (3), then identified and the nomenclature was provided in 2004 (1). To our knowledge, this is the first report of M. mumecola on P. armeniaca indicating that M. mumecola has spread to different hosts. References: (1) Y. Harada et al. J. Gen. Plant Pathol. 70:297, 2004. (2) M. J. Hu et al. Plos One, 6(9):e24990, 2011. (3) S. Nakao. Kongetsu-no-noyaku, 1:92, 1992. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

Efficacy of Essential Oils From Some African Spices Against Two Strains of Bacillus cereus Isolated From Vegetable Salad

<p>Chemical preservatives have been used to preserve our foods against spoilage and pathogenic microorganisms over the years. Consumers now frown at this hence the need to source for preservatives from natural sources. In this investigation fifteen samples of vegetable salad were collected from retail outlets in Lagos, Nigeria dilutions of which were plated on Brilliance <em>Bacillus cereus </em>agar. Isolates were identified based on morphological, biochemical characteristics and reactions to API 20E and API 50 CHB/E test kit. Two strains of <em>Bacillus cereus</em>; <em>B. cereus </em>1 and <em>B. cereus </em>2 were isolated. The organism was spread evenly on Mueller -Hinton agar and wells of 5mm in diameter were made on the inoculated agar with sterile cork borer. Different dilutions (1, 0.1, 0.01, 0.001 mg/ml) of essential oils extracted from three African spices; <em>Aframomum melegueta, Xylopia aethiopica </em>and<em> Piper guineense</em> by hydro distillation method were introduced into the wells in triplicate. After incubation diameter of zones of inhibition were measured. The essential oils of the spices inhibited growth of the two strains. <em>A. melegueta</em> produced the greatest zone of inhibition (14 to 24 mm) and with the lowest minimum inhibitory concentration (MIC) of 31.25 mg/ml, followed by <em>X. aethiopica </em>(10 to 18 mm) with MIC of 62.5 mg/ml and <em>P. guineense </em>(11 to 15 mm) and MIC of 125 and 250 mg/ml against <em>B. cereus </em>1 and <em>B. cereus </em>2 respectively. <em>P. guineense </em>was the least inhibitory. However, <em>B. cereus </em>1 was more sensitive (inhibition zone of 12 to 24 mm) to the essential oils of the spices than <em>B. cereus </em>2 (inhibition zone of 10 to 17 mm). The higher the concentration of the essential oils the greater the resultant zones of inhibition. The spices especially <em>A. melegueta</em> have proved very efficient in the inhibition of <em>B. cereus </em>a pathogen obtained from vegetable salad. The spices can therefore help in ensuring food safety.</p>

First Report on the Association Between Ceratocystis fimbriata, an Agent of Mango Wilt, Xyleborus affinis, and the Sawdust Produced During Beetle Colonization in Brazil

