GLADIOLUS THRIPS

a, Adult thrips; b. egg; c, larva; d, pupa (or resting stage) ; e, foliage and flower spike showing typical feeding injury; f, uninjured gladiolus corm; g, corms injured by feeding of thrips, showing characteristic russeted appearance. (a, b, c, and d, about 20 times natural size; e, f. and g, about one-half natural size.)

GLADIOLUS THRIPS

Gladiolus thrips overwinter and may reproduce on the stored gladiolus corms. During the growing season the adults and larvae attack the foliage and flowers of the growing plant. The eggs are inserted into the plant tissue. In the summer a generation of the thrips may be completed in 2 weeks.

The gladiolus thrips can be controlled by applying DDT to the stored corms or the growing plants.

On dormant corms use a 5 percent DDT dust. Apply 1 ounce of dust per bushel of corms in trays or 1 teaspoonful per 100 corms in paper sacks. Apply the dust with a duster over the top of filled trays soon after the corms are harvested or after cleaning. It is important to destroy the thrips before they penetrate beneath the protecting scales.

Watch the growing plants for evidence of thrips feeding. If you observe such feeding, spray or dust with DDT at once and continue at weekly intervals until the flowers appear. If infested plants are not treated until they bloom, the flowers cannot be saved from disfigurement.

Apply the spray as a fine mist, and avoid runoff. For spraying a few plants use 1 ounce, or 6 tablespoonfuls, of 50 percent DDT wettable powder to 3 gallons of water; for larger quantities use 2 pounds to 100 gallons of water.

If you use a dust, it should contain 5 percent of DDT. Apply it lightly and evenly over the plant.