Aquilegia are relatively pest and disease free but recently a few problems have appeared that you need to watch out for.
Aquilegia downy mildew
A particularly virulent fungal infection that started to attack aquilegias a few years ago and can still be a problem in some gardens. It begins as a yellow blotch on the leaves and soon spreads as a dark blotch on the stems and flowers. The white powdery spores eventually spread over the whole plant. Remove and destroy affected plants as soon as it appears. Do not replant the area with aquilegia for at least a year. As it is air borne it is exacerbated by damp weather and poor air circulation, so do not plant aquilegias too closely.
Aquilegia sawfly
Aquilegia sawfly is a small green larva that starts to eat the edges of the leaves in the spring. The adult beetles lay eggs on the underside of the leaves, and if enough larvae hatch out they can defoliate whole plants. Check for leaf damage and squash the pale green caterpillars as you spot them. Plants will usually recover with a second flush of foliage later in the summer.
Why are my aquilegia leaves turning yellow?
This can be a sign of the downy mildew, see above, or if it is throughout the plant it could be a symptom of drought or stress. If the problem persists after watering, cut back the foliage, mulch and see if it returns. If it does, it could well be disease, so remove the plant and destroy.
What is eating my aquilegia?
Thankfully neither deer nor rabbits will eat aquilegia, so it is likely to be an insect pest of some sort. If something is nibbling the edges of the leaves it is likely to be sawfly, see above. Aphids will occasionally suck the sap and leaf miners can tunnel through the leaves, which need to be removed and destroyed.
