I planted this lilac in the spring - young and small but it was green and...

Asked July 9, 2020, 3:42 PM EDT

I planted this lilac in the spring - young and small but it was green and grew well in a sunny spot. Now some its branches and leaves are turning brown, very dry and dying yet much is still green. I don’t see any pests or fungus. Could it be burning up in hot summer sun ? Trim the dead parts ? Want can I do ? Thank you

Baltimore County Maryland

3 Responses

Lilac are susceptible to a few different blight-causing diseases (some fungal, one bacterial) and they can be difficult to differentiate. In all cases, removal of dead wood needs to occur. Prune out all branches with dead leaves as close to the ground (or the next living section) as you can get without inuring other wood. It wouldn't hurt to sterilize your pruners after this to avoid transmitting the disease; this takes either a ready-to-use bleach spray (which needs to sit on the blades as long as the bottle recommends for sterilizing non-porous surfaces) or 70% rubbing alcohol, which also needs to saturate the blades for about ten minutes before air-drying. Bleach may corrode the metal after repeated use so be sure to wipe the blades clean afterwards.

Such diseases can take advantage of wounds or general plant stress. Lilacs do not want to stay wet, so make sure the root zone is being monitored several inches beneath the surface for moisture before any watering is done in case it is not needed. If the drainage is good and the plants are in full sun (6+ hours a day) then they are in a good location for recovery.

Poor root establishment can also explain this kind of dieback. Here too, overly-wet or overly-dry conditions (less likely from this spring's weather) can cause root injury. Symptoms from general drought stress or damage in hot sun would be even around the whole plant (rather than localized like this) and affect the youngest growth at the stem tips first. Leaves tend to burn and brown from the edges inward and sometimes in patches on the center of the leaf as if scalded. Collapsed foliage along the whole branch at once while other foliage appears healthy suggests other issues.

Miri

This info is very helpful.

Along with pruning, should I treat it with an anti - fungal systemic solution ?
Abs now that it has been established and finished potential blooming for the season , should I skip extra watering ( besides rainfall ) all together ?
yes gets lots of sun
thank you very much !!

Prune only dead plant material and no chemical controls are recommended.
The shrub is still establishing its root system.

Check the soil moisture and make sure mulch is no thicker than several inches and away from the base of the stems. Plants less than two years old should be watered deeply once or twice per week during the hottest and driest part of the summer. This encourages roots to grow deeper. More frequent, light watering only wets the surface promoting a shallow root system. Soil should be damp like a wrung out sponge.
After watering, probe with a screwdriver to make certain the soil is moist down about six inches. Water when the soil is dry at that depth. See watering guidelines https://extension.umd.edu/hgic/topics/watering-trees-and-shrubs

Marian