Gnomonia rostellata. [Descriptions of Fungi and Bacteria].

A description is provided for Gnomonia rostellata. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Canada (Ontario), USA (California, North Carolina, Oregon), Austria, Belgium, Bulgaria, Czech Republic, Finland, France, Germany, Netherlands, Poland, Serbia, Spain, Sweden, Switzerland, Ukraine, UK and former Yugoslavia), hosts (Fragaria sp., Rosa rugosa, Rosa sp., Rubus allegheniensis, Rubus caesius, Rubus fruticosus, Rubus idaeus, Rubus idaeus subsp. sachalinensis, Rubus laciniatus, Rubus parviflorus, Rubus villosus and Rubus sp.) and associated fungi (Lophiostoma fuckelii, Otthia spiraeae and Mollisia rosae).

Saccothecium sepincola. [Descriptions of Fungi and Bacteria].

A description is provided for Saccothecium sepincola. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Morocco, Canada (British Columbia), USA (Florida, North Carolina, Oregon, Virginia, Washington), Chile, Armenia, Republic of Georgia, India (Uttar Pradesh), Pakistan, Austria, Belgium, Bosnia-Hercegovina, Czech Republic, Denmark, France, Germany, Hungary, Italy, Luxembourg, Montenegro, Norway, Poland, Portugal, Romania, Russia (Leningradskaya oblast), Spain, Sweden, Switzerland, Ukraine and UK), hosts (Aruncus sylvestris, Celtis planchoniana, Cornus sanguinea, Cornus sp., Corylus avellana, Crataegus laevigata, Crataegus pojarkoviae, Elaeagnus angustifolia, Forsythia intermedia, Hippophae rhamnoides, Laurus nobilis, Philadelphus sp., Pistacia mutica, Populus tremula, Rosa canina, Rosa centifolia, Rosa moschata, Rosa multiflora, Rosa pendulina, Rosa trachyphylla, Rosa sp., Rubus amoenus, Rubus discolor, Rubus floridus, Rubus fruticosus, Rubus idaeus, Rubus laciniatus, Rubus leucodermis, Rubus grabowskii, Rubus villicaulis, Rubus sp., Physocarpus opulifolius, Spiraea salicifolia and Staphylea pinnata) and associated fungi (Leptosphaeria fuscella, Valsa ceratosperma, Valsa ambiens and Valsa sp.).

Factors Influencing Epidemiology and Management of Blackberry Rust in Cultivated Rubus laciniatus

The blackberry rust pathogen Phragmidium violaceum was first observed in Oregon in spring 2005 on both commercially cultivated Rubus laciniatus (Evergreen blackberry) and naturalized R. armeniacus (Himalayan blackberry). Several commercial plantings suffered severe economic losses. In 2006 to 2008, all five spore stages of this autoecious, macrocyclic rust pathogen were observed annually, and asexual perennation of the pathogen on old leaves or in leaf buds was not evident in the disease cycle. In field experiments, teliospore germination and infection by basidiospores occurred mostly during April. On potted “trap” plants exposed for periods of 1 week under dense collections of dead leaves bearing teliospores, basidiospore infection was associated with wetness durations of >16 h with mean temperatures >8°C. Trap plants placed under the bundles of collected leaves frequently developed spermagonia, whereas only 1 of 630 trap plants placed in a production field of R. laciniatus became diseased, an indication that the effective dispersal distance of basidiospores may be limited. In growth chambers programmed for constant temperatures of 5, 10, 15, 20, 25, and 30°C, a minimum of six continuous hours of leaf wetness was required for infection by urediniospores, with >9 h required for moderate infection (>4 pustules/cm2) at 15 and 20°C. With diurnal temperature regimes averaging 5, 10, 15, 20, or 25°C, urediniospore germination and infection was highest in the range of 5 to 15°C; similarly, in the diurnal environment, >9 h of leaf wetness was required to attain moderate infection. In the field, lime sulfur applied as a delayed dormant treatment significantly suppressed teliospore germination and basidiospore infection. Over two seasons, one application of myclobutanil, a demethylation-inhibitor fungicide, applied in early May near the time of spermagonial appearance provided effective suppression of the summer epidemic.

Dasineura plicatrix (Diptera: Cecidomyiidae): a recent introduction into North America

The first record of a European blackberry leaf gall midge, Dasineura plicatrix (Loew), is confirmed from North America. Specimens were reared from damaged leaves of blackberry, Rubus laciniatus Willd. (thornless variety ‘Chester’), and red raspberry, R. idaeus L. (variety ‘Cascade Delight’) (Rosaceae), in southwestern British Columbia. Photographs of the damage and illustrations of the male terminalia and female ovipositor are presented to assist future determinations.

