What's eating my iris 'benton susan'?

Iris 'Benton Susan' faces iris borers as its most destructive threat — larvae tunnel into rhizomes causing rot and collapse. Aphids cluster on new growth, and slugs rasp young leaves in spring. Good garden hygiene, removing dead foliage in autumn, and prompt action prevent most damage.

Ragged notches on leaf edges in spring as larvae hatch; later, mushy, foul-smelling rhizomes as larvae tunnel inward. Remove and destroy old foliage in autumn to eliminate overwintering eggs. Dig and inspect rhizomes in late summer; squash any larvae found. Beneficial nematodes applied in early spring target young larvae in soil.

Sticky honeydew on leaves, distorted or curled new growth, and sooty mould on stems. Blast off with a strong jet of water. Spray with insecticidal soap or neem oil. Encourage ladybirds and lacewings as natural predators.

Irregular holes and silvery slime trails on young leaves and flower stems, especially after wet weather. Apply iron phosphate or ferric phosphate slug pellets around plants. Trap under boards overnight and dispose. Remove debris where slugs shelter.

Silvery streaking and stippling on petals and foliage; flowers may be distorted or fail to open fully. Remove and bin affected flowers promptly. Apply spinosad or neem oil sprays. Avoid overhead watering which can spread thrips.