Entomology
and Integrated Pest Management |
Program Description - John Palumbo
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My role as vegetable
entomologist at the Yuma Agricultural Center is through a split
appointment (70% research, 30% extension) with responsibility for
developing a vigorous, contemporary research program on the biology
and management of arthropods associated with leafy vegetables and
melons . The position was created in 1990 in response to needs for
applied research on local insect problems associated with desert
vegetable production. Because of the magnitude of the industry in
Arizona, and the increasing economic burden and environmental uncertainty
associated with pesticide use, my research and extension programs
are primarily focused on integrated pest management.
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Most
of my efforts have focused on investigating ways to minimize pest
damage and reduce pesticide use without sacrificing crop quality and
productivity. My objectives have been to accomplish this from a fundamental
approach by gaining a better understanding of insect ecology &
insect-crop interactions, and from a more practical approach by developing
methods to optimize the use of new insecticide chemistries and application
technologies. |
The
goal of my research/extension program is to gain a fundamental understanding
of insect ecology and apply this knowledge to the development of innovative
pest management strategies in vegetable cropping systems. I have ongoing
projects to investigate insect-crop interactions, both in the field
and laboratory. The goal of this work is to determine the relationships
between insect feeding and plant injury. In particular, I have focused
my work on the impact of silverleaf whitefly, Bemisia argentifolii
on the growth, yield and quality of leafy vegetables and melons. This
information provides insight into the basic interactions occurring
between plants and insects, and has been used to develop action thresholds
and other control decision guidelines to assist growers with insect
management activities. |
I
have also concentrated my efforts on examining ways to monitor and
sample insects on vegetable crops. The goal of this work is to quantify
and statistically describe spatial distribution patterns of insect
populations for the development of sampling protocols that provide
precise estimates of species abundance for use in ecological research.
Ultimately, my goal is to develop practical and reliable sampling
plans that provide an assessment of pest status for the effective
utilization of control tactics in pest management programs. We have
recently developed and validated a presence/absence sampling plan
that is used in our research activities and by growers in commercial
melon crops. |
I
have a significant interest in examining the chemical management of
insects and investigating techniques to better utilize pesticides
in crop production. I have focused my efforts on several insect species
found on leafy vegetables and melons such as cabbage looper, beet
armyworm, Liriomyza leafminers, silverleaf whitefly, green
peach aphid and western flower thrips. My goals are to optimize pesticide
performance by gaining a better understanding of insecticide chemistries
and their interactions with the target pest and cropping system. We
continually evaluate chemistries with new modes of action, as well
as investigate alternative uses for existing insecticides and biological
control tactics. Additionally, I am examining ways to reduce pesticide
use with new pesticide application technology designed to improve
spray coverage and deposition. |
My
goals in extension have been to provide empirically-based information
on the management of insect populations in vegetable crops that can
be directly applied by growers throughout Arizona. My extension efforts
have been closely associated with my research program and are usually
initiated in response to serious insect problems occurring in local
cropping systems. I also serve as state IPM coordinator and the IR-4
liason representative for Arizona. |
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Program Description
- David L. Kerns |
I am an Integrated Pest
Management Specialist housed at the Yuma Valley Agricultural Center,
with a 70% extension, 30% research appointment. This position was
created in 1994 in response for the need for IPM expertise in leafy
vegetables, cole crops and citrus production in western Arizona. My
role in this position is to generate and disseminate research-based
information in the area of IPM of insect pests to growers and pest
control advisors. |
Research |
In vegetables, much of
my research efforts have focused on the monitoring and management
of insecticide resistance. Over the past three years, in response
to insecticide control failures, I have invested considerable effort
investigating carbamate resistance in beet armyworm, Spodoptera
exigua in Arizona and southern California. Most of this research
centered on documenting resistance and developing resistance management
strategies. I also have an active program collecting baseline toxicity
data for new and old insecticide chemistries to cabbage loopers, Trichoplusia
ni. This program is less regionally based and involves looper
populations collected from various locations throughout the United
States. This program is designed to identify areas where insecticide
resistance exists, to identify which insecticides resistance is mostly
likely to develop, and to collect historical susceptibility data for
resistance monitoring and future reference. In addition to lepidopterous
pests, I have conducted insecticide resistance studies with green
peach aphid, Myzus persicae. |
In vegetables, I have
also expended considerable effort in characterizing the activity of
insecticides, and how they best fit into IPM systems in Arizona. Within
this area, I have evaluated insecticides for their residual activity
in lettuce towards beet armyworm and cabbage looper. Additionally,
I have been evaluating techniques for managing multi-pest complexes
utilizing biorational insecticides, and their impacts on non-target
insects. |
In citrus, my research
has focused on developing an action thresholds for citrus thrips,
Scirtothrips citri, based on the interaction with fruit size.
