Phytophthora root and stem rot – new disease of Ilex aquifolium "Myrtifolia” in Poland

<i>Phytophthora cinnamomi</i> was often isolated from rotted roots and stems of English holly "Myrtifolia" together with <i>Alternaria alternata, Cylindrocarpon destructanss, Fusarium avenaceum</i> and other fungal species. Inoculation of leaf blades and stem parts of 4 species and 12 holly cultivars with <i>P. cinnamomi</i> showed the spread of rot symptoms on the most of them. On <i>Ilex crenata</i> tissues necrosis did not develop or spread slowly. Isolation of <i>P. cinnamomi</i> only from one holly cultivar in surveyed nursery indicate on transmission of the pathogen with imported young plants.

High-temperature-induced Electrolyte Leakage from Excised Leaves and Roots of Three Hollies

Membrane thermostability of `Needlepoint' Chinese holly (Ilex cornuta Lindl. & Paxt.), `Albo-marginata' English holly (Ilex aquifolium L.), and `Nellie R. Stevens', an Ilex aquifolium × Ilex cornuta hybrid, was determined by measuring electrolyte leakage in excised leaves and roots. The critical midpoint heat-killing temperature (T,) after a 30-min exposure was 54.4 ± 0.4C for `Nellie R. Stevens' leaves and was ≈ lC higher than that for Chinese (52.9 ± 0.3C) or English holly (52.9 ± 0.4C). The Tm for English holly roots (53.9 ±_ 1.5C) was higher than that for either `Nellie R. Stevens' (51.7 ± 0.3C) or Chinese holly (50.1 ± 0.3C). The results of this study suggest that English holly and `Nellie R. Stevens' leaves and roots can withstand direct heat injury equal to or greater than that of Chinese holly.

Silver Thiosulfate Prevents Ethylene-induced Abscission in Holly and Mistletoe

Low concentrations of ethylene induced abscission of leaves and berries from cut branchlets of English holly (Ilex aquifolium L.) and American mistletoe [Phoradendron tomentosum (DC.) Engelm. ex Gray ssp. macrophyllum (Engelm.) Wiens]. Application of 1 μmol of Ag+ per branchlet (as the anionic silver thiosulfate complex, STS) via the transpiration stream was found to retard this abscission. A higher application rate (4 μmol Ag+ per branchlet) stimulated leaf abscission in mistletoe. There were marked differences in sensitivity to ethylene among various types of holly.

SUPPLEMENTARY LIGHTING AND CO2 ENRICHMENT FOR ACCELERATED GROWTH OF SELECTED WOODY ORNAMENTAL SEEDLINGS AND ROOTED CUTTINGS

Daily 16-h (0400–2000 h) supplementary lighting with high-pressure sodium (HPS) lamps at 45 μE∙m2∙sec−1 increased growth of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), white spruce (Picea glauca (Moench) Voss), crape-myrtle (Lagerstroemia indica L.), and seven cultivars of English holly (Ilex aquifolium L.). Enrichment of greenhouse atmosphere with CO2 to 1000–1300 ppm increased growth of four cultivars of English holly. In comparing two different light sources in CO2-enriched greenhouses, low-pressure sodium (LPS) lamps at 42 μE∙m−2∙sec−1 were found as effective as HPS in increasing growth of white spruce, crape-myrtle, and five cultivars of English holly, but not so effective in Douglas-fir and three cultivars of English holly.