Finding dying leaves and brown spots on your “Mount Airy” fothergilla (Fothergilla major “Mount Airy”) can put a damper on your outdoor playtime with your children. According to Clemson University, this flowering shrub -- which grows in U.S. Department of Agriculture plant hardiness zones 5 through 8 -- is generally pest resistant, but does require certain cultural care to keep it healthy. Improper care can lead to dying leaves and brown spots appearing on the shrub.
“Mount Airy” needs ample moisture in well-drained soil. According to Clemson University, you should keep the soil moist until the shrub is established. Then ensure the plant has enough water to moisten its root zone but avoid overwatering. Too much water or soils with poor drainage leads to root rot, which can cause the leaves to develop brown spots and eventually die. If you suspect overwatering is the cause of the symptoms, use your hand to remove the soil around the plant roots to check for rot. Healthy roots are tough and firm with white on the inside, while rotted roots are soft, crumble easily and have an unpleasant odor. If excessive water is caused by poorly drained soil, you can either amend the soil with organic mulch or dig up and replant the shrub in soil with good drainage.
Lack of Water
“Mount Airy” cannot tolerate dry soils or drought-like conditions. Shrubs under these conditions can develop brown spots on the foliage and dying leaves that fall from the branches. So, just as too much water can be harmful, so can too little. A good rule of thumb is to insert your finger several inches into the soil and -- if the soil is dry -- water the “Mount Airy” deeply with a garden hose. According to North Carolina State University, watering deeply and infrequently prevents water waste and promotes deep root development. Applying a 3-inch-deep layer of mulch around the shrub will help keep moisture near the roots while protecting them from sudden changes in temperatures. When applying the mulch, keep it a few inches away from the base of the shrub and never allow the mulch to touch the shrub’s stems.
Insect infestations are not usually a problem with “Mount Airy,” but if they do occur, their feeding may result in discolored spots on leaves that wither, distort and fall from the branches. Sap-sucking insects -- such as aphids, mites and mealybugs -- are a common culprit that affects plants of all types and can be controlled by spraying the topside and underside of the infested shrub with non-toxic, ready-to-use neem oil. Neem oil is safe for use around children, pets and beneficial insects. Even though this organic pesticide poses no harm to humans, it is best for pregnant and nursing women to proceed with caution.
Prevention is Key
Prevention via proper care and good sanitation practices is vital to ensuring the “Mount Airy” is healthy and problem free. This includes cleaning up the ground near the shrub to remove any fallen plant matter. This debris is a hiding place and food source for insects and diseases that will harm your shrub. Remove any dead, dying or diseased limbs and leaves from the shrub. “Mount Airy” grows best in acidic soil rich with organic matter where it can receive full sun. Planting the fothergilla in the wrong location will quickly lead to problems.