Gardening tips for the week ahead: prevent pests Systemic sprays can be very helpful if used early. Spray sparingly, in the evening, and avoid plants in flower. Here are some specific examples. Clean day lilies: Daylily (Hemerocallis) flower buds can be similarly protected now against the egg-laying activities of a gall midge, whose grubs ruin them. Go pre-mixed: Ready-mixed sprays save time and have a long shelf life. Solomon's seal: The arching shoots of Solomon's seal (Polygonatum) can be sprayed now with Bug Clear or Ultimate Bug Killer as a preventive measure against a sawfly whose larvae can skeletonise foliage later on. Stroke off aphids: Aphid attacks on rose shoots tend to be temporary. Stroke off the worst and leave the rest for the blue tits. Roses that had fungal diseases last year can be sprayed preventively now. Use Systhane Fungus Fighter or Fungus Clear.