Caroline O\’Connell asked 16 years ago
there is a mould on the green parts of my onions.It started in the shallot bed and is slowly spreading to the other onion beds.I have pulled up all the shallots and sprayed the rest with Dithane.Is it too late,have I lost them all or is there something else I can do?Help!
1 Answers
Gerry Daly Staff answered 6 years ago
A number of different fungi can affect the foliage of onions, namely sclerotinia, botrytis and downy mildew. Any of these can cause rotting and mould growth.
The problem is most severe in dull wet weather and where the onions are growing in very fertile soil, high in nitrogen or with lots of manure or compost, and therefore growing soft.
It is difficult to control these fungi, because different fungi are controlled by different products, and, unless the fungus is properly indentified, the wrong product can be completely ineffective.
The best measure for the future is to add potash to overly rich soil and to increase spacing between the plants. If the weather dries up, the symptoms will probably decline.
