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Response Of Evergreen Perennial Tree Crops To Gibberellic Acid Is Crop Load-Dependent: Ii. Ga3 Increases Yield And Fruit Size Of ‘Hass’ Avocado Only In The On-Crop Year Of An Alternate Bearing Orchard, Lauren C. Garner, Grant Klein, Yusheng Zheng, Toan Khuong, Carol J. Lovatt Oct 2011

Response Of Evergreen Perennial Tree Crops To Gibberellic Acid Is Crop Load-Dependent: Ii. Ga3 Increases Yield And Fruit Size Of ‘Hass’ Avocado Only In The On-Crop Year Of An Alternate Bearing Orchard, Lauren C. Garner, Grant Klein, Yusheng Zheng, Toan Khuong, Carol J. Lovatt

Horticulture and Crop Science

Despite problems of low fruit set, small fruit size and alternate bearing, the Hass cultivar dominates commercial avocado production worldwide. To increase yield and fruit size, gibberellic acid (GA3) (25 mg L−1) was applied at different stages of ‘Hass’ avocado tree phenology: (i) mid–late April (flower abscission), end of June–beginning of July (fruit abscission and beginning of the exponential phase of fruit growth), and mid-January (beginning of pre-harvest fruit drop); (ii) end of June–beginning of July; and (iii) mid-September (near the end of the major fruit abscission period; period of exponential fruit growth). In both ...


Temperature Thresholds And Degree-Day Model For Marmara Gulosa (Lepidoptera: Gracillariidae), M. J. O'Neal, David H. Headrick, Gregory H. Montez, E.E. Grafton-Cardwell Aug 2011

Temperature Thresholds And Degree-Day Model For Marmara Gulosa (Lepidoptera: Gracillariidae), M. J. O'Neal, David H. Headrick, Gregory H. Montez, E.E. Grafton-Cardwell

Horticulture and Crop Science

The developmental thresholds for Marmara gulosa Guillen & Davis (Lepidoptera: Gracillariidae) were investigated in the laboratory by using 17, 21, 25, 29, and 33°C. The lowest mortality occurred in cohorts exposed to 25 and 29°C. Other temperatures caused >10% mortality primarily in egg and Þrst and second instar sap-feeding larvae. Linear regression analysis approximated the lower developmental threshold at 12.2°C. High mortality and slow developmental rate at 33°C indicate the upper developmental threshold is near this temperature. The degree-day (DD) model indicated that a generation requires an accumulation of 322 DD for development from egg to adult emergence. Average daily temperatures in the San Joaquin Valley could produce up to seven generations of M. gulosa per year. Field studies documented two, Þve, and three overlapping generations of M. gulosa in walnuts (Juglans regia L.; Juglandaceae), pummelos (Citrus maxima (Burm.) Merr.; Rutaceae), and oranges (Citrus sinensis (L.) Osbeck; Rutaceae), for a total of seven observed peelminer generations. Degree-day units between generations averaged 375 DD for larvae infesting walnut twigs; however, availability of green wood probably affected timing of infestations. Degree-day units between larval generations averaged 322 for pummelos and 309 for oranges, conÞrming the laboratory estimation. First infestation of citrus occurred in June in pummelo fruit and August in orange fruit when fruit neared 60 mm in diameter. Fruit size and degree-day units could be used as management ...


Meeting Learning Objectives Through Service-Learning: A Pomology Case Study, Lauren C. Garner Feb 2011

Meeting Learning Objectives Through Service-Learning: A Pomology Case Study, Lauren C. Garner

Horticulture and Crop Science

Undergraduate students enrolled in the introductory pomology course at California Polytechnic State University, San Luis Obispo, CA, from 2007 to 2010, participated in a service-learning project. Students helped the community organization, the California Rare Fruit Growers (CRFG), teach grafting skills to San Louis Obispo County high school students and community members. At the end of each quarter, pomology students completed evaluations of their experience. Results of these evaluations were used to improve teaching methodology and the experience in which the students participated. Self-reported and instructor evaluations of the service-learning project demonstrated that students increased their grafting knowledge and skills, their ...


