Effect of crop rotation on crown rot and the incidence ofFusarium pseudograminearumin wheat in the Western Cape, South Africa

Abstract

The effect of different crop rotation treatments and within-treatment crop sequences on crown rot and the incidence of Fusarium pseudograminearum in crowns of wheat from a long-term crop rotation experiment at Langgewens Experimental Farm, Moorreesburg, South Africa, were studied in 2000, 2001 and 2002. Crop rotation treatments included the following crops: canola (C), lupin (L), medic (M), medic-clover mixture (Mc) and wheat (W). Rotation treatments (RT) and within-treatment crop sequences were: RT 1=W-W-W-W, RT 2=C-W-W-W, W-C-W-W,W-W-C-W, RT 3=C-W-L-W, L-W-C-W, RT 4=W-L-C-W, L-C-W-W, RT 5=M-W-M-W, RT 6=Mc-W-Mc-W and RT 7=M-C-M-W. Crop rotation significantly affected the incidence of F. pseudograminearum, crown rot incidence and severity, dry mass and grain yield. The incidence of F. Pseudograminearum was significantly higher on wheat for the rotation treatment that included 3 years of wheat and 1 year of canola compared with the other treatments, and the highest severities and incidences of crown rot and the lowest yields were also recorded for this treatment and the monoculture wheat. The lowest incidences of the fungus, as well as crown rot incidences and severities, and the highest yields were recorded for the rotation treatment that alternated wheat with a medic-clover mixture and the treatment that included wheat after 3 years of rotation with broadleaf crops. Crop rotation should, therefore, be an important component of management strategies against crown rot of wheat.