European crab apple

Family

Rosaceae

Habit

Tree

Height

10 m

Spread

8 m

Growth

slow

Lifespan

100 years

First yield

after 5 years

Hardiness

zone 4–8

Shade tolerance

light shade

Soil

Sand, Silt, Clay

Soil moisture

dry – moist

pH

5 – 7.5

Synonyms

European crab apple, Lopâr

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: At 2.5 to 3 cm the fruit is small, firm, yellow-green and flushed red on the sunny side. Raw it is astringent, hard and barely palatable because of its high tannin content — it becomes edible dried or cooked. Crab apples were used in Central Europe as early as the Neolithic; in the 17th century they were cut up and added to crab apple beer. Since the cultivated apple took over, the crab apple has had no commercial importance, but in the household it is far from worthless: it is precisely the high tannin and acid content that makes it a seasoning fruit. On the Swabian Alb small quantities are added to high-grade apple juices to give them structure and length; the same principle applies to cider, jelly and puree. After the first frosts the fruit tastes milder.

Other uses: Today the crab apple matters chiefly as a wild fruit and landscape tree. With its broad, gnarled old crown and side shoots often ending in thorns it forms dense, barely penetrable thickets, which makes it a plant for wild hedges, field copses and protective plantings; historically it was a characteristic tree of wood pasture. The wood is hard and fine-grained and suits turnery and tool handles, the small fruit floral arrangements and autumn decoration. Its greatest significance, however, lies in its genes: as the wild form and one of the ancestral species of our cultivated apples, the crab apple is an officially registered genetic resource that remains of interest for breeding towards disease resistance and climate tolerance — and that for exactly this reason must be protected from mixing with cultivated apples.

Site: The crab apple wants light and warmth; in shade it barely flowers or fruits and does not regenerate at all. Deep, moist, nutrient- and base-rich loam is ideal; waterlogging and acid raw soils are ruled out. It reaches 5 to 10 m tall and 3 to 8 m wide, so there has to be room for a medium-sized tree. The non-flowering side shoots often end in true thorns: an argument against it beside paths, seating areas and play spaces, and exactly what is wanted on a boundary or in a wild hedge. As a member of the rose family it hosts fire blight and apple scab and should not stand next to commercial orchards in outbreak areas. One point that matters for conservation: if a cultivated apple stands within pollen range, hybrid seedlings result — anyone wanting to conserve true wild apples keeps their distance or forgoes raising seedlings on site. Care: The crab apple is undemanding, long-lived and hardy to about −34 °C. Young trees need protection from browsing, since deer and hares take to them readily, and a vole basket on soils where that is an issue; being shallow-rooted, they are worth staking for the first few years. Prune little and only in late summer — a formative cut for a stable crown in the early years, after that at most deadwood out. Do not feed; generous nitrogen costs frost hardiness and encourages scab. As a wild species it is far more robust than cultivated apples, and scab and mildew usually stay within tolerable limits. Harvest in autumn; after the first frosts the fruit tastes milder. Windfall left lying is an important winter food source for birds and mammals and should not be cleared away.

Sowing is the natural route but the tricky one: the pips need about three months of cold stratification at 2 to 5 °C in moist sand and then germinate in spring. The real problem is provenance. Because there are no crossing barriers between crab apple and cultivated apple, and because the flowers are protogynous — the stigmas ripen several days before the anthers, so spontaneous self-pollination is scarcely possible — seed from a tree near orchards almost certainly comes from a cross. Anyone wanting to propagate true wild apples collects only from demonstrably isolated populations or buys seed of verified provenance. Vegetatively, the species can be grafted onto apple seedling rootstocks in late winter, which secures identity; cuttings root poorly.

The crab apple is among the most valuable native woody plants there is. NaturaDB rates nectar and pollen value at 4 out of 4 each and counts 45 wild bee species as well as 34 butterfly and moth species whose caterpillars feed on it — four of them specialists — plus 9 hoverfly and 8 beetle species. Its nectar-bearing disc flowers are openly accessible and are visited by bees and by flies alike. The supply is just as broad in autumn and winter: 19 bird and 35 mammal species use the fruit, and windfall left lying carries them through the lean season. The dense, gnarled and thorny old crown counts as good nesting habitat and offers cover; old single trees develop cavities and deadwood and so become habitat for woodpeckers, bats and saproxylic beetles.

Special features: one of the ancestral species of our cultivated apples and an officially registered genetic resource; no crossing barrier with the cultivated apple -> hybridisation is the main threat and pure populations are barely identifiable; 92% of German woodland occurrences threatened or dying (BLE 2010-2013), on the Red List early-warning list; protogynous flowering, self-pollination scarcely possible; non-flowering side shoots end in true thorns; needs sunlit open ground to germinate and does not regenerate under a canopy; fruit barely palatable raw but valuable as a seasoning fruit in juice and cider

Europe to Western Asia. The core of the range lies in the lowlands of Central Europe; the southern and eastern limits cannot be fixed with certainty, because the species has lived alongside the cultivated apple for millennia and crosses with it. In the Alps the crab apple climbs to about 1100 m. It grows nowhere in closed stands but always singly and widely scattered — one reason why pure populations are hard to find today. In Germany it is on the early-warning list: a survey by the Federal Office for Agriculture and Food from 2010 to 2013 classed 92 percent of woodland occurrences as threatened or dying, with only five rated vigorous and adequately regenerating.

The crab apple is a light- and warmth-demanding species that needs sunlit, open ground to germinate — under a closed canopy it does not regenerate at all. It grows very scattered in floodplain woodland, along woodland edges, on stone banks and in hedges and scrub, on moist, nutrient- and base-rich, usually deep loam or stony soil in a humid, mild climate. By Ellenberg's values it is a plant of half-light, an indicator of moist ground and of weakly acid to weakly basic conditions on moderately nitrogen-rich sites, and it counts as a class character species of summer deciduous woodland and scrub (Querco-Fagetea). Historically it was a characteristic tree of wood pasture, where grazing created exactly the open, light structures it needs to regenerate.