Ground Cover Supplement : GC Supplement - Foliar fungal diseases of pulses
13 Pulses / oilseeds Staying abreast of chickpea ascochyta PHOTO:CLARISACOLLISPHOTO:GRDC GRDC-funded research, with linkages to SARDI (page 12) and Curtin University Centre for Crop and Disease Management (page 14), led by Associate Professor Rebecca Ford at the University of Melbourne is gaining a clearer picture of the relative aggressiveness of chickpea ascochyta isolates across Australian chickpea-growing regions. The aim is to supply the most destructive isolates annually to the national chickpea-breeding program, being led by Dr Kristy Hobson from the New South Wales Department of Primary Industries (DPI), for pre-emptive resistance breeding. The potential for the pathogen to erode current sources of resistance sources is also being assessed. Advanced breeding material is screened for its disease response to the most aggressive isolates under conditions optimal for disease development. The team is also using information on location, host genotype, isolate frequency and aggressiveness to determine whether the ascochyta pathogen is adapting within popular commercial chickpea varieties. The survey work has recently identified several particularly aggressive ascochyta isolates of differing pathotypes, including several from South Australia that can generate spores and cause extensive damage to the resistant chickpea varieties PBA HatTrick A and GenesisTM090. Other isolates from northern NSW have been found to sporulate on and destroy PBA HatTrick A but not GenesisTM090; however, no isolate has been detected that can overcome the ICC3996 resistance source, although moderate disease has been noted. The findings show that the ascochyta population is potentially changing and becoming more pathogenic to even the most resistant chickpea varieties. “We are always going to be a season behind the pathogen, but the survey work is so important because it enables us to keep abreast of the most aggressive isolates and where they are located regionally,” Associate Professor Ford says. “By identifying the most aggressive isolates we can ensure that future chickpea varieties are going to be as sustainable as possible for as long as possible.” Associate Professor Ford is working closely with Dr Kevin Moore from the NSW DPI to unravel the biology of the new ascochyta isolates. “We want to determine how the isolates are interacting with chickpea varieties and whether the more aggressive forms of the pathogen are in fact breaking down the physical and biochemical barriers that condition varietal resistance to the disease.” Associate Professor Ford is keen to receive more ascochyta isolates for testing. Samples should be sent to: Dr Sam Sambasivum Faculty of Veterinary and Agricultural Sciences The University of Melbourne, Parkville Victoria 3010 Collected infected tissue such as leaf and stem should be put in separate paper bags as dry as possible and posted as soon as possible. Include collector’s name and contact details, location of collection and cultivar on the bag. GRDC Research Codes UM00052, DAN00151 More information: Rebecca Ford, University of Melbourne, firstname.lastname@example.org; Dr Kevin Moore, NSW Department of Primary Industries, 02 6763 1133, email@example.com; Kristy Hobson, NSW DPI, 02 6763 1174, firstname.lastname@example.org Summer crops play an important part in the varied farming systems from central New South Wales to Central Queensland where they provide a break for wheat diseases, while enabling weed-management options and crop-income diversity. Integrated disease management (IDM) of the major diseases of summer crops, through various combinations of plant resistance, fungicides, planting seed selection, planting time, paddock selection and other agronomic practices, has been the focus of the joint University of Southern Queensland (USQ) and Queensland Department of Agriculture and Fisheries summer field crops pathology team. Examples of IDM include: the strategic use of fungicides and resistance to manage rust and leaf spot of peanuts and powdery mildew of mungbeans; and resistance/tolerance studies and planting strategies to manage tobacco streak virus in sunflowers and other crops in Central Queensland. The current focus of research is on the roles that all crops (and weeds) in the varied farming systems play in biology of pathogens of summer field crops to provide improved management options. The researchers are finding that some pathogens have a much wider host range than previously thought. Some newly found Diaporthe (Phomopsis) species are capable of causing stem cankers on sunflowers, soybeans and mungbeans and a range of other crops, but can also infect a range of live weeds and weed stubble; others can infect ‘host’ plants without causing symptoms such as the damaging D. gulyae on maize. Similarly, Fusarium thapsinum, which is a major cause of sorghum stalk rot, has been shown to be capable of invading living plants of ‘non-hosts’ including chickpeas, mungbeans and maize, with no symptoms being displayed. Plant residues are an important mode of survival of many plant pathogens, including species of Diaporthe and Fusarium. Traditionally, infected residues of the recognised major hosts, for example sorghum infected with F. thapsinum, charcoal rot on sunflowers, sorghum and soybeans and Diaporthe species on sunflowers and soybeans, have been considered to be the main means of survival from season to season. However, preliminary findings suggest that residues of asymptomatic non-hosts including crops and weeds may play a similarly important role and can be a reservoir for disease. These findings have farm-scale implications, particularly with respect to stubble and weed management and crop sequences. GRDC Research Code DAQ00186 More information: Dr Sue Thompson, USQ, 0477 718 593, email@example.com Wide host range for summer diseases Sunflowers on the Darling Downs, Queensland. Immature chickpeas.
GC Supplement - Profitable pulses and pastures
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