Expert: Kenneth Joergensen - 7/12/2006

Question
Hi! I live in Mississippi, 39168 and I have cannas planted in front of my trailer. The first year they did wonderfully producing great blooms, but this year they have a problem. Their leaves are eaten into and deformed when they're still rolled up. Some of the leaves are dying--this could be due to the drought we're experiencing right now, though. Could you help me with what do to treat whatever bugs are doing this? I desperately want to get my lovely giants back into good health! Thank you for your time.

Answer
The lesser canna leafroller is a small caterpillar related to the European corn borer. It overwinters as larvae in the leaves and stems of canna and the moths emerge to mate and lay eggs after the new growth emerges in spring. When the larvae hatch, they feed within the new, still-rolled leaves. Older larvae can actually tie the edges of older leaves together and roll the leaf back up! If not managed, lesser canna leafrollers may completely destroy the cannas. Larvae are actively feeding at this time.

A typical mistake is to leave the old dead growth on the canna bed as a sort of mulch. Canna seems to be the only host plant for this pest. It may be possible to drastically reduce the lesser canna leafrollers just by carefully removing all dead leaves and stems in the fall after the frost has killed it.

It is possible to eradicate this pest by applying insecticide (Orthene or cyfluthrin) several times, say, at ten-day intervals.