The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Stewart S. Higgins - One of the best experts on this subject based on the ideXlab platform.
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Deciduous Tree-Fruit Nursery-Stock Defoliation with Combination Sprays of Alanap, Depeg, and Ethrel
Journal of Tree Fruit Production, 1999Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Abstract Alanap (200 mg·L−1, a.i.), Depeg (0.5%) and Ethrel (150 mg·L−1, a.i.), alone and in combination, were applied once or twice to Nursery trees of ‘Bartlett’ or ‘Packham's Triumph’ pear and of several apple cultivars in October 1994 and 1995 to ascertain the usefulness of these chemicals in combination as a Nursery Stock defoliant. In 1994, the separate chemicals applied alone sometimes provided adequate commercial defoliation, but in 1995, Depeg was the only chemical that, applied alone, caused commercially-acceptable defoliation, but then only on ‘Law Red Rome’ apple. The combination of three chemicals provided acceptable defoliation in 1994 and 1995 (with the exception of ‘Red Fuji’ and ‘Braeburn’ in 1994). Regrowth during the 1996 growing season for the 1995 test trees showed no treatment effect, either positively or negatively, on four of the cultivars and no consistent trends on all others, except that the combination spray appeared to have a negative impact on growth of ‘Granny Smith’ apple. ...
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Abscisic Acid as a Potential Deciduous Fruit Tree Nursery Stock Defoliant
Horttechnology, 1998Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Abscisic acid (ABA) was tested as a defoliant for Nursery trees of `Bartlett' pear (Pyrus communis L.) and the apple (Malus×domestica Borkh.) cultivars Imperial Gala, Gibson Golden Delicious, Scarlet Spur Delicious, Law Red Rome, Granny Smith, Braeburn, and Red Fuji. ABA was sprayed once or twice, with 1 intervening week, at 500, 1000, or 2000 ppm. Percentage defoliation was assessed at 1-week intervals for 4 weeks. For all cultivars, two applications of 2000 ppm ABA ranked among the most effective treatments for rapid defoliation; this treatment led to at least 95% defoliation for all cultivars. For many cultivars, however, other treatments caused similar defoliation percentages by digging time. All tested cultivars were effectively defoliated (>80%) by two 1000-ppm applications ABA or one 2000-ppm application. One or two 500-ppm applications effectively defoliated `Bartlett', `Gibson Golden Delicious', and `Law Red Rome'. Nursery managers, therefore, need to consider a range of ABA concentrations and alternative application protocols to obtain optimum benefit from ABA. Although ABA shows promise as a defoliant, it lacks government approval for commercial use.
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Abscisic Acid as a Defoliant for Deciduous Fruit Tree Nursery Stock
Hortscience, 1997Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Artificial defoliation of deciduous fruit tree Nursery Stock is often necessary so that plants can be dug early enough to escape inclement fall weather. In this research, we assessed the efficacy of abscisic acid (ABA) as a defoliant. ABA was applied as a foliar spray at one of three concentrations—500, 1000, or 2000 ppm a.i. Trees were sprayed either once or twice for a total of six chemical treatments, plus untreated controls. The defoliation and growth responses of eight cultivars were evaluated with the cooperation of commercial nurseries in Washington State. While all treatments caused significantly greater defoliation than was observed in untreated trees, ABA at 500 ppm applied once or twice, or 1000 ppm applied only once, was generally sufficiently effective only on `Bartlett', `Gibson Golden Delicious', and `Law Red Rome', but not on `Imperial Gala', `Scarlet Spur Delicious', `Granny Smith', `Braeburn', or `Red Fuji'. Single or double applications of 2000 ppm or double applications of 1000 ppm often produced faster defoliation than double applications of 500 ppm, but defoliation was not always superior after 4 weeks. No pre-digging field damage was noted, but some treatments appeared to reduce trunk diameter increase after replanting, with no consistent trends among cultivars, except with `Bartlett' pear, which was frequently negatively affected. ABA appears to be very promising as a Nursery tree defoliant.
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608 PB 252 DEFOLIATION OF TREE FRUIT Nursery Stock
Hortscience, 1994Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Many tree fruit nurseries are limited to fall digging of deciduous Nursery Stock. Since trees may not defoliate naturally for timely digging, these nurseries may wish to defoliate chemically, which would be less expensive than hand-stripping and may more closely simulate natural leaf abscission. Consequently, test chemicals were applied with hand sprayers at commercial nurseries in central Washington State using single or double applications 1 wk apart. In 1992 on 7 apple cultivars and one pear, 500 ppm NPA + 150 ppm Ethrel significantly enhanced defoliation. Defoliation at 1000 ppm NPA was not superior to that at 500 ppm, and two applications were generally no better than one. However, in 1993, two applications were often more effective than one, and the addition of Ethrel to NPA generally enhanced defoliation if the combination of NPA + Ethrel was applied twice. Alanap and NPA were generally equally effective as defoliants. The addition of Ethrel to Alanap enhanced defoliation in only 3 of 9 cultivars, and then generally only when sprayed twice. Alanap + Ethrel was as effective with Alanap at 300 ppm as with Alanap at 500 ppm Ethrel by itself seldom increased defoliation.
