Greetings, caretaker. We, the Columbines (Aquilegia spp.), are generally resilient plants, but like all living things, we face challenges from pests and diseases that can compromise our health and beauty. Understanding these threats from our perspective is key to maintaining a thriving garden. Here is a detailed account of our most common adversaries.
One of our most frequent visitors is the leaf miner. The adult, a small fly, lays eggs on our foliage. When the larvae hatch, they do not eat the surface; instead, they burrow inside our leaves, feeding on the tender tissue between the upper and lower surfaces. From your perspective, you see winding, white or translucent trails or blotches snaking across our leaves. From our perspective, this is a severe drain on our resources. These tunnels disrupt our photosynthesis, the very process we use to create food from sunlight. While a healthy Columbine can survive a minor infestation, a severe attack weakens us significantly, making our leaves brown and withered and stunting our growth.
Aphids are tiny, soft-bodied insects that often congregate in large numbers on our succulent new growth, flower buds, and the undersides of our leaves. They pierce our stems and leaves with their needle-like mouthparts to suck out our nutrient-rich sap. This direct loss of sap causes our leaves to curl, pucker, and yellow. Furthermore, aphids excrete a sticky substance called honeydew, which attracts sooty mold—a black, fungal growth that coats our leaves, further inhibiting photosynthesis. More alarmingly, aphids can act as vectors, transmitting viral diseases from one plant to another as they feed.
Perhaps the most devastating pest we face is the Columbine sawfly. The adult is a non-stinging wasp-like insect, but it is the larvae that cause us immense distress. These greenish, caterpillar-like larvae appear in spring and can skeletonize our foliage with astonishing speed. They feed voraciously on our leaves, often starting from the edges and working inward, leaving only the tough leaf veins behind. A severe infestation can defoliate an entire plant, severely weakening it and potentially preventing flowering or even causing its demise if it occurs early in the growing season.
As the season progresses, especially in conditions of high humidity and poor air circulation, we often fall victim to powdery mildew. This fungal disease manifests as a white or grayish, powdery coating on our leaves and stems. It is more than just an eyesore; the fungus grows on the leaf surface, interfering with our ability to breathe (transpire) and photosynthesize effectively. Infected leaves may turn yellow, brown, and become distorted before eventually dying and dropping off. This weakens us overall and reduces our vigor for the following year.
To help us, we prefer gentle, targeted interventions. For leaf miners, regularly inspect our leaves and remove any that show signs of tunneling, disposing of them far away from the garden. A strong jet of water can dislodge aphids from our stems. For sawfly larvae, the most effective method is to simply pick them off by hand and dispose of them; they are easily spotted. Encouraging beneficial insects, like ladybugs and lacewings, by planting a diverse garden is our preferred long-term defense against aphids. For powdery mildew, ensuring we have good air circulation by not crowding us and watering at the base to keep our leaves dry is crucial. In severe cases, an application of a horticultural oil or a baking soda solution can help manage the fungus without harming the broader garden ecosystem. A layer of mulch around our base helps conserve moisture and suppress weeds, reducing overall stress and making us more resilient to all these challenges.
