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Summary: Enriching the micronutrients, selenium (Se) and lithium (Li), in grapes to improve their nutraceutical properties were implemented by foliar application of organic fertiliser rich in Se and Li onto five grape cultivars. The effects of this biofortification on vine vigour, fruit quality, overall micronutrients and phenolic compounds also were investigated. Agronomic biofortification was found greatly increased the Se and Li content in the whole grape by multiple times, meanwhile it did not significantly affect the vine vigour and fruit quality of grapes. However, the biofortification did impact the Ionome (including all the mineral nutrients and trace elements) and phenolic compounds in grapes and this varied among cultivars. This study demonstrated foliar spray of organic Se/Li fertiliser was a very effective strategy to biofortify these micronutrients in grape berries, particularly in the skin, and therefore might be a promising strategy to increase the consumption and awareness of these grapes. [ABSTRACT FROM AUTHOR]

The capacity to predict the geographic distribution and relative abundance of invasive species is pivotal to developing policy for eradication or control and management. Commonly used methods fall under the ambit of ecological niche models (ENMs). These methods were reviewed and shortcomings identified. Weather-driven physiologically based demographic models (PBDMs) are proposed that resolve many of the deficiencies of ENMs. The PBDM approach is used to analyze the invasiveness of the polyphagous glassy-winged sharpshooter (Homalodisca vitripennis [Germar] ), a pest native to the southeastern United States and northeastern Mexico that extended its range into California in 1989. Glassy-winged sharpshooter vectors the pathogenic bacterium, Xylella fastidiosa (Wells) that causes Pierce's disease in grape and scorch-like diseases in other plants. PBDMs for glassy-winged sharpshooter and its egg parasitoids (Gonatocerus ashmeadi Girault and G. triguttatus Girault) were developed and linked to a PBDM for grape published by Wermelinger et al. (1991). Daily weather data from 108 locations across California for the period 1995-2006 were used to drive the PBDM system, and GRASS GIS was used to map the simulation results. The geographic distribution of glassy-winged sharpshooter, as observed, is predicted to be largely restricted to the warm areas of southern California, with the action of the two egg parasitoids reducing its abundance >90%. The average indispensable mortality contributed by G. triguttatus is <1%. A temperature-dependent developmental rate model for X. fastidiosa was developed that suggests its geographic range is also limited to the warm inland areas of southern California. Biological control of glassy-winged sharp- shooter further decreases the pathogen's relative range. Climate warming scenarios of + 2°C and +3°C suggest that the distribution and severity of glassy-winged sharpshooter and X. fastidiosa will increase in the agriculturally rich central valley of California. The utility of holistic analyses for formulating control policy and tactics for invasive species is discussed. [ABSTRACT FROM AUTHOR]

The potential of systemic neonicotinoid insecticides to control potato leafhopper, Empoasca fabae (Harris), a damaging pest of wine grapes in the eastern United States, was investigated. Soil or foliar applications were made to potted or field-grown vines, and the response of leafhoppers was determined in clip cages over the following month on young or mature leaves. Foliar application of imidacloprid caused immediate and long-lasting reductions in E. fabae survival on both leaf ages, whereas the activity of soil-applied imidacloprid was delayed. Clothianidin, imidacloprid and thiamethoxam all provided long-lasting reduction in leafhopper survival on young and mature foliage when applied through either delivery route. However, the percentage of moribund nymphs was significantly greater on foliar-treated vines and increased over time in mature and immature leaves compared with soil-treated vines. Residue analysis of foliar-applied imidacloprid showed an 89% decline in mature leaves from day 1 to day 27, and a 98% decline in immature leaves over the same time period. Comparison of soil-applied clothianidin, imidacloprid and thiamethoxam in field-grown vines showed significant reduction in E. fabae only on mature leaves of vines treated with thiamethoxam. Neonicotinoids can control E. fabae in small vines, even in rapidly expanding foliage where this pest causes greatest injury. Soil application provides superior long-term vine protection because declining residues on foliar-treated vines lead to suboptimal activity within 2-3 weeks. Vineyard managers of susceptible cultivars may take advantage of this approach to E. fabae management by using foliar applications of the three neonicotinoids tested here, or by using soil-applied thiamethoxam. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Although the bacterium Xylella fastidiosa (Xf) has been confirmed to cause economic losses to numerous fruit crop species in the southeastern U.S. since 1933, no science-based information is available on the occurrence of infection in economic fruit crops grown in Alabama, as well as the presence of effective Xf vectors in the state. An investigation to identify the sharpshooter (Hemiptera: Cicadellidae) fauna and to determine their occurrence in selected orchards and vineyards was conducted in Alabama during 2008-2009. Leafhoppers were trapped in three different geographic locations: in the Gulf Coast, Central, and North Alabama. Seven species of sharpshooters were identified, including: Homalodisca vitripennis (Germar), H. insolita (Walker), Oncometopia orbona (Fabricius), Paraulacizes irrorata (Fabricius), Graphocephala coccinea (Forster), Graphocephala versuta (Say), and Draeculacephala spp. H. vitripennis and G. versuta were the most prevalent species in Alabama orchards and vineyards; however, their proportion varied by location. H. vitripennis was the most abundant species trapped in the Gulf Coast area, whereas G. versuta was the most prevalent sharpshooter species in Central and North Alabama. The results are discussed in relation to the likelihood and efficiency of these species as Xf vectors in Alabama. [ABSTRACT FROM AUTHOR]

Spring frosts are of significant concern to growers of many fruit-bearing horticultural crops such as winegrapes. In many regions of the continental United States, winegrape crops are in danger of reduction or total loss every year. Inexperienced growers are often ignorant of the potential economic ramifications that spring frosts can incur. A new index, the frost index (FI), is proposed to aid growers in choosing sites where risk of damaging spring frost is minimized. The FI presents an improvement over current frost indices because it not only accounts for temperature but frost risk period and total number of frost events. A variation of FI for assessing cultivar risk at a specific site is also presented. The FI can be adjusted for any growing location, depending on timing of frost risk and budbreak. FI allows growers to make interpretations of frost risk potential with greater precision than current indices. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the potential pest status of Harmonic axyridis (Pallas) on autumn-ripening fruit. In autumn, H. axyridis has been observed feeding on pumpkins, apples, grapes, and raspberries in Minnesota. To determine whether H. axyridis can inflict primary feeding damage to fruit (i.e., breaking the skin of the fruit), we conducted laboratory feeding experiments with undamaged pumpkins, apples, grapes, and raspberries. The only fruit that H. axyridis was able to damage directly was raspberry. Laboratory choice tests were conducted to determine whether H. axyridis exhibits a preference between damaged and undamaged fruit, between cultivars of fruit, and between sugar water and water alone. For all fruits tested, H. axyridis showed a preference for damaged fruits over undamaged fruits. H. axyridis also exhibited a strong preference for sugar water over water alone. However, few differences were exhibited in preference between cultivars of fruit. In autumn, it seems that H. axyridis is an opportunist, taking advantage of previously damaged fruit, caused by other agents. [ABSTRACT FROM AUTHOR]