alafarmnews

The lesser canna leafroller, Geshna cannalis, is a small moth native to Central and tropical South America. The caterpillar stage of this moth is one of the most damaging insect pests on cannas in Alabama and the panhandle of Florida.

The moths fasten the edges of leaves with silk before the leaves unroll or they roll up one side of an open leaf creating small frass-filled tunnels. Within

Lesser canna leafroller

this shelter, the caterpillars feed on the upper surface of the leaves. Infested leaves don’t unfurl, producing growth deformation and reduction or failure to bloom. Leaves become ragged, shot through with holes and often die, creating an unsightly, tattered appearance. There are several generations per year, with populations increasing as the season progresses.

Moth
Leafroller, now a moth

Because lesser canna leafrollers overwinter as larvae and pupae in rolled canna leaves, the preventative measure of collecting and destroying the above ground portions of cannas during late winter will remove most of the population. Selective pruning and destruction of severely infested whorls can also aid control during the growing season. In cases where an infestation has gotten out of hand and the stand has become unsightly, aggressive pruning followed by insecticide treatments applied to new growth, can help restore control and appearance. Don’t forget to destroy those infested stalks. Sealing them inside a plastic lawn bag and sending them away in the garbage is one approach.

There are a number of foliar applied insecticides that can be used to control this pest, but, because there are multiple generations, it may take several treatments, applied at intervals through the summer, to maintain control. When treating for this insect it is important to direct sprays into the unrolled whorls where the insects prefer to feed. Because cannas have slick waxy leaves, it is helpful to add a "sticker" to the insecticide spray.

Some insecticides recommended for control of lesser canna leafroller that are available through your local Co-op are Orthene 75 S (Acephate); Hi-Yield Acephate Systemic Turf, Tree and Ornamental Spray; Sevin Concentrate Bug Killer; Spectracide Triazicide Soil & Turf Insect Killer; Permethrin; and Fertilome Borer, Bagworm, Leafminer & Tent Caterpillar Spray.