Biology And Parasitism Rates Of Pteromalus Nr. Myopitae (Hymenoptera: Pteromalidae), A Newly Discovered Parasitoid Of Olive Fruit Fly Bactrocera Oleae (Diptera: Tephritidae) In Coastal California, Therese Kapaun, Hannah Nadel, David H. Headrick, Larisa Vredevoe Apr 2010

Biology And Parasitism Rates Of Pteromalus Nr. Myopitae (Hymenoptera: Pteromalidae), A Newly Discovered Parasitoid Of Olive Fruit Fly Bactrocera Oleae (Diptera: Tephritidae) In Coastal California, Therese Kapaun, Hannah Nadel, David H. Headrick, Larisa Vredevoe

Horticulture and Crop Science

An undescribed wasp, Pteromalus nr. myopitae (Hymenoptera: Pteromalidae) opportunistically parasitizes the olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae), an introduced pest of olives in California. The native or typical host of P. nr. myopitae is unknown. We demonstrate that P. nr. myopitae is a solitary, ectoparasitic, idiobiont parasitoid of the third instar host inside fruit, and pupation occurs in the host tunnel. Reproduction of P. nr. myopitae on B. oleae in olives in the laboratory and in field cages generally failed. Host-feeding was not observed, and adults fed honey and water lived longer than those provided with water alone ...


Novel Lepidopteran Sex Pheromone Components From Marmara Gulosa (Lepidoptera: Gracillariidae), J. Stephen Mcelfresh, Jardel A. Moreira, Elizabeth E. Grafton-Cardwell, David H. Headrick, John M. Heraty, Marta Guillen, Jocelyn G. Millar Apr 2009

Novel Lepidopteran Sex Pheromone Components From Marmara Gulosa (Lepidoptera: Gracillariidae), J. Stephen Mcelfresh, Jardel A. Moreira, Elizabeth E. Grafton-Cardwell, David H. Headrick, John M. Heraty, Marta Guillen, Jocelyn G. Millar

Horticulture and Crop Science

Marmara gulosa Guillén & Davis (Lepidoptera: Gracillariidae) is a sporadic pest of citrus and a number of other crops in southern and central California. Coupled gas chromatographic-electroantennogram detection analyses of headspace volatiles collected by solid phase microextraction from virgin female moths revealed at least four related compounds in the extracts that elicited significant antennal responses from antennae of male moths. These compounds were identified as (8E,10E)-tetradecadien-1-ol, and the corresponding aldehyde, acetate, and formate ester, representing the first report of a formate as a lepidopteran pheromone component. The four compounds were consistently found in headspace volatiles collected from ...


Regulated Deficit Irrigation And Density Of Erythroneura Spp. (Hemiptera: Cicadellidae) On Grape, Michael J. Costello Aug 2008

Regulated Deficit Irrigation And Density Of Erythroneura Spp. (Hemiptera: Cicadellidae) On Grape, Michael J. Costello

Horticulture and Crop Science

This study looked at regulated deficit irrigation (RDI) on leafhoppers in the genus Erythroneura (Erythroneura elegantula Osborn, or western grape leafhopper, and Erythroneura variabilis Beamer) (Hemiptera: Cicadellidae), which are serious pests of cultivated grape (Vitis vinifera L.) in California. RDI is an irrigation strategy that reduces irrigation during a critical point in the phenology of a cultivated perennial crop, to improve vegetative balance and crop quality. Erythroneura spp. are known to respond negatively to vine water stress, and the second generation of leafhoppers begins during a potential RDI initiation period, between berry set and veraison (beginning of fruit maturation). In ...


Simulated Effects Of Dynamic Row Spacing On Energy And Water Conservation In Semi-Arid Central California Greenhouses, A. Moya, T. Mehlitz, Ilhami Yildiz, S. F. Kelly, C. Hardin Jan 2008

Simulated Effects Of Dynamic Row Spacing On Energy And Water Conservation In Semi-Arid Central California Greenhouses, A. Moya, T. Mehlitz, Ilhami Yildiz, S. F. Kelly, C. Hardin

Bioresource and Agricultural Engineering

Considerable effort is expended to conserve energy and water in current greenhouse systems, and look for alternative energy sources, especially passive heating and cooling strategies. Proper environmental management systems can significantly change the energy and moisture dynamics of greenhouse production systems. In this study, specifically, influences of dynamic row spacing on energy and water conservation were investigated. A dynamic computer simulation model was used to compare different row spacings, plant heights, and leaf dimensions to draw a conclusion about energy and water conservation. The results showed that using smaller spacings between cucumber crop rows (for instance, 0.5 m instead ...


