Hoping someone can help me with my well established lilac shrub. Its had some powdery mildew for the last couple years and last year some of the foliage turned a rusty colour, some curling and dying and there was a lot of dieback. I pruned it last summer to try and increase air circulation for the mildew and take out the dead branches. I also cleared put the dead leaves in the fall from under to remove the mildew from the area. This spring there are more branches with foliage, dead looking blooms, and some of the new leaves are already rusty coloured and some are curling. The shrub typically blooms end of May into June. There is no visible mildew yet. See picture attached. Wondering what is wrong and what I can do to to save this beautiful shrub.
Below you will find basic lilac care which, when you read through, you may find some solutions to your problems.
- Plant in full sun – 6 hours minimum.
- Plant in a well drained site – lilacs hate to have ‘wet feet’.
- If you have clay soil, add compost, sheep manure or other well rotted organic matter.
- Mulch around the tree/ shrub – 2-3 inches of a shredded bark/wood mulch is ideal.
- Limit watering as lilacs can take drier conditions.
- Water using a drip hose – this targets the moisture towards the roots without wetting the foliage and also helps control the spread of disease pathogens.
- Feed in early spring – 8-20-18 fertilizer.
- Prune dead, diseased, damaged and dangerous branches to a maximum of 1/3 of the plant – should be done after flowering and will help with air circulation through the plant.
- Deadhead once this years flowers are spent to encourage formation of buds for next year.
I am also attaching a link to a great article on lilac disease from Penn State Extension which you may find helpful.