Thomas Walters - Academia.edu (original) (raw)
Papers by Thomas Walters
American Society for Horticultural Science, Aug 1, 2006
HortTechnology, 2009
The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pra... more The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pratylenchus penetrans)] and dagger nematodes [DN (Xiphinema bakeri)] in red raspberry (Rubus idaeus) were evaluated in four field studies, each conducted over 1 to 3 years. Spring spray applications of oxamyl or fosthiazate reduced RLN and DN population densities for up to 2 years, but fall oxamyl sprays and spring drip-applied oxamyl applications were not effective. Oxamyl application rate determined the duration of nematode suppression. Two spring applications of oxamyl at 2 lb/acre provided more than 2 years of suppression, while two spring applications of 0.8 lb/acre suppressed nematodes for only 1 year. Spring oxamyl applications reduced ‘Nootka’ fruit yield for one season, but did not affect ‘Willamette’ yield. Fall spray-applied fenamiphos, fall and spring spray-applied DiTera (a fermentation product of the fungus Myrothecium verrucaria), fall drip-applied 1,3-dichloropropene, and s...
Journal of Nematology, 2016
In 2012, theWashington raspberry (Rubus idaeus) industry received a special local needs (SLN) 24(... more In 2012, theWashington raspberry (Rubus idaeus) industry received a special local needs (SLN) 24(c) label to apply Vydate L® (active ingredient oxamyl) to nonbearing raspberry for the management of Pratylenchus penetrans. This is a new use pattern of this nematicide for raspberry growers; therefore, research was conducted to identify the optimum spring application timing of oxamyl for the suppression of P. penetrans. Three on-farm trials in each of 2012 and 2013 were established in Washington in newly planted raspberry trials on a range of varieties. Oxamyl was applied twice in April (2013 only), May, and June, and these treatments were compared to each other as well as a nontreated control. Population densities of P. penetrans were determined in the fall and spring postoxamyl applications for at least 1.5 years. Plant vigor was also evaluated in the trials. Combined results from 2012 and 2013 trials indicated that application timing in the spring was not critical. Oxamyl applicatio...
Adverse weather, particularly high winds and hail have prohibited strawberry production on the Te... more Adverse weather, particularly high winds and hail have prohibited strawberry production on the Texas High Plains. However, consumer interest in fresh, locally available produce, and the potential for higher grower profits have revived interest in growing them in the region. High tunnels have been utilized in other regions for season extension and climate modification, and increased production of highly sensitive crops like strawberries. Five strawberry varieties were evaluated under high tunnel culture versus the open field at the Texas AgriLife R&E Center in Lubbock, TX, for yield and quality as part of a three-state experiment with funding provided by NIFA—SCRI, SREP. Plugs of ‘Strawberry Festival’, ‘Chandler’, San Andreas, ‘LCN’ and ‘Albion’, plus bare root ‘Albion’ plants were transplanted during October 2010. The beds, previously laid with drip tape and black plastic, were arranged in two staggered rows at 30 cm apart. Ripe berries were first harvested on 21 Feb. and 5 Apr. in ...
Raspberry growers in Washington frequently fumigate soil before planting to reduce soilborne path... more Raspberry growers in Washington frequently fumigate soil before planting to reduce soilborne pathogens and nematode populations during plant establishment. The EPA’s new soil fumigant reregistration eligibility decisions will affect use of most common soil fumigants, and include the establishment of buffer zones, areas excluding all but workers and handlers involved in the application. Structures within buffer zones may not be inhabited, but many berry fields are near or adjacent to homes. Buffer zones size can be substantially reduced by fumigating planting beds only and covering fumigated beds with an impermeable tarp. However, the long-term efficacy of bed fumigation in preventing re-colonization of treated areas by soilborne pathogens and nematodes is unknown. Five trials were established in commercial raspberry fields to compare bed and broadcast fumigation. Trials were established in randomized complete blocks, with 3 or 4 replicate blocks; one was non-replicated. In four tria...
Consumers desire organically produced strawberries, but concerns about disease and pest managemen... more Consumers desire organically produced strawberries, but concerns about disease and pest management prevent many berry growers from adopting organic practices. One common strawberry disease is Botrytis gray mold, which reduces marketable yields and decreases the shelf life of harvested fruit. Strawberry plants are also susceptible to Verticillium wilt, which reduces yields by causing plant collapse. Plug plants of cultivars ‘Albion’, ‘Strawberry Festival’, ‘LCN’ and ‘Chandler’, and bare root plants of ‘Albion’ and ‘San Andreas’ were evaluated in high tunnel and open field locations in western Washington. The experiment was a split plot, with locations as main plots, and cultivars/plant types as subplots. The losses due to Botrytis in the tunnels were approximately 20% less than those in the open field (1.1% and 5.4%, respectively; P = 0.0042). The effect of cultivar/plant type on Botrytis incidence was highly significant (P < 0.0001): ‘Strawberry Festival’ and ‘Chandler’ had less ...
