Puccinia allii (rust of allium, onion, leek and garlic)

Rotation of crops, good soil drainage, sparing use of organic manure, rogueing diseased plants, destruction of related weed hosts and selection of seed from healthy plantings reduced the damage caused by P. allii (Laundon and Waterston, 1965).

Some breeding research has been carried out (Smith and Crowther, 1992; Wietsma et al, 1992). Two resistant leek cultivars were found which were of sufficiently high agronomic quality to be considered for commercial production (Uma and Taylor, 1991).

Bacillus cereus (Doherty and Preece, 1978), Ramichloridium schulzeri and Verticillium lecanii (Uma and Taylor, 1987) may be useful in the biological control of leek rust.

Copper sulphate, mancozeb, myclobutanil, triadimefon, triforine and zineb are registered for control of Welsh onion rust in Japan.Treatments reported for leek rust include: penconazole alone or in a mixture with chlorothalonil (Schepers and Meier, 1992); fenpropimorph and triadimenol (Van Melckebeke, 1991); and triadimenol, tebuconazole and their mixture (Meyer and Kessler, 1990).A plant-nutrient formulation which included calcium chloride, calcium nitrate, calcium oxide and beef extract reduced the severity of Chinese leek rust. It was suggested that control was due to several factors, including suppression of P. allii by the chemicals in the formulation, an increase in the population of microbial antagonists on leaf surfaces and changes in leaf surface structure (Huang, 1994).

In Chiba Prefecture, Japan, it was found to be possible to predict the occurrence of Welsh onion rust in November on the basis of factors such as temperature and rainfall during the first half of September (Takeuchi, 1990).