Selection and characterisation of Trichoderma isolates for suppression of Pratylenchus in wheat roots

Several species of root lesion nematode (Pratylenchus) are considered serious pests of grain crops in Australia. Two species, P. neglectus and P. thornei, are target species for this research as they are prevalent and of economic importance, causing up to $102 M per year. Currently, management relies on use of resistant crops and varieties and biological control could have an important role to provide more flexible management strategies. The programme is a collaboration between organisations in New Zealand and Australia and is funded by the Grains Research and Development Corporation of Australia. Trichoderma strains have been extensively studied for their biocontrol potential and the aim of this research is to develop a commercial bionematicide based on Trichoderma for the control of root lesion nematode when applied as a seed treatment. Over 100 Trichoderma strains have been evaluated for their rhizosphere competence and their ability to suppress nematode populations in wheat roots in a greenhouse screening assay, and greenhouse and outdoor pot trials in both New Zealand and Australia. Rhizosphere competence varied considerably between Trichoderma strains and species. The most consistently rhizosphere competent species on wheat roots were T. hamatum and T. harzianum. Suppression of live nematode numbers in the roots was up to a 65% reduction in the New Zealand greenhouse assay which compared to 55-77% for Vydate. Trichoderma treatments resulted in a 65% reduction in nematode numbers in the roots in a New Zealand greenhouse assay compared to 55-57% for Vydate. In pot trials in Australia, some Trichoderma strains significantly reduced nematode levels and increased wheat root biomass. A selection of strains is currently being evaluated in field trials in Australia. Results from the greenhouse bioassay, pot and field trials will be presented

Highly heritable resistance to root-lesion nematode (Pratylenchus thornei) in Australian chickpea germplasm observed using an optimised glasshouse method and multi-environment trial analysis

Pratylenchus thornei is a root-lesion nematode (RLN) of economic significance in the grain growing regions of Australia. Chickpea (Cicer arietinum) is a significant legume crop grown throughout these regions, but previous testing found most cultivars were susceptible to P. thornei. Therefore, improved resistance to P. thornei is an important objective of the Australian chickpea breeding program. A glasshouse method was developed to assess resistance of chickpea lines to P. thornei, which requires relatively low labour and resource input, and hence is suited to routine adoption within a breeding program. Using this method, good differentiation of chickpea cultivars for P. thornei resistance was measured after 12 weeks. Nematode multiplication was higher for all genotypes than the unplanted control, but of the 47 cultivars and breeding lines tested, 17 exhibited partial resistance, allowing less than two fold multiplication. The relative differences in resistance identified using this method were highly heritable (0.69) and were validated against P. thornei data from seven field trials using a multi-environment trial analysis. Genetic correlations for cultivar resistance between the glasshouse and six of the field trials were high (>0.73). These results demonstrate that resistance to P. thornei in chickpea is highly heritable and can be effectively selected in a limited set of environments. The improved resistance found in a number of the newer chickpea cultivars tested shows that some advances have been made in the P. thornei resistance of Australian chickpea cultivars, and that further targeted breeding and selection should provide incremental improvements