Lesser Canna Leafroller of Flowering bulbs

Disease Information

Lesser Canna Leafroller

DESCRIPTION OF THE PEST

The lesser canna leafroller (Geshnacannalis) is the larva (caterpillar) of the lesser canna leafroller moth. The caterpillar ranges in size from 1/16 inch when newly hatched to 7/8 inch when mature. As it matures its body changes from cream to greenish in color, but its head remains yellowish.

Symptoms and damage

The leafrollers survive the winter in rolled, dead leaves of the canna. They mature to adults, which appear in the spring. Adult females lay their eggs on the canna. Initially the tiny, newly hatched caterpillars tunnel inside the leaves between the upper and lower surfaces. When they become too large, they exit to the upper leaf surface where they fasten edges of leaves so that the leaves cannot unfurl or they can roll one edge of an already open leaf. While in this protected area, they generally feed on the leaf`s upper surface but will also bore through the rolled leaf. Infested leaves often have several holes through them. Heavily infested leaves may not open at all and the plants may fail to bloom. When fully mature, the caterpillars spin a cocoon where they transform to adults. More than one generation occurs per year.

Management

Since the caterpillars overwinter in the canna leaves, removing and destroying above ground plant parts in the winter will reduce numbers of this pest. For severe infestations, sprays with a foliar systemic insecticide, such as acephate, will kill the borers within the leaves. One or two sprays may be sufficient. The natural insecticide, Bacillus thuringiensis (Bt) will control the leaf rollers if sprayed 3 times at weekly intervals when damage is first noticed. Spray Btin the evening, and spray into the rolled leaves if damage is advanced.

Control of Flowering Bulb Insect Pests (Acephate –Bifenthrin –Permethrin –Cyfluthrin )

 

 



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