Studies on the occurrence and colonisation of plants by Phytophthora ramorum in Poland

Occurrence of <i>Phytophthora ramorum</i> on <i>Rhododendron, Vaccinium, Viburnum</i> and <i>Quercus</i> species in ornamental nurseris and fores stands in 2001-2002 and necrosis spead on plant parts and seedlings wewe studied. Only <i>P. citricola</i> was isolated from <i>Rhododendron</i> spp. and <i>V.vitis-idaea</i>. Shoot necrosis and dieback symptoms were not observed on <i>Viburnum</i> species in surveyed nurseries. From diseased Quercus</i> trunks among others <i>Armillaria</i> spp. and <i>Fusarium</i> spp. were isolated. Inoculation of leaves and stem parts of <i>Rhododendron</i> cultivars and other ericaceous plants with P. ramorum resulted in the development of leaf and stem rot. The species caused stem necrosis of <i>Fagus sylvatica, Q. rubra</i> and <i>Pseudotsuga</i> menziesii but symptoms developed slowly.

Phenotypic aberrations during micropropagation of Soymida febrifuga (Roxb.) Adr. Juss

Like most of the medicinal plants Soymida febrifuga (Meliaceae) possess significance for its valuable secondary metabolites. Multiplication of this endemic plant is limited by difficulty in rooting of stem cuttings, high seedling mortality rates and low seed viability period. Hence efficient protocols for in vitro mass propagation has been established from field grown and aseptic seedlings explants. Strikingly, we observed aberrant structures such as vitrified shoots, faciated shoots, albino shoots as well shoot necrosis during its micropropagation. These phenotypic maladies were observed during organogenesis and rooting. Compared to other abnormalities, shoot necrosis nonetheless was frequent and pronounced leading to plant death. Shoots when subjected to rooting also displayed necrosis which was controlled by transferring to MS medium containing various concentrations and combinations of calcium levels, activated charcoal, glucose, fructose and auxins. Microshoots initiated roots on half strength MS medium with IBA and IAA individually or in combination within two weeks. MS half strength solid medium supplemented with CAN (556 mg l–1), CAP (1.0 mg l–1), IAA (2.0 mg l–1) and IBA (2.0 mg l–1) in combination was found to be more efficient in showing high frequency (95%) of root regeneration. Rooted plantlets were successfully hardened and 70-85% of regenerated plants were successfully acclimatized to natural environment. In vitro derived plantlets were morphologically similar to in vivo plants.

Sclerotinia sclerotiorum shows potential for controlling water lettuce alligator weed and wandering Jew

The responses of six aquatic environmental weeds (water hyacinth (Eichhornia crassipes) alligator weed (Alternanthera philoxeroides) water lettuce (Pistia stratiotes) ferny azolla (Azolla pinnata) parrots feather (Myriophyllum aquaticum) and bladderwort (Utricularia giba) and a terrestrial weed (wandering Jew (Tradescantia fluminensis)) to Sclerotinia sclerotiorum were evaluated The fungus was applied as a myceliumonbarley formulation to individual containergrown plants Visual scores of lesion development revealed that a watery softrot disease caused by the pathogen developed in the treated water lettuce alligator weed and wandering Jew plants In water lettuce the pathogen resulted in 100 mortality of treated plants 54 days after application Shoot necrosis was 4 (control) and 24 (treated) for wandering Jew and 9 (control) and 17 (treated) for alligator weed at 35 and 52 days after inoculation respectively These results indicate that S sclerotiorum has potential as a mycoherbicide for controlling water lettuce and possibly also alligator weed and wandering Jew

In Vitro Colonization of Micropropagated Pieris floribunda by Ericoid Mycorrhizae. I. Establishment of Mycorrhizae on Microshoots

Selected isolates of Hymenoscyphus ericae (Read) Korf and Kernan, Oidiodendron griseum Robak, O. maius Barron, and a second O. Robak species were evaluated as inocula for in vitro establishment of micropropagated plantlets of Pieris floribunda (Pursh ex Sims) Benth. and Hook. Severity of shoot necrosis on microshoots differed for each isolate of Oidiodendron. Inoculation of micropropagated plantlets with isolates of H. ericae benefited initial shoot and root development on agar-solidified Woody Plant Medium (WPM) supplemented with sucrose and covered by a layer of autoclaved 1 peat: 1 vermiculite (v/v). Inoculation of microshoots with H. ericae or isolates of Oidiodendron did not stimulate production of adventitious roots.

Salinity Damage to Norfolk Island Pines Caused by Surfactants. II. Effects of Sea Water and Surfactant Mixtures on the Health of Whole Plants

A disorder of Norfolk Island pines, Araucaria heterophylla (Salisb.) Franco, has occurred on certain urbanized parts of the coast of New South Wales. Observation and survey work suggested that the disorder was due to excessive foliar uptake of salt, induced by surfactants derived from sewage discharged into the sea. The work described in this paper was part of a programme of studies designed to test this hypothesis. Glasshouse experiments were carried out to test the effects of distilled water and deep-sea water both with and without added surfactants sprayed onto the foliage of young potted Norfolk Island pines. Whereas the distilled water effects were minimal, some needle and shoot necrosis occurred in all plants sprayed with sea water and this effect was markedly accentuated when surfactant was present. Shoot necrosis was highly significantly correlated with the concentration of sodium and chloride taken up by the foliage, and the foliar salt levels were very similar to those found in deteriorating trees located by the seaside. The results showed that a commonly used surfactant, when sprayed in a sea-water solution onto Norfolk Island pine foliage, caused damage similar to that observed in affected seaside trees.