Mango (Mangifera indica L.) is an economically important fruit crop in many tropical and subtropical regions. Recently, the wilt disease caused by Ceratocystis fimbriata has limited mango production in Brazil and other countries (3). There are reports that Hypocryphalus mangifera (Coleoptera: Curculionidae) is a vector of Ceratocystis spp. and that other beetles, such as Xyleborus affinis (Coleoptera: Curculionidae), may attack mango trees and excavate gallery burrows, thereby producing sawdust (1,3). In March 2011, X. affinis was found colonizing diseased mango trees located in Itaperuna, Rio de Janeiro State (21°12′23″ S, 41°53′23″ W). Therefore, we aimed to evaluate whether both the beetle and the sawdust produced in colonized trees would be associated with C. fimbriata. In March 2011, three isolates of C. fimbriata were collected: CF01 in sawdust from ‘Espada’ trees with wilt symptoms (yellowish to dried leaves, dried stems, and gum exudation from the stem) in Itaperuna; CF02 from X. affinis colonizing wilted trees in Itaperuna; and CF03 from wilted ‘Palmer’ trees in Frutal, Minas Gerais State (20°1′11″ S, 48°55′10″ W). To obtain the isolates, fragments of sawdust, beetles, and mango stem were set between carrot disks and incubated in a wet chamber at 25°C with 12 h of light (4). After 10 days, the ascospores produced in perithecia in the carrot tissue were directly transferred to potato dextrose agar (PDA) in 9-cm petri dishes and incubated at 25°C with 12 h of light. After 10 days, 1-cm mycelial disks were taken from the borders of actively growing colonies. In each of 20 seedlings of 8-month-old ‘Espada,’ growing in 18 × 25 cm plastic pots with a soil-sand-cow manure mixture (3:1:1, v/v), a 1-cm diameter wound in the stem was made with a cork borer (20 cm above the soil surface). A mycelial disk was placed in each wound (a plain PDA disk was placed in control plants). After inoculation, a wet cotton plug was placed on the wound, which was then wrapped with Parafilm. Five plants were inoculated in each treatment. The seedlings were checked weekly for up to 56 days after inoculation. All three isolates were pathogenic, causing typical disease symptoms on the plants, beginning 7 days after inoculation: gum exudation (60, 60, and 0%); and yellowish and wilt (80, 100, and 80%). The % values are for isolates CF01, CF02, and CF03, respectively. No disease symptoms were observed in the control seedlings. After reisolating, the three isolates were confirmed as being C. fimbriata: perithecia (110 to 250 μm wide, 120 to 250 μm tall), base dark, globose, and long dark necks (440 to 770 μm long, 28 to 40 μm wide); ascospores hyaline, one-celled, galeate (5.0 to 7.5 μm long, 3.5 to 5.0 μm wide), exuded in sticky and cream colored mass at the apex of the perithecium neck (2). To our knowledge, this is the first report of an association between C. fimbriata and both X. affinis and the sawdust produced during beetle colonization. Therefore, both the beetle and the sawdust are potential dispersal agents of C. fimbriata in mango orchards. This finding is epidemiologically important, and the disease spread related to both sawdust and beetle is being followed in the field. References: (1) A. O. Al Adawi et al. Eur. J. Plant. Pathol. 135:243, 2013. (2) C. J. B. Engelbrecht and T. C. Harrington. Mycologia 97:57, 2005. (3) A. Masood et al. Pakistan J. Zool. 44:1545, 2012. (4) W. J. Moller and J. E. De Vay. Phytopathology 58:123, 1968.

A Severe Outbreak of Charcoal Rot in Cantaloupe Melon Caused by Macrophomina phaseolina in Chile

A severe outbreak of charcoal rot was observed in cantaloupe melon (Cucumis melo L.) in the summer of 2011 to 2012 in Curacaví Valley, Chile. Prior to harvest, of 72 plants per cultivar, charcoal rot prevalence varied from 32% to 82% in cvs. Colima, Charantias, Navigator, Origami, Otero, and Samoa. Symptoms were wilting and leaf browning associated with water-soaked lesions at the base of the crown with amber to dark brown exudates. Lesions dried out progressively, turned tan, and cracked. Affected plants declined and died before harvest. Reddish fruit decay was observed. Symptomatic stem and root samples (n = 97) were collected, surface disinfected (96% ethanol, 30 s), plated on PDA acidified with 0.5 ml/liter of 92% lactic acid (APDA), and incubated at 20 ± 1°C. A white, fast-growing mycelium was obtained that turned gray to black after 7 days due to the presence of spherical to oblong black microsclerotia 136 ± 52 μm (n = 80) in diameter. On the basis of colony morphology and microsclerotia, 57 isolates (59%), obtained from 97 melon samples, were tentatively identified as Macrophomina phaseolina (Tassi) Goid. (2,3). The morphological identification of four isolates M1HB-B, M2CO-B, M3CH-R, and M4OT-B (GenBank Accession Nos. JX203630, JX203631, JX203632, and JX203633) was confirmed by sequencing of the internal transcribed spacer region (ITS1-5.8S-ITS2) of rDNA, using primers ITS4 and ITS5, with >99% similarity with the sequences of M. phaseolina (GenBank Accession No. HQ660592) (4). Pathogenicity tests were conducted with isolates M1HB-B, M2CO-B, M3CH-R, and M4OT-B on melon fruits cvs. Colima, Origami, Charantias, and Diva. Four mature melon fruits per cultivar per isolate were surface disinfected with 0.5% sodium hypochlorite for 2 min before inserting a mycelium plug (19 mm2) in a 6 mm diameter hole made with a sterile cork borer. An equal number of perforated fruits in which a sterile agar plug was inserted were left as non-inoculated controls. After 8 days of incubation at 20°C, inoculated fruits developed a spherical, reddish, soft necrotic lesion of 15 to 20 mm in diameter in the pulp. Non-inoculated fruits remained symptomless. The pathogenicity of the four isolates was also studied in 3-month-old melon plants (n = 4) cvs. Colima and Navigator. Plants were inoculated by inserting a mycelial plug (9 mm2) underneath the epidermis of the crown, 5 cm above the soil level. The inoculation site was immediately wrapped with Parafilm to avoid dehydration. An equal number of non-inoculated, but injured plants, treated with a sterile agar plug, were left as controls. After 21 days of incubation under greenhouse conditions (17 ± 5.5°C), all inoculated plants developed water-soaked to dry necrotic lesions, 20 to 70 mm long, yellow to tan in color. No symptoms were obtained in non-inoculated controls. M. phaseolina was reisolated in 84% and 100% of the inoculated plants and fruits, respectively. To our knowledge, this study is the first report of charcoal rot in cantaloupe melon in Chile, previously found on watermelon and melon group inodorus (1). Charcoal rot appears as an emerging disease that aggressively affects current cantaloupe melon cultivars in central Chile. References: (1) G. Apablaza. Cien. Inv. Agr. 20:101, 1993. (2) B. D. Bruton and E. V. Wann. Charcoal rot. Page 9 in: Compendium of Cucurbit Diseases. T. A. Zitter, D. L. Hopkins, and C. E. Thomas, eds. APS, St. Paul, MN, 1996. (3) S. Kaur et al. Crit. Rev. Microbiol. 38:136, 2012. (4) J. Q. Zhang et al. Plant Dis. 95:872, 2011.

