This is garlic rust, and we’ve got it bad. As have most of the other garlic growers on the allotment. But it seems it’s not necessarily as devastating a problem as it looks. The bulbs were planted last autumn and are already at a reasonable size (we’ve checked a few) and the disease doesn’t make the crop inedible (or diminish their pungency). So long as it doesn’t weaken growth too much and open up the plant to nastier troubles we should still get a decent harvest, although we’ll regularly dig up a few bulbs to keep an eye on progress.
Once harvested leaves need to be burned to prevent it spreading to other alliums.
We’ll let you know how the bulbs turn out.