As a member of the Ranunculaceae family, we, columbines (Aquilegia spp.), are generally resilient perennials. However, our unique foliage and beautiful, nectar-rich flowers can attract a variety of pests and make us susceptible to certain fungal and bacterial diseases. Understanding these threats is key to maintaining our health and vigor in your garden.
From our perspective, the most frequent visitors are sap-sucking insects that find our tender new growth and stems particularly appealing. The Columbine Aphid (Brevicoryne aquilegiae) is a specialist that forms dense colonies on our undersides of leaves and flower buds. They pierce our tissues to feed on our sap, which weakens us, causes leaf curling, and promotes the growth of sooty mold. Another significant threat is the Columbine Sawfly (Pristiphora rufipes), whose larvae are voracious feeders. These gray-green, caterpillar-like insects can skeletonize our leaves rapidly, leaving behind only the veins and significantly reducing our ability to photosynthesize. We may also be visited by leaf miners, whose larvae tunnel through the layers of our leaves, creating unsightly white, serpentine trails that mar our foliage.
Our most dreaded ailment is Columbine Downy Mildew, caused by the pathogen Peronospora aquilegiicola. This disease causes yellow to brown patches on the upper surfaces of our leaves, with a corresponding fuzzy, grayish-purple growth on the undersides. It thrives in cool, wet conditions and can quickly lead to severe leaf drop, drastically weakening us. We are also highly susceptible to Powdery Mildew (Erysiphe spp. or Podosphaera spp.), which manifests as a white, powdery coating on our leaves and stems. While rarely fatal, this fungus stresses us by inhibiting photosynthesis and making our foliage unattractive.
Various fungal and bacterial pathogens can cause leaf spot diseases on us. These often appear as small, circular brown or black spots on our leaves, sometimes with yellow halos. In severe cases, these spots can coalesce, causing large areas of tissue to die. Furthermore, we are vulnerable to crown and root rot, often caused by organisms from the genus Sclerotinia or various water molds (Phytophthora spp.). This is typically a result of being planted in poorly draining soil or being over-watered. The first sign you might see is our entire plant wilting dramatically, even when the soil is moist, as the rot destroys the vascular system at our base, preventing water uptake.
It is important to note that many of our problems are exacerbated by environmental conditions not suited to our needs. We prefer well-draining soil and partial shade, especially in hotter climates. When planted in full, intense sun, our foliage can become scorched and stressed, making us much more susceptible to pest infestations and diseases. Similarly, overcrowding and poor air circulation around our leaves create a humid microclimate that is ideal for the proliferation of fungal spores like powdery and downy mildew. Ensuring we have the correct growing conditions is the first and most crucial step in keeping us healthy.
