Dear Gardening Life,
I love irises but am about to give up as they get full of worms that destroy the rhizomes. Any suggestions for an environmentally friendly solution to this?
*—Sue Rietschin, Guelph, ON *
The culprits are iris borers, which are actually the larvae of a moth. The moths lay their eggs on the iris leaves in summer and fall, so cut back the foliage in fall and put it in the garbage (not your composter). This will mean fewer borers hatching next spring.
Watch the leaves for signs of borer infestation (notched-out leaves, pinholes and/or “sawdust” at the base of the plant); pinching the borers in the leaf, or removing the leaf altogether, will stop them from descending into the rhizome.
Another option is to treat them with beneficial nematodes, which are lethal to the larvae but not harmful to pets, humans or the environment. Nematodes are available from mail-order sources such as Natural Insect Control
. Apply according to package directions.
*Karen York, GL Botanical Editor*
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