No abstract

The management options for grape phylloxera, Daktulosphaira vitifoliae, a monophagous insect pest of Vitis species are reviewed. Although in a worldwide context, grape phylloxera is managed predominantly by the use of resistant rootstocks developed through conventional breeding of hybrid crosses of American Vitis species, this management aspect is largely excluded from the review so that emerging technologies in the field of detection, quarantine and alternative management are discussed. In some viticulture regions of the world, where grape phylloxera's geographic distribution is limited (e.g. Australia), the pest is managed through a combination of surveillance, detection and quarantine. Although some alternative management options for grape phylloxera exist they have received relatively limited research attention because of the relative success of resistant rootstocks. The resilience of resistant rootstocks as the primary management option could also be challenged in the future by host‐plant interactions with diverse grape phylloxera clonal lineages and by potential impacts of climate change on both grapevine and grape phylloxera distribution. A range of control options exist which could be integrated into an improved management system for grape phylloxera. Priority areas for future evaluation and further development include early detection techniques, investigation into the use of biological control agents and development of an integrated approach to grapevine phylloxera management.

No abstract

Xyloglucan endotransglycosylase (XET) activity extractable from internodes of tal1 and dwarf varieties of pea (Pisum sativum 1.) was assayed radiochemically using tamarind seed xyloglucan as

The promotion of stem elongation in dwarf pea plants by GA3 has been correlated with an increase in extractable xyloglucan endotransglycosylase (XET) activity (Potter and Fry, 1993). Doses of auxin that caused either elongation or lateral swelling in pea stems have not been found to increase XET activity (Fry et al., 1992). We therefore explored the generality of the association between GA3 action and XET activity by testing three other bioassay systems. A similar correlation was found in the hypocotyls of intact lettuce seedlings, where GA3 strongly promoted elongation and doubled the extractable XET activity per unit fresh weight. In the hypocotyls of intact cucumber seedlings, GA3 evoked a prolonged promotion of elongation for at least 96 h; this was correlated with only a small increase in XET activity per unit fresh weight of tissue. IAA promoted elongation for only 48 h, but this effect was correlated with a larger increase in XET activity per unit fresh weight than that due to GA3. In cell suspension cultures of spinach, much of the XET activity was present in solution in the culture medium. GA3 had little effect on this fraction for the first 9 d, but thereafter the hormone suppressed a sudden burst in soluble extracellular XET activity that occurred in the untreated controls. A further proportion of the XET activity was ionically wall-bound; this fraction was enhanced by GA3 in the early phase of the growth cycle of the culture and inhibited in later phases. Pre-adaptation of the culture by growth for 6 years in the presence of 10−7 M GA3 intensified the response of the cells to re-addition of GA3. We conclude that there is no simple or unique relationship between total extractable XET activity and GA3 action. Nevertheless, we have extended the evidence that XET is often subject to the effects of GA3 in systems where this hormone influences growth.