Suppression of Wheat Growth and Yield by Pratylenchus neglectus in the Pacific Northwest

Abstract

Many wheat (Triticum aestivum) fields planted annually in the Pacific Northwest are infested by high populations of the lesion nematode, Pratylenchus neglectus. Spring wheat cultivars varying in tolerance and resistance to P. neglectus were treated or not treated with aldicarb to examine relationships between the nematode and growth and yield of annual direct-seeded (no-till) wheat. Increasing initial density of P. neglectus in soil was more strongly associated with declining growth and yield of intolerant (Machete and Spear) than moderately tolerant (Frame and Krichauff) cultivars. Yield suppression by P. neglectus was generally 8 to 36% for intolerant cultivars, but reached 71% in soil also harboring Heterodera avenae, Rhizoctonia solani AG-8, and Gaeumannomyces graminis var. tritici. Intolerant cultivars had lower yields than Krichauff in rainfed but not in irrigated experiments. Density of P. neglectus in mature roots was generally lower for moderately resistant Krichauff than for susceptible Machete and Spear. Aldicarb improved yields in irrigated but not in rainfed experiments, and increased plant height and reduced variability in tiller height, canopy temperature, and density of P. neglectus in roots. This is the first report of damage to wheat by P. neglectus in the Pacific Northwest. Breeding wheat for tolerance and resistance to P. neglectus is suggested.

The rhizosphere: a playground and battlefield for soilborne pathogens and beneficial microorganisms

“…With severe Rhizoctonia bare patch, close to 20% of the field can be covered with patches with essentially no yield in the patches (Cook et al 2002). Using a combination of a nematicide (aldicarb) and tolerant and intolerant varieties, yield suppression caused by Pratylenchus neglectus ranged from 8% to 36% in Oregon (Smiley et al 2005b). Aldicarb increased wheat yields 67% and 113% in soil infested with P. thornei (Smiley et al 2005c).…”

Influence of subsoiling on direct-seeded cereals in southeastern Idaho

“…In the PNW, Pratylenchus neglectus has been shown to be associated with declining wheat growth and up to 71% reductions in grain yield (Smiley et al 2005b). Pratylenchus populations exceeding 2500/kg of soil in the surface 20 cm of the soil profile occur in 20% of intensively cropped fields in the PNW (Smiley et al 2004), and populations exceeding 2000/kg of soil were responsible for limited grain yield in Oregon (Smiley et al 2005b). Pratylenchus neglectus populations in our study averaged from 220 to 5360/kg of soil in nonfumigated plots.…”

“…In addition to fungal root and crown rots, root-lesion nematodes, particularly Pratylenchus neglectus (Rensch) Filipjev & Schuurmans-Stekhoven, are present in cereal fields planted without tillage in both the PNW and IMW regions (Smiley et al 2005b;Strausbaugh et al 2004). When dryland fields are shifted to higher-intensity cereal cropping, Pratylenchus neglectus can increase dramatically in dryland fields (Gair et al 1969) and is associated with declining growth and yield (Smiley et al 2005b).…”

“…When dryland fields are shifted to higher-intensity cereal cropping, Pratylenchus neglectus can increase dramatically in dryland fields (Gair et al 1969) and is associated with declining growth and yield (Smiley et al 2005b).…”

Pratylenchus neglectus (Nematoda: Pratylenchidae) under the rhizosphere of Brassica napus

“…These nematodes remain mobile and may move into and out of roots and may deposit eggs in soil as well as within root tissue. They are the second most important plant-parasitic nematodes after root knot nematodes (Jatala & Bridge, 1990 (Taylor et al, 1999;Lasserre et al, 1994;Smiley et al, 2005). Oilseed rape (Brassica napus) is often used as a break crop between cereal crops and in vitro tests of Pratylenchus on rape cultivar has shown that rape cultivar could be damaged by Pratylenchus from preceding cereal crop (Webb, 1990;Webb, 1996).…”