Cedar-Apple Rust: Orange Galls, Leaf Spots and How to Protect Apples

By the Garden Voila editorial team · Updated October 30, 2026 · How we verify

Cedar-apple rust is a fungal disease that needs two hosts to complete its life cycle: eastern red cedar or other junipers, and apples or crabapples. On junipers it forms brown, woody galls that, after spring rains, sprout bright orange, jelly-like horns that release spores. Those spores infect nearby apple and crabapple leaves and fruit, causing bright yellow-orange spots in late spring that develop small tubes or hair-like structures on the undersides by midsummer. Heavy infections cause early leaf drop and blemished fruit on susceptible apples. To control cedar-apple rust, plant resistant apple and crabapple varieties, remove galls from nearby junipers in late winter, avoid planting the two hosts close together where possible, and protect susceptible apples with a fungicide labeled for rust from pink bud through a few weeks after bloom.

Cedar-apple rust basics

How does the cedar-apple rust life cycle work?

The Wikipedia article on Gymnosporangium juniperi-virginianae describes this two-year cycle. Spores from infected apple leaves blow to junipers in late summer and infect twigs, where galls develop over the next 18 months. In the second spring after infection, during warm rains, the galls swell and produce long, orange, jelly-like horns, which release spores that blow to apple and crabapple trees and infect young leaves, fruit and twigs. By midsummer, the apple leaf spots produce spores that blow back to junipers, completing the cycle. The fungus cannot spread from apple to apple or from juniper to juniper. The UMass Extension fact sheet on cedar-apple rust notes that this dependency on two hosts is the key to managing the disease.

How do you identify cedar-apple rust?

On apples and crabapples

• Small, pale yellow spots on the upper surface of leaves in late spring, enlarging to bright orange-yellow spots, often with a red border.
• Tiny black dots in the center of spots on the upper leaf surface.
• Tube-like or hair-like projections on the underside of the spots by mid to late summer.
• Orange spots on fruit, usually near the calyx (blossom) end, which may distort fruit.
• Early leaf drop on heavily infected, susceptible trees.

On junipers

• Brown, kidney-shaped or round galls on twigs, looking like small woody balls with dimpled surfaces.
• Bright orange, gelatinous horns growing from the galls after warm spring rains, making the tree look decorated.
• Little harm to the juniper itself, apart from occasional twig dieback.

Does cedar-apple rust harm trees?

On junipers, the galls cause little damage. On apples, light infections are mostly cosmetic, but heavy infections on susceptible varieties cause leaves to yellow and drop by midsummer, weakening trees, reducing fruit size and quality, and lowering winter hardiness and next year’s flowering. Infected fruit may be small, deformed and spotted. Ornamental crabapples that are highly susceptible can look ragged by midsummer. Over several years, repeated defoliation can seriously weaken young trees.

How do you control cedar-apple rust?

1. Plant resistant varieties. This is the most effective long-term solution in areas with many junipers.
2. Remove galls from nearby junipers in late winter or early spring, before the orange horns appear, by pruning out infected twigs. This is practical on small ornamental junipers but not on large trees or wild cedars.
3. Separate the hosts. When planting new trees, avoid putting susceptible apples and junipers close together. Even a few hundred yards of separation reduces infections, though spores can travel farther.
4. Protect susceptible apples with fungicides labeled for cedar-apple rust, starting at pink bud and continuing every 7 to 10 days through about three to four weeks after petal fall, especially before rains. Products with myclobutanil and sulfur are among those labeled for home use. Rust infections cannot be cured once spots appear.
5. Keep trees healthy with proper watering, mulching and pruning, so they can tolerate some leaf loss. See the mulch calculator.

Which apples and crabapples resist cedar-apple rust?

Many modern crabapple cultivars are bred for resistance to rust, scab and fire blight. Check local nursery labels or Extension lists for crabapples rated resistant in your region. See our guides to Liberty apple trees, crabapple trees and apple scab when choosing trees, since disease-resistant varieties often resist several problems at once.

Related rusts on hawthorn, quince and pear

Several related Gymnosporangium rusts alternate between junipers and other members of the rose family. Cedar-hawthorn rust produces orange spots on hawthorn, apple and serviceberry leaves. Cedar-quince rust infects fruit, twigs and thorns of hawthorn, quince, serviceberry and sometimes apples and pears, causing swollen, orange, spiky growths on fruit. Pear trellis rust, found in parts of Europe and the Pacific Northwest, causes orange spots on pear leaves. Management is similar: resistant varieties, removing juniper galls and cankers, and protective sprays on susceptible plants in spring. See flowering quince for one of the plants affected.

Should you remove junipers near apple trees?

The University of Arkansas Cooperative Extension guide to cedar apple rust recommends resistant varieties and gall removal as practical alternatives to removing every nearby cedar.

