From our perspective, thrips are our most persistent and damaging adversaries. These tiny, slender insects use their rasping-sucking mouthparts to scrape at the surface of our tender, emerging leaves and flower spikes. This feeding action leaves behind silvery-white streaks and speckles, a stark contrast to our natural vibrant green. As we try to grow and unfurl our blossoms, their damage can cause distortion, streaking on petals, and even prevent buds from opening entirely. They thrive in hot, dry conditions and can overwinter on our corms if they are not properly treated after the growing season.
Aphids are soft-bodied insects that congregate in large colonies on our undersides of leaves and along our flower stems. They pierce our tissues to feed on our sap, which weakens us by diverting essential nutrients. This feeding can cause our leaves to curl and yellow, stunting our growth. More critically, aphids act as vectors for viral diseases. As they move from one plant to another, they can transmit incurable viruses like the Cucumber Mosaic Virus, which manifests as unsightly mottling and streaks on our foliage and flowers, permanently marring our beauty.
Our corms are our lifeline, storing the energy we need to sprout and bloom each season. Bulb mites are a grave threat to this vital organ. These microscopic arachnids typically invade corms that are already damaged or stressed, but a severe infestation can attack healthy corms as well. They feed on our stored tissues, causing dry, brown, corky lesions. When planted, a mite-infested corm will either fail to emerge or produce a weak, stunted plant with yellowed leaves. The damage also creates entry points for fungal and bacterial rot, leading to our complete decay.
Certain caterpillars, such as the gladiolus borer, and cutworms find our foliage and flower spikes to be a delicious meal. These pests chew large, irregular holes in our leaves, diminishing our ability to photosynthesize and gather energy. Cutworms are particularly troublesome for our young shoots, as they sever them at the soil line overnight, toppling us before we even have a chance to grow. The gladiolus borer caterpillar will tunnel into the central spike, causing it to wilt and collapse, destroying the potential flower display entirely.
To protect ourselves, we rely on a strategy of cultural and, if necessary, targeted interventions. Please practice crop rotation; do not plant new corms in the same bed year after year. After digging up our corms in the fall, inspect them carefully and discard any that are soft or damaged. A crucial step is to dust them with a pesticide like permethrin or soak them in hot water (just warm enough for human hands to tolerate) to kill any hiding thrips or mites before storage. During the growing season, a strong spray of water can dislodge aphids. Introducing beneficial insects like ladybugs and lacewings provides natural predation. For severe infestations of thrips or caterpillars, insecticidal soaps, neem oil, or spinosad are effective options that are gentler on the environment than harsh chemicals. Always remove and destroy any severely infested plant material to prevent the pests from spreading.