The goal of this work is to better characterize at what thrips population
density insecticide treatments should be initiated based on the size
and susceptibility of the fruit to scarring. By doing so, I hope to
reduce the number of insecticide applications required to produce
a high quality crop, and thus save the grower from unnecessary expenses.
I also have significant interest in developing sound citrus thrips
management programs based on the most efficient rotations of conventional
and biorational insecticides, and developing these rotation schemes
into economically feasible programs for Arizona growers. |
Additionally, I have been
active in developing management strategies for minor and secondary
pests of Arizona citrus, including citrus peel miner, Maramara
salictella, woolly whitefly, Aleurothrixus floccosus and
citrus mealybug, Planococcus citri. Within these pest areas,
I have been active in evaluating sampling techniques, chemical and
biological control strategies. |
Extension |
My extension efforts have
concentrated on the delivery of information to growers and pest control
advisors through meetings, field days and workshops, and through the
publication and distribution of various informational bulletins, guidelines,
and the utilization of various University of Arizona research publications.
I have also developed a web site for the rapid dissemination of information
concerning vegetable disease, weed and insect pest activity in Yuma
County, and current vegetable research updates. |
Future extension goals
include the development and implementation of a IPM Vegetable Crop
Certification Program in cooperation with the Arizona Department of
Agriculture. This program will allow growers the opportunity to produce
and market vegetables using set guidelines that would qualify that
crop to be certified as being grown using IPM practices. |
Plant
Pathology |
Program Description
- Mike Matheron |
My research program is
focused primarily on the biology of fungal plant pathogens and the
ecology and management of economically important diseases of fruit
and nut trees, vegetable and certain field crops that occur in Arizona.
The primary goal of this research is to develop new or improve upon
existing practical solutions for plant disease problems confronting
growers in Arizona. |
Two fungal pathogens of citrus are responsible
for yield losses as well as death of infected trees. One of these pathogens,
Phytophthora, is a soil-borne fungus that infects and destroys
root and trunk tissue of citrus trees. Effective disease management
strategies have been developed for root rot and gummosis caused by Phytophthora.
On the other hand, Coniophora infects the above-ground portions
of lemon trees, colonizing and destroying wood tissue. This disease
has reached epidemic levels in mature lemon groves in southwestern Arizona.
Effective management approaches for Coniophora brown wood have not yet
been developed; therefore, a major research effort is directed at studying
the biology of the pathogen and the ecology of disease development,
so that effective disease control strategies can be formulated. |
Several diseases caused
by plant pathogenic fungi effect the vegetable industry in Arizona.
Downy mildews are important diseases on broccoli, cabbage, cauliflower,
lettuce and onions. Powdery mildews can cause significant yield losses
on lettuce and melons. Sclerotinia leaf drop is a significant disease
problem on lettuce in Arizona and essentially everywhere this crop
is grown. The severity of these diseases is greatly influenced by
the environment. Downy mildews and Sclerotinia leaf drop are enhanced
by cool moist conditions, whereas powdery mildews are favored by a
dry and relatively warm environment. Effective management of these
diseases caused by fungi involves the integrated use of host resistance
as well as cultural and chemical disease control approaches. The use
of fungicides is and will likely continue to be an important component
of the total disease management tool kit. Many new fungicides are
being developed with novel modes of action and with a reduced risk
toxicological profile to nontarget organisms. I conduct a comprehensive
field testing program each year to compare the efficacy of these new
chemistries to established fungicides and to establish effective rates
and application sequences on lettuce, broccoli and cantaloupes. |
Nonchemical disease management studies
are also in progress. One of these investigations involves the analysis
of soil conditions that will promote rapid destruction of the overseasoning
sclerotia of the fungi that cause Sclerotinia leaf drop of lettuce.
