What is the impact of winter grain crops on Pratylenchus thornei grown in rotation with tolerant and intolerant wheat?

Abstract

Management of the root-lesion nematode, Pratylenchus thornei (Pt), is central to wheat production in the northern grain region of Australia and relies on rotation with resistant crops and growing tolerant wheat cultivars. We determined the residual populations of Pt to 90 cm soil depth after winter grain crops and their impact on the growth of subsequently planted tolerant and intolerant wheat cultivars. A weed-free fallow and 5–6 cultivars each of faba bean, chickpea, barley and wheat were treatments on two areas of land, 1) 4,500 Pt/kg soil at 0–45 cm after 7 months fallow after wheat and 2) 2,100 Pt/kg soil at 0–45 cm following 14 months fallow after sorghum. Six months after harvest there were 10,000–22,700 Pt/kg soil 0–45 cm after most barley, faba bean and commercial wheat cultivars; 2,600–6,000 Pt/kg soil 0–45 cm after wheat cvv. QT9050, GS50a, chickpea cv. PBA Hattrick and fallow. There was a negative, linear relationship between Pt (to 90 cm) and biomass of the intolerant wheat cv. Strzelecki (max. R2 = 0.70 P<0.001 at 0–45 cm). There was no impact of residual Pt on the tolerant wheat cv. EGA Wylie. The tolerance of cv. EGA Wylie was robust but breeding resistant barley, faba bean and wheat will improve management options