Whitefly: There are several weeds that will harbour whitefly outside the glasshouse only to allow them to flock in through the vents as soon as it is warm enough. Keep the weeds down around the outside walls by burning off the foliage with Roundup. Follow that with a residual herbicide mix containing Devrinol and Stomp 400 SC to reduce regrowth.
Tree lifting: Make sure that trees are not damaged during the lifting process if the machinery is struggling with wet conditions because they can lead to stem cankers.
Winterisation: Make sure that staff know what to do and make someone accountable for doing it. I see so much plant and equipment damage caused by a lack of management in this area. Protection in the early stages does help plants to acclimatise to cold weather gently. Check that spray lines in tunnels and low-level pipes are drained and only filled when needed. Pumps, fertiliser injectors, irrigators and sprayers should all be drained down too. Land needed for spring planting should be ploughed now, if conditions allow, for the winter frosts to break it down. Autumn applications of herbicides should be made to a suitable soil surface. Make sure that the soil is fine and crumbly to get the best herbicide activity because large lumps will breakdown in the winter and leave large patches without herbicide action. It is too wet for Basamid application at the moment.
Trimming: If you normally trim your shrubs at potting this late in the year, consider a change of procedure. I believe that you should not allow a plant to be dormant for a long period after trimming. Either trim a few weeks before potting, while there is still some growth, or wait until late winter so the plant will start growing soon afterwards.
Cleaning up: Protected nursery stock should still be sprayed with Rovral WG, Scotts Octave or Switch during the winter period as a precautionary treatment. Add in a wetting agent for plants with hairy foliage. Use an air-assisted sprayer if possible to get good penetration. Focus applications on Helleborus, Cordyline, Phormiums and Yucca this month to prevent damage by leaf spots. Certis Spraying Oil will provide over-wintering control of spider mites, mealy bug and scale insects. You should avoid spraying if a frost is forecasted that night or you can get foliar damage.