Factors affecting production of inoculum of the blackleg fungus (Leptosphaeria maculans) in south-eastern Australia

2003 ◽  
Vol 43 (10) ◽  
pp. 1231 ◽  
Author(s):  
S. J. Marcroft ◽  
S. J. Sprague ◽  
S. J. Pymer ◽  
P. A. Salisbury ◽  
B. J. Howlett

The production of windborne ascospore inoculum of the blackleg fungus (Leptosphaeria maculans) was determined during 2000 and 2001 in 3 environments (Birchip, low rainfall; Wonwondah, medium rainfall; Lake Bolac, high rainfall) in Victoria. The weight of canola stubble (kg/ha) remaining on the soil surface in paddocks was estimated 6, 18, 30 and 42 months after harvest of the original canola crop. In all 3 environments only small amounts of stubble were present 18 months after harvest. Eighty percent of the 6-month-old stubble comprised stems and branches, with the remaining 20% being root material, while 42-month-old stubble consisted only of root material. Paddocks subjected to raking and burning contained only half the weight of stubble compared with paddocks that were harrowed. Where canola was harvested in January, even when no management strategy was used, 80% of subsequent stubble was no longer on the soil surface by July of that year. Pseudothecia from 6-month-old stubble from the high rainfall environment discharged significantly more ascospores than stubble of the same age from the medium rainfall environment, which in turn discharged more than stubble from the low rainfall environment. In all environments, paddocks containing 6-month-old canola stubble discharged 30-fold as many ascospores per hectare as older stubble paddocks.


2001 ◽  
Vol 52 (3) ◽  
pp. 329 ◽  
Author(s):  
G. D. Li ◽  
K. R. Helyar ◽  
M. K. Conyers ◽  
B. R. Cullis ◽  
P. D. Cregan ◽  
...  

A long-term trial, known as ‘managing acid soils through efficient rotations’ (MASTER), commenced in 1992 to develop and demonstrate a cropping system that is economically viable on the highly acid soils of the traditional permanent pasture region in south-eastern Australia, so that their fertility is sustained or improved. There were 2 permanent pasture systems and 2 pasture–crop rotations, each with and without lime. This paper reports the effect of lime on crop production over the first cycle (6 years). On annual pasture–crop rotations, lime significantly increased the dry matter production at anthesis and grain yields of wheat (cv. Dollarbird) compared with the unlimed treatments. Averaged across years from 1992 to 1997 (excluding the severe drought year 1994), wheat crops produced 1.6 t/ha more grain on the limed treatments than on the unlimed treatments (3.6 v. 2.0 t/ha). On perennial pasture–crop rotations, the lime effects varied with crops grown at each phase and year. For example, despite being tolerant of acidity, oats (cv. Yarran) responded to lime in 1996. Likewise, triticale (cv. Abacus) responded to lime in 1997. Wheat (cv. Dollarbird) that is moderately tolerant to acidity responded to lime in phase 6 from 1992 to 1997 excluding 1994 (3.5 v. 1.7 t/ha). Acid-tolerant wheat varieties, triticale, and narrow-leaf lupins are considered the most viable crops for the soil and climatic conditions encountered in this high rainfall (5000—800 mm per annum) area of south-eastern Australia.



2013 ◽  
Vol 95 (2) ◽  
pp. 269-285 ◽  
Author(s):  
Robert H. Harris ◽  
Sally J. Officer ◽  
Patricia A. Hill ◽  
Roger D. Armstrong ◽  
Kirsten M. Fogarty ◽  
...  


2008 ◽  
Vol 17 (5) ◽  
pp. 586 ◽  
Author(s):  
Suzanne M. Prober ◽  
Ian D. Lunt ◽  
Kevin R. Thiele

Frequent disturbances such as fire are widely considered important drivers of plant composition and diversity in productive grassy ecosystems. Effects of fire frequency on grassland soils, however, are less well understood. We established replicated disturbance regimes in a high-quality, representative Themeda australis–Poa sieberiana-derived grassland in south-eastern Australia that had historically been burnt every 4–8 years. Effects on soil chemical, physical and biological properties were measured after 10 years of application of 2-, 4-, and 8-yearly burning, 2-yearly mowing and an undisturbed treatment. Contrary to other grassy ecosystems, there were no detectable effects of disturbance regime on total soil nitrogen and carbon, or a range of other soil chemical properties in the top 10 cm. However, a cumulative effect of burning on the grassland soil was evident from a suite of changes to soil surface properties, available nutrients and biological activity. In particular, on biennially burnt plots, reduced litter and plant protective cover were associated with increased soil surface compaction, decreased infiltration and decreased soil biological activity, which in turn were related to poor sward recovery after fire and drought. These relationships indicate potential for positive feedbacks whereby repeated removal of soil protective cover and changes to soil surface chemistry through very frequent burning ultimately lead to further reduction in soil protective cover through reduced productivity. However, this is only likely in extreme cases: data from unburnt plots indicated that soils that had historically been burnt every 4–8 years had not passed a threshold beyond which such soil changes were irreversible or damaging. Contrary to other predictions, cessation of burning for 13 years did not lead to detectable soil nutrient release through senescence of dominant grasses. Biennial mowing with slash retention was an effective alternative disturbance for maintaining sward vigour while avoiding soil surface damage.



