The use of undisturbed soil cores to study methods of controlling rhizoctonia patch of cereals

Abstract

Methods of controlling rhizoctonia patch including cultivation, compaction and fertilizer were investigated using undisturbed soil cores removed from patches. Root rot on wheat seedlings was reduced by deep mixing (5 and 10.5 cm) but not shallow mixing (2.5 cm); deep mixing increased root dry weight from 6 mg per plant in undisturbed soil to 15 and 21 mg respectively. Mixing dry and mixing moist gave similar results. Compaction of undisturbed soil from bulk density 1.45 to 1.74 had no measurable effect, but the same level of compaction on soil mixed to 10.5 cm did cause a significant reduction in root weight. Top dressings of sodium nitrate, ammonium sulphate or urea had no effect on root rot. None of the treatments affected the root growth of seedlings grown in cores from adjacent non‐patch sites.