The potential of non‐pathogenic Gaeumannomyces spp., occurring naturally or introduced into wheat crops or preceding crops, for controlling take‐all in wheat

Abstract

Take-all disease (Gaeumannomyces graminis var. tritici) in wheat crops is known to be suppressed by naturally occurring antagonistic fungi, closely related to the pathogen, that infect grasses and cereals. This form of suppression was re-investigated because of the changing importance and role of grass weeds and grass covers in arable farming. Natural populations of the competitive fungus Gaeumannomyces cylindrosporus, allowed to develop under rye-grass, were more effective than artificially introduced populations in suppressing the development of take-all in following wheat crops. To be effective, the antagonist needs to be present before the start of wheat cropping. Introducing G. cylindrosporus, but not G. graminis var. graminis (a potential antagonist that is faster growing), into a previous crop, or just after the previous crop, sometimes suppressed take-all, but the effect was small. It is concluded that, for any future attempts at biocontrol by these fungi, they should be introduced into a preceding crop not susceptible to take-all. Take-all inoculum in the soil should be at a minimum and effective hosts of the take-all pathogen must not be present as weeds or volunteers.

A new species of Harpophora (Magnaporthaceae) recovered from healthy wild rice (Oryza granulata) roots, representing a novel member of a beneficial dark septate endophyte

“…After 30 days of coculture in half‐strength Murashige and Skoog (1/2 MS) medium under aseptic conditions (25 °C, 18 h light/6 h darkness), H. oryzae strongly promotes growth and biomass formation of rice plants (see Supporting Information, Figs S1 and S2), similar to H. graminicola , a beneficial DSE of grasses (Kirk & Deacon, 1987; Newsham, 1999). In previous reports, isolates of the naturally occurring nonpathogenic G. cylindrosporus were effective in controlling talk‐all when introduced into wheat crops (Gutteridge et al ., 2007).…”

Genetic variation, pathogenicity and mycelial growth rate differentiation between Gaeumannomyces graminis var. tritici isolates derived from winter and spring wheat

“…In many soils, second or subsequent wheat crops are at risk of severe damage from take-all (Gutteridge et al, 2007). tritici (Ggt) is one of the most economically important root and stem-base diseases of wheat worldwide.…”

“…tritici (Ggt) is one of the most economically important root and stem-base diseases of wheat worldwide. In many soils, second or subsequent wheat crops are at risk of severe damage from take-all (Gutteridge et al, 2007). Disease impact on yield is likely to vary according to earliness of disease and consequently to the nature of the affected yield components (Shoeny et al, 2001).…”

Susceptibility to take-all of cereal and grass species, and their effects on pathogen inoculum

“…Grasses such as L. perenne can host antagonists of Ggt such as Phialophora graminicola (teleomorph Gaeumannomyces cylindrosporus ) (Deacon, 1976). Phialophora radicicola is common in L. perenne in New Zealand pastures (Skipp & Christensen, 1989), and has been shown to reduce the level of take‐all in subsequent wheat crops (Slope et al , 1979; Gutteridge et al , 2007). Micro‐organisms that either suppress take‐all or inhibit take‐all suppression are suspected to contribute to variation within and between studies on effects of different grass species (Jenkyn et al , 1998; Bateman et al , 2005; Gutteridge et al , 2006, 2007).…”

“…Previous studies have either used bioassays to measure Ggt inoculum during break crops and fallow (Dulout et al , 1997; Gutteridge et al , 2005) or assessed take‐all severity in following wheat crops (Ennaifar et al , 2005; Gutteridge et al , 2007). However, where suppressive or conducive factors affect the level of infection, symptoms may not provide a reliable measure of inoculum.…”