A complex of foliar diseases affects onion production in New York, including Botrytis leaf blight (Botrytis squamosa), purple blotch (Alternaria porri), Stemphylium leaf blight (SLB; Stemphylium vesicarium), and downy mildew (Peronospora destructor). Surveys were conducted in 2015 and 2016 to evaluate the cause of severe premature foliar dieback in New York onion fields. SLB was the most prevalent disease among fields with the greatest incidence, surpassing downy mildew, purple blotch, and Botrytis leaf blight. Sequencing of the internal transcribed spacer region of ribosomal DNA and the glyceraldedyhe-3-phosphate dehydrogenase and calmodulin genes identified S. vesicarium as the species most commonly associated with SLB. S. vesicarium was typically associated with a broad range of necrotic symptoms but, most commonly, dieback of leaf tips and asymmetric lesions that often extended over the entire leaf. Because of the intensive use of fungicides for foliar disease control in onion crops in New York, the sensitivity of S. vesicarium populations to various fungicides with site-specific modes of action was evaluated. Sensitivity of S. vesicarium isolates collected in 2016 to the quinone outside inhibitor (QoI) fungicide, azoxystrobin, was tested using a conidial germination assay. Isolates representing a broad range of QoI sensitivities were selected for sequencing of the cytochrome b gene to evaluate the presence of point mutations associated with insensitivity to azoxystrobin. The G143A mutation was detected in all 74 S. vesicarium isolates with an azoxystrobin-insensitive phenotype (effective concentrations reducing conidial germination by 50%, EC50 = 0.2 to 46.7 µg of active ingredient [a.i.]/ml) and was not detected in all 31 isolates with an azoxystrobin-sensitive phenotype (EC50 = 0.01 to 0.16 µg a.i./ml). The G143A mutation was also associated with insensitivity to another QoI fungicide, pyraclostrobin. Sensitivity to other selected fungicides commonly used in onion production in New York was evaluated using a mycelial growth assay and identified isolates with insensitivity to boscalid, cyprodinil, and pyrimethanil, but not difenoconazole. The frequency of isolates sensitive to iprodione, fluxapyroxad, and fluopyram was high (93.5 to 93.6%). This article discusses the emergence of SLB as dominant in the foliar disease complex affecting onion in New York and the complexities of management posed by resistance to fungicides with different modes of action.
The reactions of a series of β-diketiminate stabilised aluminium dihydrides with ruthenium bis(phosphine), palladium bis(phosphine) and palladium cyclopentadienyl complexes is reported.
In this paper we compare three different orthogonal systems in $$\textrm{L}_2({\mathbb {R}})$$ L 2 ( R ) which can be used in the construction of a spectral method for solving the semi-classically scaled time dependent Schrödinger equation on the real line, specifically, stretched Fourier functions, Hermite functions and Malmquist–Takenaka functions. All three have banded skew-Hermitian differentiation matrices, which greatly simplifies their implementation in a spectral method, while ensuring that the numerical solution is unitary—this is essential in order to respect the Born interpretation in quantum mechanics and, as a byproduct, ensures numerical stability with respect to the $$\textrm{L}_2({\mathbb {R}})$$ L 2 ( R ) norm. We derive asymptotic approximations of the coefficients for a wave packet in each of these bases, which are extremely accurate in the high frequency regime. We show that the Malmquist–Takenaka basis is superior, in a practical sense, to the more commonly used Hermite functions and stretched Fourier expansions for approximating wave packets.
In this paper we compare three different orthogonal systems in L2(R) which can be used in the construction of a spectral method for solving the semi-classically scaled time dependent Schrödinger equation on the real line, specifically, stretched Fourier functions, Hermite functions and Malmquist-Takenaka functions. All three have banded skew-Hermitian differentiation matrices, which greatly simplifies their implementation in a spectral method, while ensuring that the numerical solution is unitary -this is essential in order to respect the Born interpretation in quantum mechanics and, as a byproduct, ensures numerical stability with respect to the L2(R) norm. We derive asymptotic approximations of the coefficients for a wave packet in each of these bases, which are extremely accurate in the high frequency regime. We show that the Malmquist-Takenaka basis is superior, in a practical sense, to the more commonly used Hermite functions and stretched Fourier expansions for approximating wave packets.
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