Abstracts
101st Annual International Conference of the
American Society for Horticultural Science
Austin, Texas
Presenting authors are denoted by an astrisk (*) phytotoxicity at the lowest application rate, suggesting that the some of
the phytotoxins were volatile. Dichloromethane, methanol and water
Number preceeding title corresponds to the location of the poster
extracts of the wetted seedmeal were bioassayed against wheat and
in the Rio Grande Exhibit Hall sicklepod radicle elongation. Only the dichloromethane extract was
found to be strongly inhibitory to both species. Fractionation of the
dichloromethane extract identified two major phytotoxins, identified
by GC-MS and NMR analyses as 2-propen-1-yl (allyl) isothiocyanate
Poster Session 1—Weed Control and Pest Management
(AITC) and allyl thiocyanate (ATC), which constituted 80.9 and 18.8%,
July 17, 2004, 12:30–1:30 PM Rio Grande Exhibit Hall respectively, of the active fraction. When seeds of wheat, arugula and
sicklepod were exposed to volatilized AITC and ATC, the germination
of all three species were completely inhibited by both compounds at
1GIS Analysis of Sweetpotato Weevil Trap Data in Louisiana concentrations of 5 ppm or less.
Arthur Villordon*1, Craig Roussel2, Tad Hardy3
1
LSU AgCenter, Sweetpotato Research Station, Chase, LA 71324; 2Louisiana Dept. of 4 Phytotoxicity and Weed Control Efficacy of Three Non-labeled
Agriculture and Forestry, Agriculture and Environmental Sciences, Baton Rouge, LA
Herbicides for Field-grown Hemerocallis spp.
70821; 3Louisiana Dept. of Agriculture and Forestry, Agriculture and Environmental Sci-
ences, Baton Rouge, LA 70821 Patricia R. Knight*1, Christine E. Coker2, Benedict Posadas3, John
M. Anderson4
The Louisiana Dept. of Agriculture and Forestry (LDAF) conducts 1
Mississippi State Univ., Coastal Research and Extension Center, Poplarville, MS 39470;
sweetpotato weevil [SPW, Cylas formicarius (Fabricius)] monitoring 2
Mississippi State Univ., Coastal Research and Extension Center, Biloxi, MS 39531; 3Mis-
in support of the statewide SPW quarantine program. The monitoring sissippi State Univ., Coastal Research and Extension Center, Biloxi, MS 39531; 4Mississippi
activity primarily involves a statewide pheromone-based trapping State Univ., Coastal Research and Extension Center, Poplarville, MS 39470
process that generates trap data for sweetpotato beds and production The IR-4 program works to identify potential minor-use horticultural
fields. We conducted GIS analysis of SPW trap data, collected over chemicals and evaluate them for phytotoxicity and efficacy. The objec-
three years, to assess the potential use of GIS tools in managing and tive of this experiment was to evaluate phytotoxicity and weed control
interpreting the data. The LDAF has already generated shapefiles for of three unlabeled herbicides on field production of Hemerocallis spp.
