Hemp-nettles (Galeopsis)

Powdery mildew is a common fungal disease caused by various fungi species including Erysiphe, Podosphaera, Oïdium, and Leveillula. It affects over 10,000 plant species worldwide. The disease thrives in warm, dry climates with high humidity and appears as a distinctive white powdery coating on plant surfaces.

Septoria leaf spot is a destructive fungal disease caused by Septoria lycopersici, particularly devastating during seasons of moderate temperature and abundant rainfall. The disease starts on lower leaves and progresses upward, causing small circular spots with tan to gray centers and dark brown margins. If left untreated, it can dramatically reduce plant yields and cause complete leaf blight.

Phyllosticta is a genus of fungi responsible for leaf spot diseases in a wide range of garden and indoor plants. These pathogens thrive in warm, humid conditions, spreading primarily through water splash and prolonged leaf wetness. Symptoms typically include small, circular lesions that transition from tan or light brown to having distinct dark brown or black margins. As the disease progresses, these spots may coalesce, leading to chlorosis (yellowing) and premature abscission (leaf drop). Characteristic pycnidia—tiny, black, pinhead-sized fruiting bodies—often develop within the lesions. Phyllosticta commonly affects ornamentals like hydrangeas, irises, peonies, lilacs, maples, and roses, as well as citrus and various fruit trees.

Curculionidae (weevils) are small beetles that feed on plants. Adults chew leaf margins, leaving crescent-shaped notches, primarily at night. The larvae live in the substrate and consume roots, causing decline, yellowing, and wilting even when the substrate is moist, and in severe cases, plant death. They frequently affect ornamentals and garden plants such as strawberries, citrus, roses, hydrangeas, azaleas, blueberries, begonias, and many potted plants.