What's eating my diascia barberae 'piccadilly'?

Diascia 'Piccadilly' is most vulnerable to aphids on its flower spikes and soft stems. Slugs target seedlings and new basal growth, especially in cool damp spring weather. In hot summers, red spider mite can cause bronzing. Vine weevil grubs may attack container-grown plants at the roots.

Soft-bodied insects clustered on flower stems and buds; distorted blooms; sticky honeydew and black sooty mould. Knock off with a water jet; apply insecticidal soap or pyrethrin spray. Repeat weekly until the population collapses.

Jagged holes in lower leaves and crown; shredded young stems; silvery mucus trails. Use iron-phosphate pellets or copper tape around pots. Hand-pick after dark or set beer traps nearby.

Container plants suddenly wilt; root ball riddled with white grubs; plant lifts out of pot easily. Apply nematode drench (Steinernema kraussei) in late summer to autumn when soil is above 5 °C. Repot annually to check for grubs.