all beds and fields in each of three years, facilitating GIS analysis. ʻMing Toyʼ. Ten-cm pots of ʻMing Toyʼ were planted into the field 16
However, trap data was manually collected and statewide data was July 2001. Each plot consisted of 3 plants per treatment with 6 replica-
compiled and stored in spreadsheet files. Trap data was mapped to tions in a completely random design. Each herbicide was analyzed as
specific beds and fields in each of three years, generating layers that a separate experiment. Herbicide treatments consisted of clopyralid
clearly showed fields and parishes that reported high trap counts. GIS (0.14, 0.28, 0.56, or 1.1 kg·ha–1 a.i.), clethodim (125, 250, or 500 mL·L–1
analysis showed potential SPW “hotspots” in each year, indicating that a.i.), or bentazon (1.1, 2.2, or 4.4 kg·ha–1 a.i.). Data collected included
certain beds or fields are more prone to SPW infestation than others. weed number, percentage of weed coverage (% weed coverage), and
This information can be useful in planning SPW management strategies phytotoxicity and foliar color ratings for ʻMing Toyʼ. Clopyralid
by growers and other stakeholders. The GIS database also provides the reduced total weed number 90 DAT although % weed coverage was
foundation for the development of descriptive and predictive models of similar or worse compared to the control treatment. Phytotoxicity 90
SPW occurence in Louisiana. Compiling the SPW trap data into a GIS DAT was not significant for plants treated with clopyralid, but foliar
database allows the data to be distributed over the Internet, facilitating color ratings were reduced. Application of clethodim to ʻMing Toyʼ
real-time access by stakeholders. plots, regardless of rate, resulted in similar weed numbers compared to
the control 49 DAT. Clethodim application, regardless of rate, reduced
2 Poster withdrawn. % weed coverage compared to the control treatment. Phytotoxicity 90
DAT was not significant, regardless of herbicide treatment, but foliar
color ratings were lower for herbicide treated plants compared to the
3 Biofumigation Potential of Field Pennycress (Thlaspi arvense) control. Bentazon, regardless of rate, reduced weed number and %
Seedmeal weed coverage 49 DAT compared to the control. Phytotoxicity was
Steven Vaughn*1, Terry Isbell2, David Weisleder3, Mark Berhow4 similar to the control for plants treated with 1.1 kg·ha–1 a.i.
1
USDA-ARS, National Center for Agricultural Utilization Research, New Crops and
Processing Technology Research, Peoria, IL 61604; 2USDA-ARS, National Center for 5 Preemergence Weed Control in Container-grown Herbaceous
Agricultural Utilization Research, New Crops and Processing Technology Research, Peo-
Perennials
ria, IL 61604; 3USDA-ARS, National Center for Agricultural Utilization Research, New
Crops and Processing Technology Research, Peoria, IL 61604; 4USDA-ARS, National James Klett*1, Dave Staats2, Matt Rogoyski3
Center for Agricultural Utilization Research, New Crops and Processing Technology 1
Colorado State Univ., Horticulture and Landscape Architecuture, Fort Collins, CO 80523;
Research, Peoria, IL 61604 2
Colorado State Univ., Horticulture and Landscape Architecture; 3Colorado State Univ.,
Horticulture and Landscape Architecture
Field pennycress (Thlaspi arvense L.) seedmeal was found to suppress
seedling germination/emergence and biomass accumulation when During the 2003 season, preemergence herbicide was applied to twelve
added to a sandy loam soil containing wheat (Triticum aestivum L.), container grown herbaceous perennials and woody plants and evalu-
arugula [Eruca vesicaria (L.) Cav. subsp. sativa (Mill.) Thell.] and ated for weed control, phytotoxicity, and effect on plant growth. The
sicklepod (Senna obtusifolia (L.) H.S. Irwin & Barneby) seeds. Covering herbicide and rates were: Flumioxazin (Broadstar) 113.5 g (label rate),
the pots with petri dishes containing the soil-seedmeal mixture increased 227 g and 454 g a.i./A. Herbicides were applied to Buxus microphylla
HORTSCIENCE, VOL. 39(4), JULY 2004 745
,ʻWinter Gemʼ, Cytisus purgans ʻSpanish Goldʼ, Festuca ovina glauca of broadleaf and grass species and number of annual and perennial
ʻElijah Blueʼ, Hakonechloa macra ʻAureolaʼ, Lonicera tatarica ʻArnold species. The total number of weeds in weeded and non-weeded sub-
Redʼ, Pachysandra terminalis ʻGreen Sheenʼ, Hydrangea arborescens plots was lowest in the buckwheat and highest in the clover. Species
ʻAnnabelleʼ, Mahonia aquifolium, Phalaris arundinacea ʻPictaʼ, diversity in weeded subplots was lowest for the control and highest in
Carex buchananii,Cerastium tomentosum, and Achillea millefolium clover while species diversity in non-weeded subplots was lowest in
ʻRed Beautyʼ. Weed control was excellent at all rates and controlled buckwheat and highest in the control. Overall, most weeds present were
at least 99% of all weeds. No phytotoxicity symptoms were apparent broadleaf annuals including pigweeds (Amaranthus spp.), shepardʼs
on Mahonia,Buxus, Cytisus, Festuca, Hakonechloa, Pachysandra or purse (Capsella bursa-pastoris), common lambsquarters (Cheno-
Phlaris. Phytotoxicity resulted on some of the other plants. Carex podium album) and common purslane (Portulaca oleracea). Based
had smaller plants (dry weights) at all rates. Cerastium had severe on this 1-year study, which will be repeated in 2004, the buckwheat
phytotoxicty at the 227 g and 454 g rates and moderate stunting at treatment is likely the most effective in managing weeds in edamame
the recommended label rate, 113.5 g. Hydrangea became chlorotic field production for consideration by Pennsylvania growers.