First Report of Seimatosporium botan Associated with Trunk Disease of Grapevine (Vitis vinifera) in Chile

Grapevines are planted on 180,000 ha in Chile. In 2010 and 2011, necrotic lesions and hard texture were observed on woody tissue on 10-year-old vines of cvs. Cabernet Sauvignon, Carménère, Moscatel de Alejandría, and Pedro Jimenez in Ovalle (lat. 30°58′ S) and Cauquenes (lat. 35°58′ S). Symptoms were on 10 to 25% of the arm cross sections, resembling symptoms caused by Botryosphaeriaceae (4). Prevalence of 5% was estimated visually in Ovalle (n = 920 grapevines) and Cauquenes (n = 350 grapevines). Small pieces (3 mm) of necrotic tissues from the margins of lesions in cordons (n = 32) were surface sterilized (96% ethanol, 15 s), and plated on acidified PDA plus 0.5 ml/liter of 92% lactic acid, 0.005% tetracycline, 0.01% streptomycin, and 0.1% Igepal CO-630 (Sigma-Aldrich, St. Louis, MO) (APDA). The plates were incubated at 20°C for 14 days. Isolates (n = 12) were obtained from the yellow to dark green slimy colonies with white irregular margins, staining brown the underside of APDA plates. Black acervuli and ellipsoid to fusiform conidia were obtained. Conidia were triple septated, with hyaline upper and bottom cells and brown middle cells (n = 30) of 17.7 ± 1.2 × 5.8 ± 0.8 μm. A basal conidial appendage (6.2 ± 1.0 μm) was always obtained, but conidia having appendages at both ends also were observed. Morphologically, these isolates were identified as Seimatosporium botan Sat. Hatak. & Y. Harada (2). The identification of isolates sei-302 and sei-316 was confirmed by amplifying and sequencing the region ITS1-5.8S-ITS2 of rDNA using ITS4 and ITS5 primers (GenBank Accession Nos. JN088482 and JN088483). BLAST analyses showed 100% similarity with S. botan (Accession No. HM067840) (2). Pathogenicity tests were conducted with isolates sei-302 and sei-316 on detached green shoots (GS) and on rooted 2-year-old vines ‘Carménère.’ Rooted vines were inoculated at the base of canes and trunks. Inoculations were performed by placing a mycelial agar plug taken from APDA on a wound aseptically made with a cork borer. Wounds were sealed with Parafilm to avoid a rapid dehydration. The inoculated GS were incubated for 2 weeks in a moisture chamber (relative humidity >80%) at 20°C. Inoculated 2-year-old vines were placed in a lath-house for 7 and 15 months for canes and trunk inoculation, respectively. An equal number of GS and vines were inoculated with sterile agar plugs and left as controls. Necrotic lesions with mean of 23.7 ± 2.5 mm on GS, 50.5 ± 3.4 mm on canes, and 41.9 ± 2.3 mm on trunks developed. No significant difference (P < 0.05) was obtained in lesion length between S. botan isolates. After 7 months, 40% of inoculated canes had died. No symptoms were observed in GS controls and rooted control vines treated with sterile agar plugs. S. botan was reisolated from 93 to 100% of the inoculated samples. Previously, S. botan was reported as pathogenic in Paeonia suffruticosa (1), and Seimatosporium sp. was isolated from V. vinifera in California, but their pathogenicity was not demonstrated (3). To our knowledge, this is the first report of pathogenic isolates of S. botan associated with trunk disease of grapevines. These results contribute to the knowledge of the trunk disease of grapevines worldwide. References: (1) Y. Duan et al. Plant Dis. 95:226, 2011. (2) S. Hatakeyama et al. Mycoscience 45:106, 2004. (3) Z. Morales et al. Phytopathol. Mediterr. 49:109, 2010. (4) J. R. Úrbez-Torres. Phytopathol. Mediterr. 50:S5, 2011.