Simulated Effects Of Reflective Mulch On Energy And Water Conservation In Semi-Arid Central California Greenhouses, T. Mehlitz, Ilhami Yildiz, S. Rahman, C. Hardin Jan 2008

Simulated Effects Of Reflective Mulch On Energy And Water Conservation In Semi-Arid Central California Greenhouses, T. Mehlitz, Ilhami Yildiz, S. Rahman, C. Hardin

Bioresource and Agricultural Engineering

In addition to the labor, energy and water consumption are the two main cost drivers in current greenhouse systems. Consequently, considerable effort is expended to conserve energy and water, and look for alternative energy sources. Greenhouses in hot and arid regions also require large quantities of water for irrigation. Proper environmental management systems can significantly change the energy and moisture dynamics of greenhouse production systems. This study aims to focus on reducing energy and water consumption in semi-arid California greenhouses. Influences of mulch (having different reflectivities) on energy and water conservation were investigated. The reflectivity of mulch used as a ...


Simulated Performance Of A Renewable Energy Technology – Heat Pump Systems In Semi-Arid California Greenhouses, C. Hardin, T. Mehlitz, Ilhami Yildiz, S. F. Kelly Jan 2008

Simulated Performance Of A Renewable Energy Technology – Heat Pump Systems In Semi-Arid California Greenhouses, C. Hardin, T. Mehlitz, Ilhami Yildiz, S. F. Kelly

Bioresource and Agricultural Engineering

In addition to the labor, energy and water consumption are the two main cost drivers in current greenhouse systems. Consequently, considerable effort is expended to conserve energy and water, and look for alternative energy sources, especially environmentally friendly renewable energy sources and technologies. Greenhouses in hot and arid regions also require large quantities of water for irrigation. Using proper technologies and environmental management systems can significantly change the energy and moisture dynamics of greenhouse production systems. This study aims to focus on reducing natural gas, electricity, and water consumption in semi-arid California greenhouses introducing renewable energy heat pump technologies to ...


Design And Evaluation Of A Greenhouse Interface For Climate Control Programming And Networking, G. Diaz, S. F. Kelly, Ilhami Yildiz Jan 2008

Design And Evaluation Of A Greenhouse Interface For Climate Control Programming And Networking, G. Diaz, S. F. Kelly, Ilhami Yildiz

Bioresource and Agricultural Engineering

At Cal Poly the motto is “Learn by Doing”. In the College of Agriculture, this is especially true and many of the labs provide an opportunity for students to implement this philosophy. Updated climate controls were installed in a series of greenhouses on the top floor of the Agricultural Science building that are used for student and faculty research projects. A Programmable Logic Controller (PLC) was installed to actuate the various vents, shading, heating, cooling and irrigation. A control program was developed to control and log temperatures and other operating parameters to monitor the greenhouse. An easy to use computer ...


Simulated Effects Of Various Environmental Management Practices On Water Consumption In Open And Confined Greenhouse Systems, Ilhami Yildiz, D. P. Stombaugh Jan 2008

Simulated Effects Of Various Environmental Management Practices On Water Consumption In Open And Confined Greenhouse Systems, Ilhami Yildiz, D. P. Stombaugh

Bioresource and Agricultural Engineering

The objective of this study was to evaluate the effects of relative humidity, light management, minimum ventilation rates, CO2 enrichment and canopy size on water consumption in three different greenhouse systems (conventional, open heat pump, and confined heat pump) in winter, spring, and summer months. Using different relative humidity set points resulted in almost the same relative humidity regimes within the confined greenhouse system, resulting in similar transpiration rates. No difference was observed in transpiration rates in the open system in winter either, because the inside relative humidity levels never reached the 70% and 80% set points. Some differences ...