and stunted at the 113.5 g rate and some fatal toxicity ocurred at the
227 g and 454 g rates. Phytotoxicity resulted on Lonicera at all rates
and ranged from mild chlorosis in leaf veins (113.5 g rate) to plant 8 Pre and Early Postemergence Herbicide Phytotoxicity and Yield
death (454 g rate). Achillea at the 113.5 g rate only resulted in stunted Effects in Transplanted Peppers
plant growth while the 227 g and 454 g rates resulted in severe phy- Russell W. Wallace*1
totoxcity and plant death. 1
Texas A&M Univ., Horticultural Sciences, Lubbock, TX 79403
Field research was conducted to evaluate pre-transplant (PRE) applica-
6Mugwort (Artemisia vulgaris) Rhizome Regeneration in Pine tions of sulfentrazone (0.20 or 0.41 kg·ha–1 a.i.) and flufenacet (0.045
Bark, Soil and Sand Substrates kg·ha–1 a.i.), or early postemergence (EPOST) halosulfuron (0.027,
William E. Klingeman*1, Darren K. Robinson2, Gary L. McDaniel3 0.036 or 0.054 kg·ha–1 a.i.) on phytotoxicity and yield of field-grown
1
Univ. of Tennessee, Plant Sciences, Knoxville, TN 37996-4561; 2Univ. of Tennessee,
chili (var. Sonora), jalapeño (var. Grande) and bell (var. Giant Belle)
Plant Sciences; 3Univ. of Tennessee, Plant Sciences peppers (Capiscum annuum) in Texas. Crop injury recorded 15 days
after sulfentrazone treatments (DAT) showed minor stunting at the
Mugwort, or false chrysanthemum (Artemisia vulgaris L) is a well- low rate, but moderate stunting and temporary leaf malformation
adapted invasive plant that presents increasing management challenges when applied at 0.41 kg·ha–1 a.i. Increased stunting occurred 37 DAT
to agricultural producers, Green Industry professionals and homeowners at both rates; however, new leaf growth was not affected. Flufenacet
across portions of the eastern U.S. The ability of mugwort to regener- did not result in crop injury to any of the three types grown. Phyto-
ate from cut rhizome sections has not been adequately quantified for toxicity from halosulfuron recorded 7 DAT gave significantly higher
substrates that are typical of landscapes and nursery fields, container ratings for stunting/chlorosis for broadcast EPOST treatments when
nurseries, and propagation beds. Cut rhizome sections were analyzed compared to EPOST-directed applications. Injury from halosulfuron
by rhizome color, length, and the presence or absence of a leaf scale. was temporary and considered minor with all EPOST treatments by
Media substrates included pine bark, sand, and soil. Rhizomes darken 22 DAT. Pepper yield data showed that EPOST halosulfuron treat-
with time and color did not account for differences in growth among ments were statistically equivalent to the untreated controls for each
treatments. When grown in pine bark, sand, and soil substrates dur- of the three types, but there was a trend for lower yields with rates
ing 45-d trials, 85%, 78%, and 69% of 2 cm-long rhizome sections higher than 0.027 kg·ha–1 a.i. All peppers treated with flufenacet
produced both roots and shoots. These results contrast with previous gave excellent yields. Sulfentrazone applied at the high rate gave the
research. When rhizome fragments 0.5 cm long did not include a greatest yield losses in all three types, and this was significant in the
leaf scale, slightly fewer than 31% produced both roots and shoots jalapeños. The results indicate that all three herbicides have potential
in soil. Fewer rhizomes survived in soil, but root and shoot fresh for use in commercial pepper production in Texas. However, more
masses of soil-grown rhizomes were greater than rhizomes that were research is needed to evaluate these and other herbicides for improved
regenerated in pine bark and sand. When rhizome sections had a leaf crop safety in peppers.
scale, survival, fresh masses of roots and shoots, shoot height, leaf
number and root lengths were greater, regardless of substrate type.
