Last summer my gladioluses got thin white streaks on the buds before they opened, and the blooms were distorted. Could you tell me what caused the streaks? M. B. F. Washington, Mo. It sounds like a case of thrips, tiny insects that suck sap from the blooms and leaves, thus causing the cells to collapse. White or silvery streaks then appear.
You can spray with a hot pepper and detergent solution (one tablespoon each of hot pepper sauce and liquid dishwashing detergent to a gallon of water).
Thrips also infest corms, so before planting, soak the corms in a solution of one tablespoon of Lysol per gallon of water for three hours and plant when wet.
To treat while in storage, put four tablespoons naphthalene (moth flakes) per 100 corms in a paper bag for four weeks at 60 degrees F. Then store at 40 degees F.
White break mosaic also causes streaking, but the florets are more deformed and more mottled. Leaves turn brownish on the tips and eventually all brown. Destroy the plants, in this case.
Doc and Katy Abraham are nationally known horticulturists.