Persistence and leaching of sulfonylurea herbicides over a 4-year period in the highly alkaline soils of south-eastern Australia

2006 ◽  
Vol 46 (8) ◽  
pp. 1069 ◽  
Author(s):  
K. L. Hollaway ◽  
R. S. Kookana ◽  
D. M. Noy ◽  
J. G. Smith ◽  
N. Wilhelm
Keyword(s):  
Crop Damage ◽  
Sulfonylurea Herbicides ◽  
Alkaline Soils ◽  
Metsulfuron Methyl ◽  
South Eastern ◽  
Eastern Australia ◽  
Current Product ◽  
Potential Damage ◽  
Ph Range ◽  
South Eastern Australia

The sulfonylurea herbicides are commonly used in the cereal belt of south-eastern Australia and there is concern that their persistence in alkaline soils is long enough to damage subsequent rotational crops such as legumes and oilseeds. In this study, we investigated leaching and persistence of 3 commonly used herbicides (chlorsulfuron, triasulfuron and metsulfuron-methyl) in alkaline soils of south-eastern Australia (pH range 7.4–8.6) for at least 4 years after treatment. In general, chlorsulfuron was predicted to persist for 3–5 years [time to degrade to 1% (DT99) of 33–63 months after treatment depending on the field site], triasulfuron for 1–3 years (DT99 of 13–37 months after treatment), and metsulfuron-methyl for less than 1 year (although data were insufficient for degradation estimates) after its application. However, this varied between sites and years of application. Although, the majority of residues remained in the top 20 cm of the soil profile throughout the study, leaching of a small fraction of the residue to deeper layers of the profiles (up to 1 m) was observed. Despite their slow rate of degradation, the herbicides did eventually dissipate, even in soils with very high pH (8.5). In most cases, the current product labels provide an adequate safety period to protect sensitive rotational crops from potential damage due to excessive persistence. However, in particular years at 3 of the 5 field sites, metsulfuron-methyl and triasulfuron persisted beyond the recommended recropping period (9 months for metsulfuron-methyl and 22 months for triasulfuron in soils up to pH 7.5 or 24 months in soils pH 7.6 and above). An accurate measurement of soil pH and its variability within the paddock is essential to minimise any subsequent crop damage by these herbicides.

Crop damage caused by residual acetolactate synthase herbicides in the soils of south-eastern Australia

2006 ◽  
Vol 46 (10) ◽  
pp. 1323 ◽  
Author(s):  
K. L. Hollaway ◽  
R. S. Kookana ◽  
D. M. Noy ◽  
J. G. Smith ◽  
N. Wilhelm
Keyword(s):  
Acetolactate Synthase ◽  
Clay Soils ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Metsulfuron Methyl ◽  
Herbicide Residues ◽  
South Eastern ◽  
Eastern Australia ◽  
The Impact ◽  
South Eastern Australia

Grain growers in south-eastern Australia have reported unexpected crop failures with theoretically safe recropping periods for acetolactate synthase herbicides in alkaline soils. This experience has led to the concern that these herbicides may degrade very slowly in alkaline soils, and herbicide residues have at times been blamed for unexplained crop losses. To address this issue, we established 5 recropping trials across Victoria and South Australia with 5 acetolactate synthase herbicides (chlorsulfuron, triasulfuron, metsulfuron-methyl, imazethapyr, and flumetsulam). The herbicides were applied to separate plots in years 1, 2 or 3, and sensitive crop species were sown in year 4 to measure the impact of herbicide residues. We observed that the persistence of the sulfonylureas (chlorsulfuron, triasulfuron, metsulfuron-methyl) varied between herbicides, but all persisted longer in alkaline soils than in acid soils, and were, therefore, more likely to damage crops in alkaline soil. Imazethapyr persisted longer in clay soils than in sandy soils and was, therefore, more likely to damage crops in clay soils. All herbicides persisted longer when rainfall was below average. Canola was more sensitive to imazethapyr than either pea, lentil or medic, but was less sensitive to the sulfonylureas. In contrast, lentil and medic were the most sensitive to sulfonylureas. Despite some damage, we found that safe recropping periods could be predicted from the product labels in all but one situation. The sole exception was that metsulfuron-methyl reduced dry matter and yield of lentil and medic sown 10 months after application in a soil with pH 8.5. We hypothesise that the real cause of crop failure in many situations is not unusual herbicide persistence, but failure to take full account of soil type (pH and clay content including variation in the paddock) and rainfall when deciding to recrop after using acetolactate synthase herbicides.

scholarly journals Cost-benefit trade-offs of bird activity in apple orchards

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2179 ◽  
Author(s):  
Rebecca K. Peisley ◽  
Manu E. Saunders ◽  
Gary W. Luck
Keyword(s):  
Crop Yields ◽  
Codling Moth ◽  
Crop Damage ◽  
Apple Orchards ◽  
Net Benefit ◽  
South Eastern ◽  
Trade Offs ◽  
Eastern Australia ◽  
Bird Damage ◽  
South Eastern Australia

Birds active in apple orchards in south–eastern Australia can contribute positively (e.g., control crop pests) or negatively (e.g., crop damage) to crop yields. Our study is the first to identify net outcomes of these activities, using six apple orchards, varying in management intensity, in south–eastern Australia as a study system. We also conducted a predation experiment using real and artificial codling moth (Cydia pomonella) larvae (a major pest in apple crops). We found that: (1) excluding birds from branches of apple trees resulted in an average of 12.8% more apples damaged by insects; (2) bird damage to apples was low (1.9% of apples); and (3) when trading off the potential benefits (biological control) with costs (bird damage to apples), birds provided an overall net benefit to orchard growers. We found that predation of real codling moth larvae was higher than for plasticine larvae, suggesting that plasticine prey models are not useful for inferring actual predation levels. Our study shows how complex ecological interactions between birds and invertebrates affect crop yield in apples, and provides practical strategies for improving the sustainability of orchard systems.