Root initials emerged in the internode between leaf scales and also 9 Weed Control in No-tillage Cucumber Production
adjacent to leaf scales. Shoot emergence preceded root emergence S. Alan Walters*1, Scott A. Nolte2, Joseph L. Matthews3, Bryan G.
from rhizome sections. Growers, landscape managers and homeowners Young4
should scout regularly and initiate aggressive controls when mugwort 1
Southern Illinois Univ., Plant, Soil, and Agricultural Systems, Carbondale, IL 62901-
populations are found. 4415; 2Southern Illinois Univ., Dept. Plant, Soil, and Agricultural Systems, Carbondale,
IL 62901-4415; 3Southern Illinois Univ., Plant, Soil, and Agricultural Systems, Carbon-
dale, IL 62901-4415; 4Southern Illinois Univ., Plant, Soil, and Agricultural Systems,
7Investigating the Use of Living Mulches in Edamame (Glycine Carbondale, IL 62901-4415
max) Field Production for Weed Management
A field study was conducted in 2002 and 2003 to evaluate various
Dru Bernthal*1, Elsa Sánchez2, Kathleen Kelley3 herbicides (ethafluralin & clomazone, halosulfuron, and ethafluralin
1
The Pennsylvania State Univ., Dept. of Horticulture, Univ. Park, PA 16802; 2The Penn- & clomazone + halosulfuron) with or without a winter rye (Secale
sylvania State Univ., Dept. of Horticulture, Univ. Park, PA 16802; 3The Pennsylvania cereale L.) cover crop in no-tillage ʻDaytonaʼ cucumber (Cucumis
State Univ., Dept. of Horticulture, Univ. Park, PA 16802 sativus L.) production. All herbicides were applied preplant prior to
A field trial investigating the use of living mulches for weed manage- cucumber transplanting, and no injury or stunting to cucumber was
ment in edamame (Glycine max), also known as vegetable soybean, observed with any of the treatments evaluated at any time during the
was conducted in 2003 at the Russell E. Larson Agricultural Research two growing seasons. Winter rye provided a significant advantage for
Center, Rock Springs, Pa. Edamame was direct seeded on 24–25 June weed control compared to the no cover crop production system. The
2003. Seven weeks later, the living mulch treatments were broadcast combination of ethafluralin & clomazone + halosulfuron provided the
seeded. The living mulch species were white clover (Trifolium repens), greatest control of smooth crabgrass [Digitaria ischaemum (Schreb.
buckwheat (Fagopyrum esculentum) and a control with no living mulch Ex Schweig) Schreb. Ex Muhl.] and redroot pigweed (Amaranthus
(bare ground). Each living mulch plot was divided into a weeded and retroflexus L.). Ethafluralin & clomazone provided little redroot pig-
non-weeded subplot. Weed pressure was evaluated every 2 weeks from weed control, while halosulfuron alone provided no control of smooth
the time living mulches were sown. Data collected included the total crabgrass. Winter rye enhanced cucumber yields in 2002 (drought
number of weeds present, number of different species present, number conditions), while in 2003 (sufficient moisture and cooler soil tempera-
746 HORTSCIENCE, VOL. 39(4), JULY 2004
,tures), winter rye tended to suppress yields. During drought conditions tended to be higher in plots where cucurbits and/or solanaceaous crops
(2002), treatments with ethafluralin & clomazone and ethafluralin & were grown more frequently, whereas the presence of Criconemoides
clomazone + halosulfuron produced similar yields. However, in 2003, seemed to be associated with plots where cassava, corn or sorghum
treatments with ethafluralin & clomazone + halosulfuron produced had been grown recently.
