火棘属果实发育解剖学研究

火棘属植物的托附杯呈深杯状,具有５个分离心皮,子房半不位。托附杯发育成肉质果壁,主要藉细胞体积增大,子房壁全部石细胞化,发育成骨质瘦果状小果的果皮。火棘属的果实不是典型和梨果,是蔷薇科果实在演化过程中的一个过渡类型。火棘属肉质果壁的厚角组织经过角隅减薄后再转变成厚壁组织。     

Behavioral observations of codling moth, Cydia pomonella, in orchards permeated with synthetic pheromone

Mating disruption of codling moth, Cydia pomonella, was studied in apple orchards treated with the main pheromone compound codlemone, (E,E)-8,10-dodecadienol, and a blend of codlemone and codlemone acetate, (E,E)-8,10-dodecadienyl acetate, a strong pheromone antagonist. Codlemone alone and the pheromone/antagonist-blend had a similar effect on the behavior of males emerging into air-permeated orchards. Male flights within tree canopy and upwind orientation along tree rows were strongly enhanced by both formulations, compared to untreated plots. However, the codlemone/codlemone acetate-blend increased the rate of cross-wind and downwind flights within the orchard, compared to codlemone alone. The major difference between these two formulations was that males from nearby, untreated orchards were attracted towards orchards treated with codlemone, but not towards treatments with codlemone/codlemone acetate. Additional tests were done with an equilibrium blend of codlemone and its geometric isomers. Aerial pheromone concentrations in the orchards were recorded by the field electroantennogram technique. Decreasing pheromone concentrations towards the upper part of the tree canopy, together with the stimulation of male flight activity by synthetic pheromone explains failures to control codling moth at high population densities with current dispenser formulations.     

Tebufenpyrad (Pyranica®) resistance detected in two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) from apples in Western Australia

A strain (WA) of Tetranychus urticae Koch was collected from apples in Western Australia following a reported field-control failure of tebufenpyrad. The WA strain had been exposed to five tebufenpyrad applications over four seasons. The tebufenpyrad resistance in the WA strain was confirmed at 63.29× which is the first reported instance of tebufenpyrad resistance in T. urticae. The tebufenpyrad resistance in T. urticae conferred a >210× cross-resistance to pryidaben, a 24.60× cross-resistance to fenpyroximate and a 2.20× cross-resistance to chlorfenapyr.Exp Appl Acarol 22: 633–641 © 1998 Kluwer Academic Publishers     

Quinic acid esters of hydroxycinnamic acids in stone and pome fruit

In 21 varieties of stone and pome fruit the quinic acid esters of caffeic, p-coumaric and ferulic acids have been determined by capillary GC and HPLC. The total content of hydroxycinnamoylquinic acids was found to be between 80 and almost 900 ppm fr. wt. The results confirm that the main hydroxycinnamic acid compound in pome fruit is 5′-caffeoylquinic acid, whereas in stone fruit it is 3′-caffeoylquinic acid. Our investigations also show the regular occurrence of 3′-p-coumaroylquinic acid in stone fruit species. In sweet and sour cherries it can be the main component in concentrations of 100–200 ppm. Significant amounts of feruloylquinic acid are only found in plums and apricots. The 4′-isomers of all acids occur only in very small concentrations with the exception of 4′-p-coumaroylquinic acid in apples, the content of which exceeds that of 5′-p-coumaroylquinic acid.     

Dual pheromone dispenser for combined control of codling moth Cydia pomonella L. and oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) in pears

Codling moth (CM) and oriental fruit moth (OFM) are very important orchard pests worldwide, and particularly in Victoria, Australia, where both species damage pome fruit. Individually CM and OFM have been controlled successfully by pheromone‐mediated mating disruption, but treatment of pome fruit with full registered rates of two individual hand‐applied dispensers for CM and OFM could be uneconomical for growers. Field trials conducted over three seasons in plots sprayed with insecticides consistently demonstrated that dual Isomate C/OFM TT dispensers, designed to disrupt both CM and OFM, were as effective as Isomate CTT and Isomate OFM Rosso dispensers applied individually in pears for control of CM and OFM respectively. The dual‐ and individual‐species dispensers reduced moth catches and fruit damage to a similar degree. The results suggest that combined control of CM and OFM in pears by applying dual Isomate C/OFM TT dispensers at the full‐recommended rate of 500 dispensers per hectare will be more economical than use of individual species dispensers, because the price and application cost of dual dispenser is about half that for individual dispensers.     

Floral development and anatomy of Dirachma socotrana, (Dirachmaceae): a controversial member of the Rosales

The floral development and anatomy of Dirachma has been investigated with SEM and LM to discuss the relationship of Dirachmaceae with putative sister taxa (e.g. Rhamnaceae, Malvaceae, Barbeyaceae, Elaeagnaceae) on the basis of morphological synapomorphies. Flowers are initiated in axillary position on terminal branches. An epicalyx consisting of six to eight bracteoles surrounds the valvate calyx. Petal initiation is strongly retarded and primordia arise independently opposite the stamen primordia. The carpels arise independently and become weakly fused at the base; a single ovule develops in an axile position. A hypanthium develops by interprimordial growth between petals and stamens. Nectaries arise in a pouch and are covered with trichomes positioned on a protuberance at the base of the petal. It is suggested that the solitary flowers are derived from compound cymose inflorescences. Comparison between Dirachma and species of Rhamnaceae demonstrates striking similarities in floral structure and anatomy. However, several characters are unique to Dirachma and support a family Dirachmaceae separate from Rhamnaceae.We thank Frieda Christie for technical assistance with the SEM and LM preparations. We very much appreciate the constructive comments of Peter Endress and Paula Rudall.     

Investigations into peach seedling stunting caused by a replant soil

Replant diseases often occur when pome and stone fruits are grown in soil that had previously been planted with the same or similar plant species. They typically lead to reductions in plant growth, crop yield and production duration. In this project, greenhouse assays were used to identify a peach orchard soil that caused replant disease symptoms. Biocidal treatments of this soil led to growth increases of Nemaguard peach seedlings. In addition, plants grown in as little as 1% of the replant soil exhibited reduced plant growth. These results suggest that the disease etiology has a biological component. Analysis of roots from plants exhibiting various levels of replant disease symptoms showed little difference in the amounts of PCR-amplified bacterial or fungal rRNA genes. However, analysis using a stramenopile-selective PCR assay showed that rRNA genes from this taxon were generally more abundant in plants with the smallest top weights. Nucleotide sequence analysis of these genes identified several phylotypes belonging to Bacillariophyta , Chrysophyceae , Eustigmatophyceae , Labyrinthulida , Oomycetes , Phaeophyceae and Synurophyceae . Sequence-selective quantitative PCR assays targeting four of the most abundant phylotypes showed that both diatoms ( Sellaphora spp.) and an oomycete ( Pythium ultimum ) were negatively associated with plant top weights.