Transmission of African Cassava Mosaic by Mechanical Inoculation

Abstract

The casual agent of the cassava mosaic disease was transmitted from cassava to cassava by using a standard method of inoculation of plant viruses, the manual inoculation of infective sap. Transmission were made in phosphate or borate bufers, kor in deinozed water. Mosaic disease of cassava (Manihot esculenta) is the most important factor limiting yield of the crop in Africa (8). The causal agent, which is presumed to be a virus (9), is known to be transmitted by grafting and by the whitefly, Bemisia tabaci (2,9). Storey and Nichols (9) were unable to substantiate early reports of experimental transmission by injection of infective sap (4) or by needle scratch (3). They also failed to transmit the disease by rubbing young leaflets with infective sap. The Plant Disease Reporter, Volume 62 transmission of African Go Great interest has recently been shown in African cassava mosaic disease (CMD), and efforts have been renewed to isolate and characterize the pathogen (1,6). Several Institutes have attempted electron microscopy of ultrathin sections of infected cassava material (5, 7, and Bock, Guthrie, and Woods, unpublished data), but no virus like particles or mycoplasmalike bodies have been seen. This paper reports the first transmission of CMD by standard methods of mechanical inoculation of infected sap.