Aphids - These pests are still alive on some protected crops and acers. Control at this time of the year can often be effective by the use of smokes or fogging as it reduces the amount of water you apply to the crop. Smokes available include Fumite Pirimiphos Methyl Smoke (approval ends September 2009) or Nicotine 40% Shreds. If you spray, you can use Chess WG, Decis, Majestik, SB Plant Invigorator or Stalwart.
Fleece - Covering plants at night with white fleece is superior to polythene for frost protection. There are several grades of fleece available so choose one with adequate thickness for your requirements.
Whitefly - Control any active adults outside with applications of Hallmark WZT, Toppel 10 or Decis and Gyro, Majestik or SB Plant Invigorator on protected crops. Don't use Gyro after January if you intend to introduce IPM next season. Outside, make sure you avoid spraying just before a frost to prevent foliage damage.
Heaters - At this time of year growers call me to report leaf scorch on heated crops under protection. Ensure that if you are using a paraffin (28 sec) heater that is direct fired (where the flame goes straight into the structure and not through a chimney) and that you only use premium grade paraffin with low sulphur content. This is particularly important if we have snow or the tunnels are shut up for extended periods.
Weed control - Use the milder days to spray diquat (eg Reglone), glufosinate-ammonium (eg Harvest) or carfentrazone-ethyl (Shark) over dormant herbaceous perennials. This will kill off the leftover weeds from last season and give you a clean start to the season. The application of the residual herbicides to field-grown crops such as Devrinol, Stomp 400 SC, Flexidor 125, Kerb formulations or Butisan S can be carried out on suitable spraying days. Avoid spraying residual herbicides during periods of heavy rainfall.
Powdery mildew - Some protected crops are still being affected by this disease. Consider food-grade potassium bicarbonate or Stroby WG for effective control at this time of year.
Botrytis - Check that the ventilation fans are all running in tunnels and glasshouses; this is one of the most important times for them to be fully operational. Open the doors of your tunnels at least once a day for a short period to change the air and control the humidity.
John Adlam is managing director of Dove Associates