Susceptibility of winter and summer crops to root and crown infection by Bipolaris sorokiniana

Abstract

The susceptibility of 24 winter and 17 summer crops to infection by Bipolaris sorokiniana was tested in a glasshouse experiment by growing them in soil amended with wheat-barley grain colonized by B. sorokiniana (0-2 g per lOOgsoil). At anthesis, infection of both lesionedand randomly selected segments of roots and of crowns was determined by plating them on modified Czapek-Dox Agar. Incidence of infection in winter crops was higher than in summer crops. Guar, mung bean, soybean and sunflower were the least infected of the summer crops while chickpeas and safflower were the least infected of the winter crops. Amongst the taxonomic groups tested, the highest incidence of infection occurred in the gramineous species and the lowest in the leguminous species.Five summer crops growing in the field were sampled and infection by B. sorokiniana confirmed. Cultivars of wheat, barley, triticale and oats were also screened in a field experiment. Amongst these winter cereals, oats was the least susceptible in both field and glasshouse experiments. Differences between cultivars in susceptibility to common root rot, measured by the degree of lesion development in the subcrown intcrnode, were identified in wheat, triticale and oats but not in barley.

Contribution ofAvenaspp., used in crop rotation systems under conservation tillage, to the inoculum levels of some cereal pathogens

“…Shoem. ), and Fusarium graminearum Schwabe (Diehl 1983, Ledingham & Chinn 1964, Mehra 1978, Oswald 1950, Reis & Santos 1987, Spurr & Kiesling 1961, Wildermuth & McNamara 1987. Other reports have indicated that Avena spp.…”

Fungal populations in subcrown internodes and crowns of oat crops in Saskatchewan

“…to C. sativus was 4.8 for SIs and 5.9 for CLCs, compared with 0.76 for SIs and 0.87 for CLCs for barley, and 0.49 for SIs and 0.45 for CLCs for common wheat. Wildermuth and McNamara (1987) also reported that oat was more resistant than other cereal species to root infection by C. sativus, whereas Makela and Makki (1980) did not isolate this pathogen from oat roots.…”

“…Shoemaker] is an important leaf, root and kernel pathogen of wheat and barley (Conner 1990). This pathogen causes less severe root rot symptoms in oat than in wheat or barley (Wildermuth and McNamara 1987), and was also reported to occur at lower levels in field residues of oat than in those of wheat or barley (Fernandez and dos Santos 1992). Reports from Saskatchewan and Manitoba leaf spot surveys showed that C. sativus was isolated at lower frequencies in oat leaves compared with Pyrenophora avenae Ito & Kurib.…”

Stubble trouble! Moisture, pathogen fitness and cereal type drive colonisation of cereal stubble by three fungal pathogens

“…All three pathogens colonised further in oat and barley stubble compared with bread wheat, even though oat exhibits lower incidence and severity of Fusarium crown rot , common root rot (Wildermuth and McNamara 1987) and yellow leaf spot (Hosford et al 1987;Rees and Platz 1979), and barley is not a recognised host of P. tritici-repentis. The barley and oat stubble had larger and hollow tillers which may allow pathogens to colonise more freely than in bread wheat.…”