greater yields than treatments with ethafluralin & clomazone. Overall,
the handweed treatment provided the greatest yields, while the non-
treated and halosulfuron only treatment provided the lowest yields. 12 Insecticides from Five Chemical Classes Differentially Affect the
Winter rye will provide some additional weed control in a no-tillage Plant Growth and Development of Chrysanthemum (Dendranthema
vegetable production system, but may also provide negative effects by grandiflora Tzvelev var. Charm)
suppressing crop yield depending on seasonal growing conditions. James D. Spiers*1, Fred T. Davies2, Chuanjiu He3, Amanda Chau4,
Kevin M. Heinz5, Terri W. Starman6
1
Texas A&M Univ., Horticulture, College Station, TX 77843-2133; 2Texas A&M Univ.,
10 Seasonal Influence on Infection Rates of Malus sylvestris var. Horticulture; 3Texas A&M Univ., Horticulture; 4Texas A&M Univ., Entomology; 5Texas
domestica Roots by Phymatotrichopsis omnivora A&M Univ., Entomology; 6Texas A&M Univ., Horticulture
Wesley T. Watson*1, David N. Appel2, Michael A. Arnold3, Charles This research focused on the influence of insecticides on plant growth,
M. Kenerley4, James L. Starr5 gas exchange, rate of flowering, and chlorophyll content of chry-
1
Texas A&M Univ., Forest Science, College Station, TX 77843-2135; 2Texas A&M Univ., santhemum (Dendranthema grandiflora Tzvelev cv. Charm) grown
Plant Pathology and Microbiology, College Station, TX 77843-2132; 3Texas A&M Univ., according to recommended procedures for pot plant production . Five
Horticultural Sciences, College Station, TX 77843-2133; 4Texas A&M Univ., Plant Pa-
thology and Microbiology, College Station, TX 77843-2132; 5Texas A&M Univ., Plant
insecticides were applied at recommended concentrations at three dif-
Pathology and Microbiology, College Station, TX 77843-2132 ferent frequencies: weekly (7 days), bi-weekly (14 days), or monthly
(28 days). A separate treatment was applied weekly at 4× the recom-
Phymatotrichopsis omnivora (Duggar) Hennebert (syn. Phymatotri- mended concentration. Insecticides used were: acephate (Orthene®)
chum omnivorum Duggar) is a recalcitrant soilborne pathogen that Turf, Tree & Ornamental Spray 97), bifenthrin (Talstar®) Flowable),
causes serious root rot problems on numerous plant species in the endosulfan (Thiodan®) 50 WP), imidacloprid (Marathon®) II), and
southwestern United States and northern Mexico. Apple trees [Malus spinosad (Conserve®) SC). Phytotoxicity occurred in the form of leaf
sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. (syn. M. domestica burn on all acephate treatments, with the greatest damage occurring at
Borkh. non Poir.)] are highly susceptible to P. omnivora with most the 4× concentration. Photosynthesis and stomatal conductance were
tree death occurring in the summer months. Studies were conducted influenced primarily by the degree of aphid and/or spider mite infesta-
from 1996 to 1999 to examine when and at what rate infection and tion—except for acephate and endosulfan treatments (weekly and 4×
colonization of roots of apple trees by P. omnivora actually occurs. In ), which had reduced photosynthesis with minimal insect infestations.
three-year-old trees growing in orchard soils in 45-gallon containers Plants receiving imadacloprid monthly had the greatest leaf dry mass
(171,457 cm3) and inoculated with sclerotia in August 1997, infec- (DM). Plants treated with acephate had lower leaf and stem DM with
tion occurred in the nursery after 12 weeks. For trees inoculated with bi-weekly and 4× treatments. Spinosad treatments at recommended
sclerotia in February 1998, infection occurred within 15 weeks. After concentrations had reduced stem DM, in part due to aphid infestations.
18 weeks, 100% of trees were infected after inoculation in August and The flower DM was not significantly different among treatments. There
80% of trees were infected after the February inoculation. This infor- were treatment differences in chlorophyll content as measured with a
mation is vital to understanding the epidemiology of Phymatotrichum SPAD-502 portable chlorophyll meter.
root rot in apple orchards.