Louise M Nelson - One of the best experts on this subject based on the ideXlab platform.
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quantification of agrobacterium vitis from grapevine Nursery Stock and vineyard soil using droplet digital pcr
Plant Disease, 2018Co-Authors: Tanja Voegel, Louise M NelsonAbstract:: Current detection methodologies for Agrobacterium vitis, causing crown gall of grapevines, are time intensive and lack the ability to quantify pathogen abundance in Nursery Stock and soil. Information on pathogen abundance is a key component to develop management strategies. The aim of this study was to develop a rapid and sensitive quantification assay for grapevine Nursery Stock and vineyard soil via droplet digital polymerase chain reaction targeting the virA gene. DNA isolated from roots of dormant grapevines originating from nurseries in Germany, California, and Ontario were tested for virA abundance. Bacterial numbers varied with grapevine origin; plants from California had the highest numbers. In addition, rhizosphere soil from two vineyards in the Okanagan valley in British Columbia was tested over a growing season. Sampling time during the season did not affect virA gene abundance. The older vineyard had higher soil A. vitis populations than the younger vineyard. The assay developed here has potential for use in national clean plant programs to prevent import of infected grapevine Nursery Stock and to test vineyard soil for abundance of the pathogen before planting.
Fenton E. Larsen - One of the best experts on this subject based on the ideXlab platform.
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Deciduous Tree-Fruit Nursery-Stock Defoliation with Combination Sprays of Alanap, Depeg, and Ethrel
Journal of Tree Fruit Production, 1999Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Abstract Alanap (200 mg·L−1, a.i.), Depeg (0.5%) and Ethrel (150 mg·L−1, a.i.), alone and in combination, were applied once or twice to Nursery trees of ‘Bartlett’ or ‘Packham's Triumph’ pear and of several apple cultivars in October 1994 and 1995 to ascertain the usefulness of these chemicals in combination as a Nursery Stock defoliant. In 1994, the separate chemicals applied alone sometimes provided adequate commercial defoliation, but in 1995, Depeg was the only chemical that, applied alone, caused commercially-acceptable defoliation, but then only on ‘Law Red Rome’ apple. The combination of three chemicals provided acceptable defoliation in 1994 and 1995 (with the exception of ‘Red Fuji’ and ‘Braeburn’ in 1994). Regrowth during the 1996 growing season for the 1995 test trees showed no treatment effect, either positively or negatively, on four of the cultivars and no consistent trends on all others, except that the combination spray appeared to have a negative impact on growth of ‘Granny Smith’ apple. ...
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Abscisic Acid as a Potential Deciduous Fruit Tree Nursery Stock Defoliant
Horttechnology, 1998Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Abscisic acid (ABA) was tested as a defoliant for Nursery trees of `Bartlett' pear (Pyrus communis L.) and the apple (Malus×domestica Borkh.) cultivars Imperial Gala, Gibson Golden Delicious, Scarlet Spur Delicious, Law Red Rome, Granny Smith, Braeburn, and Red Fuji. ABA was sprayed once or twice, with 1 intervening week, at 500, 1000, or 2000 ppm. Percentage defoliation was assessed at 1-week intervals for 4 weeks. For all cultivars, two applications of 2000 ppm ABA ranked among the most effective treatments for rapid defoliation; this treatment led to at least 95% defoliation for all cultivars. For many cultivars, however, other treatments caused similar defoliation percentages by digging time. All tested cultivars were effectively defoliated (>80%) by two 1000-ppm applications ABA or one 2000-ppm application. One or two 500-ppm applications effectively defoliated `Bartlett', `Gibson Golden Delicious', and `Law Red Rome'. Nursery managers, therefore, need to consider a range of ABA concentrations and alternative application protocols to obtain optimum benefit from ABA. Although ABA shows promise as a defoliant, it lacks government approval for commercial use.
