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 Soybean Rust Caused by Phakopsora pachyrhizi in Nebraska.

Soybean rust caused by Phakopsora pachyrhizi Sydow was first observed in the continental United States in Louisiana in November 2004 (2). As part of the national soybean rust monitoring effort, samples were collected on 3 October 2007 during the scouting of fields with green leaves in southeastern Nebraska. After incubation at room temperature for 24 h, uredinea and urediniospores were observed with microscopic examination. Urediniospores were obovoid, hyaline to pale brown, and measured 20 to 30 × 18 to 20 µm. The observed morphology was typical of P. pachyrhizi (1). In addition to microscopic observation, P. pachyrhizi was confirmed with real-time (q)-PCR with Taq DNA polymerase on 4 October 2007 with the q-PCR standard operating procedure version 1.9 outlined by the USDA-CSREES and utilized by the National Plant Diagnostic Network with appropriate positive and negative controls (1). Samples initially identified with soybean rust were from Richardson County near the town of Rulo and in Otoe County south of Nebraska City. On 12 October 2007, soybean rust was confirmed in adjacent Pawnee and Nemaha counties. Soybean rust was identified in six fields with an incidence and severity of less than 1%. In fields where the disease was identified, the disease was distributed in low-lying, shaded areas near wind breaks. Although soybean rust was detected in four southeastern Nebraska counties, soybean yields were not affected by the disease. At the time of first detection, more than 80% of the Nebraska soybean crop was harvested. To our knowledge, this is the first report of P. pachyrhizi on soybeans in Nebraska, and currently, the northwestern most find on any host in the continental United States. References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

First Report of Sudden Death Syndrome of Soybean Caused by Fusarium solani f. sp. glycines in Nebraska.

During August of 2004, soybean (Glycine max (L.) Merr.) plants exhibiting symptoms typical of sudden death syndrome (SDS) caused by Fusarium solani (Mart.) Sacc. f. sp. glycines (= Fusarium virguliforme Akoi, O'Donnell, Homma, & Lattanzi) (1) were observed in Nemaha and Pierce counties in eastern Nebraska. Leaf symptoms ranged from small chlorotic spots to prominent interveinal necrosis on plants at R5-R6 growth stages. Taproots of symptomatic plants were plated on potato dextrose agar (PDA) amended with hymexazol, ampicillin, and rifampicin (HAR). Resulting fungal isolates grew slowly and developed masses of blue macroconidia, characteristic of F. solani f. sp. glycines. Sorghum seed infested with the isolates were placed 1.5 cm below soybean seeds of the susceptible cv. Sloan planted in clay pots (3). Noninfested sorghum seed and sorghum seed infested with F. oxysporum were controls. Plants were maintained for 32 days at 27.5 ± 2.5°C in the greenhouse. Small cholorotic spots were observed on leaves of F. solani f. sp. glycines-inoculated plants within 21 days followed by the development of interveinal chlorosis. Roots of symptomatic plants were plated on PDA with HAR and F. solani f. sp. glycines was recovered. Identification of the fungal cultures was further confirmed as F. solani f. sp. glycines by a real-time quantitative polymerase chain reaction (qPCR) assay described by Gao et al. (2). During 2005, SDS symptoms were also reported in early planted soybeans from Jefferson and Seward counties and the presence of SDS was confirmed by qPCR. The confirmation of SDS at multiple locations suggests that the pathogen is widely distributed in the eastern one-third of Nebraska. SDS could be a serious threat to soybean production in this area since spring weather conditions favor SDS infection and many producers plant soybean early in cool soils. References: (1) T. Akoi et al. Mycologia 95:660, 2003. (2) X. Gao et al. Plant Dis. 88:1372, 2004. (3) K. W. Roy et al. Plant Dis. 81:259, 1997.

Substance abuse/mental illness: diagnostic issues.

"Dual diagnoses" of substance abuse and mental illness disorders are common both in psychiatric and substance abuse treatment settings. Recent studies have demonstrated that specific diagnostic categories of mental illness have implications for treatment outcomes of dually disordered patients, but a diagnostic standard has not emerged. The present study compared lay-administered DIS diagnoses with clinical diagnoses of patients in a state hospital treatment program for "dual diagnoses" patients. Categories of DIS diagnoses showed weak association with categories of clinical diagnoses. Several frequent DIS diagnoses were not made clinically and vice versa. Implications for choice of diagnostic instruments to use with this patient population are discussed, as is the potential value of structured assessments in supplementing clinical data.