Warm days The early shooting of growth means that cutting material of protected herbaceous and shrubs is maturing now and will need to be either utilised or cut off and allowed to break again, rather than be allowed to get too long and leggy.
Lavender The common shab disease or Phoma is now appearing on lavender plants. If you see branches dying back from the base, drench at the base with Scotts Octave or Delsene 50 Flo. Dying from the tip downwards is Botrytis and needs a Rovral WP, Switch, Frupica SC or Amistar spray to the growing points.
Clematis wilt Drench newly potted Clematis with Aliette 80 WG then spray with Scotts Octave as a precaution against Clematis wilt.
Downy mildew Keep an eye out on pansy, Digitalis and Geum as well as other susceptible herbaceous perennials as they can begin to get downy mildew during March. In some cases you can be misled into thinking it is powdery mildew as it is white, not the usual greenish colour of downy mildew. Spray with Fubol Gold WG (SOLA required) or Aliette 80 WG if the tell-tale yellowing on the top surface and angular darker patterns are seen on the leaf.
Tortrix moth Where you see tortrix moth caterpillar activity, spray with Nemolt, Runner, Majestik or SB Plant Invigorator in biological control areas and Dimilin Flo, Insegar WG, Stalwart, Decis or Toppel 10 in others.
Box blight Nurseries can control this disease successfully with sprays of Delsene 50 Flo + Bravo 500 or Signum. Those in public gardens or non-commercial environments have very few effective products and are basically reduced to the use of copper or the citrus-oil-based products.
Powdery mildew Use Cyflamid, Amistar or Systhane 20EW for control on miniature roses if seen.
Leaf spotting Leaf spots on pansies, Phormium, Yucca, Ceanothus and Viburnum are likely to develop this month if unchecked. Spray with Scotts Octave now and Delsene 50 Flo + Bravo 500 in the middle of the month.
Phytophthora Consider a drench of Aliette 80WG, Subdue, Proplant, Terrazole 35 WP or Filex to Chamaecyparis species to suppress Phytophthora in the growing media or field. Drenches of Revive or Trianum P give added security to these susceptible crops and I have seen good early season control from their use. Cytisus also benefits from a drench to control Pythium root damage.