When the lilac is sick, the lilac friend is sick too, emergency pruning is painful. Not for the lilac, plants don’t feel pain (evolutionally pointless, plants can’t flee from predators). With normal lilacs, however, radical pruning remains the exception; otherwise healthy plants can usually be kept below the damage threshold with little effort. It is only with the lilac that the chance of damage from diseases, pests and fungi is a little higher, but perhaps the special requirements of a particularly sensitive cultivar were not observed or an uncritical purchase was to blame. Here is an overview.
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Syringa vulgaris or common lilac
Syringa vulgaris is still by far the most common lilac in our country – and a real Syringa vulgaris or common lilac never gets sick. The tree actually comes from Southeast Europe and is used to a little more warmth, but has been growing in cottage gardens in Central Europe since around 1600. He is now really familiar with our climate. So familiar that the Federal Agency for Nature Conservation put it on the management list of the black list of invasive species in 2013 because it can displace native trees and shrubs growing wild because only a few small native shrubs and herbs grow under it.
This lilac is so hardy that if it becomes seriously ill, something could be fundamentally wrong. If other plants in the garden are also growing poorly, it should be ruled out.
Check soil condition
Perhaps young lilacs were planted as the first planting on a new building plot on which construction machines were just circling around. Then the soil could be so compacted that the roots of the lilac rot / wither. Green manure would be the remedy against it, maybe the lilac can be saved if it is transplanted into sufficiently permeable soil.
Perhaps there were or are conifers or rhododendrons near the lilac in the affected (taken over) garden, under which the soil is/was systematically acidified. Lilacs need at least a pH of 5.5 to grow. Liming after measuring the soil pH value would bring improvement here.
Common lilacs don’t even get sick on sites along railway embankments. Maybe a gardener in the past on your property managed to spread even more pesticides in the garden than the railway – unfortunately not unusual for home gardeners, even the remains of long-banned substances are sometimes used fearlessly until the soil simply dies and not even one more lilac can feed. A soil analysis provides certainty.
If you took over the lilac with the property, you might get the idea that if your lilac doesn’t look quite fit, it’s because of age. The lilac belongs to the olive tree family. The oldest existing olive tree was already a few hundred years old when Noah took the olive branch from his dove.
Syringa x and ®: The precious lilac
If it can’t be because of age and soil, it could be because of the purchase. Today you no longer necessarily bought a hardy Syringa vulgaris if you simply wanted to buy a lilac; perhaps you have also deliberately acquired a precious lilac.
Syringa vulgaris hybrids have been bred since the mid-19th century. There is now an abundance of precious lilacs in many new colors and color mixtures. They are usually beautiful, but have often lost some of the resilience of the robust original lilacs during breeding. In addition, there are excellent lilac breeders who produce new lilac varieties with a lot of knowledge and time – but in times of escalating neoliberalism there are also breeds where “the market” takes precedence over specialist knowledge and patience. This gives rise to many a highly cultivated lilac, which looks magnificent with its strikingly colored, double-double flowers; but only grows splendidly if each of its absolutely necessary requirements is met with pinpoint accuracy.
If such a sensitive lilac becomes ailing with the best care, in the worst case you have caught a cross with an Asian lilac, which is not hardy here, but in most cases simply does not sufficiently consider the requirements of the “prima donna”, you e.g. B. assigned a location that is too dark.
With such a lilac, you should carefully check all location and care requirements and use plant strengtheners before you start fighting any diseases/weaknesses.
If your lilacs were damaged in such a way that they did not survive shortly after planting, the fault may also lie in the condition of the plant material supplied. When ordering online, next time you should read all the comments carefully or go straight to the nearest specialist nursery/nursery.
The non-blooming lilac
If it’s just because your lilac doesn’t want to bloom, it may not be the right age for it right now.
It could be too young, a freshly planted lilac sometimes needs a few years until it has properly rooted itself and begins to flower. Three years is normal, but there are also late bloomers in plants… the same applies here, of course: check the location and care requirements carefully again, maybe strengthening the plant with horsetail and co., combined with biological bloom fertilizer, will help.
The lilac could also be too old, which, as I said, is not very likely with the original form of Syringa vulgaris, with the cultivated varieties it can look very different. When a cultivar is possibly struggling with age, a radical rejuvenation pruning could help; if already signs of aging such as (otherwise harmless)
Lichens appear, it is time to ensure successors through propagation.
Check maintenance errors
There are many diseases, etc., which theoretically a lilac can also get. If it is a lilac or a weakened Syringa vulgaris, it may also get diseases, pests, fungi handy.
That doesn’t mean you need to panic – these nuisances only afflict weakened plants to a degree that harms them. Pathogens, pests and fungi are present in every garden.
Under no circumstances should you rush to the nearest garden center and ask for something against diseases, pests, fungi. First of all you should check the general conditions and shower/collect crawling little animals regardless of their provenance. Corrections in the care plus plant strengtheners made from stinging nettle or horsetail could help a slightly damaged lilac get back on its feet.