Spatial Distributions Of Heating, Cooling, And Industrial Degree-Days In Turkey, Ilhami Yildiz, B. Sosaoglu Nov 2007

Spatial Distributions Of Heating, Cooling, And Industrial Degree-Days In Turkey, Ilhami Yildiz, B. Sosaoglu

Bioresource and Agricultural Engineering

The degree-day method is commonly used to estimate energy consumption for heating and cooling in residential, commercial and industrial buildings, as well as in greenhouses, livestock facilities, storage facilities and warehouses. This article presents monthly and yearly averages and spatial distributions of heating, cooling, and industrial degree-days at the base temperatures of 18 °C and 20 °C, 18 °C and 24 °C, and 7 °C and 13 °C, respectively; as well as the corresponding number of days in Turkey. The findings presented here will facilitate the estimation of heating and cooling energy consumption for any residential, commercial and industrial buildings ...


Impact Of Sulfur On Density Of Tetranychus Pacificus (Acari: Tetranychidae) And Galendromus Occidentalis (Acari: Phytoseiidae) In A Central California Vineyard, Michael J. Costello Jun 2007

Impact Of Sulfur On Density Of Tetranychus Pacificus (Acari: Tetranychidae) And Galendromus Occidentalis (Acari: Phytoseiidae) In A Central California Vineyard, Michael J. Costello

Horticulture and Crop Science

Sulfur is the oldest and most widely used fungicide in the vineyards of California, where it is used for control of powdery mildew (Uncinula necator [Schw.] Burr). For decades, sulfur use has been associated with outbreaks of Tetranychus pacificus McGregor (Acari: Tetranychidae) on cultivated grapes in the San Joaquin Valley. I undertook large-scale field studies to test this association, to evaluate the impact of sulfur on Galendromus occidentalis (Nesbit) (Acari: Phytoseiidae), a major predator of T. pacificus, and to determine if timing of sulfur applications with respect to grape bloom has an impact on T. pacificus density. The studies took ...


Spontaneous Hybridization Between Maize And Teosinte, Norman C. Ellstrand, Lauren C. Garner, Subray Hedge, Roberto Guadagnuolo, Lesley Blancas Mar 2007

Spontaneous Hybridization Between Maize And Teosinte, Norman C. Ellstrand, Lauren C. Garner, Subray Hedge, Roberto Guadagnuolo, Lesley Blancas

Horticulture and Crop Science

The closest wild relatives of maize, Zea mays ssp. mays are various Zea taxa known as ‘‘teosinte.’’ Hybrids between maize and the teosinte taxon, Zea mays ssp. mexicana, often occur when the 2 are sympatric in Mexico. Measuring the spontaneous hybridization rate of the 2 taxa would shed light on the mechanisms contributing to the evolution and persistence of these hybrid swarms. We conducted a series of field experiments in Riverside, CA, to measure the natural hybridization rates between maize and 2 teosinte taxa, Z. m. ssp. mexicana and Zea mays ssp. parviglumis. We planted teosinte within and near maize ...


Dynamic Modeling Of Microclimate And Environmental Control Strategies In A Greenhouse Coupled With A Heat Pump System, Ilhami Yildiz, D. P. Stombaugh Jan 2006

Dynamic Modeling Of Microclimate And Environmental Control Strategies In A Greenhouse Coupled With A Heat Pump System, Ilhami Yildiz, D. P. Stombaugh

Bioresource and Agricultural Engineering

The purpose of this study was to develop and validate a dynamic simulation model to be employed in accurate prediction of microclimate in a greenhouse as a function of dynamic environmental factors. The model has options to evaluate the effects of location, time of the year, orientation, single and double polyethylene glazings, conventional and heat pump heating and cooling systems, open and confined greenhouse systems, CO2 enrichment, variable shading, and the use of night curtains. Conventional gas furnace and evaporative cooling, respectively, provided heating and cooling in the conventional system. In the heat pump systems, gas-fired heat pump units ...


Simulated Performances Of A Heat Pump System For Energy And Water Conservation In Open And Confined Greenhouse Systems, Ilhami Yildiz, D. P. Stombaugh Jan 2006

Simulated Performances Of A Heat Pump System For Energy And Water Conservation In Open And Confined Greenhouse Systems, Ilhami Yildiz, D. P. Stombaugh

Bioresource and Agricultural Engineering

The purpose of this study was to determine and compare the performances of conventional and heat pump systems for energy and water conservation in open and confined greenhouse systems. Conventional gas furnaces and evaporative cooling, respectively, provided heating and cooling in the conventional system. In the heat pump systems, gas-fired heat pump units provided both heating and cooling. The greenhouse with heat pump units also had an option to be operated as a completely confined system, using one of the heat pump units as a dehumidifier. Average energy consumption in winter was 56.9, 23.5, and 11.3 MJ ...


