I tried planting my elephant garlic a little more deeply last year as I felt it was not getting as much moisture as it needed in my dry soils and this combined with a little extra watering I believed helped to produce a bumper crop, which only had a little rust in the last few weeks.
I have tried planting later this year as per Charles to see if this has as much impact. May also be different with Elephant Garlic as it is related to leek you may be able to plant much deeper then traditional garlic?