Lilac borer larvae, which eat the plant’s sapwood, are the main cause of damage to lilacs. Another pest that harms lilacs is the scale insect, which feeds on the sap of the plant’s leaves, stems, and roots. Lilacs that are severely infested with scales may look sickly.
Who or what consumes lilacs?
The majority of the caterpillars and leaf miners that may visit lilacs are harmless, and just a few significant pests are drawn to them. But if either of these pests shows up, take action now:
ScalesScales might be challenging to find. Numerous species resemble waxy or cottony growths on the stems and branches of shrubs used in landscaping. But if you raise their coverings, you’ll see tiny, vividly colored insects there. Neem oil treatments spread seven to fourteen days apart work best for treating scales. Pruning them out is a great solution when they are grouped together in one area of the plant.
Borers
Boring bug that prefers to eat lilacs is the clearwing moth larva. These tiny caterpillars only emerge to mate after spending the most of their life inside the stems and branches of your plant. Maintaining the lilac’s health and happiness is the key to effective management because sick plants are significantly more likely to draw borers. When the lilac is stronger and less alluring, its many natural enemies will take them out.
What do you use to spray lilacs?
Portland, Oregon – Do the fresh blooms and branches on your lilac plant resemble burnt wood from a blowtorch? Lilac blight is a bacterial plant disease that could affect your bush.
Lilac blight is more likely to occur in a cool, wet, rainy spring, especially if there has been a late frost or other winter damage. Plant pathologists at Oregon State University Extension are cautioning that this year may be favorable for the disease.
Lilac bacterial blight, as the disease is officially known to plant pathologists, is brought on by the bacterium Pseudomonas syringae pv. Syringae. The bacterial blight that affects pear, blueberry, cherry, maple, and many other woody plants is caused by the same organism, and the symptoms of lilac blight resemble those of fire blight in fruit trees.
Initially, leaves appear to be in full health, but a short while later, they appear to have an open flame nearby. Young shoots with dark black stripes on one side demonstrate the disease’s progression. Unopened flower buds turn black and the blossoms fade, turning brown.
Never fertilize after the growing season has ended. Don’t fertilize young plants excessively.
Lilac blight is challenging to eradicate, therefore anytime you plant new lilacs, it is advised that you use blight-resistant kinds.
In order to prevent friction and allow air to easily circulate between the plants, it also helps to space and clip your lilac plants. Never fertilize after the growing season has ended. Melodie Putnam, an OSU Extension plant pathologist, advised against overfertilizing young plants since excessive nitrogen levels encourage the development of diseases.
If your lilac bush does have an infection, immediately cut and burn all affected areas. A copper sulfate spray applied in the early spring each year should help stop the issue before the buds start to open.
In order to prevent friction and allow air to easily circulate between the plants, it also helps to space and clip your lilac plants.
Bacteria that cause lilac blight can overwinter on good wood or sickly twigs. Plants are more susceptible to the illness when they are weak or injured by factors such as wounds, frost damage, soil pH, inadequate or poor nutrition, and infection by other diseases.
Old cankers, healthy buds, leaf surfaces, and adjacent weeds and grasses can all be sources of this disease. The bacteria were dispersed by wind, rain, insects, tools, and diseased nursery stock.
In western Washington, some lilac species, including S. josikaea, S. Komarowii, S. microphylla, S. pekinensis, and S. reflexa, have demonstrated resistance. The majority of S. vulgaris cultivars are prone to the illness, however others, like “Edith Cavell,” “Glory,” “Ludwig Spaeth,” and “Pink Elizabeth,” have been seen to be less afflicted when grown in gardens. Be aware that ‘Ludwig Spaeth’ is quite vulnerable in systems with large nursery production.
If your lilac bush does have an infection, immediately cut and burn all affected areas. Early in the spring, apply copper sulfate to the ground.
As young shoots form in the early spring, the disease first appears as brown blotches on their stems and leaves. The area may also have a yellow halo surrounding it. Especially when it rains, spots quickly turn dark and spread out. The age of the plant component that was damaged determines how far the infection can spread.
On immature stems, the infection encircles and girdles the stem, causing the shoot to crook at the lesion and the sections above it to wilt and die. On mature wood, lilac trees do not get infected; only cherry trees do.