Somaclonal Variation among ex vitro `Thornless Evergreen' Trailing Blackberries: The Morphological Status of Selected Clones after Seven Years of Field Growth

Chimeral `Thornless Evergreen' (CTE), (Rubus laciniatus Willd.) somaclones selected in 1983 and field planted in 1985 were reexamined in 1992 for various vegetative and reproductive characteristics. Two major types of thornless (prickle-free) plants, intermediate-sized (`UI 6-6' = `Everthornless') and dwarf (`UI 6-4'), originally selected from a chimeral thornless parent plant, were compared with thorny plants. The intermediate and dwarf somaclones have maintained their distinctive habits over 7 years' growth in the field, indicating that their growth habits are stable and not a transient effect of tissue culture. Although the thornless somaclones remained thornless, the degree and type of prickle-like structures varies considerably, indicating that the thornless gene (Ste) does not entirely suppress the production of prickles, but apparently alters their development. Increasing suppression was directly related to increasing dwarfism, suggesting a link between thornlessness and internode length.

Drying Interferes with Germination of Blackberry (Rubus sp.) Seeds in Vitro

To study the causes of low germinability in dried blackberry seeds, seeds harvested from fresh `Thornless Evergreen' (TE) blackberry (Rubus laciniatus Willd.) were either air-dried (12, 24, 36, 48, 60, 72, 96, or 120 hours) or explanted directly onto growth-regulator-free medium after bleach disinfestation. Seeds were either cut in half before explanting or kept intact. None of the intact seeds germinated. Fewer of the halved seeds dried 12 hours or more germinated than control (fresh moist) seeds (42.7% and 54.5%, respectively). Germination decreased to <12% following >48 hours of air-drying. In a separate study, fresh seeds of TE and `Navaho' were either dried as described or held in sealed petri dishes on moist filter paper (moist treatment) for up to 60 hours. After 60 hours, germination of dried seeds of both cultivars had decreased significantly; there was no significant change in germination percentage for moist seeds. Since moist halved seeds germinated well and dried halved seeds did not, the inability of dried blackberry seeds to germinate is due to more factors than just the hard seedcoat typical of the genus.

574 PB 047 STABILITY OF A VARIANT LEAF TYPE OF `THORNLESS EVERGREEN' BLACKBERRY FOLLOWING A REGENERATION CYCLE IN VITRO

Rubus laciniatus Willd. `Thornless Evergreen' (TE) is a chimeral blackberry with a thornless epidermis that overlies a genetically thorny interior. Most canes of TE produce leaves with 5 finely cut (lacinate) leaflets. Occasionally, canes appear which produce leaves with entire leaflets. Genetically pure thornless plants were regenerated from epidermal cells of chimeral TE with lacinate leaves. These regenerants exhibited somaclonal variation for growth habit, degree of thornlessness, and fruitfulness. All had lacinate leaves. When moved to the field, some of these regenerants produced canes with entire leaflets. To examine the stability of the entire leaflet characteristic, plants were regenerated from lacinate leaves and entire leaves of both dwarf and normal pure thornless TE regenerants. Regenerants were rooted, moved to soil, and grown in the greenhouse for observation. Stability of this characteristic will be discussed.

Septocyta ruborum. [Descriptions of Fungi and Bacteria].

A description is provided for Septocyta ruborum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Rubus laciniatus, R. nessensis, R. procerus and wild blackberry (R. fruticosus agg.). DISEASE: Purple blotch or stem spot disease (8, 288) or sometimes referred to as dieback of blackberries (32, 572). First symptoms appear in the summer on the basal portions of the shoots as intense dark green spots, the size of a pin's head, reddening after a few weeks and enlarging to a diameter of about 2 cm. Later the centres turn brown, the margin remaining red. The pathogen remains inactive during winter but at the end of February and beginning of March infection recommences, progressing rapidly upwards to a distance of 2.5-3 m from the root stock. The attack results in metabolic disturbances, the leaves and flowers or fruit rudiments becoming discoloured and sooner or later fading and shrivelling. In Switzerland the disease is widely distributed throughout the country on the cultivated variety, Theodor Reimers (Rubus procerus). GEOGRAPHICAL DISTRIBUTION: Europe (Britain, Czechoslovakia, France, Germany, Italy, Netherlands, Norway); North America (USA). TRANSMISSION: By conidia liberated from pycnidia in wet weather. Infection can also be spread from old branches to young shoots. In the Netherlands, in spore trapping experiments, conidia were caught daily from the beginning of April until the end of August with a sharp peak of over 4, 000 per sq. cm. daily at the end of June and beginning of July. No conidia were trapped in dry weather (32, 572). On blackberry shoots conidia on germination were observed to produce germ tubes which grew in the direction of the stomata and penetrated them (31, 561).