Heathers: Erica and Calluna can suffer from Rhizoctonia during this time, particularly protected crops and young overwintering plugs. Those where no control programme is in place are often most at risk. A spray with Rovral WG or Basilex will give control, but do note the restrictions on the Basilex label.
Rust: Rust is often a problem on Mahonia aquifolium 'Apollo' Award of Garden Merit in December. Spray Nimrod or Systhane 20EW.
Azalea gall: This infection can be expected from late December onwards if wet conditions continue. Spray with Croptex Fungex when the first signs of this disease are seen. This tends to be related to wet times.
Roses: At the HTA's British Rose Group R&D Forum Tim O'Neill of ADAS, Jane Thomas of the National Institute of Agricultural Botany and Xiangming Xu of East Malling Research all talked about HDC projects on rose downy and powdery mildew with several products showing good control. Other projects on the use of ethylene to improve basal breaking and replant disease were also presented. Take time during the winter to look through some of these excellent research documents.
Leaf hoppers: There is still some insect activity on protected crops. Check closely on overwintering plants and control with rapid knockdown products such as Stalwart, Majestik, SB Plant Invigorator or Chess WG at the off-label rate.
Leaf spot: Spray Scotts Octave, Switch or Rovral WG once before Christmas on protected crops to control leaf spot fungal diseases.
Mites: Two-spotted spider mite can still be found on protected crops. Control the adults with Gyro but do not apply after January if you intend to use IPM next year. These mites overwinter as eggs and these can be controlled by applications of Apollo 50 SC. It is a little late now but spray again in the early spring when the eggs start to lose colour.
Scale: Soft scale can be seen on a range of both indoor and outdoor crops. Spray with Croptex Spraying Oil (avoiding frosty conditions) to reduce eggs or young present under the shell.
Cold stores: Watch the temperature and humidity levels in cold stores during changeable days. Consider spraying stored material with Bravo 500 or Repulse as protection against fungal growth on the stems and old foliage. Milder autumns mean more old foliage is left on the stems and this becomes a breeding ground for fungi.