Question

This year %26 last year I had a major problem with leeks on my allotment, and so did all the other plot holders who grew leeks.   The leeks towards the end of August rotted from the top downwards on everybodies plot.   The location of the leeks were changed from last year and therefore I do not think it is anything to do with the soil, I may be wrong.  I did find a small grub in one of the stems of a leek and I am wondering whether this has anything to do with the problem.  I cannot find any reference to this specific problem in any gardening books that I have.   Can someone help me in relation to this problem

Answer
Brian:
What you saw could have been an onion maggot, they attack the plants at the base of the leaves. Grubs could also be a problem, but they usually attack at the roots. Both pupate in the soil. Onion maggots also attack radishes, so if radishes were planted where you had the leeks this year that could have been the source. However, since the adults are flies, this could be the first year they have appeared in your garden.

To avoid the problem next year, be sure all the infected onions have been removed from the allotments. It's OK to compost them. Try dusting around the bulbs in the spring with diatomaceous earth or wood ashes.

Elyse