Persistence and leaching of imazethapyr and flumetsulam herbicides over a 4-year period in the highly alkaline soils of south-eastern Australia

2006 ◽  
Vol 46 (5) ◽  
pp. 669 ◽  
Author(s):  
K. L. Hollaway ◽  
R. S. Kookana ◽  
D. M. Noy ◽  
J. G. Smith ◽  
N. Wilhelm
Keyword(s):  
Clay Soil ◽  
Soil Depth ◽  
Sandy Soils ◽  
Clay Content ◽  
Acetolactate Synthase ◽  
Alkaline Soils ◽  
South Eastern ◽  
Adequate Information ◽  
Eastern Australia ◽  
South Eastern Australia

Imazethapyr and flumetsulam are acetolactate synthase herbicides commonly used in the cereal belt of south-eastern Australia. As their labels recommend recropping periods of up to 34 months for imazethapyr and 24 months for flumetsulam, there are concerns that in some cases their persistence may damage subsequent rotation crops. This is the first major study in south-eastern Australia to investigate their leaching and persistence for up to 4 years after treatment. Imazethapyr persisted for more than 3 years at 2 sites and flumetsulam for more than 2 years at 3 sites. For imazethapyr, soil type (clay content) rather than soil pH seemed to be most important in determining persistence, with residues of 10% of applied imazethapyr predicted to persist for 24 months after treatment in clay soil and 5 months after treatment in sandy soil. The potential for leaching below our studied soil depth of 40 cm is of concern for imazethapyr but not for flumetsulam. The current labels appear to provide adequate information for safe recropping periods, but may be conservative for imazethapyr in sandy soils.

Subsoil constraints to crop production on neutral and alkaline soils in south-eastern Australia: a review of current knowledge and management strategies

2007 ◽  
Vol 47 (11) ◽  
pp. 1245 ◽  
Author(s):  
D. Adcock ◽  
A. M. McNeill ◽  
G. K. McDonald ◽  
R. D. Armstrong
Keyword(s):  
Crop Production ◽  
Rooting Depth ◽  
Nutrient Deficiencies ◽  
Alkaline Soils ◽  
Management Options ◽  
Deep Placement ◽  
South Eastern ◽  
Eastern Australia ◽  
The Impact ◽  
South Eastern Australia

Crop yield variability and productivity below potential yield on neutral and alkaline soils in the semiarid Mediterranean-type environments of south-eastern Australia have been attributed, in part, to variable rooting depth and incomplete soil water extraction caused by physical and chemical characteristics of soil horizons below the surface. In this review these characteristics are referred to as subsoil constraints. This document reviews current information concerning subsoil constraints typical of neutral and alkaline soils in south-eastern Australia, principally salinity, sodicity, dense soils with high penetration resistance, waterlogging, nutrient deficiencies and ion toxicities. The review focuses on information from Australia (published and unpublished), using overseas data only where no suitable Australian data is available. An assessment of the effectiveness of current management options to address subsoil constraints is provided. These options are broadly grouped into three categories: (i) amelioration strategies, such as deep ripping, gypsum application or the use of polyacrylamides to reduce sodicity and/or bulk density, deep placement of nutrients or organic matter to overcome subsoil nutrient deficiencies or the growing of ‘primer’ crops to naturally ameliorate the soil; (ii) breeding initiatives for increased crop tolerance to toxicities such as salt and boron; and (iii) avoidance through appropriate agronomic or agro-engineering solutions. The review highlights difficulties associated with identifying the impact of any single subsoil constraint to crop production on neutral and alkaline soils in south-eastern Australia, given that multiple constraints may be present. Difficulty in clearly ranking the relative effect of particular subsoil constraints on crop production (either between constraints or in relation to other edaphic and biological factors) limits current ability to develop targeted solutions designed to overcome these constraints. Furthermore, it is recognised that the task is complicated by spatial and temporal variability of soil physicochemical properties and nutrient availability, as well as other factors such as disease and drought stress. Nevertheless, knowledge of the relative importance of particular subsoil constraints to crop production, and an assessment of impact on crop productivity, are deemed critical to the development of potential management solutions for these neutral to alkaline soils.

Mobility and persistence of three sulfonylurea herbicides in alkaline cropping soils of south-eastern Australia

1999 ◽  
Vol 39 (4) ◽  
pp. 465 ◽  
Author(s):  
I. D. Black ◽  
R. N. Pederson ◽  
A. Flynn ◽  
M. Moerkerk ◽  
C. B. Dyson ◽  
...  
Keyword(s):  
Field Trials ◽  
Biologically Active ◽  
Alkaline Soil ◽  
Sampling Depth ◽  
Metsulfuron Methyl ◽  
South Eastern ◽  
Eastern Australia ◽  
Sampling Zone ◽  
Low Levels ◽  
South Eastern Australia

Biologically active residues of the herbicides metsulfuron-methyl, chlorsulfuron and triasulfuron were estimated with field pea bioassays in soil samples to 80 cm depth from 4 field trials in south-eastern Australia situated on neutral to highly alkaline soil. Residues were both mobile and persistent at low levels. Leaching occurred beyond the lowest sampling depth during the winter–spring growing season. Metsulfuron-methyl was the most mobile of the 3 herbicides. Plant-back experiments involving susceptible crop and pasture species on 2 of the sites showed that the rates of decline of these residues in the sampling zone were slower than might be inferred from label plant-back recommendations in 1 of 2 seasons.

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