Young, infected leaves quickly become black, first at the margin and then down to the petiole in a wedge-shaped pattern. The leaf eventually withers completely. Spots on older leaves slowly grow. The margin or the mid-vein of the leaf may crumple when numerous areas occasionally run together. Additionally, flower clusters may become diseased, quickly blighted, and darkened. Buds may not open properly or they may turn black and die soon after they do. The signs are the same as those of a winter injury.
Visit the PNW Plant Disease Management Handbook of OSU Extension to view pictures of this disease. The guideline reiterates the following cultural restrictions on treatment:
- Maintain proper plant spacing and prune to encourage proper airflow within the canopy.
- Cut all afflicted tissues out and burn them right away.
- Plant species or cultivars that are resistant.
- Never fertilize after the growing season has ended. Don’t fertilize young plants excessively.
Do you want to know more about this subject? View further materials from OSU Extension here:
How can I keep my lilac bushes safe?
Lilacs are more resilient than other plants to a chilly winter. If there is no precipitation accessible to the roots, they do benefit from sporadic watering. Winter protection for lilacs is provided by watering close to the root zone, which actually maintains the soil warmer than dry soil.
Rarely, you might have to cover the plant to keep the buds safe. When buds are just starting to open in late winter or early spring, a severe freeze strikes. Cover the shrub with a blanket, canvas, or even a plastic tent to help shield the buds from the cold. If it gets warm enough during the day, take it off so the plant may enjoy some sunlight and air.
What creature consumes lilac leaves?
Lilac bushes are not eaten by deer. Deer would generally avoid them because of their offensive fragrance. Never forget though that no plant is completely deer-proof.
Even if lilac plants occasionally and only rarely have seriously damaged kinds, they are still edible.
During the winter or during times when there are few other food sources, deer will probably devour the lilac shrubs. Because deer will gladly eat lilac bushes when they are young, it also occurs then. There’s a good probability that lilac bushes, if they’re native to your area, will end up being a deer’s preferred food.
Why is my lilac bush acting strangely?
Examine the branches for damage like as exit holes and sawdust, sap, and frass, which are indicators of insect infestation. Damage from damaged branches could be stopped by pruning them off. Next spring, as the lilacs begin to bloom, keep an eye out for the adults and place pheromone-activated traps (see Lilac borer).
How can aphids on lilacs be removed?
You could occasionally encounter lilac disease and insect issues, just like with any other kind of plant. Fortunately, they don’t happen often and are typically not serious.
Always be diligent and look for issues before they spiral out of control.
Lilac Insect Problems
The lilac plant is resilient. They are generally not much bothered by most insect pests. Use insecticidal soap or a mild insecticide like Sevin to handle sporadic insect issues like aphids or borers. During the blooming season, ants will occasionally show up in great numbers. They do not harm the flower or plant because they are just looking for the sweet nectar in the blossom.
Cicadas, which periodically appear in great numbers east of the Mississippi, are a threat to lilacs. You should cover any large broods that emerge in your area with 1/4 pest netting at the time of emergence.
Does Miracle Grow benefit lilac plants?
When the lilacs begin to blossom, it is a solid indicator that spring has arrived for good. While many people only have a limited knowledge of common lilac (also known as French lilac) shrubs that can reach a height of 15 feet or more, there are now a lot more options available than there were fifty years ago. Some varieties that rebloom enhance the garden’s appeal the entire growing season.
How to Choose Lilacs
The common lilac is what you will most likely find when you go plant shopping. This traditional plant comes in a variety of cultivars and variations, each of which yields fragrant spring flowers in pink, purple, white, or even combinations of those hues. Common lilacs are typically the most fragrant variety of lilac and can grow to be rangy and large.
Rebloomers have arrived in the garden center thanks to recent introductions of hybrids between the common lilac and other shrub-type lilacs. Some of these more recent types are a little less fragrant, but they also tend to be smaller, bloom more frequently throughout the growing season, and have fewer powdery mildew issues.
The tree lilac is another common variety of lilac. It can grow to a height of around 20 feet and blooms with cream-colored flowers in the middle of the summer. Though it doesn’t require much trimming, keep in mind that the tree lilac is a tree, not a shrub.
Where to Plant Lilacs
Lilacs should be planted in full light (at least 6 to 8 hours per day), as too much shadow will prevent them from blooming. Lilacs also prefer moist, well-drained soil that is slightly alkaline.