The vast majority of “attacks on the lilacs” can be contained by collecting/showering off (pests) or by pruning the lilacs (diseases, fungi). In the event of a significant infestation with whatever, the damaged shoots should always be removed down to a piece of healthy wood and disposed of in the garbage. Cutting tools are always disinfected with denatured alcohol or high-proof alcohol after each cut. You can then thin out the lilac thoroughly, the more light and air gets into the tree, the harder it is for fungi to spread. If it is highly probable that fungi have already migrated in, you should refrain from using plant strengtheners with manure and fertilizing with compost and instead planting under, with wild garlic or common mallow (Malva neglecta), for example.
If diseases, pests and fungi are found that could be combated by intervention in the plant household, such interventions should only be carried out when the disease, pest or fungus has exceeded a certain damage threshold. Then the smallest conceivable intervention is started. Only at the very end of an impairment is the use of plant protection products – if there is an approved plant protection product against the respective impairment, which is not always the case.
lilac diseases
1. Pseudomonas syringae, bacterial disease, lilac disease, Pseudomonas are ubiquitous on host plants, there is a risk of forest damage, since the bacterium reduces the temperature for ice formation
- Symptoms: Brown striped, dark bark, brown-black wilted shoots that rot, dry up, break off. Leaves with light to dark brown “wet” spots
- Measures: No pesticides available, strengthen lilacs well for the winter in autumn, no pruning in winter, winter protection if necessary, remove damaged shoots as described above in the event of severe infestation
2. Viral diseases (rare)
- Symptoms: light spots, lines, rings on the leaves, deformation, growth failure
- Measures: Cannot be fought, lilacs must be removed, never in the compost
Lilac Pests
1. Caloptilia syringella, lilac (minier) moth, inconspicuous small butterfly
- Symptoms: Olive-grey spots on leaves, leaf tissue destroyed, leaf skin visible, droppings crumbs, yellowish larvae eat in the leaf, parts of the leaf die and turn brown
- Measures: Control is not normally necessary, ask the local environmental agency in the event of severe, repeated infestations (no pesticides are permitted for use in the house and small garden)
2. Eriophyes loewi, Gallmilben
- Symptoms: Light green leaves, thickened buds, ugly witches’ brooms, short shoots
- Measures: loosening the soil of the tree disc, e.g. B. by wild garlic, remove infested leaves, spray shoots with rapeseed oil preparation in early spring
3. Otiorynchus smreczynskii, lilac weevil
- Symptoms: eroded leaf edges
- Measures: Collecting, for healthy lilacs no more than a “natural root trimming”, effective chemicals do not exist, if the weevils increase every season, try biological pest control with nematodes
4. Xanthospilapteryx syringella, Gelbfleckflügelmotte
- Symptoms: Mottled, nibbled leaves, crumbs of feces, parts of the leaves discolor/die
- Measures: see lilac moth above
Mushrooms on the lilac
1. Ascochyta syringa, Ascochyta leaf spot
- Symptoms: Light gray spots with a brown edge, later shoots wilt, branches open
- Measures: Remove diseased shoots
2. Chondrostereum purpureum, galena disease, milky shine, dangerous disease
- Symptoms: Silvery to lead-grey leaf color, purple fruiting bodies on the wood
- Measures: Heavy trimming
3. Gloeosporium syringae, Fliederfäule
- Symptoms: Large brown spots on the leaves
- Measures: Remove diseased, clear cut
4. Heterosporium syringae, Blattbrand
- Symptoms: Grey-brown circular spots, velvety leaf surface
- Measures: Remove diseased, clear cut
5. Microsphaera syringae, Echter mildew
- Symptoms: Whitish coating
- Measures: Control is not normally necessary, strengthen the plant with lecithin (as an organic powdery mildew agent), remove diseased shoots in winter, treat extreme infestations with an approved fungicide
6. Phyllosticta syringae, Schlauchpilz
- Symptoms: various Damage to leaves/shoots
- Measures: Remove diseased, clear cut
7. Septoria syringae, leaf spot disease
- Symptoms: Yellow-brown leaf spots.
- Measures: Remove diseased, clear cut
8. Verticillium alboatrum or other Verticillium, nasty vaso-clogging micro-fungi
- Symptoms: Brown leaves, leaf fall, shoots wither, possibly to the point of death
- Measures: Remove diseased parts of the plant immediately, cutting back clearly into the healthy wood, disinfect cut surfaces/treat with wound closure
Conclusion
Diseases, pests, fungi are part of nature and can never be eradicated. There is much more than what is listed, no one can say what actually occurs when, where and how often – the secret of success is therefore to enable the garden and plants to deal with them. Sensible and harmless means of control can be used, but any prolonged control with means that interfere with the plant balance could disturb the balance even more. If a plant cannot cope with its environment over a long period of time, it is better to eventually replace it with a more resilient plant.
