Suppression of Pratylenchus thornei after sequences of resistant summer grain crops maximised production of an intolerant wheat cultivar
Kirsty Owen: University of Southern Queensland, Centre for Crop Health
<div>When populations of the root-lesion nematode, <em>Pratylenchus thornei,</em> have been reduced by cropping sequences with resistant crops, it is unknown how rapidly they increase in subsequent susceptible, intolerant crops. Summer crop cultivars of sorghum, maize, sunflower, mungbean and soybean were grown on adjacent sites with <em>P. thornei</em> at i) low levels (<125/kg soil) following five resistant summer crops (cotton-sorghum-sorghum-sorghum-maize) or ii) at moderate levels (2500/kg soil) following a wheat-sorghum-wheat sequence. In the subsequent season, wheat cultivars with tolerance or intolerance to <em>P. thornei</em> were grown. There was no difference in biomass or grain yield of the summer crop cultivars between the two sites, but <em>P.</em> <em>thornei</em> increased substantially at the site with initially moderate levels after susceptible soybean and mungbean cultivars (12000–20000/kg soil). In contrast, at the initially low <em>P. thornei</em> site, populations increased slightly but remained <250/kg soil with no significant difference (<em>P</em>>0.05) between summer crop cultivars. This effect then impacted the next crop in the cropping sequence, where the grain yield of the intolerant wheat cv. Strzelecki was similar to the tolerant cv. Wylie at the low <em>P. thornei</em> site (mean yield ~3650 kg/ha) but reduced by 49% at the moderate <em>P. thornei</em> site (mean yield 1890 kg/ha). Optimal crop sequences to reduce <em>P. thornei</em> take many years, but the subsequent benefits can expand cultivar choice for farmers.</div>
View Presentation |