Day Vs. Night Sampling For Spiders In Grape Vineyards, Michael J. Costello, Kent M. Daane Jan 2005

Day Vs. Night Sampling For Spiders In Grape Vineyards, Michael J. Costello, Kent M. Daane

Horticulture and Crop Science

We compared day sampling (between 0700 and 1100) and night sampling (between 1900 and 2300) of spiders on grapevines in a California vineyard in 1993 and 1994, shaking spiders from the vines onto a drop cloth and vacuuming them up. Pooled density of the seven most abundant spider species did not differ significantly between day and night sampling, nor did density of Cheiracanthium inclusum (Miturgidae), Trachelas pacificus (Corrinidae), Oxyopes spp. (Oxyopidae) or Neoscona oaxacensis (Araneidae). Under day sampling Metaphidippus vitis (Salticidae) was 60% more abundant and Hololena nedra (Agelenidae) more than 2.5 fold more abundant than under night sampling ...


Spider And Leafhopper (Erythroneura Spp.) Response To Vineyard Ground Cover, Michael J. Costello, Kent M. Daane Jul 2003

Spider And Leafhopper (Erythroneura Spp.) Response To Vineyard Ground Cover, Michael J. Costello, Kent M. Daane

Horticulture and Crop Science

Ground cover is used in some vineyards to improve soil structure and help manage insect pests; previous studies have shown lower leafhopper (Erythroneura spp.) densities on vines grown with ground cover. We undertook a 2-yr study to determine why ground cover is associated with reduced leafhopper densities. Ground cover consisted of a fall-planted cover crop of purple vetch (Vicia benghalensis) and barley (Hordeum vulgare), which senesced in May and was replaced by a complex of resident vegetation comprised primarily of the grasses Echinochloa spp., Digitaria sanguinalis, and Setaria spp., as well as common knotweed (Polygonum aviculare). We compared three treatments ...


Biological Control As A Tool For Ecosystem Management, David H. Headrick, Richard D. Goeden Jul 2001

Biological Control As A Tool For Ecosystem Management, David H. Headrick, Richard D. Goeden

Horticulture and Crop Science

Biological control is proposed as a tool useful for ecosystem management and compatible with the goals of often competing interests regarding the restoration and maintenance of ecosystems. We summarize the effects of introduced species on ecosystems in three broad groups: insects, vertebrates, and weeds. We then discuss the role of biological control for each of these groups in the context of ecosystem management and realistic outcomes. Of the three groups, we show that biological control of weeds appears to have the best chance for success in ecosystem management. We provide two case studies to support our ideas and finally discuss ...


Fork-Tailed Katydid Studies, David H. Headrick Jan 2000

Fork-Tailed Katydid Studies, David H. Headrick

Horticulture and Crop Science

The fork-tailed katydid, Scudderia furcata Brunner (Orthoptera: Tettigoniidae) was considered a minor pest of citrus in California, but in the last few years has increasingly become a problem due to reduction in organophosphate and carbamate pesticides (Grafton-Cardwell 1999). Our objective is to study the biology and behavior of the fork-tailed katydid as a pest of commercially grown citrus in order to develop ecologically-based control methods for application in commercial citrus production.


Development And Reproduction Of A Population Of Eretmocerus Eremicus (Hymenoptera: Aphelinidae) On Bemisia Argentifolii (Homoptera: Aleyrodidae), David H. Headrick, Thomas S. Bellows, Jr., Thomas M. Perring Apr 1999

Development And Reproduction Of A Population Of Eretmocerus Eremicus (Hymenoptera: Aphelinidae) On Bemisia Argentifolii (Homoptera: Aleyrodidae), David H. Headrick, Thomas S. Bellows, Jr., Thomas M. Perring

Horticulture and Crop Science

Although the aphelinid parasitoid Eretmocerus eremicus Rose & Zolnerowich is the most abundant naturally occurring parasitoid of Bemisia argentifolii Bellows & Perring in the U.S. desert southwest, its effectiveness in different cropping systems varies. Development and reproduction of a population of this parasitoid attacking B. argentifolii infesting cotton, Gossypium hirsutum L., and sweet potato, Ipomoea batatas L., were quantified and compared. Females potato; there were no significant differences of these parameters between host plant species. A preoviposition period of 0.61 d was recorded, and a maximum number of eggs laid in a day was 69 on cotton and 13 on sweet potato. The average preimaginal developmental periods for males and females on either host plant were not significantly different and averaged 22.58 d. The mean number of progeny produced on cotton was 25.4 with 51.5% of these female, whereas the mean number of progeny produced on sweet potato was 7.5 with ...


