From our perspective as yarrow plants, we are generally resilient and pest-resistant due to our potent aromatic foliage. However, when our growing conditions are not ideal—often from too much shade, overwatering, or poor air circulation—we can become stressed and vulnerable to attack. Here is what we experience and how you can help us recover.
We often feel the first signs of an attack as a slight, sticky sensation on our new, tender shoots and flower buds. This is the honeydew excreted by aphids, tiny soft-bodied insects that cluster to suck our sap. This draining weakens us, causing our vibrant growth to become stunted and distorted. The sticky residue can also attract ants and lead to the growth of sooty mold, which further blocks our sunlight absorption.
This is a particularly distressing infestation. Spider mites are minuscule pests that thrive in hot, dry, and dusty conditions. We feel them as a faint, tickling sensation on the undersides of our feathery leaves as they pierce our cells to feed. This causes a tell-tale stippling of tiny yellow dots across our foliage. As the damage worsens, our leaves may turn bronze, feel dry, and we might even detect the fine, silken webbing they spin for protection, which is a sure sign of a severe infestation.
While not an insect, this fungal disease is a common plight for us when our leaves are consistently damp and air circulation is poor. We experience it as a white, powdery coating spreading across our leaf surfaces. This substance inhibits our ability to photosynthesize effectively, weakening us overall and causing our leaves to yellow, curl, and potentially die back if left untreated.
The best treatment always begins with correcting our environment. Please ensure we are planted in full sun and well-draining soil. Avoid overhead watering that leaves our foliage wet for long periods; water us at the base instead.
For aphids and spider mites, a strong blast of water from a hose can physically dislodge many of the pests, providing immediate relief. For more persistent cases, insecticidal soap or neem oil solutions are highly effective. Please ensure you spray the undersides of our leaves thoroughly where these pests hide. These treatments suffocate the pests without leaving harmful residues that could damage us or beneficial insects.
For powdery mildew, improve air flow around us immediately. You can treat us with a homemade solution of one tablespoon of baking soda mixed with a half-teaspoon of liquid soap in a gallon of water. Spray us thoroughly every 7-10 days. As a last resort, a fungicide specifically labeled for powdery mildew on ornamentals can be used, but we prefer gentler, organic options whenever possible.
Regularly checking our leaves for early signs of trouble is the greatest gift you can give us. Catching an infestation early makes treatment far easier and allows us to channel our energy into producing the beautiful, cheerful blooms we know you enjoy.
