Early-onset neonatal sepsis: rate and organism pattern between 2003 and 2008.

OBJECTIVE: Organisms causing early-onset neonatal sepsis (EONS) have consistently changed over time. The distribution of organisms in EONS helps to influence the appropriate type of antibiotic prophylaxis strategy during labor and the antibiotics used in neonates with suspected sepsis. STUDY DESIGN: To compare the organisms distribution for EONS between 2003 and 2008 for infants admitted to neonatal intensive care units (NICUs) in Canada. Data were retrieved from infants with a positive bacterial blood or cerebrospinal fluid culture in the first 72 h after birth who were admitted to NICUs participating in the Canadian Neonatal Network from 2003 to 2008. Comparisons of incidence rate, demographics and causative organisms were carried out between earlier cohort (2003 to 2005) and later cohort (2006 to 2008). RESULT: A total of 405 infants had positive blood and/or cerebral spinal fluid cultures over the study period. The EONS rate was 6.8/1000 admissions (n=24969) in the earlier cohort compared with 6.2/1000 admissions (n=37484) in the later cohort (P=0.36). Rate of clinical chorioamnionitis was higher in the later cohort (38 vs 26%; P=0.02). For term infants, coagulase-negative Staphylococcus (CONS) (2.4/1000) followed by group B Streptococcus (GBS) (1.9/1000) were the most common organisms identified. For preterm infants, CONS (2.5/1000) followed by Escherichia coli (2.6/1000) were the most common organisms identified. There was a significant reduction in GBS EONS over time (P<0.01) and a trend toward an increase in other organisms. CONCLUSION: Although the rate of EONS among neonates admitted to NICUs has not changed, the pattern of infection has changed over the past 6 years. With the increased use of prophylactic antibiotics to mothers, careful surveillance of the changing trend of bacterial organisms among neonates is warranted.

Predicting Soybean Rust Incursions into the North American Continental Interior Using Crop Monitoring, Spore Trapping, and Aerobiological Modeling.

Between 2005 and 2009, millions of U.S. and Canadian soybean acres that would have received fungicide application remained untreated for soybean rust due to information disseminated through the Integrated Pest Management Pest Information Platform for Extension and Education (ipmPIPE), increasing North American producers' profits by hundreds of millions of dollars each year. The results of our analysis of Phakopsora pachyrhizi urediniospores in rain collections, aerobiology model output, and observations of soybean rust spread in 2007 and 2008 show a strong correspondence between spore collections and model predictions for the continental interior of North America, where soybean is an important crop. The analysis suggests that control practices based on up-to-date maps of soybean rust observations and associated commentary from Extension Specialists delivered by the ipmPIPE may have suppressed the number and strength of inoculum source areas in the southern states and retarded the northward progress of seasonal soybean rust incursions into continental North America. The analysis further indicates that spore trapping and aerobiological modeling can reduce our reliance on the costly Sentinel Plot Network while maintaining the effectiveness of the ipmPIPE system for soybean rust management.

Integrated Management Strategies for Phytophthora sojae Combining Host Resistance and Seed Treatments.

Phytophthora sojae has re-emerged as a serious soybean pathogen in the past decade. This may be due in part to changes in resistance levels in current cultivars, adoption of P. sojae populations to deployed Rps genes, and highly favorable environments in the past decade. This multilocation study evaluated the effect of seed treatments on the incidence and severity of Phytophthora root and stem rot on soybeans with different combinations of Rps genes and levels of partial resistance. The efficacy of the seed treatments was highly variable across locations. Seed treatments (metalaxyl and mefenoxam) provided protection and increased yields across cultivars in locations where rain or irrigation occurred shortly after planting (Ohio, South Dakota, and Ontario). However, there were no significant differences in stand or yield consistently across cultivars in Iowa, Nebraska, Wisconsin, or Ohio, where heavy precipitation did not occur until later growth stages. The environment, levels of inoculum, and pathogen complex may have played a role in the different responses to the seed treatments and to the different combinations of Rps genes and levels of partial resistance to P. sojae in the cultivars. Fields that are poorly drained and have P. sojae populations with complex pathotypes may benefit the most from seed treatments. Individual fields where producers may see the greatest benefit to utilizing these integrated management strategies will need to be identified.

First Report of Brown Root Rot of Alfalfa Caused by Phoma sclerotioides in Maine, Ontario, and Pennsylvania.