Reproductive Biology And Search Behavior Of Amitus Bennetti (Hymenoptera: Platygasteridae), A Parasitoid Of Bemisia Argentifolii (Homoptera: Aleyrodidae), Andrea L. Joyce, Thomas S. Bellows, Jr., David H. Headrick Jan 1999

Reproductive Biology And Search Behavior Of Amitus Bennetti (Hymenoptera: Platygasteridae), A Parasitoid Of Bemisia Argentifolii (Homoptera: Aleyrodidae), Andrea L. Joyce, Thomas S. Bellows, Jr., David H. Headrick

Horticulture and Crop Science

No abstract provided.


Abundance Of Spiders And Insect Predators On Grapes In Central California, Michael J. Costello, Kent M. Daane Jan 1999

Abundance Of Spiders And Insect Predators On Grapes In Central California, Michael J. Costello, Kent M. Daane

Horticulture and Crop Science

We compared the abundance of spiders and predaceous insects in five central California vineyards. Spiders constituted 98.1% of all predators collected. More than 90% of all spiders collected were from eight species of spiders, representing six families. Two theridiids (Theridion dilutum and T. melanurum) were the most abundant, followed by a miturgid (Cheiracanthium inclusum) and an agelinid (Hololena nedra). Predaceous insects comprised 1.6% of all predators collected, and were represented by six genera in five families. Nabis americoferis (Heteroptera, Nabidae) was the most common predaceous insect, with its densities highest late in the growing season. Chrysoperla carnea, Chrysoperla ...


Can Cover Crops Reduce Leafhopper Abundance In Vineyards?, Kent M. Daane, Michael J. Costello Sep 1998

Can Cover Crops Reduce Leafhopper Abundance In Vineyards?, Kent M. Daane, Michael J. Costello

Horticulture and Crop Science

In 3 of 4 vineyards we studied, late-season leafhopper density was lower on vines in cover cropped plots than in plots with no cover crops. However, the level of leafhopper reduction (about 15%) was rarely economically important and the mechanisms leading to reduction were not clear. For example, there were few differences in the number of leaf hopper predators or parasitoids on the vines in cover cropped versus no cover plots. However, there were significant between-treatment differences in vine growth. Plots with seasonwide maintenance of a cover crop and resident grasses had a reduction in vine vigor. Lower vine vigor ...


The Biology Of Nonfrugivorous Tephritid Fruit Flies, David H. Headrick, Richard D. Goeden Jan 1998

The Biology Of Nonfrugivorous Tephritid Fruit Flies, David H. Headrick, Richard D. Goeden

Horticulture and Crop Science

This review is the first comprehensive treatment of the biology of nonfrugivorous fruit flies of the family Tephritidae. Feeding habits of destructive and useful species, morphology of immature stages, and hypotheses regarding structural homology and the evolutionary biology of nonfrugivorous tephritids are reviewed, including zoogeography and theories involving resource heterogeneity, guild structure, resource partitioning, resource utilization, facultative niche exploitation, extrinsic and intrinsic factors, host associations, seasonal distribution and phenology, aggregative and circumnatal life history strategies, voltinism, diapause, aestivation, oviposition site, clutch size, and supernumerary oviposition.


Influence Of Ground Cover On Spider Populations In A Table Grape Vineyard, Michael J. Costello, Kent M. Daane Jan 1998

Influence Of Ground Cover On Spider Populations In A Table Grape Vineyard, Michael J. Costello, Kent M. Daane

Horticulture and Crop Science

1. Cover crops and/or resident ground vegetation have been used in California vineyards to increase the number of predators and decrease the number of pestiferous herbivores. The most common resident predators in vineyards are spiders (Araneae). Several observational studies suggest that the addition of cover crops results in an increase in spider density and a decrease in insect pest densities. 2. To test experimentally the effects of cover crops and/or resident ground vegetation (hereafter collectively referred to as ground cover) on spider populations, a 3-year study was undertaken in a commercial vineyard. Large, replicated plots were established with ...