13 Feeding and Oviposition Behavior of Diaprepes abbreviatus (L.)
11 Nematode Genera Associated with Selected Vegetable Crops on Peach Prunus persica L. in Puerto Rico
in a Tropical Region
Alexandra Delgado1, Angel L. Gonzalez*2, Maria Del C. Libran3
Cesar A. Martinez-Mateo1, A. Jimenez2, Miguel Martinez3, J. Pablo 1
Univ. of P. R.- Mayaguez, Crop Protection, Mayaguez, PR 00681; 2Univ. of P. R. -Maya-
Morales-Payan*4 guez, Crop Protection, Mayaguez, PR 00681; 3Univ. of P. R.- Mayaguez, Horticulture,
1 Mayaguez, PR 00681
Instituto Politecnico Loyola, Plant Sciences, San Cristobal, Dominican Republic;2Instituto
Politecnico Loyola, Plant Sciences, San Cristobal, Dominican Republic; 3Instituto Politec- Peach cultivars are being evaluated for their adaptation to the condi-
nico Loyola, Plant Sciences, San Cristobal, Dominican Republic; 4SODIAF, Horticultural
Sciences, Santo Domingo, Dominican Republic
tions of the central region of Puerto Rico. The root weevil, Diaprepes
abbreviatus (L.), a common insect pest in the area, is being previously
A survey was conducted in a tropical region under continuous crop reported on peach trees. With the purpose of evaluating the potential
production for more than a century in the Dominican Republic, to feeding damage that this insect might represent for future peach produc-
determine the incidence of nematode genera in the soil and in tomato, tion, choice and no-choice tests were made with leaf discs (feeding)
eggplant, okra, carrot, cabbage, onion, Sweetpotato, squash, and and leaf strips (oviposition) to determine adult feeding and oviposition
cucumber roots. Typical crop sequences in the region were tomato, behavior in comparison with ʻNavelʼ orange. Larval feeding behavior
eggplant, or beans, followed by either corn, sorghum, cassava, squash on the roots was studied on a peach rootstock and ʻCleopatraʼ mandarin
or Sweetpotato, followed by either onion, carrot or cabbage, all the planted in 18.9-L containers. In the no-choice test, adults fed significantly
crops being grown with medium to high agrichemical input levels. more on ʻNavelʼ orange foliage than on peach foliage. In the choice
The genera Meloidogyne, Rotylenchulus, Pratylenchus, Aphelenchus, test, adults preferred to feed on ʻNavelʼ orange leaf discs. Oviposition
Helicotylenchus, Tylenchus, and Criconemoides were found in soil occurred on both peach cultivars tested, but more egg masses were
and/or crop root samples. Meloidogyne was the most prevalent genus laid on Navel orange leaf strips in the no-choice test. However, given
in the soil (41% of the samples) and in roots of squash, cucumber, the choice, adults preferred to oviposit on peach leaf strips while fed
tomato, Sweetpotato, and carrot (50% of the samples). Rotylenchulus on ʻNavelʼ orange leaf strips. In some replications this behavior was
was found in 27% of the soil samples, and in 33% of the tomato, okra, reversed. At 90 days after infestation, larval feeding damage on the
and carrot root samples. Aphelenchus was isolated from 2.5% of the roots was severe on ʻCleopatraʼ mandarin where most of the cortex
eggplant, onion, and cabbage root samples, and from 11% of the soil tissue on the primary root was removed and growth of roots and foliage
samples. Pratylenchus was found only in cucumber roots (13% of was reduced. Larvae bore also on peach trees, but there was no sign
the samples) and soil samples (10%). Helicotylenchus, Tylenchus, of growth reduction on foliage or the roots compared to the control.
and Criconemoides were isolated from soil (5%, 4%, and 1% of the These preliminary results indicate that D. abbreviatus will not be a
samples, respectively), but were not found in crop roots. The incidence primary pest on peach.