Brown root rot (BRR), caused by the fungal pathogen Phoma sclerotioides G. Preuss ex Sacc. (synonym Plenodomus meliloti Dearn. & G.B. Sanford), is associated with yield loss of alfalfa (Medicago sativa L.) in regions with severe winters (1). In the spring of 2007, 9 to 69 alfalfa plants were collected from each of five production fields in Maine, 10 fields in Ontario, and nine fields in Pennsylvania. All alfalfa stands existed at least two winters. P. sclerotioides was isolated from alfalfa root and crown lesions from five fields in Maine (Penobscot, Somerset and Waldo counties), seven fields from southwestern (Woodstock and Niagara), south-central (Lindsay and Belleville), and southeastern Ontario (near Ottawa), and four fields in Pennsylvania (Columbia, Crawford, and Jefferson counties; 41.1 to 41.6°N). BRR incidence was 9 to 29% in Maine, 5 to 29% in Ontario, and 8 to 22% in Pennsylvania. In Ontario, some lesions girdled the crown; in three fields in Maine, large pycnidia characteristic of P. sclerotioides were present on alfalfa crowns and overwintered stems. On potato dextrose agar, conidia (5 to 8 × 2 to 3 µm, unicellular, hyaline, and ovoid) and pycnidia (0.33 to 1.15 mm in diameter with multiple beaks) of single-conidium isolates were characteristic of P. sclerotioides (2). Diagnostic PCR (3) of isolates resulted in a single amplicon of expected size (500 bp). The internal transcribed spacer (ITS) 1, 5.8S, and ITS2 of the rDNA were sequenced for 12 representative isolates, and sequences (GenBank Accession Nos. FJ179151 to FJ179162) were 95.5 to 100% identical to P. sclerotioides ATCC isolate 56515 over a 488-bp alignment. Eight months after seeding, potted 'Vernal' alfalfa was inoculated (4), kept at 4°C for 8 weeks, 0 to -2°C for 12 weeks, 4°C for 8 weeks, and 10 to 15°C for 7 weeks. Of 108 plants inoculated with the Maine isolates, 35 developed severe cortical lesions and 16 died. Of 18 plants inoculated with the Ontario isolates, 16 developed severe cortical lesions and eight died. Of 18 plants inoculated with a Pennsylvania isolate, 11 developed severe cortical lesions and five died. Lesions were typical of BRR: light to very dark brown, sometimes with a darker border, and often containing abundant pycnidia. Plant mortality was associated with lesions that girdled the root and crown. Of 18 plants in the control treatment, three developed severe cortical lesions and none died. BRR is common in Alberta, Saskatchewan, and Manitoba, but in eastern Canada it has been reported only in Nova Scotia. To our knowledge, this is the first report of BRR in Maine, Ontario, and Pennsylvania and the southernmost report of BRR in eastern North America. References: (1) B. Berkenkamp et al. Can. J. Plant Sci. 71:211, 1991. (2) G. H. Boerema et al. Persoonia 15:431, 1994. (3) R. C. Larsen et al. Plant Dis. 86:928, 2002. (4) M. J. Wunsch et al. Plant Dis. 91:1293, 2007.

First Report of Gray Leaf Spot Caused by Cercospora zeae-maydis on Corn in Ontario, Canada.

During an annual corn disease survey in mid-September 2001, sporadic symptoms typical of gray leaf spot (causal agent Cercospora zeae-maydis Tehon & E.Y. Daniels) (4), consisting of long, narrow, rectangular, 0.3 to 0.5 × 2 to 5 cm, tan or gray-to-tan spots, were found in nine fields in southern Ontario. Leaf samples with symptoms were placed in petri dishes containing moistened filter paper to maintain high humidity and stored at room temperature for 48 h. Clustered conidiophores arose from stomata on both leaf surfaces. Slightly curved, hyaline conidia, 4 to 8 × 25 to 88 µm long with 3 to 5 septa appeared on the tops of conidiophores, similar to those described by Kingsland (3). When single-spore isolates were cultured on carrot leaf decoction agar (2) at room temperature, aerial mycelia were rare, but slightly larger conidia were produced in 3 weeks. When single-spore isolates were cultured on V8 agar (1) at room temperature, aerial mycelia were abundant, and conidiophores and conidia were produced on the tops of mycelia in 1 to 2 weeks, but conidia were slightly smaller. Greenhouse-grown plants of two commercial corn hybrids (Pioneer 32Y52 and Zimmerman NX7208) were inoculated at the 8- to 10-leaf stage by injecting a suspension of 5 × 103 conidia per ml (washed from a V8 agar culture with sterile water) into the whorl and by spraying the suspension on the leaves. High moisture was maintained in the greenhouse by a misting system. After 14 to 21 days, typical symptoms of gray leaf spot and typical conidiophores and conidia were observed. Gray leaf was reisolated from inoculated plants, fulfilling Koch's postulates. We have suspected that gray leaf spot has been present in Ontario for a few years based on unconfirmed reports from the seed corn industry, but to our knowledge, this is the first confirmed report of this pathogen in Canada. Voucher specimens of field material, dried cultures, and greenhouse-inoculated leaves have been deposited in the National Mycological Herbarium (DAOM 229597 to 229600) in Ottawa, ON, Canada; and the isolate has been deposited with the Canadian Collection of Fungal Cultures (CCFC). References: (1) S. T. Coates et al. Plant Dis. 78:1153, 1994. (2) O. D. Dhingra and J. B. Sinclair. Page 287 in: Basic Plant Pathology Methods. CRC Press, Inc., Boca Raton, FL, 1985. (3) G. C. Kingsland. Plant Dis. Rep. 47:724, 1963. (4) G. P. Munkvold and C. A. Martinson. Page 6 in: Iowa State University Extension Publication Pm-596, Iowa State University Press, Ames, 1994.

