Abstract

Nine grass weed species common to cropping rotations in southern Australia were assessed as hosts of the root lesion nematodes, Pratylenchus neglectus (Rensch) Filipjev Schuurmans & Stekhoven and P. thornei Sher & Allen. Weeds were grown at 20°C and individual plants inoculated with 1000 P. neglectus or P. thornei. Weed species were classified as non-hosts, poor hosts or good hosts, based on comparison of the reproductive factor (final population/initial population, or Pf/Pi) with the cereal controls, triticale cv. Abacus (moderately resistant to P. neglectus and moderately susceptible to P. thornei) and wheat cv. Machete (susceptible to both nematodes). Hordeum glaucum Steudel, H. leporinum Link, Lolium rigidumGuadin and Bromus diandrus Roth were not hosts of P. neglectus (Pf/Pi = 0.35–0.77). B. rubens Roth, Vulpia bromoides (L.) Gray and V. fasciculata(Forssk.) Gray (Pf/Pi = 0.94–1.19) were poor hosts, and Avena sterilis L. and A. fatua L. (Pf/Pi = 4.10–5.93) were good hosts of P. neglectus. The Avenaspp. were more susceptible (P < 0.05) to P. neglectus than triticale cv. Abacus, and were as susceptible as wheat cv. Machete. V. bromoides, V. fasciculata, L. rigidumand A. fatua were resistant to P. thornei (Pf/Pi = 0.15–0.54). H. glaucum, B. diandrus and B. rubens were poor hosts of P. thornei(Pf/Pi = 1.06–1.46). A. sterilisand H. leporinum (Pf/Pi = 1.58–1.92) were good hosts of P. thornei, and both were as susceptible as wheat cv. Machete. Growth of susceptible weeds will allow increase and persistence of nematodes in cropping soils, compromising the use of resistant crops in rotations for management of P. neglectus and P. thornei.