Increasing soil temperature to reduce sclerotial viability of Sclerotium cepivorum in New Zealand soils

Effect of environmental factors and Sclerotium cepivorum isolate on sclerotial degradation and biological control of white rot by Trichoderma

“…The spatial distribution of S. cepivorum sclerotia and Trichoderma inoculum is important, as temperature and water potential will change down the soil profile and S. cepivorum sclerotia have been shown to infect roots of garlic from as deep as 30 cm (Crowe & Hall, 1980a). Temperature and water potential have also been shown to affect dormancy and survival of S. cepivorum sclerotia (Crowe & Hall, 1980b; Adams, 1987; Gerbrandy, 1992; McLean et al ., 2001). Further work is therefore required to predict the efficacy of biological control of S. cepivorum in the field as modified by natural environmental conditions, in order to identify periods when other disease control measures may be needed within an integrated crop protection system.…”

“…This allows the use of pesticides on some minor crops in the UK where manufacturers have sought approval only on major crops such as cereals. Other potential control strategies focus on the removal of primary sclerotial inoculum, and include soil solarization (Melero‐Vara et al ., 2000; McLean et al ., 2001); aerobic composting of infected residues; incorporation of plant residues or composts (Smolinska, 2000; Coventry et al ., 2002); or application of diallyl disulphide to stimulate sclerotial germination (Merriman et al ., 1980; Entwistle et al ., 1982; Slawson et al ., 1989; Crowe et al ., 1994; McDonald & Hovius, 1998). However, these approaches are either unsuitable for UK conditions or require further development.…”

Selection of fungal biological control agents of Sclerotium cepivorum for control of white rot by sclerotial degradation in a UK soil

“…This is the first time that biological control of white rot has been demonstrated in the field using this method, and the success of BCAs selected primarily to reduce initial sclerotial inoculum by degradation confirms the usefulness of the screening system and the effectiveness of this strategy for white rot control. This removal of primary sclerotial inoculum has also been demonstrated using other methods, including soil solarization (Melero‐Vara et al ., 2000; McLean et al ., 2001); incorporation of plant residues or composts (Smolinska, 2000; Coventry et al ., 2002); or application of sclerotial germination stimulants such as diallyl disulphide (Merriman et al ., 1980). Disease control in the field experiments might also have been improved if additional BCA treatments had been made preseeding (perhaps as a different formulation), and also if the fluid‐drill configuration had allowed more BCA to be delivered, thereby potentially destroying more sclerotia and affording further plant protection.…”

Integrated control of Allium white rot with Trichoderma viride, tebuconazole and composted onion waste

“…Nevertheless, these results still suggest that the use of T. viride is potentially compatible with tebuconazole, but further work on quantifying the effect of the fungicide on T. viride L4 and S17A is now required. In New Zealand, McLean et al (2001) showed that T. harzianum (another effective BCA of S. cepivorum ), although sensitive to tebuconazole in vitro , was only partially suppressed by the fungicide in soil, and populations of the fungus recovered over time. Similarly, C. minitans was demonstrated to be compatible with iprodione for control of Sclerotinia sclerotiorum in glasshouse soil despite its sensitivity to the fungicide in agar tests (Budge & Whipps, 2001).…”

“…Despite efforts to find resistance to S. cepivorum within existing cultivars and other Allium species (Utkhede et al , 1982; Brix & Zinkernagel, 1992), there are no commercial Allium cultivars with sufficient resistance that currently can be exploited for AWR control. Other potential control strategies for AWR have therefore been investigated, including soil solarization (Melero‐Vara et al , 2000; McLean et al , 2001) and application of diallyl disulphide (DADS) to stimulate sclerotial germination in the absence of a host (Crowe et al , 1994; Hovius & McDonald, 2002), but these approaches are generally unsuitable for UK conditions. More recently, cruciferous residues (Smolinska, 2000) and composted onion and other vegetable wastes (Coventry et al , 2005) have been shown to eradicate S. cepivorum sclerotia and control AWR when incorporated into soil, but in the UK this type of approach has yet to be fully developed by researchers and exploited by growers.…”