Since many kinds of weeds serve as alternate hosts for thrips, you'll want to keep them out of your garden or greenhouse; however, there is evidence that a diverse and varied natural plant community, including some weeds, supports natural thrip predators, too. Overzealous weed control near vulnerable plants may simply make those plants a better target. Keeping a few weeds in the background may not be a bad idea.
Soaking Corms in Cold Storage
To fight gladiolus thrips, just before planting gladiolus corms, soak them in a solution of 1;1/4 tablespoons Lysol in a gallon of water. Storing corms at 40F to 45F also effectively eliminates remaining thrips. Generally, trouble with gladiolus thrips is much less serious when bulbs are planted early rather than late. Don't leave corms in the ground from one year to the next, particularly in an area where neighbors grow gladiolus. Dig them early in the fall, before they're mature, and cut off the tops, which harbor most of the pests.
Some species of thrips are actually beneficial insects, preying upon other thrips and small insect pests. Other naturally occurring beneficials that control thrips include ground beetles, damsel bugs, minute pirate bugs, and syrphid flies.
Preventing Thrips Next Year