First Report of Pestalotiopsis clavispora Causing Dieback on Blueberry in Uruguay

During the last 10 years, blueberry (Vaccinium corymbosum) production in Uruguay has increased to more than 850 ha. From 2005, symptoms of dieback characterized by the death of twigs and branches have been frequently observed in blueberry plants cv. O'Neal in orchards located in Uruguay. Symptomatic 4-year-old plants (cv. O'Neal) were collected and small pieces of necrotic tissues were surface disinfected and plated onto potato dextrose agar (PDA) with 0.2 g liter–1 of streptomycin sulfate. Plates were incubated at 25°C in the dark. All affected tissues consistently developed colonies with white and cottony mycelium, turning slightly yellow after 7 to 10 days. Black acervuli distributed in concentric circles were observed after 10 days. Conidia were fusiform, straight, and had five cells. Basal and apical cells were colorless while the three median cells were dark brown. Conidia (n = 50) had an average of 22.1 (16.5 to 28.2) × 6.6 (5.6 to 7.7) μm. All conidia had one basal appendage of 6.1 (3.9 to 14.3) μm and two to four (usually three) apical appendages of 22.8 (17.4 to 42.9) μm. According to colony and conidia morphology, the isolates were initially identified as Pestalotiopsis clavispora (G.F. Atk.) Steyaert (1). To identify, the internal transcribed spacers (ITS1, 5.8S, ITS2) region of rDNA of a representative isolate (Ara-1) was amplified with ITS1/ITS4 primers (4), sequenced, and compared with those deposited in GenBank. The isolate Ara-1 (Accession No. JQ008944) had 100% sequence identity with P. clavispora (Accession Nos. FJ517545 and EU342214). To confirm pathogenicity, isolate Ara-1 was inoculated onto asymptomatic 1-year-old blueberry plants (cv. O'Neal). Mycelial plugs (4 mm in diameter) from an actively growing colony on PDA were applied to same-size bark wounds made with a cork borer in the center of the stems previously disinfected with 70% ethanol and covered with Parafilm. Control plants were inoculated with sterile PDA plugs. Inoculated plants (five per treatment) were randomly distributed in a greenhouse and watered as needed. After 2 weeks, all stems inoculated with P. clavispora showed brown necrotic lesions 2 to 3 cm in length and 1 to 2 mm deep. White mycelium was observed over lesions. Control plants remained symptomless. The pathogen was reisolated from all necrotic lesions, thus fulfilling Koch's postulates. P. clavispora has been reported as associated with blueberry in Hawaii (3) and Chile (2). To our knowledge, this is the first report of P. clavispora causing dieback disease on blueberry in Uruguay. References: (1) E. F. Guba, Monograph of Pestalotia and Monocheatia. Harvard University Press, Cambridge, MA, 1961. (2) J. G. Espinoza et al. Plant Dis. 92:1407, 2008. (3) L. M. Keith et al. Plant Dis. 90:16, 2006. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Occurrence of Grapevine Trunk Disease Caused by Botryosphaeria rhodina in China

