Breeding gall mite-resistant Fuchsia hybrids at Strybing Arboretum:
Update 2001
Peter Baye
Annapolis Field Station
33660 Annapolis Road
Annapolis, California 95412
baye@earthlink.net
The following is an update of the long-term breeding program for fuchsias resistant to fuchsia gall mite and suitable for landscaping in coastal California. This breeding program is a contribution of Strybing Arboretum and Botanical Garden, San Francisco, California, to rehabilitate the outdoor cultivation of fuchsias. The information below is condensed from slide talks hosted by chapters of the American Fuchsia Society in the San Francisco Bay area. Horticultural information on the species and hybrids listed below is based mostly on the last several years of their growth at various locations, including the immediate California coast (Sunset Zone 17), fog-free coastal mountains (Sunset Zone 15), with some anecdotal reports from more extreme climates.
1. Overview: Fuchsia species in the section Quelusia with horticultural uses
Quelusia is a section of the genus Fuchsia (a group of related species) with reddish tubes and sepals and purplish corollas. A diagnostic trait of this section other than floral pigmentation is the relatively long sepal (at least as long as the floral tube). Most Quelusia species are from Brazil; a few are from Chile and elsewhere in southern South America. Quelusia includes some of the principal ancestors of classic garden hybrid fuchsias. The wild Brazilian Quelusia species are generally adapted to resist to fuchsia gall mite injury, and lack the acute gall symptoms when infested.
Fuchsia magellanica - one of the principal ancestors of traditional garden hybrid fuchsias; a shrubby Chilean species highly susceptible to fuchsia gall mite. Classic old fuchsia hybrids are derived from a melange of hybrids with Section Ellobium (F. splendens [=F. "cordifolia"), F. fulgens), F. magellanica, and to a lesser extent, F. regia and other species. The pale lavender-white form once called "variety molinae" or cv. ‘Alba’ is not taxonomically distinct, but is horticulturally distinctive.
Fuchsia regia - a large climbing (liana) Brazilian fuchsia, quite resistant to the (also Brazilian) fuchsia gall mite. Flowers are relatively large, and the growth habit is that of a rampant liana. It can be forced into a shrub form with much pruning effort. Many or most "regias" in commercial trade recently in California are mislabeled F. hatschbachii. F. regia was a small part of the original melange of fuchsia hybrids early in its horticultural breeding history, and was returned to hybridization in recent decades. It is resistant to fuchsia gall mite. Some, not all, of its hybrids exhibit resistance to fuchsia gall mite.
Fuchsia campos-portoi - a low, shrubby, high montane Fuchsia (found above treeline, in a heath-like vegetation) with small flowers and leaves, rhizomes and suckers. It has a much-branched, ascending slender growth form, but produces rhizomes (creeping sucker shoots) which spread vegetatively like spearmint. This species is relatively rare, occurring in a narrow geographic area in Brazil. Its gall mite-resistance, as well as other less desirable traits, tend to dominate in its hybrids. Many or most "campos-portois" in retail nurseries recently are its mislabeled hybrid ‘Campo Thilco’.
Fuchsia hatschbachii - a willowy fuchsia with long, unbranched arching to semi-climbing shoots, glossy, lance-shaped, large leathery leaves, curved floral tubes, and partially fused sepals; overall, reminscent of F. regia, with which it is sometimes confused. It can be distinguished from F. regia by the nearly sessile leaves (extremely short leafstalk) and willow-like, narrow, lance-shaped, glossy leaves. It grows at relatively low latitudes on limestone soils in Brazil. It is resistant to fuchsia gall mite, and some, but not all, of its hybrids are as well. Recently it has appeared in retail nurseries mislabeled as F. regia. It is resistant to fuchsia gall mite, as are many of its hybrids.
Fuchsia glazioviana - A remarkable species with exceptional garden value. In bright sun in cool coastal California climates, it grows as a low, spreading shrub with thick (nearly leathery), light-green, slightly glossy small evergreen leaves, closely spaced. In shade, either the whole plant or individual shoots will form long "vine" (liana) shoots which grow up and through adjacent shrubs. When the shaded vine-shoot reaches bright light, it branches profusely and reverts it its shrubby habit, perching a fuchsia shrub on top of another species’ shrub or tree. The flowers are deep pink and purple, and are prolific from early spring to fall. The most widely grown clone has stiff pedicels (flower-stalks) that hold the flower out at an angle. It is resistant to fuchsia gall mite, as are some of its hybrids. It is now widely available in retail trade, and deservedly so.
