Q. Last year my onions grew well in the garden, but when I harvested them, many were mushy and rotting inside. The ones in storage are also rotting. I followed the correct drying procedures. What went wrong?

- R. F., Lambertville, NJ

A. "Your onions probably had bacterial neck rot. The bacteria enter the neck of the onions through wounds made during growing, harvesting and curing. Unfortunately, there isn't much you can do once your onions have the disease, but you can prevent neck rot in future crops.

Avoid using mulch and take care not to wound the tops while cultivating. When selecting varieties, plant onion seeds rather than sets, which can carry the disease over from year to year, and avoid white and thick necked varieties such as 'Sweet Spanish,' which are more susceptible to the disease.

To harvest and cure onions properly, wait until 75% of the tops have fallen over naturally, gently dig/pull all the onions and store them in a dry, shady place with good ventilation, such as an outdoor shed or barn, for 10 days to two weeks. After the onions have cured, put them in slatted crates or mesh bags and store them indoors in a cellar with low humidity and temperatures between 33F and 45F."

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Provided by NationalGardening.com, the online publisher of the National Gardening Association.

Q. For the last few years, a tiny white worm has made pin holes in my onion bulbs, causing the onion to rot. What is this insect and how do I control it?

A. It's most likely the onion maggot, the larva of a small, black fly. The adult fly overwinters on crop debris and emerges in spring to lay white eggs on young onion plants near the soil line. The white larvae burrow into the base of the onion.

Onion maggots like soils high in organic matter and cool, damp conditions. Avoid applying manure, compost or even mulch in spring. Wait until the weather gets above 60F to top dress with compost and apply mulches. If using manure, apply it in the fall and till it in right away. Fall tilling also buries the overwintering pupae. During the growing season, remove and destroy infected onions immediately because the maggot can spread to nearby plants. Applying diatomaceous earth around the onion transplants can be effective, although you must reapply it after rain. Row covers placed tightly over an onion bed can prevent flies from getting to the plants, but in a badly infested area, onion flies can emerge, mate and lay eggs, all under the cover, so check periodically.

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Provided by NationalGardening.com, the online publisher of the National Gardening Association.

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