From our perspective as zinnias, we are vibrant and resilient plants, but our succulent stems and lush foliage make us a target for a variety of pests. These invaders disrupt our ability to photosynthesize, drain our vital fluids, and can ultimately lead to our decline if left unchecked. Understanding these adversaries and the treatments that help us is key to a thriving garden.
We often feel the tiny, soft-bodied insects clustering on our tender new growth, buds, and the undersides of our leaves. They pierce our tissues with their needle-like mouthparts to suck out our sap, which weakens us, causes our leaves to curl and distort, and promotes the growth of sooty mold on the sticky honeydew they excrete. A strong spray of water from a hose can dislodge them effectively. For more persistent colonies, insecticidal soap or neem oil sprays, applied directly to the pests, are very effective and gentle on our beneficial pollinators.
These are nearly invisible to the human eye, but we feel their presence intensely. Spider mites are tiny arachnids that suck chlorophyll from our individual leaf cells. The first sign we show is a subtle stippling of tiny yellow dots on our leaves. As the infestation grows, fine, silken webbing becomes visible, and our leaves may turn entirely yellow, brown, and crisp. They thrive in hot, dusty conditions. Increasing humidity with overhead watering and consistently spraying our leaves, especially the undersides, with insecticidal soap or horticultural oil can suffocate them and disrupt their life cycle.
We experience caterpillars, like those of the cabbage looper or beet armyworm, as voracious consumers of our foliage and petals. They leave behind large, irregular holes in our leaves and can quickly skeletonize them, severely impacting our energy production. The most direct and pollinator-friendly method of control is to physically inspect us and hand-pick these pests off, dropping them into soapy water. For organic treatment, the microbial insecticide Bacillus thuringiensis (Bt) is highly effective; when ingested, it specifically targets and stops caterpillar feeding without harming other insects.
When disturbed, these tiny, white, moth-like flies rise in a cloud from our undersides. Like aphids, they are sap-suckers, leading to our general yellowing, wilting, and stunted growth. Their honeydew also encourages sooty mold. They can be difficult to control due to their rapid reproduction. Yellow sticky traps can help monitor and reduce adult populations. Thorough spray applications of insecticidal soap or horticultural oil, making sure to coat the underside of every leaf, are necessary to contact and suffocate the nymphs and adults.
While not an insect, this fungal disease is a common affliction that feels like a pest to us. It appears as a white, powdery coating on our leaves and stems, inhibiting photosynthesis and causing our leaves to wither and die prematurely. It thrives in humid conditions with poor air circulation. The best treatment is prevention: please plant us with adequate space between each plant to ensure good airflow. If it appears, treat us with a fungicide such as neem oil or a homemade solution of one part milk to nine parts water, applied weekly.