Outlooks on Pest Management, 2010
ABSTRACT Methyl bromide has been phased out due to its activity as a stratospheric ozone depleter... more ABSTRACT Methyl bromide has been phased out due to its activity as a stratospheric ozone depleter. Exemptions allowing the use of methyl bromide are increasingly difficult to obtain. Raspberry nurseries rely upon preplant soil fumigation with methyl bromide:chloropicrin (mb:pic) combinations to produce disease- and nematode-free plants. Successful alternatives to mb:pic must provide full control of plant-parasitic nematodes, Agrobacterium tumefasciens, and Phytophthora rubi. Trials in commercial raspberry nurseries (Macdoel CA, Burlington WA and Lynden WA) evaluated mb:pic and alternative fumigants, including: Midas® (Methyl Iodide:cloropicrin), Telone® C-35 and Pic Clor 60 (Telone:cloropicrin) under conventional (HDPE) and virtually impermeable (VIF) films. P. rubi and A. tumefasciens control was evaluated with a greenhouse biossay; A. tumefasciens control was also evaluated by soil dilution plating on a selective medium. All of the treatments controlled P. penetrans and buried bags of perennial quackgrass and nutsedge propagules. Midas® applied at 350 lb/A under a conventional (HDPE) tarp consistently provided excellent control of all weeds and pathogens. VIF film enhanced efficacy of Midas® applied at 225lb/A and of Telone®C-35 applied at 39 gal/A for controlling Agrobacterium and P. rubi.
ABSTRACT This SCRI SREP (No. 2009-02484) awarded on 1 Oct 2009 to a team of agricultural, materia... more ABSTRACT This SCRI SREP (No. 2009-02484) awarded on 1 Oct 2009 to a team of agricultural, materials, social and textile scientists, is ascertaining whether one experimental spun-bond nonwoven biodegradable mulch (BDM) and two leading commercially-available BDM products (BioBag, BioTelo) are of similar quality to conventional black plastic mulch for high tunnel and open field specialty crop production. A multi-site field experiment in the coastal climate of western WA, high plains of central TX, and subtropical region of TN is underway, with cellulose and non-mulch treatments as reference controls and tomato as the test crop. Three experiments on adaptability of six cultivars each of lettuce, strawberry and tomato to high tunnel production in these contrasting environments have also been initiated. In TN and TX field plantings have been established and in WA plants are ready for transplanting. Field and laboratory protocols for monitoring crop and soil interactions with the BDMs as well as assessing BDM properties, performance and degradation have been refined by team and advisory committee members. Also coordinated or under review for synchronous approaches are field plot designs; cultural practices; crop and harvest assessments; environmental monitoring; soil sampling and analysis; BDM sample receipt, storage and analysis; crop budgets; and, a framework for defining clean technologies. Input from growers in the three regions will be critical to successful adaptation, implementation and long-term feasibility of BDMs. Thus, procedures and criteria for recruitment and selection of potential focus group participants and survey respondents are being developed to understand values, beliefs and attitudes towards BDMs, and the social norms and practices of participating communities. To date, an experimental BDM manufactured in Saxon, Germany for the project and the other four mulch products have been received at all three sites. One post-doctoral associate and four graduate students have been hired. Analytical equipment for the textile laboratory in WA and environmental monitoring instruments and field supplies for WA, TX and TN have been purchased. Baseline soil samples from TN have been analyzed for bulk density, microbial biomass C, two enzyme potentials related to C and N cycling, and microbial community structure via phospholipid fatty acid profiling (PLFA); baseline data from TX and WA soil samples is commencing. One internal website has been created for information sharing among team members, and one public website (http://vegetables.wsu.edu/plasticulture.html) has been dedicated for general outreach. This SCRI team and its advisory committee will meet June 24-25, 2010 in Mount Vernon, WA.
Journal of the Science of Food and Agriculture, 2010
International Journal of Fruit Science, 2009
The Pacific Northwest (PNW) raspberry industry has undergone substantial structural changes over ... more The Pacific Northwest (PNW) raspberry industry has undergone substantial structural changes over the last two decades driven by shifts in production and trade and strengthened intellectual property rights to protect cultivars. Since the mid-1980&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s, Washington raspberry production has increased substantively while British Columbia (BC) production has exhibited a downward decline. Plant breeding in the PNW has been affected by the
International Journal of Fruit Science, 2013
Drying Technology, 2011
US sales of organic products continue to climb due to consumer perception of both environmental a... more US sales of organic products continue to climb due to consumer perception of both environmental and health benefits of organic produce. The objectives of this study were to evaluate the effects of air and freeze drying and blanching treatment prior to air drying on phytochemical ...
