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Parker M.L.,North Carolina State University | Clark M.B.,North Carolina State University | Campbell C.,Valent BioSciences
Acta Horticulturae | Year: 2012

Abscisic acid (ABA) is one of the primary plant hormones reportedly involved in many plant responses to stress. Studies were undertaken to determine the effectiveness of exogenous ABA applications on bloom delay, fruit thinning, yield and fruit quality parameters at harvest in peach (Prunus persica L. Batsch). Foliar applications during the growing season (270 or 300 mg L -1) did not significantly affect shoot extension, fruit set or total yield and there were no consistent effects on flesh firmness, soluble solids content or red color development. Dormant applications to the top portion of the tree (300-1000 mg L-1) and dormant soil drench applications (150-500 mg L-1) were also evaluated. Three dormant applications of 300 mg L-1 ABA to the top portion of the plant may have accelerated bloom with no impact on fruit set in one year. Dormant soil applications did not appreciably affect bloom time consistently or fruit quality at harvest. A greenhouse study was also conducted with one year old grafted peach trees to see if a single ABA drench could impact young tree establishment under a drought condition. Dormant trees were potted, watered weekly and 59 days after planting, the pots were allowed to dry for approximately 10 days and then drenched with a 223 mg L-1 solution of ABA. After the ABA treatment one-half of the trees were watered 15 days later, and the other half 25 days after treatment when the untreated control trees were wilting. The trees were grown for the remainder of the season under optimal growing conditions. After leaf abscission the trees were destructively harvested and the trees treated with ABA had a significantly larger trunk diameter, 2-yr old fresh weight and overall tree fresh weight. The dry weight for the trees treated with ABA was significantly greater for the 1 and 2 year old wood, root system, and overall tree weight. © ISHS 2012. Source

Sanchez E.,Instituto Nacional de Tecnologia Agropecuaria | Curetti M.,Instituto Nacional de Tecnologia Agropecuaria | Retamales J.,Valent BioSciences
Acta Horticulturae | Year: 2011

Fruit set in pear (Pyrus communis L.) can be low and unpredictable. The aim of this study was to increase fruit set and subsequently yield in 'Abate Fetel' (AF) and 'Packham's Triumph' (PT) pears. The influence of aminoethoxyvinylglycine (AVG) application was investigated in a semi-commercial statistical trial in Río Negro, Argentina in the 2009-2010 season. The applications were randomly performed on eight rows at two stages of growth (full bloom and 14 days after full bloom) and two rates (125 and 250 mg L -1) with an untreated control. Application volume was set at 500 L ha -1 in order to make the application economically affordable for growers. Fruit drop, fruit set 60 DAFB, number of fruit per cm 2 branch cross sectional area, fruit size (weight, width, height), number of seeds per fruit and yield were evaluated. AVG 250 mg L -1 treatment at full bloom reduced yield in both cultivars (12% in PT and 8% in AF). However, treatments at 14 days after full bloom improved fruit set in both cultivars, but only the higher rate was effective in PT. In this cultivar, a 22% increase in fruit set and a 33% increase in yield were recorded with AVG application at 250 mg L -1. In AF, AVG 14 days after full bloom reduced fruit drop at 30 DAFB, improved fruit set (65%) and yield (16%), especially during the first harvest. We conclude that AVG at 250 mg L -1 applied two weeks after full bloom can increase fruit set and yield in the cultivars PT and AF. Source

Bruckner J.V.,University of Georgia | Osmitiz M.T.G.,Science Strategies | Anand S.,DuPont Company | Minnema D.,Syngenta | And 3 more authors.
ACS Symposium Series | Year: 2012

The widespread use of pyrethroids as insecticides has resulted in exposure of much of the U.S. populace, including pregnant women and children. Greater susceptibility of preweanling rats to high doses of pyrethroids has led to concern that infants and children may be more sensitive than adults to neurotoxic effects at contemporary exposure levels. Research has shown that preweanling rats' low metabolic detoxification capacity is a major contributor to elevated blood and brain levels of the neurotoxic parent compounds. The Council for the Advancement of Pyrethroid Human Risk Assessment (CAPHRA) is initiating a series of research projects to learn more about factors that may contribute to age-dependent sensitivity to pyrethroids, and for their incorporation into physiological models capable of accurately predicting target organ (brain) dosimetry and toxicity in different age-groups for different exposure scenarios. In our own laboratory, CAPHRA is sponsoring investigations of age- and species-dependent: pyrethroid transportation in blood (plasma protein and lipoprotein binding); tissue:blood distribution; and blood-brain barrier (BBB) gastrointestinal (GI) barrier efficiency, including the potential role of GI and BBB efflux transporters. Experiments are underway with Caco-2 cells to characterize GI membrane flux and to learn whether pyrethroids are substrates for P-glycoprotein or other transporters. © 2012 American Chemical Society. Source

Iburg J.P.,University of Georgia | Gray E.W.,University of Georgia | Wyatt R.D.,University of Georgia | Cox J.E.,University of Georgia | And 2 more authors.
Environmental Entomology | Year: 2011

Water was collected from a site on the Susquehanna River in eastern Pennsylvania, where less-than-optimal black fly larval mortality had been occasionally observed after treatment with Bacillus thuringiensis subsp. israelensis de Barjac insecticidal crystalline proteins (Bti ICPs). A series of experiments was conducted with Simulium vittatum Zetterstedt larvae to determine the water related factors responsible for the impaired response to Bti ICPs (Vectobac 12S, strain AM 6552). Seston in the water impaired the effectiveness of the ICPs, whereas the dissolved substances had no impact on larval mortality. Individual components of the seston then were exposed to the larvae followed by exposure to Bti ICPs. Exposure of larvae to selected minerals and nutritive organic material before ICP exposure resulted in no significant decrease in mortality. Exposure of larvae to silicon dioxide, cellulose, viable diatoms, and purified diatom frustules before Bti ICP exposure resulted in significant reductions in mortality. Exposure of larvae to purified diatom frustules from Cyclotella meneghiniana Ktzing resulted in the most severe impairment of mortality after Bti ICP exposure. It is postulated that frustule-induced impairment of feeding behavior is responsible for the impairment of larval mortality. © 2011 Entomological Society of America. Source

Jacups S.P.,James Cook University | Rapley L.P.,James Cook University | Johnson P.H.,James Cook University | Benjamin S.,Valent BioSciences | Ritchie S.A.,James Cook University
American Journal of Tropical Medicine and Hygiene | Year: 2013

In Australia, dengue is not endemic, although the vector mosquito Aedes aegypti is established in far north Queensland (FNQ). Aedes albopictus has recently invaded the Torres Strait region, but is not established on mainland Australia. To maintain dengue-free, public health departments in FNQ closely monitor introduced dengue infections and confine outbreaks through rigorous vector control responses. To safeguard mainland Australia from Ae. albopictus establishment, pre-emptive strategies are required to reduce its breeding in difficult to access habitats. We compare the residual efficacy of VectoBac WDG, Bacillus thuringiensis var. israelensis (Bti) formulation, as a residual treatment when misted across a typical FNQ bushland using a backpack mister (Stihl SR 420 Mist Blower) at two dose rates up to 16 m. Semi-field condition results, over 16 weeks, indicate that Bti provided high mortality rates (> 80%) sustained for 11 weeks. Mist application penetrated 16 m of dense bushland without efficacy decline over distance. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene. Source

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