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The pathogenicity of 45 isolates of Ascochyta pinodes, Ascochyta pisi and Phoma medicaginis var. pinodella collected in South Australia has been examined on selected pea lines. Twenty-six isolates of A. pinodes were differentiated into 15 pathotypes, 15 isolates of A. pisi were differentiated into 13 pathotypes, and four isolates of P. medicaginis var. pinodella into one pathotype. Adequate sources of resistance were identified against all the pathotypes excepting pathotypes 1 of A. pinodes and A. pisi. The necessity to breed for broadly based resistance to Ascochyta species is discussed.

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Th excess in Guatemalan mafic samples, on the other hand, is crustal contamination, consistent with the relatively high Th/Nb and low Ba/Th ratios in these samples. We suspect, however, that crustal contamination only exerts a sizable control over the U-series disequilibrium of mafic magmas in Guatemala, and not elsewhere along the Central American volcanic front. This agrees with previously published trace element and isotopic evidence that throughout Central America, with the exception of Guatemala, mafic magmas are largely uncontaminated by crustal material.