Eelworm (stem and bulb)

Symptoms
Stem eelworms impact over 400 species including strawberries, a number of vegetables, and ornamentals - including narcissus, tulips, hyacinths, scillas and snowdrops. In tulips, the leaves split, flower stems bend, and petals remain green. Masses of dormant 'eelworm wool' forms on infested bulbs in dry store.

Spot them
Adults are 1-2 mm long, and move in soil, entering the plants in small cuts and natural openings.