When to Plant Lilacs
Before the ground freezes in the late fall is the ideal time to plant lilacs. After the earth thaws in the early spring, that is the next ideal period to plant. Lilacs will likely need to be planted as soon as you can locate them at the garden center, which is great; if you choose to do so during a warmer season, they might require additional watering.
How to Prepare the Soil for Planting Lilacs
A soil test should be performed prior to planting since lilacs thrive in slightly alkaline (6.5 to 7.0 pH), moist, well-drained soil that is high in organic matter. Lime must be added to raise the pH if it is below 5.5. It’s time to get the soil ready when you’ve obtained the ideal pH. Improve individual planting holes by mixing Miracle-Gro Garden Soil for Trees & Shrubs in a 50:50 ratio with the natural soil to give lilacs a nutrient-rich start. Iron and phosphorus are also present in this garden soil to promote root development and ward off leaf fading.
How does bacterial blight on lilacs appear?
Gina Foreman* and Brian Hudelson, UW-Madison Plant Pathology *Fulfilled in part the criteria for the Plant Pathology 875Plant Disease Diagnostics Clinic Internship.
Describe the bacterial blight. A common and frequently deadly disease of Chinese, Japanese, Persian, and common lilacs as well as walnut, apple, pear, plum, and cherry is bacterial blight, commonly known as blossom blight or shoot blight. The disease is most likely to affect common lilac cultivars with white flowers.
What appearance does bacterial blight have? Initially, dark brown necrotic (dead) leaf patches with yellow haloes could be a sign of bacterial blight. Leaf bending and twisting may occur if leaf spots appear before leaves have fully developed. Necrotic blotches that begin at the leaf borders and move within are signs of a more advanced condition, as are black streaks on twigs. Bacterial blight can cause the death of branch tips, leaves, and blooms in its most severe form.
Where is the origin of bacterial blight? The bacterium Pseudomonas syringae pv. syringae (Pss), which thrives in damaged stem tissue (cankers), plant detritus, and soil, is responsible for bacterial blight. Pss is distributed more frequently by wind and rain than by insects or by pruning instruments. Pss frequently lives on the surface of healthy plants without harming them. The bacterium can cause infections when it enters tissue naturally or by wounds brought on by insects, pruning, wind damage, or hail.
How can a plant that has bacterial blight be saved? Dispose of sick branches by burning or burying them after cutting them off 10 to 12 inches below the point of noticeable symptoms. Always prune in dry weather, and after every cut, disinfect pruning shears by putting them in a 10% bleach solution or alcohol for at least 30 seconds (spray disinfectants that contain at least 70 percent alcohol can also be used).
How can I prevent bacterial blight issues in the future? Lilacs should be planted with sufficient space between the shrubs. Each winter, thin individual shrubs to encourage proper airflow (see UW Garden Facts XHT1015 for pruning tips). To prevent stress that could make shrubs susceptible to disease, properly fertilize, water, and mulch them. Avoid watering overhead because it can keep the leaves damp. You might want to use a mixture of copper- and mancozeb-containing fungicides to reduce bacterial blight if you’ve experienced issues. Fungicides should be applied twice to three times, seven to ten days apart, as leaves emerge but before symptoms appear. To ensure that you use the fungicide in the safest and most efficient way possible, make sure to read and adhere to all label directions.
Why are my lilac bush’s leaves falling off?
They thrive in soil that is well-draining, somewhat alkaline, and in full sun. However, sudden leaf loss is likely a sign of an insect pest or another issue. Lilacs may typically be brought back to life with appropriate maintenance and yearly pruning.
Are lilacs suited for coffee grounds?
Lilac plants don’t require a lot of food or fertilizer. A 10-10-10 fertilizer mixture applied yearly in the early spring is what we advise. (The amounts of nitrogen, phosphorus, and potassium, or NPK as they are popularly known, are represented by the digits 10-10-10 in the formula.) Early spring fertilization of lilacs with a high phosphorus solution encourages blossoming.
Coffee grounds and grass clippings are also excellent sources of nitrogen. Use in moderation since an excess of nitrogen in the soil can lead to subpar blooms. The ideal soil conditions for lilacs are slightly alkaline (6.5–7.0 pH), wet, and well-drained. The soil may become more alkaline by adding bone meal to it. Use Miracle-Gro Shake ‘n Feed Flowering Trees & Shrubs Plant Food in the spring if you decide to feed your plant. Last but not least, lilac plants dislike acidic soil. Epsom salts can be used to encourage blossoming while the plant is dormant.