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California Polytechnic State University, San Luis Obispo

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Horticulture and Crop Science

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Evaluation Of Fungicides For Control Of Dollar Spot And Brown Patch Of Greens Height Creeping Bentgrass In Kansas, 2013, C. Thompson, R. Braun, M. Kennelly Aug 2014

Evaluation Of Fungicides For Control Of Dollar Spot And Brown Patch Of Greens Height Creeping Bentgrass In Kansas, 2013, C. Thompson, R. Braun, M. Kennelly

Horticulture and Crop Science

No abstract provided.


Evaluation Of Fungicides For Control Of Dollar Spot Of Fairway Height Creeping Bentgrass In Kansas, 2012, C Thompson, Z Raundenbush, Megan Kennelly Aug 2013

Evaluation Of Fungicides For Control Of Dollar Spot Of Fairway Height Creeping Bentgrass In Kansas, 2012, C Thompson, Z Raundenbush, Megan Kennelly

Horticulture and Crop Science

No abstract provided.


Evaluation Of Granular Fungicides For Control Of Brown Patch Of Lawn Height Tall Fescue In Kansas, 2012, Cole Thompson, M. Kennelly Aug 2013

Evaluation Of Granular Fungicides For Control Of Brown Patch Of Lawn Height Tall Fescue In Kansas, 2012, Cole Thompson, M. Kennelly

Horticulture and Crop Science

No abstract provided.


Evaluation Of Headway G For Control Of Brown Patch Of Lawn Height Tall Fescue In Kansas, 2011, C Thompson, M Kennelly Aug 2012

Evaluation Of Headway G For Control Of Brown Patch Of Lawn Height Tall Fescue In Kansas, 2011, C Thompson, M Kennelly

Horticulture and Crop Science

No abstract provided.


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 ...


Evaluation Of Fungicides And Fungicide Programs For Control Of Dollar Spot Creeping Bentgrass In Kansas, 2010, M Kennelly, C Thompson, Z Raudenbush Aug 2011

Evaluation Of Fungicides And Fungicide Programs For Control Of Dollar Spot Creeping Bentgrass In Kansas, 2010, M Kennelly, C Thompson, Z Raudenbush

Horticulture and Crop Science

No abstract provided.


Preventative Fungicide Application For Control Of Dollar Spot On Creeping Bentgrass In Kansas, 2010, M Kennelly, Z Raudenbush, Cole Thompson Aug 2011

Preventative Fungicide Application For Control Of Dollar Spot On Creeping Bentgrass In Kansas, 2010, M Kennelly, Z Raudenbush, Cole Thompson

Horticulture and Crop Science

No abstract provided.


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 ...


Preventative Fungicide Applications For Control Of Dollar Spot And Brown Patch On Creeping Bentgrass In Kansas, 2009, M Kennelly, C Thompson Aug 2010

Preventative Fungicide Applications For Control Of Dollar Spot And Brown Patch On Creeping Bentgrass In Kansas, 2009, M Kennelly, C Thompson

Horticulture and Crop Science

No abstract provided.


Preventative Fungicide Applications For Control Of Dollar Spot And Brown Patch On Creeping Bentgrass In Kansas, 2009, M Kennelly, C Thompson Aug 2010

Preventative Fungicide Applications For Control Of Dollar Spot And Brown Patch On Creeping Bentgrass In Kansas, 2009, M Kennelly, C Thompson

Horticulture and Crop Science

No abstract provided.


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 ...


The Impact Of Outcrossing On Yields Of ‘Hass’ Avocado, Lauren C. Garner, Vanessa E.T.M. Ashworth, Michael T. Clegg, Carol J. Lovatt Sep 2008

The Impact Of Outcrossing On Yields Of ‘Hass’ Avocado, Lauren C. Garner, Vanessa E.T.M. Ashworth, Michael T. Clegg, Carol J. Lovatt

Horticulture and Crop Science

‘Hass’ avocado (Persea americana Mill.) is characterized by excessive flower and fruit abscission, resulting in extremely low fruit set. Low outcrossing rates might be a factor contributing to low yields. It is hypothesized that self-fertilized flowers and resulting fruit abscise at a much higher rate than fruit that are the product of outcrossing. However, significant relationships between outcrossing rates and yields have only been established in a few avocado studies. The objective of this research was to investigate the importance of outcrossing to yield in a commercial ‘Hass’ orchard containing ‘Bacon’, an effective pollinizer of ‘Hass’. Microsatellite markers were used ...


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 ...


The Relationship Between Flower And Fruit Abscission And Alternate Bearing Of ‘Hass’ Avocado, Lauren C. Garner, Carol J. Lovatt Jan 2008

The Relationship Between Flower And Fruit Abscission And Alternate Bearing Of ‘Hass’ Avocado, Lauren C. Garner, Carol J. Lovatt

Horticulture and Crop Science

Despite profuse flowering, ‘Hass’ avocado (Persea americana Mill.) yields are low because of excessive flower and fruit abscission. Whether the dynamics of flower and fruit abscission are influenced by or contribute to alternate bearing, the production of a heavy on-crop followed by a light off-crop that is characteristic of many avocado cultivars, remains unresolved. The objective of this research was to determine whether abscission of reproductive structures from ‘Hass’ avocado trees during specific developmental stages, including flowering, fruit development, and fruit maturity, was influenced by crop status of the current or preceding year. Abscised reproductive structures were collected from commercially ...


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 ...


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.


Mechanical Conditioning Of Tomato Seedlings Improves Transplant Quality Without Deleterious Effects On Field Performance, Lauren C. Garner, Thomas Björkman Sep 1999

Mechanical Conditioning Of Tomato Seedlings Improves Transplant Quality Without Deleterious Effects On Field Performance, Lauren C. Garner, Thomas Björkman

Horticulture and Crop Science

Excessive stem elongation reduces plant survival in the field and hinders mechanical transplanting. Mechanical conditioning is an effective method for reducing stem elongation during transplant production. This investigation examined the consequences of mechanical conditioning, using brushing and impedance, on subsequent field performance of tomatoes (Lycopersicon esculentum Mill.). Mechanically conditioned transplants of processing tomatoes resumed growth after transplant shock as quickly as did untreated plants, and subsequent canopy development was also equal. In 4 years of field trials, yield was not reduced by mechanical conditioning. Transplants for fresh-market tomatoes may be more sensitive to injury than those for processing tomatoes because ...


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 ...