Sky Pencil is a narrow, upright form of Japanese holly, and most gardeners buy it because it is easy to care for. When it struggles, the cause is usually its soil, water, or exposure rather than a mysterious disease.1Ask Extension. Japanese Holly Sky Pencil A few pests and the plant’s tall, loose branches account for most of the remaining troubles.2NC State Extension. Ilex crenata ‘Sky Pencil’
Root Rot From Soggy or Heavy Soil
Sky Pencil roots need fast-draining soil that lets air reach them.3Weekand. Diseases in Sky Pencil Holly In heavy clay or soil that stays soggy, root-rotting fungi such as Phytophthora and Pythium move in.4Weekand. Diseases in Sky Pencil Holly Infected roots turn brown or black and mushy.5Weekand. Diseases in Sky Pencil Holly As the roots die, the foliage above yellows and then dies.6Weekand. Diseases in Sky Pencil Holly Overwatering alone can cause the same damage, even in decent soil.7Gardening Know How. Common Sky Pencil Holly Problems and How to Handle Them8LSU AgCenter. Pencil Holly
A wilting or yellowing plant in wet soil is often mistaken for a thirsty one. Push a finger or a stick a few inches into the soil near the base. If it comes out wet and cool days after the last watering, water is not the shortage. Root rot often shows up first in the hottest weather, because damaged roots cannot supply the water the leaves are losing.
To check the roots yourself, gently dig at the base, or slide a potted plant out of its container. Healthy roots are firm and light colored. Rotted roots are dark and mushy, and they may peel away from the core. If most of the roots are mushy, replacing the plant is usually wiser than nursing it. If only a few are bad and the rest are firm and pale, trim off the bad ones with clean pruners and replant in a better-draining spot. Don’t put the plant back into the same soggy hole, since the fungi and the wet conditions are still there. Skip heavy fertilizer too, because damaged roots cannot take up much and the salts add stress.
Fixing drainage comes before replanting. Fill the planting hole with water and see whether it is still standing hours later; if it is, drainage is poor. In clay soil, plant on a raised bed or mound. Water deeply, then let the top inch or two dry out before watering again, and keep mulch thin and pulled back from the trunk.
Fungicides containing mefenoxam can help protect healthy plants before infection, with repeat applications as the label directs, but they are no substitute for good drainage.9Home & Garden Information Center. Holly Diseases and Insect Pests in South Carolina They only prevent infection, though, and will not cure a plant that is already infected.10Home & Garden Information Center. Holly Diseases and Insect Pests in South Carolina
Yellow Leaves From Alkaline Soil and Other Stress
Sky Pencil wants light, moist, acidic soil.11Ask Extension. Japanese Holly Sky Pencil In alkaline soil the leaves turn yellow.12NC State Extension. Ilex crenata ‘Sky Pencil’ In alkaline ground, iron and other nutrients are present but locked up, so the roots cannot take them in. The yellowing typically starts on the newest leaves, with the veins staying greener for a while. Adding more general fertilizer rarely fixes it, because the problem is access to nutrients, not the amount in the soil. Chelated iron products can green up leaves for a time, but they treat the symptom while the pH stays high.
A cheap home kit or an extension soil test will show your pH. Readings above neutral point to an alkaline problem. Elemental sulfur and acid-forming fertilizers lower pH, but slowly.
The plant also does poorly in drought.13NC State Extension. Ilex crenata ‘Sky Pencil’ Poor drainage stresses the roots and can show up as yellowing or browning.14Simply Trees. Sky Pencil Holly Care Guide
Nematodes are microscopic worms that attack the roots.15Garden Guides. Diseases In ‘Sky Pencil’ Holly They cause more trouble in sandy soils.16Garden Guides. Diseases In ‘Sky Pencil’ Holly Affected plants are stunted, yellow, drop leaves, and barely respond to water or fertilizer.17Garden Guides. Diseases In ‘Sky Pencil’ Holly If feeding and watering haven’t helped a yellowing plant in sandy ground, nematodes are worth suspecting, and a lab soil sample can confirm it.
Browning From Sun, Heat, Wind, and Cold
Intense sun and heat reflected off walls and paving can scorch and brown the foliage.18Green Thumb Nursery. Common Sky Pencil Holly Problems and How to Handle Them Afternoon shade and steady watering keep the plant looking its best.19Green Thumb Nursery. Common Sky Pencil Holly Problems and How to Handle Them Avoid south- or west-facing hot corners beside pavement. Sky Pencils in pots dry out and heat up faster than plants in the ground, so they scorch sooner.
Scorch usually appears on the side facing the wall, pavement, or afternoon sun, while the shaded side stays green. Scorched tissue is dry and crisp, often at leaf tips or edges, unlike the soft dark rot of overwatered plants. It tends to appear after a hot spell or in midsummer, which is one clue among several. Scorched leaves do not turn green again.
The plant needs protection from wind and cold, using a windbreak and mulch.20NC State Extension. Ilex crenata ‘Sky Pencil’ In hollies the leaves usually handle cold less well than the stems do,21Journal of Environmental Horticulture. Leaf and Stem Cold Hardiness of 17 Broadleaf Evergreen Taxa so winter can brown the leaves while the branches survive. In windy winter spots, a burlap screen helps.
Before you cut anything, scratch a brown twig lightly. Green tissue underneath means it is still alive. Wait until new spring growth appears before pruning. Watering before the ground freezes sends the plant into winter well hydrated.
