V. L. Rosenkranz
University of Maryland, Wicomico Cooperative Extension
P.O. Box 1836, Salisbury, MD  21802

Keywords:  silver plastic, thrips, gladiolus

Abstract:  Growing gladiolus as a fresh cut flower can be a very lucrative crop for the fresh cut flower market.  Western flower thrips and gladiolus thrips can damage both the flowers and the foliage of the gladiolus, rendering the flowers un-saleable.  Thrips can also severely damage the gladiolus corm.

Black plastic was laid on soil that had been formed into three raised beds with trickle tape set under the plastic. Silver plastic was hot glued onto the top and sides of black plastic on three other raised beds.  Bulb planters were used to cut a four-inch hole evenly into the plastics and at one-foot intervals.  The gladiolus corms were planted six inches deep into the soil and the irrigation system watered them into the soil.  When the gladiolus was in full bloom, the flower stalks were cut off the plant.   The flower stalks were rapped three times on a sheet of white paper to cause the thrips to fall off and out of the flowers.  The paper was examined and the thrips were counted and recorded.

Gladiolus flowers grown on the black plastic and silver plastic were divided into color groups.  The flower colors of pink and white, white, purple and peach were grown on the black plastic, and the flower colors of yellow, red and pink were grown on the silver plastic.  The thrip count on the flowers grown on the black plastic was significantly higher than the thrip count on the flowers grown on the silver plastic.  Although only one year of data was collected and more research data will need to be collected, the practice of growing the Gladiolus on silver colored plastic may prove to be a way to reduce the amount of pesticides needed to raise saleable flowers for market.

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