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Abscisic Acid as a Defoliant for Deciduous Fruit Tree Nursery Stock
Hortscience, 1997Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Artificial defoliation of deciduous fruit tree Nursery Stock is often necessary so that plants can be dug early enough to escape inclement fall weather. In this research, we assessed the efficacy of abscisic acid (ABA) as a defoliant. ABA was applied as a foliar spray at one of three concentrations—500, 1000, or 2000 ppm a.i. Trees were sprayed either once or twice for a total of six chemical treatments, plus untreated controls. The defoliation and growth responses of eight cultivars were evaluated with the cooperation of commercial nurseries in Washington State. While all treatments caused significantly greater defoliation than was observed in untreated trees, ABA at 500 ppm applied once or twice, or 1000 ppm applied only once, was generally sufficiently effective only on `Bartlett', `Gibson Golden Delicious', and `Law Red Rome', but not on `Imperial Gala', `Scarlet Spur Delicious', `Granny Smith', `Braeburn', or `Red Fuji'. Single or double applications of 2000 ppm or double applications of 1000 ppm often produced faster defoliation than double applications of 500 ppm, but defoliation was not always superior after 4 weeks. No pre-digging field damage was noted, but some treatments appeared to reduce trunk diameter increase after replanting, with no consistent trends among cultivars, except with `Bartlett' pear, which was frequently negatively affected. ABA appears to be very promising as a Nursery tree defoliant.
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608 PB 252 DEFOLIATION OF TREE FRUIT Nursery Stock
Hortscience, 1994Co-Authors: Fenton E. Larsen, Stewart S. HigginsAbstract:Many tree fruit nurseries are limited to fall digging of deciduous Nursery Stock. Since trees may not defoliate naturally for timely digging, these nurseries may wish to defoliate chemically, which would be less expensive than hand-stripping and may more closely simulate natural leaf abscission. Consequently, test chemicals were applied with hand sprayers at commercial nurseries in central Washington State using single or double applications 1 wk apart. In 1992 on 7 apple cultivars and one pear, 500 ppm NPA + 150 ppm Ethrel significantly enhanced defoliation. Defoliation at 1000 ppm NPA was not superior to that at 500 ppm, and two applications were generally no better than one. However, in 1993, two applications were often more effective than one, and the addition of Ethrel to NPA generally enhanced defoliation if the combination of NPA + Ethrel was applied twice. Alanap and NPA were generally equally effective as defoliants. The addition of Ethrel to Alanap enhanced defoliation in only 3 of 9 cultivars, and then generally only when sprayed twice. Alanap + Ethrel was as effective with Alanap at 300 ppm as with Alanap at 500 ppm Ethrel by itself seldom increased defoliation.
Tanja Voegel - One of the best experts on this subject based on the ideXlab platform.
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quantification of agrobacterium vitis from grapevine Nursery Stock and vineyard soil using droplet digital pcr
Plant Disease, 2018Co-Authors: Tanja Voegel, Louise M NelsonAbstract:: Current detection methodologies for Agrobacterium vitis, causing crown gall of grapevines, are time intensive and lack the ability to quantify pathogen abundance in Nursery Stock and soil. Information on pathogen abundance is a key component to develop management strategies. The aim of this study was to develop a rapid and sensitive quantification assay for grapevine Nursery Stock and vineyard soil via droplet digital polymerase chain reaction targeting the virA gene. DNA isolated from roots of dormant grapevines originating from nurseries in Germany, California, and Ontario were tested for virA abundance. Bacterial numbers varied with grapevine origin; plants from California had the highest numbers. In addition, rhizosphere soil from two vineyards in the Okanagan valley in British Columbia was tested over a growing season. Sampling time during the season did not affect virA gene abundance. The older vineyard had higher soil A. vitis populations than the younger vineyard. The assay developed here has potential for use in national clean plant programs to prevent import of infected grapevine Nursery Stock and to test vineyard soil for abundance of the pathogen before planting.
D M. Richardson - One of the best experts on this subject based on the ideXlab platform.
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Chemical control of vine weevil larvae on container‐grown hardy ornamental Nursery Stock 1986–1989
Annals of Applied Biology, 1995Co-Authors: J V. Cross, J H. Buxton, R. Jacobson, D M. RichardsonAbstract:Summary In a search for alternatives to the former standard aldrin compost incorporation treatment for control of vine weevil (Otiorhynchus sulcatus) larvae on container-grown hardy ornamental Nursery Stock, a series of 87 tests of insecticides were done at four experimental centres of the ADAS (Leeds, Reading, Wolverhampton and Wye) from 1986 to 1989. Insecticidally-treated plants and untreated controls were artificially infested with vine weevil eggs at varying intervals before and after treatment, and the survival of the pest was assessed. Aldrin treatment gave consistent and excellent preventive control of vine weevil larvae for over 2 years. Of the candidate materials tested, a slow-release granular formulation of chlorpyrifos incorporated into compost at a dose rate of 100 g a.i. m-3 of compost gave good control for up to 34 wk after treatment (the longest period evaluated) and a micro-encapsulated slow release formulation of fonofos incorporated at a dose rate of 43.3 g a.i. m-3 usually gave good control for up to two years (the longest period evaluated). Surface applications of these two organophosphates or of carbofuran granules, though sometimes effective, were unreliable as either preventive or remedial treatments even for short term control.