2. Strybing Quelusia hybrids
‘Campo Thilco’ - A seedling of F. campos-portoi, confirmed by repeated crosses as F. campos-portoi x magellanica. This is the first of the mite-resistant Strybing hybrid fuchsias, and perhaps the most useful for landscaping. It bears prolific flowers and is gall mite-resistant. With its long bloom period, and frost-tolerance, it is easily grown, and a good mite-resistant surrogate for F. magellanica, which it closely resembles in flower. It is also rust-resistant. ‘Campo Thilco’ has the suckering habit of F. campos-portoi, and can spread like spearmint when mature. Now found in the wholesale and retail nursery trade, it is sometimes erroneously labeled as one of its parent species, F. campos-portoi, from which it is readily distinguished by the spreading, larger sepals of its magellanica-type flowers. ‘Campo Thilco’ is suitable as a hedge or shrub to replace gall-mite infested Fuchsia magellanica specimens. It can be grown as a perennial in frosty climates. Quite hardy in Sunset zone 15, even in hard frost pockets (lowlands with hard freezes), and probably in much colder areas as well. More reports of cold hardiness (or lack thereof) would be welcome.
‘Campo Moline’ - A selection of a very uniform cross between F. campos-portoi x F. magellanica cv. ‘Alba’ (= "var. molinae"). Like ‘Campo Thilco’, but a larger, heavier-wooded shrub that develops a thicker, taller trunk. Overall, more similar to a small-leaved F. magellanica. Not quite as floriferous as ‘Campo Thilco’, but equal to F. magellanica. Resistant to gall mite and rust.
‘Campo Victrix’ - F. campos-portoi x ‘Venus Victrix’. The parent ‘Venus Victrix’ is an old hybrid very close to F. magellanica, but lacking wild-type genes for pigment development in tubes and sepals, as well as lack of resistance to leaf rust. Its hybrid ‘Campo Victrix’ has intermediate floral pigmentation and form: multicolor small flowers (greenish sepal tips, pale pink sepals, darker pink tubes) have unusual "tubes" which are nearly spherical. Flowers are typically born three to a node. The progeny of this cross had variable "dilution" of pigmentation in tubes and sepals, and ‘Campo Victrix’ is useful for breeding with flower colors other than deep pink and purple into gall mite-resistant strains. Unfortunately, some of the progeny of ‘Campo Victrix’ also inherit some reduced resistance to leaf rust, even though most are quite resistant to gall mite
‘Campo Victrix’ x ‘Lye’s Unique’ crosses
‘Galfrey Lye’ - One of the first successful crosses between classic garden hybrid fuchsias and mite-resistant Quelusia species hybrids, which expressed "classic" garden hybrid fuchsia form and color. ‘Galfrey Lye’ has a prevalence of ‘Lye’ traits, but smaller leaves. Flowers have exceptionally long, lax pedicels (stalks), white tubes and sepals (light blush), and deep smoky carmine-pink petals. It blooms very early, and flowers are produced in abundance (usually 3 to 6 per node). Stems are wine-red, with lax arching habit adaptable as lax-upright or trailing. Gall symptoms reduced to leaf surface deformation and shoot tip abortion, both infrequent. Not resistant to leaf rust, but far more so than ‘Venus Victrix’. Quite frost-hardy; one of the first fuchsias to refoliate after freezes, and new growth holds up after repeated late winter-spring frosts in the mid-20o F range in shade.
‘Galfrey Blush’ - Sibling of ‘Galfrey Lye’: flowers are similar to ‘Galfrey Lye’, but sepals have contrasting light pink tips, fading to white to blush-white tubes. The foliage is lighter green, and the habit is strongly self-branching, lax-upright. It blooms later than ‘Galfrey Lye’, mostly on branches on older wood and larger plants. It is strongly resistant to both gall mite (like ‘Galfrey Lye’) and leaf rust. Not quite as floriferous as ‘Galfrey Lye’. Frost-hardiness is similar to ‘Galfrey Lye’.
‘Alta’ - Taller, relatively unbranched ‘Campo Victrix’ x ‘Lye’s Unique’ sibling, but with larger deep pink flowers (darker smoky-pink petals). Habit is upright but unbranched, with few lateral shoots. Strongly resistant to gall-mite, fairly resistant to rust.
‘Miri’ - Moderate in size, with slightly watercolor-washed pink tube and sepals fading to greenish sepal tips; dark smoky pink petals. Leaves are serrate, bronze-purplish to green, and unfortunately susceptible to rust. Strongly resistant to gall mite.
