Subterranean clover decline in permanent pastures in north-eastern Victoria

Abstract

Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35-140%) were obtained with subterranean clover at both sites, with corresponding decreases in A1 in the 0-10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4/~g g-~) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg-1 at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p= 0.05) at both sites.An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.

Development and characterization of microsatellite markers for the oomyceta Aphanomyces euteiches

“…Aphanomyces euteiches Drechsler is an oomycete pathogen of legumes, which causes a devastating root rot of pea (Pisum sativum L.) worldwide (Kraft and Pfleger, 2001). Initially considered as a pea root pathogen (Scott, 1961), A.euteiches was later reported to attack other legume species such as common bean, broad bean, faba bean, clover, and alfalfa (Pfender and Hagedorn, 1982;Greenhalgh and Merriman, 1985;Lamari and Bernier, 1985;Tofte et al, 1992;Burnett et al, 1994;Tivoli et al, 2006;Moussart et al, 2008). The only two efficient ways to control the disease are diverse crop rotations with non-host or suppressive crops and breeding for resistance.…”

Pathogenic characteristics of isolates of Aphanomyces euteiches from pea in France

“…Several authors also reported A. euteiches to be a pathogen of alfalfa ( Medicago sativa ) (Greenhalgh & Merriman, 1985), green bean ( Phaseolus vulgaris ) (Pfender & Hagedorn, 1982), broad bean ( Vicia faba ) (Lamari & Bernier, 1985) and clover ( Trifolium pratense , Tofte et al ., 1992; and Trifolium subterraneum , Burnett et al ., 1994). Many control measures have been tested (Papavizas & Ayers, 1974), but the only efficient way to control the disease identified to date is to avoid planting peas in contaminated fields and to ensure that there is an appropriate time interval between successive pea crops in the rotation (Carrouée et al ., 1995).…”

Damage to roots of Trifolium subterraneum L. (subterranean clover), failure of seedlings to establish and the presence of root pathogens during autumn–winter

“…The magnitude and prevalence of seedling losses indicated by the present results re‐emphasize the importance of treating pasture seeds with fungicide to maximize the establishment and yield of the sown species (Smiley et al. , 1986; Burnett et al. , 1994), even though it is known that fungicide treatments are usually only partially effective in controlling damping‐off and root disease (Barbetti et al.…”