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#BACTERIAL BLIGHT LILAC BUSH DISEASES SERIES#

Pupal cases may be visible at adult exit holes. Look for dead stems in the center of a lilac bush. Avoid wounding the stems, especially with lawnmowers and string trimmers. Keep shrubs well-watered during dry periods. To prevent borers, keep mulch away from the base of the shrub. Photo: Lilac borer exit hole on a branch Management

Continual reinfestation of the shrub will result in branch dieback.

As they feed they push frass out of the tunnels via the holes.

The hatched larvae tunnel into the wood and feed, boring into the heartwood.

The moths emerge in mid-May and lay eggs on the bark.

They are a serious pest of lilac and ash trees (ash trees are scarce in the landscape due to emerald ash borer).

Lilac borer, Podosesia syringae, is a clearwing moth that resembles a wasp in appearance.

Prune out diseased shoots right away during dry periods and remove the clippings from the area to prevent reinfection. Prune or thin out lilacs in early summer, after flowering, to promote better air circulation and allow time for wounds to heal before the next season. Photo: William Jacobi, Colorado State University, Prevention and managementĪvoid overfertilization and excessive pruning to prevent an overabundance of young susceptible shoots in the spring. Symptoms of bacterial blight (Pseudomonas syringae) on a lilac

In Maryland, spring frost damage and late fall or winter pruning seem to predispose shoots to bacterial blight infection.

Rainy, mild spring weather promotes the disease.

Leaf spots quickly grow together and blight entire shoots. Leaf symptoms are irregular dark spots on leaves sometimes ringed by yellow halos. Early symptoms include the blackening of new green shoots, leaves, and flower buds.This bacterium is commonly found on leaf surfaces as part of the natural population of microorganisms on plants.Bacterial blight of lilac is caused by the bacterium Pseudomonas syringae cv.Littleleaf lilac, Syringa microphylla, is heat tolerant and mildew resistant.Syringa ‘Tinkerbelle’ is a cross between Syringa meyeri ‘Palibin’ and Syringa microphylla ‘Superba’ with good powdery mildew resistance.Syringa meyeri ‘Palibin’ – matures about 4-5’ tall and 5-7’ wide blooms slightly later than common lilac powdery mildew resistant.Syringa patula ‘Miss Kim’ – matures about 4-7’ in height blooms slightly later than common lilac powdery mildew resistant deep burgundy fall color.It is susceptible to bacterial blights, Phytopthora, and leaf spot. Japanese tree lilac, Syringa reticulata, a lovely small tree or large shrub, h as moderate resistance to powdery mildew, scale, and borers.Syringa vulgaris cultivars with above-average powdery mildew resistance include ‘Charles Joly,’ ‘Sensation,’ and ‘Old Glory’.

#BACTERIAL BLIGHT LILAC BUSH DISEASES SERIES#

Members of this series also have the distinction of sporadically re-blooming later in the summer or autumn. Like many dwarf hybrid lilacs, the Bloomerang series is more disease-resistant than typical Syringa vulgaris and matures shorter in height. Bloomerang ® series of lilacs is powdery mildew resistant and reblooms.