2015 ◽  
Vol 66 (4) ◽  
pp. 377 ◽  
Author(s):  
H. Dove ◽  
J. A. Kirkegaard ◽  
W. M. Kelman ◽  
S. J. Sprague ◽  
S. E. McDonald ◽  
...  

In south-eastern Australia, low winter temperatures often reduce pasture growth and thus winter herbage supply relative to livestock requirements. Grazing of vegetative grain crops in winter is one strategy that might overcome this feed gap. In a study with young sheep over two seasons near Canberra, ACT, we compared pasture-only grazing with three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these, for intervals over the period May–August. We measured forage biomass, sheep grazing days (SGD) and liveweight accumulated per ha. Crop-grazing treatments resulted in much more winter forage for grazing sheep (t DM ha–1): in 2010, one crop 2.5–3.0, two crops 3.5 v. pasture only 1; in 2011, one crop 2, two crops 3 v. pasture only 1.4. In the first season, grazing one crop resulted in ~2000 extra SGD ha–1 and the accumulation of more liveweight per ha than in the pasture-only treatment; grazing of two crops resulted in >3500 extra SGD ha–1. Equivalent values in the second, drier season were: one crop, ~1000 extra SGD ha–1; two crops, 2600 extra SGD ha–1. Spelling of pastures during crop grazing led to extra pasture growth, such that in each of the two seasons, 40% of the total benefit in extra SGD per ha came from the extra pasture. The results indicate that, like grazed wheat, grazed canola can provide valuable winter forage, especially when used together with wheat. The data also provide the first quantification of the effect of crop grazing on pasture spelling and subsequent pasture supply, and suggest value in the incorporation of grazing wheat and canola into grazing systems in the high-rainfall zone.





1972 ◽  
Vol 20 (2) ◽  
pp. 197 ◽  
Author(s):  
RW Rogers ◽  
RT Lange

Lichens on soils in Australia have been neglected until recently. This paper describes a study area of nearly 1 million km2 in south-eastern Australia, and the methods used to determine the lichens found on the soil surfaces in that area. In all, 343 locations were examined, 227 of which had soil surface lichens. From the range of lichens encountered a total of 42 taxa were delimited, and in 36 cases ascribed to previously described species or complexes; the remaining six were either un- described, or depauperate forms which could not be placed. The world phytogeographic implications of this study are discussed.



2016 ◽  
Vol 106 (1) ◽  
pp. 113-128 ◽  
Author(s):  
Robert H. Harris ◽  
Roger D. Armstrong ◽  
Ashley J. Wallace ◽  
Oxana N. Belyaeva


2014 ◽  
Vol 156 ◽  
pp. 30-39 ◽  
Author(s):  
Susan J. Sprague ◽  
John A. Kirkegaard ◽  
John M. Graham ◽  
Hugh Dove ◽  
Walter M. Kelman


2018 ◽  
Vol 69 (3) ◽  
pp. 303 ◽  
Author(s):  
Corinne Celestina ◽  
Jon Midwood ◽  
Stuart Sherriff ◽  
Sam Trengove ◽  
James Hunt ◽  
...  

In the high-rainfall zone of south-eastern Australia, deep incorporation of organic matter has previously been reported to increase crop yields by improving access to subsoil water and nutrients, resulting from the amelioration of subsoil constraints. However, previous experiments did not separate the yield response resulting from nutrients contained in the amendment from yield response due to amelioration of subsoil constraints. In order to separate these effects, eight field experiments were conducted on a range of soil types across the medium- and high-rainfall zones of south-eastern Australia between 2014 and 2016. Grain yield and quality responses of a range of annual crops (canola, wheat, barley and lentil) to surface and deep placement of poultry litter and inorganic fertilisers with matched nutrition were assessed. Over 15 site × year combinations, there was no consistent, significant positive interaction between amendment and incorporation treatments necessary to demonstrate that deep placement of amendment (i.e. subsoil manuring) had advantages over surface application of the same amendment. Differences in crop yield in these experiments are attributed to nutrients (particularly nitrogen) supplied by the amendment, and not to the amelioration of subsoil constraints. Future research, including analysis of subsoil physicochemical properties and plant nutrient concentrations after treatment, is necessary to confirm the role of nitrogen and other nutrients in the crop response to subsoil manuring.



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