Take All, Rhizoctonia, Crown Rot and Pratylenchus status of Western Australian paddocks

[摘要] Soil borne pathogens are ever present in the Western Australian (WA) farming landscape. Pathogens such as rhizoctonia (Rhizoctonia solani AG8), crown rot (Fusarium pseudograminearum), take-all (Gaeumannomyces graminis var. tritici) or root lesion nematodes (Pratylenchus spp) have periodically infected crops and reduced production.New technologies have been developed by the South Australian Research and Development Institute (SARDI) that measure the concentration of DNA of many pathogens that infect crops and pastures. This test, known as the SARDI PreDictaB, has not been widely used in WA.The PreDicaB test provides insight into what pathogens are present in the soil.However, a pathogen may not infect a plant and trained pathologists must score a plant for disease symptoms to confirm whether the process of infection took place or not. This project monitored the pathogen DNA levels and pathologists disease scores for 188 farmer’s paddocks from 2010 to 2014. Paddocks were sampled across rainfall zones (Low ( 300mm), Medium (300 – 450mm) and High ( 450mm)) and in the Northern and Southern Regions of the WA wheatbelt. There were two objectives. Firstly, to determine whether pathogen DNA levels and disease infection were increasing, decreasing or remaining stable across the WA wheatbelt. Secondly, to determine whether soil type, climate, and the PreDictaB test influenced the disease symptoms observed on the crop. From the survey, the incidence of rhizoctonia root rot, crown rot, take-all or root lesion nematodes (Pratylenchus spp) across the WA Wheat belt were either stable or in decline. This finding was in contrast to the pathogen DNA concentration in the soil.The SARDI PreDicta B test suggests Rhizoctonia solani AG8, Fusarium pseudograminearum and Pratylenchus spp DNA concentrations are increasing. Break crops such as canola, lupins or field peas were historically grown to manage disease. Pastures were also grown to break up the life cycle of disease.These surveys indicate that the break crops are reducing disease levels, but disease incidence in pastures averaged 36% and often failed to offer a break from pathogens for the cereal crop.Pastures are still the dominant break from cereals, and farmers should be encouraged to manage these pastures and ensure disease pressures remain low. High pathogen DNA concentrations levels (log score2.0) measured at anthesis were associated with higher levels of disease incidence (p0.0001 for all pathogens). Therefore the PreDictaB test did provide a statistically significant indicator that does relate to disease incidence. However, the PreDictaB test is one component of a complex dynamic that includes attributes of the soil and climate.All three components (climate, soil type and pathogen DNA) influence the expression of disease infection in a crop. The capacity to generate precise and accurate predictions about disease incidence was complicated because very few paddocks had serious disease problems with high incidence and severity ratings. Future studies should source a selection of paddocks with these attributes to facilitate constructing models that can predict severe disease problems.

[发布日期] 2015-10-13 [发布机构] CSIRO

[学科分类] 地球科学(综合)