Microplot Experiments On the Effect of Plant Hosts On Populations of the Cereal Cyst Nematode (Heterodera a Venae) and On the Subsequent Yield of Wheat

Abstract

Microplots containing soil, naturally infested with the cereal cyst nematode (Heterodera avenae) were left fallow or sown to one of nine cereal cultivars or grass species for five consecutive years. Wild oat (Avena fatua) was the most efficient host and, after three plantings, the nematode reached a potential increase ceiling of 42.2 eggs/g soil. Of the cereal cultivars tested, wheat (cv. Olympic) and barley (cv. Prior) were the most efficient hosts and levels of approximately 40 eggs/g were reached after five plantings. Barley grass (Hordeum leporinum) was less efficient than Wimmera ryegrass (Lolium rigidum) which maintained a ceiling population of about 10 eggs/g. Under fallow, populations declined to 0.5 eggs/g after 4 years. The most inefficient cereal hosts were the oat, cv. Avon, and cereal rye, cv. South Australian. The low populations maintained under continuous cropping with these cereals suggested that a rapid selection of a resistance-breaking biotype is unlikely to result from the continued use of inefficient hosts. Growth and yield of a subsequent wheat crop on all plots reflected the relative levels of nematode populations. At the low levels of infestation, grain yields were more than double those on heavily infested plots.

Yield Loss Caused by Heterodera avenae in Cereal Crops Grown in a Mediterranean Climate1

“…Also, it has been reported that populations decline under a cereal monoculture, apparently due to biological control (Graham & Stone, 1975 ;Kerry & Crump, 1977). A similar decline has not been observed in Australia and populations increase to a ceiling level under a monoculture of susceptible cereals (Meagher & Brown, 1974). Field observations show that intensive cropping with susceptible cereal crops leads to a decline in yields and, sometimes, crop failure.…”

“…Under these conditions, yield loss is much greater (Meagher, 1972 ;Brown, 1972 ; Meagher & Brown, 1974 ;Meagher et al, 1978) than has been reported from Northern Europe (Graham & Stone, 1975 ;Williams & Beane, 1980). Yield loss of less than 10 % is difficult to detect by visual observation but, under Australian conditions, yield loss is often spectacular and frequently exceeds 50 ?6 of yield potential (Meagher et al, 1978).…”

“…In studies with field-grown crops in Australia, Meagher & Brown (1974) found that, at a population level of 2 eggs/g soil, yield was reduced by 20 % while at 16 eggs/g soil yield was reduced by 40 06.…”

Effect of the cereal cyst nematode, Heterodera filipjevi, on wheat in microplot trials

“…The reduction in grain yield increased with both increasing P i and P f . Meagher and Brown (1974), Fisher and Hancock (1991), Ibrahim et al (1999), Al-Hazmi et al (1999) and Smiley et al (2005a) reported similar results with H. avenae. In a similar experiment conducted by Fisher and Hancock (1990) a density of 5 egg (g soil) −1 or fewer of H. avenae caused a significant loss of about 10% in yield of wheat.…”

Global Knowledge And Its Application For The Integrated Control And Management Of Nematodes On Wheat

“…the given population of a pathogen to cause a given yield loss) must be determined under many environmental and genotypic factors, such as water and nutrient availability and tolerance and/or resistance reaction of a given cultivar or variety. Furthermore, interpretation of the damage threshold between specific nematological studies should be done with extreme caution, as very few studies are truly comparable, with inherent differences in sampling protocol, extraction procedure and nematodes counting (Duggan, 1961;Stone, 1968;Dixon, 1969;Gill & Swarup, 1971;Meagher & Brown, 1974;Simon & Rovira, 1982;Handa et al, 1985b;Dhawan & Nagesh, 1987, Rivoal & Sarr, 1987Fisher & Hancock, 1991;Zancada & Althöfer, 1994;Al-Hazmi, Al-Yahya, & Abdul-Razig, 1999;Ibrahim et al, 1999).…”