What's eating my gijnlim asparagus?

Gijnlim is a high-yielding Dutch cultivar grown commercially and in gardens; it faces asparagus beetles as the dominant threat to fern health and yield longevity. Slugs attack emerging spears, and aphids occasionally colonize fern stems. In the UK, where Gijnlim is widely grown, asparagus beetle pressure is significant from June onward.

Adults lay eggs on spears; larvae strip fern fronds systematically, reducing the energy stored in crowns for the next harvest. Hand-pick adults and larvae daily from June; apply pyrethrin or spinosad if infestation is severe; clear debris in autumn.

Holes and channels in emerging spear tips; slime trails on soil surface around crowns. Scatter iron phosphate pellets around crowns at bud-break; hand-collect at dusk; avoid over-watering which creates ideal slug habitat.

Blue-gray colonies on fern stems cause needle-like foliage to turn yellow and plants to appear 'witches'-broomed'. Apply insecticidal soap or neem oil to fern stems; introduce parasitic wasps (Aphidius spp.); avoid high-nitrogen feeds that promote soft growth.