Applied Soil Ecology, 2013
American Society for Horticultural Science, Aug 1, 2006
HortTechnology, 2009
The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pra... more The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pratylenchus penetrans)] and dagger nematodes [DN (Xiphinema bakeri)] in red raspberry (Rubus idaeus) were evaluated in four field studies, each conducted over 1 to 3 years. Spring spray applications of oxamyl or fosthiazate reduced RLN and DN population densities for up to 2 years, but fall oxamyl sprays and spring drip-applied oxamyl applications were not effective. Oxamyl application rate determined the duration of nematode suppression. Two spring applications of oxamyl at 2 lb/acre provided more than 2 years of suppression, while two spring applications of 0.8 lb/acre suppressed nematodes for only 1 year. Spring oxamyl applications reduced ‘Nootka’ fruit yield for one season, but did not affect ‘Willamette’ yield. Fall spray-applied fenamiphos, fall and spring spray-applied DiTera (a fermentation product of the fungus Myrothecium verrucaria), fall drip-applied 1,3-dichloropropene, and s...
Journal of Nematology, 2016
In 2012, theWashington raspberry (Rubus idaeus) industry received a special local needs (SLN) 24(... more In 2012, theWashington raspberry (Rubus idaeus) industry received a special local needs (SLN) 24(c) label to apply Vydate L® (active ingredient oxamyl) to nonbearing raspberry for the management of Pratylenchus penetrans. This is a new use pattern of this nematicide for raspberry growers; therefore, research was conducted to identify the optimum spring application timing of oxamyl for the suppression of P. penetrans. Three on-farm trials in each of 2012 and 2013 were established in Washington in newly planted raspberry trials on a range of varieties. Oxamyl was applied twice in April (2013 only), May, and June, and these treatments were compared to each other as well as a nontreated control. Population densities of P. penetrans were determined in the fall and spring postoxamyl applications for at least 1.5 years. Plant vigor was also evaluated in the trials. Combined results from 2012 and 2013 trials indicated that application timing in the spring was not critical. Oxamyl applicatio...
Adverse weather, particularly high winds and hail have prohibited strawberry production on the Te... more Adverse weather, particularly high winds and hail have prohibited strawberry production on the Texas High Plains. However, consumer interest in fresh, locally available produce, and the potential for higher grower profits have revived interest in growing them in the region. High tunnels have been utilized in other regions for season extension and climate modification, and increased production of highly sensitive crops like strawberries. Five strawberry varieties were evaluated under high tunnel culture versus the open field at the Texas AgriLife R&E Center in Lubbock, TX, for yield and quality as part of a three-state experiment with funding provided by NIFA—SCRI, SREP. Plugs of ‘Strawberry Festival’, ‘Chandler’, San Andreas, ‘LCN’ and ‘Albion’, plus bare root ‘Albion’ plants were transplanted during October 2010. The beds, previously laid with drip tape and black plastic, were arranged in two staggered rows at 30 cm apart. Ripe berries were first harvested on 21 Feb. and 5 Apr. in ...
Raspberry growers in Washington frequently fumigate soil before planting to reduce soilborne path... more Raspberry growers in Washington frequently fumigate soil before planting to reduce soilborne pathogens and nematode populations during plant establishment. The EPA’s new soil fumigant reregistration eligibility decisions will affect use of most common soil fumigants, and include the establishment of buffer zones, areas excluding all but workers and handlers involved in the application. Structures within buffer zones may not be inhabited, but many berry fields are near or adjacent to homes. Buffer zones size can be substantially reduced by fumigating planting beds only and covering fumigated beds with an impermeable tarp. However, the long-term efficacy of bed fumigation in preventing re-colonization of treated areas by soilborne pathogens and nematodes is unknown. Five trials were established in commercial raspberry fields to compare bed and broadcast fumigation. Trials were established in randomized complete blocks, with 3 or 4 replicate blocks; one was non-replicated. In four tria...
Consumers desire organically produced strawberries, but concerns about disease and pest managemen... more Consumers desire organically produced strawberries, but concerns about disease and pest management prevent many berry growers from adopting organic practices. One common strawberry disease is Botrytis gray mold, which reduces marketable yields and decreases the shelf life of harvested fruit. Strawberry plants are also susceptible to Verticillium wilt, which reduces yields by causing plant collapse. Plug plants of cultivars ‘Albion’, ‘Strawberry Festival’, ‘LCN’ and ‘Chandler’, and bare root plants of ‘Albion’ and ‘San Andreas’ were evaluated in high tunnel and open field locations in western Washington. The experiment was a split plot, with locations as main plots, and cultivars/plant types as subplots. The losses due to Botrytis in the tunnels were approximately 20% less than those in the open field (1.1% and 5.4%, respectively; P = 0.0042). The effect of cultivar/plant type on Botrytis incidence was highly significant (P < 0.0001): ‘Strawberry Festival’ and ‘Chandler’ had less ...