‘Corallina’ x hatschbachii crosses
‘Turner Matthew’ - Flowers larger than those of either parent, with long, slender tubes and sepals. Flower production intermediate between parents. The growth habit is coarse, with lax to trailing (when young) or arching (mature) shoots and very large leaves. Foliage is similar to ‘Corallina’ in color, but flowers are very large, narrow and slender. Resistant to leaf rust and gall mite.
‘Kyle Peter’ - This looks more like a sibling of ‘Corallina’, but sepals are recurved, and leaves are smaller and more leathery. It has the look of a very old garden fuchsia, showy but showing its wild ancestry. Flowering is prolific, with up to 4 nodes flowering at once, each with 3 flowers. The bloom period is long. Growth similar to ‘Corallina’, but young plants may initially try to trail before producing tall, arching stout woody shoots. Leaves are slightly folded upwards; stems are purple-red, leaves dark green flushed purple. Relatively resistant to gall mite: galls are very infrequent or lacking under high infestation pressure, and don’t develop much; very soft young growth produced when water and fertilizer is lush may develop a few galls. It is completely rust-resistant.
‘Isaac Rowan’ - Like a compact ‘Corallina’, also similar to ‘Angel’s Earrings’, but a shrub, and slower-growing. It exhibits some of the prolific bloom and leaf leatheriness of F. hatschbachii. Apparently gall mite-resistant, and rust resistant.
Other Strybing Arboretum fuchsia hybrids resistant to fuchsia gall mite
‘Porphyrio’ (F. ‘Campo Thilco’ x regia) - Large, vigorous arching, much-branched shrub, purplish foliage, quickly reaching 9 feet tall. It combines the rampant growth of F. regia with the profuse branching and purplish pigmentation of ‘Campo Thilco’. Blooms mostly on branches of older wood, so flowering really commences the second year after transplanting. The bloom season is late, usually beginning mid-summer to winter. The handsome purplish foliage and architecture of the plant is an aesthetic asset which offsets its shorter bloom period. This is a large, robust landscaping shrub, not a tame container subject. It is resistant, but not completely immune, to gall mite: galls are very infrequent under high infestation pressure, occurring with low frequency and limited development on soft new growth. It is completely rust-resistant.
[unnamed: ‘Voltaire’ X F. regia] - Testing two robust seedlings which came of this relatively infertile cross in 2000. Replicated clones have been challenged with fuchsia gall mite indoors under lights through the winter of 2001, but no symptoms have developed. Dark purplish-green leaves are similar to ‘President’, but with contrasting vein color. Flowers have not yet formed, but if leaf size is a good indicator, this may be a good gall mite-resistant substitute for ‘President’. 2001growing season will tell.
[unnamed: ‘California’ X ‘Campo Victrix’] - Still testing 3 of 8 plants of this 1999 cross which appear to be gall mite-resistant. Flowers are warm pink to near coral. At issue is the flower production, which needs to be tested in suitable growing conditions lacking in 2000.
‘Grand Harare’ (F. ‘Fanfare’ x harlingii) - Needs a maritime or cloud forest climate, like most F. denticulata hybrids. Lax, erect/arching growth, dark green glossy leaves. Very long, fluted, orange tubes, very glossy; tubercled (warty), glossy short sepals tipped blackish green; dark smoky orange-red petals. For Sunset Zone 17 only.
‘Dr. Mahoney’ and ‘Dr. Godronson’ (F. ‘Dominiyana’ x denticulata) - a re-creation of a series of old Lemoine crosses (‘Charles Darwin’, ‘Dr. Godron’, ‘Captain Boynton’...) with large, oval purplish leaves, huge scarlet waxy flowers on purple stems. Unlike ‘Dominyana’, these hybrids exhibit relatively high resistance to fuchsia gall mite (limited leaf surface deformation only) when grown in gall mite heaven, Golden Gate Park and vicinity. For Sunset zone 17 only.
‘Strybing’s Peach’ (F. fulgens x splendens) - Unique pale yellow petals, peach tube and sepals, tipped green. Flowers appear in showy terminal panicles (large, branched clusters). Prolific flowering at the expense of vegetative vigor, and the shape of the plant is irregular; the shape and unique color of the flowers are the redeeming features.
F. denticulata ‘Blush Fandent’ (F. denticulata ‘Strybing’s Improved x self) - a mutant white-tube and green-tip sepal form of F. denticulata, flowering at the expense of vigor. Hard to propagate, and limited to maritime climates. A difficult specimen, also redeemed mostly by the unique flower color and shape. For Sunset zone 17 only.