Removing every juniper is rarely practical or desirable, because junipers are valuable landscape plants and wildlife habitat, and spores can blow from trees far beyond your property. In the past, some apple-growing states required eastern red cedars to be removed near orchards. Today, most gardeners are better served by planting resistant apples and crabapples, removing visible galls from ornamental junipers they own, and using protective sprays only on susceptible trees. If you are planting new junipers, choose rust-resistant juniper cultivars where possible and site them away from apples.

When are the orange galls most visible?

The striking orange, gelatinous horns appear on junipers during warm rains in spring, usually around the time apples bloom, often in April or May depending on region. They swell dramatically when wet and shrink back when dry, repeating with each rain for several weeks. Many people first notice the disease when they see these strange orange “blobs” on their cedar trees. Once you see them, protect susceptible apple and crabapple trees nearby, because spores are being released.

Still not sure what you are looking at? Compare symptoms in the plant pests and diseases library.

Cedar-apple rust FAQ

What weather favors cedar-apple rust?

Infection depends on spring rains. The galls on junipers need to be thoroughly wetted for several hours, at temperatures roughly between 50 and 75°F, before the orange horns swell and release spores. Those spores then need wet apple leaves for several hours to infect. Years with frequent warm rains during apple bloom tend to bring heavy rust, while dry springs bring little. Unlike apple scab, rust spores are released mainly during a few weeks around bloom, so protection on susceptible trees can be focused on that window rather than the whole season.

How far do cedar-apple rust spores travel?

Spores can be carried by wind for a mile or more, but most infections come from junipers within a few hundred yards. In rural areas where eastern red cedars grow wild along fencerows and fields, there may be thousands of galls nearby, making removal impractical and resistant varieties essential. In suburban gardens, removing galls from your own ornamental junipers, or replacing highly susceptible junipers with resistant ones, can make a noticeable difference.

How do you remove galls from junipers?

In late winter or early spring, before the galls produce orange horns, inspect junipers for brown, woody, golf-ball-like growths on twigs. Prune each gall off a few inches below where it attaches, using clean pruners, and put the galls in the trash. Galls are easiest to spot right after a warm spring rain, when they swell and turn orange, but by then they may already be releasing spores, so earlier removal is better. Check again each year, because new galls develop continually from infections the previous summer.

Do apples lose fruit to rust?

Fruit infections, which show as raised orange spots near the blossom end, cause blemished and sometimes misshapen apples, but rarely make the whole crop unusable. The bigger effect on yield comes from early leaf drop, which weakens trees and reduces fruit size and next year’s flowering. Protecting leaves during the spring infection period is therefore what matters most on susceptible trees.

Which junipers are most susceptible?

Eastern red cedar (Juniperus virginiana) is the main host in North America, and it grows wild across much of the eastern and central US. Rocky Mountain juniper and some cultivars of Chinese juniper and creeping juniper are also susceptible. Several juniper cultivars are reported to be resistant or rarely infected, and nurseries in rust-prone regions can suggest options. When choosing new evergreens near an apple or crabapple, consider non-host conifers such as spruce, fir, arborvitae, pine or yew instead of susceptible junipers.

Cedar-apple rust seasonal checklist

Track bloom timing in your area with the growing degree days calculator, which helps predict when apples reach the pink and bloom stages each spring.

Can organic gardeners control cedar-apple rust?

Yes. Resistant varieties, removing galls from nearby junipers and siting new trees away from cedars are all organic methods, and they solve most problems. Sulfur products allowed in organic production can protect susceptible apples during the spring infection window when applied before rain, though they must be repeated and should not be used in very hot weather or with oil sprays. Healthy, well-mulched trees tolerate some leaf spotting without serious harm.

In most home landscapes, a combination of resistant trees and a little spring vigilance keeps cedar-apple rust a minor, mostly cosmetic problem.

If you notice orange galls on cedars near your apples this spring, that is your signal to protect susceptible trees now and to plan resistant varieties for future plantings.

Happy growing, and enjoy your apples.

Sources: UMass Extension, Cedar-Apple Rust; University of Arkansas Cooperative Extension, Cedar Apple Rust; Wikipedia, Gymnosporangium juniperi-virginianae.

The two-host life cycle and what to plant

Iowa State Extension’s cedar-apple rust entry explains that the fungus needs both an apple or crabapple and a cedar or juniper to complete its life cycle. On cedar it forms reddish-brown galls on young twigs, up to golf-ball size. In warm, rainy weather in late April and early May the galls swell and push out bright orange gelatinous tubes, whose spores are carried by wind to susceptible apples. Yellow-orange spots appear on the upper leaf surface shortly after bloom, and in late summer tube-like structures on the leaf undersides release spores back to the junipers. Spores can travel as far as two miles, so removing every nearby juniper is often impractical.

For cultural control, prune rust galls from small cedars and junipers in late winter or early spring, by April 1. Fungicide sprays, where used, go on at the pink and petal-fall stages per the label. Cedars and junipers generally suffer little damage, though severe infection can cause twig dieback, while heavily infected apple leaves may drop early.

Reviewed October 2026. Sources: Iowa State University Extension, Cedar-Apple Rust