Garlic Rust - New Distribution Report

A severe rust epidemic has been observed in garlic fields near Brandfort, Free State. Typical of many rusts this disease, caused by Puccinia allii (=P. porri), is favoured by moderate temperatures and humid conditions.

Although rust is known to occur on garlic, the current epidemic levels have not been noted in the central Free State. Other hosts of P. allii include onion, leek, shallot and chives. Most likely the oversummering of inoculum on volunteer plants, and an exceptionally wet autumn and warmer winter temperatures, contributed to disease development. In addition to rainfall, overhead irrigation maintains high humidity levels. Field inspections of 10 ha garlic on 26 June 2001 showed that rust severity levels on individual plants varied between 20 and 90% with the onset of necrosis in heavily infected leaves clearly visible.

Infection foci can also be seen in wetter patches of garlic fields. As this crop grown for the export market needs another 4 months to mature, it is likely that yield losses will be experienced.