Outlooks on Pest Management, 2010
ABSTRACT Methyl bromide has been phased out due to its activity as a stratospheric ozone depleter... more ABSTRACT Methyl bromide has been phased out due to its activity as a stratospheric ozone depleter. Exemptions allowing the use of methyl bromide are increasingly difficult to obtain. Raspberry nurseries rely upon preplant soil fumigation with methyl bromide:chloropicrin (mb:pic) combinations to produce disease- and nematode-free plants. Successful alternatives to mb:pic must provide full control of plant-parasitic nematodes, Agrobacterium tumefasciens, and Phytophthora rubi. Trials in commercial raspberry nurseries (Macdoel CA, Burlington WA and Lynden WA) evaluated mb:pic and alternative fumigants, including: Midas® (Methyl Iodide:cloropicrin), Telone® C-35 and Pic Clor 60 (Telone:cloropicrin) under conventional (HDPE) and virtually impermeable (VIF) films. P. rubi and A. tumefasciens control was evaluated with a greenhouse biossay; A. tumefasciens control was also evaluated by soil dilution plating on a selective medium. All of the treatments controlled P. penetrans and buried bags of perennial quackgrass and nutsedge propagules. Midas® applied at 350 lb/A under a conventional (HDPE) tarp consistently provided excellent control of all weeds and pathogens. VIF film enhanced efficacy of Midas® applied at 225lb/A and of Telone®C-35 applied at 39 gal/A for controlling Agrobacterium and P. rubi.
ABSTRACT This SCRI SREP (No. 2009-02484) awarded on 1 Oct 2009 to a team of agricultural, materia... more ABSTRACT This SCRI SREP (No. 2009-02484) awarded on 1 Oct 2009 to a team of agricultural, materials, social and textile scientists, is ascertaining whether one experimental spun-bond nonwoven biodegradable mulch (BDM) and two leading commercially-available BDM products (BioBag, BioTelo) are of similar quality to conventional black plastic mulch for high tunnel and open field specialty crop production. A multi-site field experiment in the coastal climate of western WA, high plains of central TX, and subtropical region of TN is underway, with cellulose and non-mulch treatments as reference controls and tomato as the test crop. Three experiments on adaptability of six cultivars each of lettuce, strawberry and tomato to high tunnel production in these contrasting environments have also been initiated. In TN and TX field plantings have been established and in WA plants are ready for transplanting. Field and laboratory protocols for monitoring crop and soil interactions with the BDMs as well as assessing BDM properties, performance and degradation have been refined by team and advisory committee members. Also coordinated or under review for synchronous approaches are field plot designs; cultural practices; crop and harvest assessments; environmental monitoring; soil sampling and analysis; BDM sample receipt, storage and analysis; crop budgets; and, a framework for defining clean technologies. Input from growers in the three regions will be critical to successful adaptation, implementation and long-term feasibility of BDMs. Thus, procedures and criteria for recruitment and selection of potential focus group participants and survey respondents are being developed to understand values, beliefs and attitudes towards BDMs, and the social norms and practices of participating communities. To date, an experimental BDM manufactured in Saxon, Germany for the project and the other four mulch products have been received at all three sites. One post-doctoral associate and four graduate students have been hired. Analytical equipment for the textile laboratory in WA and environmental monitoring instruments and field supplies for WA, TX and TN have been purchased. Baseline soil samples from TN have been analyzed for bulk density, microbial biomass C, two enzyme potentials related to C and N cycling, and microbial community structure via phospholipid fatty acid profiling (PLFA); baseline data from TX and WA soil samples is commencing. One internal website has been created for information sharing among team members, and one public website (http://vegetables.wsu.edu/plasticulture.html) has been dedicated for general outreach. This SCRI team and its advisory committee will meet June 24-25, 2010 in Mount Vernon, WA.
Journal of the Science of Food and Agriculture, 2010
International Journal of Fruit Science, 2009
The Pacific Northwest (PNW) raspberry industry has undergone substantial structural changes over ... more The Pacific Northwest (PNW) raspberry industry has undergone substantial structural changes over the last two decades driven by shifts in production and trade and strengthened intellectual property rights to protect cultivars. Since the mid-1980&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s, Washington raspberry production has increased substantively while British Columbia (BC) production has exhibited a downward decline. Plant breeding in the PNW has been affected by the
International Journal of Fruit Science, 2013
Drying Technology, 2011
US sales of organic products continue to climb due to consumer perception of both environmental a... more US sales of organic products continue to climb due to consumer perception of both environmental and health benefits of organic produce. The objectives of this study were to evaluate the effects of air and freeze drying and blanching treatment prior to air drying on phytochemical ...
Applied Soil Ecology, 2013