Diseased Onions

New Zealand Herald, Volume LXXVII, Issue 23839, 14 December 1940, Page 11 (Supplement)

Diseased Onions

r PHERK are two main diseases of the onion which may be showing now; white rot and downy mildew. Both are serious and may cause a lot of damage to the crop. In the case of white rot the onions are seen to wilt, the leaves turn yellow and by .January the plants are usually dead. The white mould or rot develops at the liase of the bulb and if there is any doubt about the disease, the shrivelled, inleetcd onions, when pulled up. will be found covered with black bodies, like poppy seeds, embedded in the white fungus. In this case the infected onions together with the surrounding soil should be dug up carefully and removed in a bucket tor burning. If left, they will continue to contaminate the soil. No effective method of control is known. Downy mildew is indicated by small yellow patches on the leaves, plus a white or grey mildew which seems to In 1 covered with a whitish powder. Later this "powder" may have a lilac tint. I f a crop is attacked in its young stage it may easily lie destroyed. The liest wav to check the disease is t*» spray with Bordeaux mixture, but as ilie onion foliage is diliieult to wot with the spray, it is advisable to add a sticker in the form of a tablespoon of treacle to each gallon of spray.