Dwarf Leaves and Fungus (trees and perennials)

Question: Last season (2022) I had multiple perennials that had leaves which did not grow out (dwarfed budding); they also had a fungus.  This occurred on lilac, smokebush, dogwood and peonies.  It didn't occur on all of each variety on the property but on multiples of each.  What is it; cause; treatment?

Thank you!

responder: An Ask Extension Expert Replied March 09, 2023, 1:13 PM EST
response: The small leafy growth on the trunks of your shrubs and dogwood tree are suckers. They are generally not a serious issue, but they do sap water and nutrients from the plant. Sometimes they appear after large limbs have been removed. And they could be an indication that the roots have been damaged in some way. The tree is simply trying to stay alive by producing more leaves.   These kinds of suckers are generally produced when the tree is under stress or perhaps dying. You should examine the overall health of your dogwood tree and shrubs that are producing these suckers.  Are they healthy otherwise? Do they bloom as expected? If so, these suckers are not a concern; you can simply prune them off close to the trunk. But they do indicate that the plant is in need of some TLC. You should be sure your plants are getting the water and nutrition they need.   The white spots on your perennials are caused by a common fungal disease called powdery mildew. Powdery mildew spores are air-disseminated and subsequently infect leaves and stems of plants under humid conditions. This disease rarely kills a plant; it is just unsightly. Powdery mildew is plant specific, so it will not necessarily spread to other plants. For example if the disease appears on peony leaves, it won't necessarily spread to other perennials.   Remove and destroy infected leaves (do not compost) if you can, including at the end of the season. Spores on infected leaves left lying on the ground can overwinter and encourage infection the following year.  Try to reduce the level of relative humidity around the affected plants if possible. High relative humidity is conducive to powdery mildew development. And increase spacing around the plants to promote air movement around them.   Fungicides can help prevent the spread of this disease to other plants, but they will not "cure" leaves already infected. They should be applied at the first sign of the disease. Select a fungicide that states on the label that it controls powdery mildew and be careful to follow all instructions on the label.

responder: The Question Asker Replied March 09, 2023, 3:19 PM EST
response: Thank you for the helpful information.  I will watch for the powdery mildew this year.    The suckers were very dominant on the lilac and smokebushes.  Mostly, normal foliage was not present.  I don't normally water these areas.  Should I try doing so this spring?  (Not sure if we have had unusually dry summers the past 2 year?  They were fine before last year.  Thank you

responder: An Ask Extension Expert Replied March 10, 2023, 7:37 AM EST
response: Hi Cathy, It’s odd that your shrubs declined so rapidly. But if, as you said, your lilac and smokebush failed to leaf out last year and all they produced were the trunk suckers, it’s likely they may not show any life at all this spring. If they are alive but look scraggly or unwell, you may want to remove and replace them. If they’re that far gone, water and food may not be enough to bring them back to health. It’s worth a try, though, if you want.  All plants need water. Perhaps your shrubs are planted in an exceptionally sandy or dry area. If you replace them, be sure to water well at planting and give them  an inch of water each week until they get firmly established and going forward. If it rains you can reduce that amount. Sprinkle granular fertilizer around the drip line as directed on the package, or use a liquid fertilizer as directed. Adding compost to the planting hole will help retain moisture. Good luck!