of Meloidogyne, Rotylenchulus, Pratylenchus, and Aphelenchus
HORTSCIENCE, VOL. 39(4), JULY 2004 747
, Poster Session 2—Vegetable Crop Management 1 16 A Survey of Sweetpotato Growers—Practices and Conditions
Associated with Good Root Appearance
July 17, 2004, 12:30–1:30 PM Rio Grande Exhibit Hall
Luz Reyes*1, Sylvia M. Blankenship*2, Jonathan R. Schultheis*3,
Michael D. Boyette4
14 Productivity and Quality of Green Snap Beans Varieties Under 1
North Carolina State Univ., Horticultural Science, Raleigh, NC 27695-7609; 2North Carolina
Desertic Conditions in Northwestern Mexico State Univ., Horticultural Science, Raleigh, North Carolina, 27695-7609; 3North Carolina
Raul Leonel Grijalva-Contreras*1, Eduardo Liñeiro-Celaya2, State Univ., Horticultural Science, Raleigh, NC 27695-7609; 4North Carolina State Univ.,
Gerardo Araiza-Celaya3, Victor Salvador-Rivas4, Francisco Lopez- Biological & Agricultural Engineering, Raleigh, NC 27695-7625
Vilchez5 Sweetpotato roots, especially the cultivar Beauregard, tend to experience
1
INIFAP-Caborca, Horticulture, Caborca, Sonora, 83600, Mexico;2Growers Club, Horti- epidermal loss during harvest and postharvest handling which results in
culture, Caborca, Sonora, 83600, Mexico;3Growers Club, Horticulture, Caborca, Sonora,
83600, Mexico,4Growers Club, Horticulture, Caborca, Sonora, 83600, Mexico; 5Growers
a less attractive product in the market. A survey study was conducted
Club, Horticulture, Caborca, Sonora, 83600, Mexico among North Carolina (N.C.) sweetpotato growers in Fall 2001 and
2002. The purpose of the survey was to gather information and try to
The agricultural activity in Caborca, Sonora, depends on fruit trees and correlate cultural practices, growing conditions and site characteristics
vegetable production, and the main crops are grapes, olive, and aspara- with the occurrence of attractive roots and to define new scientific
gus. However, is necessary to evaluate other vegetables. An alternative approaches to reducing epidermal loss. Samples were obtained from
is the green snap beans production. This vegetable can be harvested 42 N.C. farms. Survey field information and laboratory results were
during the last week of November,when, good prices aare available correlated to identify possible factors affecting the appearance of the
in the market. The objective of this experiment was to evaluate seven roots. 1300 roots were used to measure skin adhesion, peeling suscepti-
green snap beans varieties with round pod. The experiment was on 24 bility, skin moisture, skin anthocyanin and lignin content. From survey
Aug. The density used was 20 seeds per meter (about 60 kg·ha¯¹). The questions, 50 characteristics were defined for each sample, according
experiment was carried out during 2001 with commercial growers. to field characteristics, cultivar information, cultural practices and
The date of sow was distance between beds was 2.0 m and we used harvest and postharvest practices. Statistical analyses were performed
two rows with 36 cm of separation. In our experiment, we used a drip to determine the relationship between the skin characteristics analyzed
irrigation system. The first harvest was 67 days after the date sowing at the laboratory, and the survey descriptors information. Analysis of
and it was for 28 days with seven cuttings. The varieties with more yield variance was used for laboratory data analysis. Person correlations
were Festina, Mercury, and Castaño with 771, 632 and 558 boxes/ha, were made between survey variables and laboratory characteristics.
(30 pounds/box), respectively. The control variety (Savannah) yielded Several possible relationships between root appearance and other char-
only 345 boxes/ha. The pod quality distribution was 26%, 32%, 50%, acteristics/practices were identified. Root skin adhesion may improve
and 15% for classification 1, 2, 3, and no commercial value respec- in later generations from elite propagation material. Early application
tively. The Savannah variety was the best pod color (dark green) and of phosphate and potash fertilizers were correlated to improved root
more yield during the last cutting. None of the varieties evaluated had skin adhesion. There appeared to be a relationship between soil mois-
problems of pest and diseases. ture at harvest time, increased lignin content in the skin and peeling
susceptibility. Future areas of study were identified.