First Report of Bean pod mottle virus in Soybean in Canada.

In 2001, soybean fields were surveyed to determine the incidence of viruses because soybean aphids (Aphis glycines Matsamura), known to transmit Soybean mosaic virus (SMV) (2), were found in Ontario. In addition, bean leaf beetle (Cerotoma trifurcata Forster) was found during 2000 to be contaminated with Bean pod mottle virus (BPMV), although soybean plants, on which the beetles were feeding, tested negative (3). In the current survey, young soybean leaves were selected at random in July and August from 20 plants per site at growth stages R4 to R5 (1) from 415 sites representing the entire soybean-producing area in Ontario. Samples were maintained under cool conditions until received at the laboratory, where they were promptly processed. A combined sub-sample was obtained from the 20 plants per site. The 415 sub-samples were tested for SMV, BPMV, Tobacco ringspot virus (TRSV), and Tobacco streak virus (TSV) using polyclonal antibody kits for double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) (Agdia Inc., Elkart, IN). The ELISA plates were read with a plate reader (MRX, Dynex Technologies Inc., Chantilly, VA), and results were analyzed using ELISA software (Leading Edge Research, Merrickville, Ontario) and compared positive and negative controls (Agdia). TRSV was detected in one sample from Essex County and another sample from Middlesex County. SMV, BPMV, and TSV were not found in commercial soybean fields. However, SMV and BPMV were found in samples originating from two soybean breeding nurseries, one in Essex County and one in Kent County. Seedlings of soybean cv. Williams 82 were inoculated in the greenhouse with sap from leaf samples that tested positive for BPMV. Leaves of plants that developed mosaic symptoms were retested using ELISA and confirmed to be positive for BPMV. SMV and TRSV have been found previously in commercial soybean fields in Ontario (4). To our knowledge, this is the first report of BPMV on soybean plants in Canada. References: (1) W. R. Fehr et al. Merr. Crop. Sci. 11:929, 1971. (2) J. H. Hill et al. Plant Dis. 85:561, 2001. (3) A. U. Tenuta. Crop Pest. 5 (11):8, 2000. (4) J. C. Tu. Can. J. Plant Sci. 66:491, 1986.

First Report of Fusarium solani f. sp. glycines Causing Sudden Death Syndrome of Soybean in Canada.

Sudden death syndrome (SDS), caused by Fusarium solani (Mart.) Sacc. f. sp. glycines, is a disease of soybean (Glycine max (L.) Merr.) in several central and southern states of the United States. In Ontario, Canada, individual soybean plants with typical foliar symptoms of SDS (1) have been observed annually in Kent County since 1993 but the causal organism was not isolated or identified. In 1996, plants with symptoms of SDS were observed in six fields located in Essex, Kent, and Lambton counties. Interveinal chlorosis and necrosis occurred on top leaves of affected plants and a pale brown discoloration occurred in the vascular system in lower stems and upper tap roots. Slow-growing isolates of F. solani f. sp. glycines with typical blue sporodochia were isolated from symptomatic plants on acidified potato dextrose agar (1). Root inoculation of 15 2-week-old seedlings with colonized oat kernals with each of five single-spore isolates caused typical SDS symptoms on 5-week-old soybean plants of cvs. Conrad, A2540, S19-90, and Ripley in the greenhouse. The severity and incidence of symptoms varied with cultivar and isolate. Of 125 plants inoculated, 6% of Conrad, 10% of A2540, 14% of S19-90, and 17% of Ripley plants developed foliar symptoms. Symptoms did not develop on noninoculated controls. F. solani f. sp. glycines was reisolated from roots of symptomatic plants. Although Ripley is known to have resistance to SDS (2), foliar and root symptoms developed following inoculation with each Ontario isolate of F. solani f. sp. glycines. Yield losses in 1996 were difficult to assess because of the scattered distribution of diseased plants in most fields. Diseased plants had few and poorly filled pods. In two fields, soybean growth was severely restricted in large areas covering 2 ha each; however, soybean cyst nematode (SCN) was present in both fields. SCN was present at all locations. Although total yield losses are currently low, it is evident that F. solani f. sp. glycines causing SDS has become widely distributed in southwest Ontario and disease severity is increasing. References: (1) K. W. Roy et al. Phytopathology 79:191, 1989. (2) P. A. Stevens et al. Crop Sci. 33:929, 1993.