3. Some gall mite-resistant fuchsia hybrids from outside Strybing Arboretum
‘Miep Aalhuizen’ (F. paniculata x venusta) - Spectacular panicles of lavender-rose flowers, combining the best of F. venusta and F. paniculata on large shrubs with large glossy leaves; tropical appearance; bred in Holland, but destined for the California coast. Perennial in Sunset zone 15, best in zone 17.
‘Angel’s Earrings’ and ‘Dainty Angel’s Earrings’ - These Japanese hybrids (hybridizer unknown to me) have met or exceeded Barney Gonsalves’ high praise. They have unfortunately ordinary names for such splendid, gall mite-resistant, rust-resistant, vigorous, extremely floriferous, self-branching, heat-tolerant, trailing plants. Now widely available in retail trade, and well worth growing. Parentage is undisclosed, but the cultivars are clearly a section Quelusia species hybrid, probably F. regia X F. glazioviana, or hybrids involving them. They are readily trained as hanging baskets, topiary, and low, spreading shrubs; probably could be made into standards as well. I will attempt to repeat the cross between these suspected parent species to determine whether similar (unpatented!) plants result. The plants are quite fertile (many large purple-black berries), and they promise to be a great "stud fuchsias". They may produce some good non-patented "selfed" seedlings as well, and should be tried.
‘Lechlade Gorgon’ - a cross between closely related Section Schufia species, F. paniculata and F. arborescens, fortunately combining the best of each. The mature plant is more reminiscent of a lilac than a classic garden fuchsia, but the ornamental value is exceptional for Sunset zone 17 and 16.
‘Fanfare’ - A San Francisco/Berkeley hybrid from the 1940s, combining species which would today be referred to F. denticulata and probably F. austromontana. A large, climbing shrub with very large, long, waxy red flowers with orange-red tubes, for cool maritime climates. A spectacular plant when grown well. Best in Sunset zone 17 or 16, but works as a perennial or sub shrub in some zone 15 locations.
4. Some species cultivated in California which are usually resistant to fuchsia gall mite (exceptions may vary with individual genotypes of some species)
Fuchsia arborescens
Fuchsia x bacillaris (mistakenly labeled F. thymifolia in commerce; a few forms are susceptible to mite)
Fuchsia boliviana
Fuchsia campos-portoi
Fuchsia denticulata
Fuchsia fulgens (most strains are mite-resistant; a few hybrids are not)
Fuchsia hatschbachii (often mistakenly labeled F. regia in commerce; distinguished by sessile, leathery, lance-shaped leaves)
Fuchsia microphylla
Fuchsia paniculata
Fuchsia regia
Fuchsia splendens (most strains are mite-resistant; a few hybrids are not)
Most of these species, and many of the named hybrids described above (as well as their unnamed siblings) are planted in the Fuchsia Dell in Golden Gate Park, San Francisco, between the Conservatory (Kew Gardens replica Victorian glasshouse) and Stanyan Street. Strybing Arboretum and U.C. Berkeley Botanical Gardens have important collections of fuchsia species. Labeling, unfortunately, is deficient in all these gardens. This list is not exhaustive, and includes only those species regularly found in retail nursery trade and in botanical garden sales by the general public along the California coast.
5. A note on fuchsia gall mite "resistance
Resistance to fuchsia gall mite is a quantitative response, not qualitative. It can be very misleading to describe a fuchsia as "resistant" or "susceptible" without qualification. There is much heritable (genetic) variation in the intensity of gall development among cultivars and hybrids. A provisional rank (numeric scale) classification for fuchsia gall mite which I have used for my own observations and notes is provided below. This system can also be modified for a relative quantitative scale, based on measurements of gall type and frequency compared with standardized susceptible reference cultivars.
Rank 1: no galls ever produced, regardless of infestation pressure or stage of growth or development. Full immunity. Examples: wild Fuchsia regia, F. hatschbachii, F. glazioviana, F. campos-portoi, F. denticulata, F. paniculata, others. ‘Campo Thilco’, ‘Campo Moline’, ‘Angel’s Earrings’ and ‘Dainty Angel’s Earrings’ are intermediate between this rank and Rank 2, but closer to Rank 1.
Rank 2: slight leaf surface deformation and shoot tip abortion of intact shoots, but no stem galls. Leaves and stems develop distinctly, with only superficial damage. Very infrequent and local development of superficially deformed foliage or aborted shoot tips. Healthy growth regenerates alongside affected growth. Frequency of affected shoots is very low compared with susceptible cultivars, even when gall mite infestations are abundant. This defines an intermediate range of resistance typical of mite-resistant (not immune) crosses between Brazilian Quelusia species and traditional garden hybrids. Examples: ‘Campo Victrix’, ‘Galfrey Lye’, Galfrey Blush’.