Spider Mites, Scale Insects, and Black Sooty Mold
Spider mites are occasional pests of Sky Pencil.22NC State Extension. Ilex crenata ‘Sky Pencil’ Fine webbing is good evidence of them, while holes in the leaves point to a different problem.23Ask Extension. Damage to my Japanese Holly bushes, Sky Pencil variety24Ask Extension. Damage to my Japanese Holly bushes, Sky Pencil variety
Mites are tiny, so the first signs are often a dull, stippled, or bronzed look to the leaves rather than visible bugs. Tap a branch over white paper: tiny moving specks are mites. They thrive in hot, dry, dusty conditions, so plants next to driveways or dry sunny walls often get them first. Hosing the foliage and using horticultural oil or insecticidal soap controls them.
Scale insects suck sap and give off a sticky, sugary liquid.25Walter Reeves: The Georgia Gardener. Holly – Scale Insects The sticky droppings land on the leaves below,26Henderson County Center. Pest Alert: Scale Insects on Holly and a black fungus called sooty mold grows on them.27Henderson County Center. Pest Alert: Scale Insects on Holly
Scale look like small bumps on the stems and the undersides of leaves. Horticultural oil smothers them, and it works best on the young crawler stage. Once the scale are gone, the sooty mold weathers off over time. Check the plant again a few weeks later, because scale often come back.
Branch Dieback and Web Blight
Dieback first shows up as a few branches turning brown.28eXtension. Sky Pencil branches are drying up #670265 A canker, a dead spot on the stem, blocks the flow of nutrients to the branch.29eXtension. Sky Pencil branches are drying up #670265 If those branches are left, dieback can spread to the rest of the plant.30eXtension. Sky Pencil branches are drying up #670265 Cut out the whole branch, or at least cut about 6 inches below the canker.31eXtension. Sky Pencil branches are drying up #670265
Check the plant regularly in spring and summer, since a single browning branch is easiest to handle before more turn. Look along the stem for sunken, discolored patches where the branch starts to fail, since that spot marks the canker. Dieback on branches after hard freezes or storm damage may have started from the wound.
When you prune, clean the pruners with alcohol between cuts. Cut back into healthy wood that shows no discoloration inside, and bag the cut material instead of composting it.
Web blight starts as brown spots on leaf edges and bases.32Ask Extension. Japanese Holly Sky Pencil The spots spread quickly into blotches that cover the whole leaf.33Ask Extension. Japanese Holly Sky Pencil Dead leaves cling to the plant instead of falling,34Ask Extension. Japanese Holly Sky Pencil and the disease spreads upward from the bottom of the plant.35Ask Extension. Japanese Holly Sky Pencil
Humid summers favor this disease. Water the soil, not the foliage, and leave space between plants so air can move through. Rake up debris under the shrub.
Splaying and Split Branches From Snow and Age
Heavy snow can bend branches outward, and they may not return upright.36Gardening Know How. Common Sky Pencil Holly Problems and How to Handle Them Ice storms can do the same.37Mary Snoddy. Sky Pencil Holly — Gardening Hints for the Southeast / Gardening In The Southeast Once the shrubs reach about six feet, they tend to separate at the top on their own.38Mary Snoddy. Sky Pencil Holly — Gardening Hints for the Southeast / Gardening In The Southeast
A plant already open at the top is more likely to be pushed apart by the next storm. Wet snow and ice weigh much more than dry powder, which is why they cause most of the damage.
Tying stems together in heavy-snow areas is common practice.39Gardening Know How. Common Sky Pencil Holly Problems and How to Handle Them Wrap loosely with foam-covered wire, or tie the plant to a nearby structure.40Hyannis Country Garden. Protecting Plants Before Winter ~ How, When and Why Never tie anything tightly all the way around a stem, because it strangles the stem as it grows.41Hyannis Country Garden. Protecting Plants Before Winter ~ How, When and Why Avoid fishing line, which cuts into branches and kills them.42Mary Snoddy. Sky Pencil Holly — Gardening Hints for the Southeast / Gardening In The Southeast
Wrap the plant in a loose spiral from the lower part upward, leaving enough room to slide a finger between the tie and the stems. Tie the stems to each other or to a stake or wall so the pull is gentle and spread out. Do the wrapping in late fall before the first heavy snow, since it is harder once branches are weighed down.
To retrain a splayed plant, gather the stems gradually over a season rather than all at once. Check the soft ties every few months, and remove the supports once the stems hold their shape. When snow does pile up, brush it off gently, pushing upward on the branches.
Potted Sky Pencils and Root-Bound Plants
When you take the holly from its container, loosen any tangled roots.43Plant Addicts. Growing Hollies in Pots If the roots are extremely tight, slice a large X across the root ball and tease the roots apart.44Plant Addicts. Growing Hollies in Pots Pot-bound roots often form a dense mat on the outside of the root ball, which water can run past without soaking in.
When transplanting into the ground, plant at the same depth as it grew in the pot. Water thoroughly afterward to settle soil around the loosened roots and remove air pockets. A holly that was root-bound for years may be slow to settle, so keep the soil evenly moist during the first season.
For a plant that stays in a pot, use a container with drainage holes and an acidic potting mix. Check moisture with your finger before watering. Potted plants freeze faster, so move them to a sheltered spot or insulate the pot in winter. Move up one pot size every few years.
Feed with a slow-release fertilizer made for acid-loving plants in spring. If a white crust builds up on the pot, flush the soil with water.