In the early summer of 2009, grapevine (Vitis vinifera), an important fruit crop in China, declined in most of the vineyards in Hunan, Hubei, and Zhejiang provinces. Characteristic symptoms of Botryosphaeria canker were apparent, including trunk cankers (visible in cross-section), leaf drop, shriveling and drying of fruit clusters, and berry rot (1). To identify the causal pathogen, we tested 126 samples by attempting to culture the pathogen from a small piece of tissue from the canker margin between the necrotic and apparently healthy tissue. Plant tissue was surface sterilized by placing it in 75% ethanol for 1 min and rinsed with sterilized water three times before culturing to potato dextrose agar (PDA) at 28°C. Five days later, the cultures were hyphal-tip purified and then single-spore isolates were used for identification. On the basis of colony characteristics in PDA, these colonies were identified as Botryosphaeria spp. (2). They were grayish white, becoming dark brown with age, and pycnidia were formed after incubation for approximately 9 days. Conidia measured 11 to 15 × 22 to 28 μm. A subset of isolates were used for rDNA ITS (internal transcribed spacer) sequence analysis with primers ITS1 and ITS4 (3). PCR products were separated by electrophoresis and bands were purified (Qiagen Plasmid Mini Kit; Qiagen, Valencia, CA) for sequencing (Sunbiotech Company, Beijing). BLAST searches of three ITS sequences (Accession Nos. GU226851, GU226853, and GU226856) had 100% identity to B. rhodina. EF1-α and β-tubulin sequence analysis gave similar results. Koch's postulates were completed in the laboratory on grape shoots inoculated with two isolates of B. rhodina, originally isolated from plants in the field with symptoms of Botryosphaeria canker. Isolates were incubated on PDA at 25°C for 1 week. Inoculations were made on green shoots of V. vinifera cvs. Muscat Hamburg and Crimson Seedless. Five shoots per cultivar were inoculated per isolate by wounding with a 4-mm cork borer (2 mm deep), placing a colonized agar plug on the wound, and wrapping the wound with Parafilm. Controls were mock inoculated with an agar plug from sterile PDA. Inoculated shoots were incubated in the laboratory in the dark under moist conditions for 10 days at 25°C. Inoculated shoots had necrotic cankers after 10 days and B. rhodina was recovered from each canker margin. The results suggest that some grapevines in China with symptoms of Botryosphaeria canker were indeed infected by B. rhodina. To our knowledge, this is the first report of this pathogen on grapevine in China. References: (1) J. Luque et al. Mycologia 97:1111, 2005. (2) J. M. Niekerk et al. Mycologia 96:781, 2004. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Efficacy of a Peroxyacetic Acid Formulation as an Antimicrobial Intervention To Reduce Levels of Inoculated Escherichia coli O157:H7 on External Carcass Surfaces of Hot-Boned Beef and Veal

The efficacy of a peroxyacetic acid formulation (POAA) at reducing Escherichia coli O157:H7 contamination on external carcass surfaces of hot-boned beef and veal with a commercial spray apparatus was determined. Hot-boned external carcass surfaces were inoculated with either a high dose (106 CFU/cm2) in fresh bovine feces or with a low dose (103 CFU/cm2)in diluent of laboratory-cultured E. coli O157:H7. Treatments included a water wash, a POAA (180 ppm) wash, or a water plus POAA wash. Samples were extracted from the external carcass surface with a cork borer to determine the numbers of viable E. coli O157:H7 remaining on the carcass surface after treatment. Although a water wash alone resulted in a 1.25 (94.4%) and a 1.31 (95.1%) mean log reduction on veal and beef inoculated with a high dose of E. coli O157:H7, the POAA treatment resulted in a substantially greater mean log reduction of 3.56 and 3.59 (&gt;99.9%). The water wash only resulted in a 33.9% reduction on veal and 62.8% on beef inoculated with a low dose of E. coli O157:H7, whereas POAA treatment greatly improved pathogen reduction to 98.9 and 97.4% on veal and beef, respectively. The combination of a water wash followed by a POAA treatment resulted in a similar E. coli O157:H7 reduction to that achieved by POAA treatment alone. In conclusion, POAA treatment significantly reduced viable E. coli O157:H7 numbers on experimentally contaminated beef and veal carcasses, which justifies its use as a chemical intervention for the removal of this human pathogen.