Rank 3: Very infrequent true leaf and stem gall of very limited and local development, mostly on "soft" new growth produced rapidly (much moisture and fertilizer). Individual leaves and stems become locally fused, disorganized, twisted, or curled (tearooms) under heavy infestation pressure, but only rarely, and without spread to the rest of the plant as a whole. Plants are normally gall-free, and infestations do not alter the ornamental appearance of plant in a landscape setting, requiring no treatment. Infestations self-correct. Example: ‘Porphyrio’.
Rank 4: The range of almost all traditional garden hybrids with F. magellanica (and most true F. triply) ancestry belong in this rank. Gall mite populations spread readily over most growing points on the plant, causing disorganization of growth (galls: fusion of leaves and stems in twisted, curled tissue masses). Cultivars vary in the rate of spread (frequency of galls developed in a given amount of time), and the development of galls. Rank 4 could be divided into more sub-categories to distinguish the severity of gall symptoms, but Rank 4 is intended to distinguish cultivars which lose ornamental value when infested, and require special treatment and maintenance to achieve ornamental value in the landscape.
This ranking system may be useful for other fuchsia growers who wish to rate or communicate "resistance" to others. The unqualified term "resistant" can be misleading and equivocal, used in different ways by different growers.
Often, susceptible cultivars with strong F. cordifolia traits, such as ‘Chang’ and ‘Baby Chang’, and many old red-and-purple fuchsia hybrids with unusually thick leaves and waxy flowers, are either relatively slower to develop galls, or develop relatively few when infested. This, however, is not a reliable generalization. In contrast, some cultivars like ‘Bon Accord’ (= ‘Erect Novelty’) or ‘Display’, and many white-flowered cultivars, develop galls on almost every growing point if plants become infested at all. Some plants vary in resistance depending on growth rates: some F. cordifolia and F. fulgens hybrids are gall mite-resistant when growing slowly or in flower, but develop limited leaf gall symptoms when producing rapid, soft growth, such as after pruning, watering, and fertilizing.
There is only one diagnostic test for resistance to fuchsia gall mite. Fuchsias must be challenged with direct, repealed inoculation by young gall-mite infested fuchsia shoots, adjacent to indicator varieties which are known to be susceptible. I use Fuchsia magellanica and ‘Bon Accorde’ (= ‘Upward Look’) as indicator "control plants" because they appear to be good "magnets" for fuchsia gall mite, and develop galls readily. I use F. magellanica ‘Alba’ (= F. m. var. molinae) as a source plant for infested inoculum, because it survives infestation well, infests readily, but continues to grow vigorously and produce good supplies of infested material. Merely growing fuchsias in areas where gall mites are present cannot be used as a reliable test of resistance because of many chance factors which may affect the frequency of gall mite populations. For example, hummingbird activity, flower abundance, and temperatures may affect gall mite dispersal (spread) and population growth. It is also important to repeat inoculations throughout the entire growing season, and in all stages of fuchsia growth. Soft, rapid young growth is usually more susceptible to gall formation than is slow, woodier growth. Chance factors which may slow infestation are usually overcome by repeated or replicated inoculation trials (many "copies" test plants grown from cuttings).
I have tested a limited number of fuchsia cultivars for resistance, mostly Strybing hybrids. There are a few traditional hybrids such as ‘Bell Buoy’, which appear to be of "Rank 2" or "Rank 1" resistance. I suspect this may be due to chance expression of heritable traits from F. regia ancestors, or chance mutations. Not all F. regia hybrids are resistant (rank 1, 2, 3), but they may be the among the best prospects for testing. For breeding, F. campos-portoi seems to have the most "penetration" of resistance traits in subsequent hybrid generations, but it carries some hereditary liabilities, such as small leaf and flower size, and brushy, suckering growth habit (which, fortunately, can be lost in some second generation crosses). F. regia, F. hatschbachii, and F. glazioviana are good prospective parents of resistant hybrids, but they are not consistent: many of their hybrids, even in first-generation crosses among resistant species, can exhibit breakdown of gall mite resistance. Much replication and multiple generations of crosses will be needed to recombine and sort out selections with the best combinations of ornamental value and resistance to gall mite and foliar diseases. It is very encouraging to see this beginning to occur outside of Strybing Arboretum, particularly in recent introductions by some European hybridizers.