Comparison Of Sampling Methods Used To Estimate Spider (Araneae) Species Abundance And Composition In Grape Vineyards, Michael J. Costello, Kent M. Daane Apr 1997

Comparison Of Sampling Methods Used To Estimate Spider (Araneae) Species Abundance And Composition In Grape Vineyards, Michael J. Costello, Kent M. Daane

Horticulture and Crop Science

The effectiveness of 3 methods for sampling spiders in grape vineyards was tested. The sampling methods were as follows: (1) a drop-cloth method in which spiders were dislodged from a 5.1-m2 area of grapevine onto a drop cloth, (2) a funnel method in which spiders were dislodged into a 0.74-m2 funnel, and (3) a D-vac method in which 50 sections of grapevine (30-cm sections, total area of 5.4 m2) were suctioned with a gasoline-powered vacuum. Data from all sampling methods were adjusted for area sampled and compared with an absolute control, in which foliage from an entire ...


Brushing Pansy (Viola Tricolor L.) Transplants: A Flexible, Effective Method For Controlling Plant Size, Lauren C. Garner, F. A. Langton Feb 1997

Brushing Pansy (Viola Tricolor L.) Transplants: A Flexible, Effective Method For Controlling Plant Size, Lauren C. Garner, F. A. Langton

Horticulture and Crop Science

Though brushing is an effective method for controlling excessive elongation in many species, its adoption by the commercial plug transplant industry will depend on the ease and flexibility of its application. Brushing was applied to pansy (Viola tricolor L.) seedlings growing at a density of 1500 plants m-2 by daily stroking with 20/20 gauge netting. In dose response experiments, final petiole length appeared to approach a lower asymptote as number of brush strokes increased, and the number of strokes required to give near full reduction in length increased under environmental conditions favouring extension growth. Ten or 20 daily ...


Behavior Of Female Eretmocerus Sp. Nr. Californicus Howard (Aphelinidae: Hymenoptera) Attacking Bemisa Argentifolii Bellows And Perring (Aleyrodidae: Homoptera) On Two Native Californian Weeds, David H. Headrick, Thomas S. Bellows, Jr., Thomas M. Perring Jan 1997

Behavior Of Female Eretmocerus Sp. Nr. Californicus Howard (Aphelinidae: Hymenoptera) Attacking Bemisa Argentifolii Bellows And Perring (Aleyrodidae: Homoptera) On Two Native Californian Weeds, David H. Headrick, Thomas S. Bellows, Jr., Thomas M. Perring

Horticulture and Crop Science

Searching and ovipositional behaviors by female Eretmocems sp. nr. californicus Howard on Bemisia argentifolii Bellows and Perring infesting velvetleaf, Abutilon theophrasti Medic. (Malavaceae), and telegraph weed, Heterotheca grandiflora Nutt. (Asteraceae), were quantified. Adult female behaviors were described and quantified for E. sp. nr. californicus to establish a behavioral time budget analysis. Females departed from leaves of A. theophrasti in 83.3% of the trials, and of those that remained and searched for hosts, walking speeds averaged 0.29 mm/s. Females departed from the leaves of H. grandiflora in 44.4% of the trials, and those remaining readily searched for ...


Issues Concerning The Eradication Or Establishment And Biological Control Of The Mediterranean Fruit Fly, Ceratitis Capitata(Wiedemann) (Diptera: Tephritidae), In California, David H. Headrick, Richard D. Goeden Jun 1996

Issues Concerning The Eradication Or Establishment And Biological Control Of The Mediterranean Fruit Fly, Ceratitis Capitata(Wiedemann) (Diptera: Tephritidae), In California, David H. Headrick, Richard D. Goeden

Horticulture and Crop Science

Classical biological control is suggested as a tool worth developing now for possible future use in the integrated pest management of the Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann), in California. Three factors that impact broadly on developing and implementing such a biological control program are: (1) the question of Medfly establishment, (2) quarantine considerations, and (3) agricultural and urban concerns. Each of these factors and their combined effects must be considered when discussing biological control of Medfly in California as shaped by historical perspectives on Medfly invasions, methods of Medfly eradication, and past biological control efforts against Medfly. We ...