We stand tall and vibrant, our flower spikes a bold declaration of summer. Yet, beneath our striking appearance, we constant vigilance against a host of pests and diseases that seek to compromise our health and beauty. For us Gladiolus, thriving in the gardens of the United States requires not just sun and fertile soil, but also a keen understanding of the adversaries we face. These threats can attack our corms, our leaves, and our prized blossoms, often with devastating results if left unchecked.
Several insects view our succulent leaves and stems as their personal feeding grounds. Aphids are a particularly common nuisance; these small, soft-bodied insects cluster on our undersides, piercing our tissues to siphon sap. This weakens us and causes leaf distortion. More alarmingly, they are prolific vectors of viral diseases. Thrips, especially the Gladiolus thrips (Thrips simplex), are our arch-nemesis. They rasp the surface of our leaves and petals, leaving behind telltale silvery streaks and stippling. They also attack our developing flower buds, causing them to abort or open into disfigured, blotched blooms, and they can infest stored corms.
Our corms are our lifeline, the storehouse of energy from which we grow each season. Therefore, threats to them are existential. Bulb mites (Rhizoglyphus species) infest our corms, particularly those already wounded or stressed. They feed on our tissues, often introducing rot-causing pathogens in the process. Wireworms, the larval stage of click beetles, are soil-dwelling pests that bore directly into our corms, creating tunnels that lead to decay and a general decline in our plant's vigor, often killing young shoots before they even break the soil surface.
Excess moisture is a primary enabler of our most destructive diseases. Fusarium corm rot and yellows, caused by the fungus Fusarium oxysporum, is a widespread and serious disease. It causes a dry, brown rot of the corm, often starting at the base, and leads to yellowing, stunting, and wilting of our foliage. Botrytis blight, or gray mold (Botrytis cinerea), thrives in cool, wet conditions. It appears as small, water-soaked spots on our leaves and flowers that rapidly expand into brown lesions covered in a characteristic gray, fuzzy mold, ruining our spectacular floral display.
Unlike localized pests or rots, viral diseases affect our entire system. Bean Yellow Mosaic Virus and Cucumber Mosaic Virus are the most common. They are primarily transmitted by aphids from infected plants. Once inside us, these viruses cause a range of symptoms including a distinct yellow mosaic patterning or mottling on our leaves, streaking on our flowers (breaking the pure color), and overall stunting. There is no cure; the infection is permanent within the plant and is passed on to the next generation through our corms.
