Ash: The ash leaf gall sucker causes ash leaf gall, which is recognised by a leaf edge curl and purple discolouration and can be active at any time now. It is a small bluish-green insect about 3mm long with red eyes, a blunt head and very pointed tail. Spray ash with Hallmark WZT (SOLA 2008-2944) at least once this month.
Feeding: Older plants left from last season will need to be included in the nursery's liquid feeding of 2:1:1 or top dressing programme for sales this year. Hibiscus, Skimmia and Cytisus will benefit from the addition of iron.
Scale insects: Spray mobile stages now with Decis (non-IPM), Chess WG (SOLA 2008-2834), Majestik, Savona, SB Plant Invigorator or Spraying Oil. Sooty mould can be cleaned up with chlorothalonil. Check bay trees, Hedera and Camellia.
Nicotine: All products containing nicotine lose their approval for storage and use on 8 June.
Eucalyptus: Keep plants shaded and do not over-water during hot, sunny weather to avoid "bumpy" leaves. This is oedema, which is caused by high temperatures and high humidity. It will have no effect on the plant and growth will be quite normal.
CRF: Compost temperatures under protection can get high during sunny days. Reduce CRF levels by 10 per cent for crops under glass or polythene to avoid root damage.
Tree seeds: Cover vulnerable crops with white fleece while trees like poplar, willow and alder are dropping their seeds. This physical barrier will help to reduce the need for hand-weeding these woody seedlings later.
PGRs: If you use Bonzi, then the second or third application should be given to shrub subjects now. I still prefer the frequent low-dose effect of the product to large doses after potting.
Pine shoot moth: These are now very active and can have devastating effects on the plant structure. Spray with Toppel 100 EC, chlorpyrifos or Decis if you see moth activity. The aim is to control either the adults during egg-laying or young larvae during hatching. Good needle and stem coverage is essential - use high water rates and a wetting agent.
John Adlam is managing director at Dove Associates