What's eating my pelargonium 'paton's unique'?

Pelargonium 'Paton's Unique' is a vigorous aromatic Unique pelargonium. Its scented foliage deters most browsing animals. The chief pest threats are aphids massing on young shoots and buds, geranium bronze butterfly caterpillars boring into stems, and vine weevil grubs attacking roots in containers. Whitefly is a lesser secondary pest.

Colonies on shoot tips and flower stems; distorted growth, sticky honeydew, and sooty mould can build up rapidly in warm weather. Blast off with a strong jet of water; apply insecticidal soap or neem oil spray weekly until clear.

Caterpillars bore into buds and stems leaving frass-filled tunnels; affected shoots wilt suddenly and flower buds fail to open. Cut out and destroy infested stems. Spray spinosad or pyrethrin. Monitor buds carefully throughout summer.

Root-feeding grubs cause sudden wilting and death of container plants; characteristic notching of leaf margins indicates adult activity. Apply Steinernema kraussei nematodes to moist compost in late summer. Check root balls at repotting; remove and destroy any grubs.