Anthers and ovaries of Vitis longii 'Microsperma' produced embryogenic callus when cultured on solidified Murashige and Skoog medium with 5/~M 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 #M benzyladenine (BA). The initial callus was short-lived. However, long-term embryogenesis from callus was maintained through serial transfers by careful selection of clustered embryos with subtending callus. Alternatively, long term culture maintenance was through secondary embryogenesis which occurred directly from previously formed embryos on medium lacking growth regulators. Somatic embryos were white, exhibited frequent pluricotyly and tended to be larger than zygotic embryos. Histology of embryogenic callus demonstrated the presence of lipidlike substances and abundant starch. Somatic embryos were attached to callus by narrow to wide suspensor-like structures and possessed typical epidermal, cortical, and vascular tissue. Embryo cells contained abundant lipid-like accumulations but no starch. Embryos germinated when placed on medium containing 1 #M BA and produced plants of normal appearance.

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Ovules of seedless bunch grapes (Vitis spp.) fertilized by controlled pollination increased in size during berry development. More ovules cultured 10 days or 60 to 70 days after pollination became brown compared to those cultured at 20 to 40 days. Cultured ovules developed with and without endosperm. Globular to torpedo stage embryos were recovered. More embryos and plants were recovered from ovules cultured at 40 or 60 days than at 10 or 20 days after pollination. Pollen parent significantly affected both embryo and plant recovery at certain sampling times. BA incorporated into medium significantly increased embryo germination percentage. Electrophoretic analysis of glucosephosphate isomerase in progeny showed that 67% to 88% were hybrids of controlled crosses. Of four vines that fruited thus far, two were seedless. Seedless progeny had smaller seed traces than either parent. Chemical name used: N-(phenylmethyl) -1H-purin-6-amine (BA).

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Under conditions favoring Pierce’s disease (PD) infection in the vineyards at Leesburg, Florida, 222 Euvitis scion clones, 60 Muscadinia clones, and 49 Euvitis rootstock clones were grown and observed for PD symptoms for 8 or more years. There were 21 PD-resistant scion clones, 20 of which derived their resistance from 1 or more of 4 species: Vitis smalliana Bailey, V. simpsoni Munson, V. shuttleworthi House, and V. aestivalis Michx. There were 22 PD-resistant Muscadinia clones, predominantly of V. rotundifolia Michx. background. There were 15 Euvitis rootstock clones with resistance derived from one of six native species: V. candicans Engelm., V. champini Planch., V. cordifolia Michx., V. shuttleworthi, V. simpsoni, and V. smalliana.

The hypothesis was tested that the growth of in vitro-propagated, nonrooted grape shoots (Vitis L. hybrid) directly after transfer from culture (ex vitro) is limited by photosynthetic C supply and that growth would be stimulated by CO2 enrichment (CDE). Plantlets were grown for 30 days in air with 350 or 1200 ppm (v/v) CO2 in humidified, flow-through chambers at 26°C. Destructive growth analyses were made at 0, 10, 20, and 30 days after transfer from culture to soil. CDE had no significant effect on total plant dry weight increase in the first 10 days. By 20 and 30 days, CDE-treated plants were 2 and 4 times greater in dry weight, respectively, than controls. Root growth was most improved by CDE, being almost 6 times greater than controls by 30 days. Leaf area per plant and root : shoot ratio were both doubled by CDE at 20 and 30 days. Since these results were under nonstress conditions, the use of CDE for growth stimulation needs to be evaluated under stress-hardening regimes.

Rickettsia-like bacteria, implicated as the casual agent of Pierce’s disease, were easily observed by electron microscopy in the xylem of muscadine grape (Vitis rotundifolia Michx.) with symptoms of Pierce’s disease. The symptoms included severe stunt, marginal leaf burn, and dieback. The bacterium was observed only in the tracheary elements of the xylem. Differences in levels of tolerance to Pierce’s disease were found in muscadine cultivars and breeding selections. Muscadine cultivars and selections developed at Experiment, GA were generally more tolerant to the disease than those developed at Meridian, MS or Raleigh, NC, however, there were some highly tolerant cultivars from all 3 locations. Cultivars from MS were much more tolerant to the disease than were selections from that location which were never considered acceptable for release to commercial growers.

Additional index words. Vitis, fruit breeding, disease resistance mildew [Unicinula necator (Schw.) Burr.], and Isariopsis leaf blight. 'Florilush' has a high tolerance to various nematodes that has been demonstrated by 100% replant survival in the vineyard and by planting into heavily infested nematode areas without general symptoms. Principal parasitic nematodes in replant sites were Criconemoides, Belonolaimus, Meloidogyne, and Trichodorus.'Florilush' promotes good vigor in mature vines grafted onto it (Table 1). Replicated yield data are not available, but fruit set and cluster size and shape were excellent in mature 'Orlando Seedless' vines on 'Florilush' rootstock. Although 'Florilush' has less tendency to sprout below graft unions than its parent 'Dog Ridge', cuttings should be debudded before planting to reduce root sprouts further. 'Florilush' is adapted to well-drained soils of Florida. To our knowledge, no useful data exist as to how it will perform on bedded soils in flatwood areas.