15 Irrigation Levels Affect Plant Growth and Fruit Yield of
Drip-Irrigated Bell Pepper 17 Environmental Stressors That May Influence Internal Heat
Juan C. Diaz-Perez*1, Darbie Granberry2, Kenneth Seebold3, David Necrosis in Potato Production in Northeast Florida
Giddings4, Denne Bertrand5 Christine M. Worthington*1, Chad M. Hutchinson2
1
Univ. of Georgia, Horticulture, Tifton, GA 31793-0748; 2Univ. of Georgia, Horticulture; 1
3 Univ. of Florida, Horticultural Sciences, Hastings, FL 32145; 2Univ. of Florida, Horticul-
Univ. of Georgia, Plant Pathology; 4Univ. of Georgia, Horticulture; 5Univ. of Georgia,
tural Sciences, Hastings, FlL, 32145
Horticulture
Bell pepper (Capsicum annum L.)plants have a high demand for water ʻAtlanticʼ potatoes (Solanum tuberosum L.) are grown on approximately
and nutrients and are sensitive to water stress during the establishment 8100 hectares with seepage irrigation in Northeast Floridaʼs Tri-County
period and fruit setting. High levels of irrigation are often applied Agricultural Area (St. Johns, Putnam, and Flagler counties). ʻAtlanticʼ
in order to maximize yields. However, field observations suggest is preferred for its chipping quality, high specific gravity and yield, but
that excessive irrigations may negatively affect bell pepper plants. is susceptible to internal heat necrosis (IHN), a physiologic disorder
The objective was to evaluate the effects of irrigation rate on plant that affects potato tuber quality. The relationships of environmental
growth and fruit yield. The trial was conducted in Spring 2003 at stressors (growing degree days, GDD and rainfall) to IHN were
the Coastal Plain Experiment Station, Tifton, Ga. Drip-irrigated bell evaluated on two fields (fields 3 and 4) on a local producerʼs farm.
pepper (ʻStilettoʼ) plants were grown on black plastic mulch in 1-m IHN reduced marketable tuber yield by 100% in the 1995 and 2003
wide beds (1.8-m centers). Plants were irrigated with an amount of seasons, but not in 2001 and 2002 seasons. From 3 to 6 weeks after
water that ranged from 33% to 167% the rate of evapotranspiration planting (WAP), GDD for 1995, 2001, 2002, and 2003 were 470, 325,
(ET), adjusted by crop stage of development. Soil moisture content 386, and 628 (45o F base), respectively. This is the only 4 week period
(% by volume) over the season was continuously monitored with during the 14 week season that GDD accumulation by week was dif-
time domain reflectometry sensors connected to a datalogger. The ferent among treatments. Average rainfalls (cm) for the same periods
results showed that the average soil moisture content for the season were 1.60, 1.12, 2.23 and 7.91, respectively. Both warmer/dryer and
increased with increasing rates of irrigation. Vegetative top fresh wt. warmer/wetter early season conditions occurred during seasons with
and marketable fruit yield were reduced at both, low (33% ET) and higher rates of IHN. Although circumstantial, higher accumulated heat
high (166% ET) rates of water application. However, irrigation rate units and water stress within the first 6 weeks of the growing season
had a stronger effect on fruit yield than on top fresh wt. Plants supplied resulted in higher percentages of tubers with IHN. These relationships
with high irrigation rates appeared to be more chlorotic compared to should be evaluated further with other growers.
plants irrigated at medium rates (100% ET). There was a tendency for
higher incidences of soil borne diseases (Pythium sp., Phytophtora 18 Weather Affects Seedless Watermelon Yield, But Not Fruit
capsici) in plants receiving higher rates of irrigation. The conclusion Size or Quality
is high irrigation rates (>166% ET) are not recommended since they
waste water and may result in both, higher incidences of soil-borne Timothy E. Elkner*1, David H. Johnson2
1
diseases and reduced bell pepper yields. Penn State Univ., Lancaster County Cooperative Extension, Lancaster, PA 17601; 2Penn
State Univ., Penn State Southeast Research and Extension Center, Manheim, PA 17545
Medium-sized triploid watermelons were evaluated in southeast Penn-
748 HORTSCIENCE, VOL. 39(4), JULY 2004