In another long-term experiment, the world peanut collection is being
examined to discover potential resistance in this plant to preharvest
aflatoxin contamination, a costly and serious food safety problem confronting
peanut producers and consumers around the world. |
The intent of my outreach
activities is to develop and deliver educational programming pertaining
to plant diseases and their management to clientele in Arizona as
well as to a broader worldwide audience. Effective control of any
plant disease involves the development and use of an integrated disease
management system. The components of disease management systems are
developed from my research as well as information from other sources. |
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Plant
Science |
Program Description
Glenn C. Wright |
My role as extension specialist at the
Yuma Agriculture Center is through a split appointment (60% extension,
40% research) with responsibility for developing an externally funded
applied research and extension program centered on fruit crop physiology,
chiefly with citrus. My position has existed in Yuma since 1935, and
I am the fourth person to occupy it. Because citrus can be grown in
six Arizona counties (trees are found as far east as Tucson and as far
north as Bullhead City), and the commercial industry is found in four
counties, my position has state-wide responsibility. I also conduct
some research in the California desert citrus growing areas. |
Some of my cooperative work has focused
on investigating ways to improve irrigation and fertilization efficiency
while not sacrificing citrus yield or quality. These projects have included
the use of low volume irrigation systems, in contrast to the traditional
flood, and the application of nitrogen through those irrigation systems
in accordance with "Best Management Practices". Other related
projects have included a determination of the ways to improve the application
efficiency of flood irrigation through the use of soil moisture deficit
data. Also, I am testing foliar slow release nitrogen fertilizers that
may lead to more efficient nitrogen application |
I am also investigating cultural practices
that may be used in improve citrus fruit packout. Packout refers to
the combination of fruit size and quality that leads to the best grower
return. In two separate studies, I am researching the effect of potassium
applications on citrus fruit yields and quality. Plant growth regulators
and citrus tree girdling are two additional cultural practices that
I am investigating. Several of my projects involve orchard floor management.
Together with cooperators, I investigate how traditional disking, non-traditional
cultivation methods and clean culture with herbicides affects plant
growth, water usage, fruit yield and quality, and weed population dynamics.
We are also investigating the effects of clover cover crops on the above
parameters. |
I have also concentrated
my efforts on citrus scion and rootstock evaluation and breeding.
Some cultivars that are commonly grown in other citrus growing areas
of the US do not perform well in the desert Southwest. Additionally,
the Arizona citrus industrys reliance on lemons necessitates
a continual search for new lemon cultivars and rootstocks that are
compatible with lemon. One major study involves the search for a rootstock
that is resistant to brown heartwood rot fungus, Coniophora eremophila.
In this work, we wish to determine why some rootstocks appear to be
more susceptible to fungal invasion than do others. |
My
breeding work also is aimed toward developing new citrus scions or rootstocks
that are compatible with lemon. I also evaluate new deciduous stone
fruit and blackberry cultivars for their suitability to the climate
of the low deserts of southern Arizona. |
My
extension work involves education, chiefly in regards to citrus. I speak
to commercial growers, master gardeners and homeowners regarding citrus
in several locations across the state annually. Additionally, I write
for the local newspaper and appear occasionally on television. Also,
I edit the Arizona Citrus Newsletter, a quarterly publication that is
now on the World Wide Web at http://ag.arizona.edu/aes/yuma-mesa/ |

Potted citrus rootstock
seedlings.
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Spraying K and Bin a attempt to reduce granulation
in navel orange. |
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Spiral girdle around young lemon trunk. |

Lemons under clean culture.
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Lemons infected with brown Heart wood rot. |
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Lemon rotstock trial. |

Young lemon in irrigation trial. |
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Valencia oranges under clover and native weed cover
crop. |
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Color formation in lemon retarded by application of
GA. |
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Soil
& Water |
Program
Description - Charles A. Sanchez |
The
primary objective of this program is to improve fertilization and irrigation
efficiencies for vegetables and citrus produced in the southwest desert.
Work involves evaluation of soil testing and tissue testing as diagnostic
tools for predicting and assessing the fertilizer requirements of vegetables.
Both traditional laboratory test and quick test are being evaluated.
We have also evaluated various reflectance technologies, including digital
analysis of aerial photographs. |
Research
also involves evaluation of fertilizer placement, timing and use of
controlled release fertilizers as "Best Management Practices"
for vegetables. Work is being conducted to evaluate irrigation management
practices and fertilization and irrigation combination which minimize
nitrate leaching and optimize crop yield and quality. Studies
are also being conducted to develop effective salt management strategies
for desert vegetables. |

Field plots used in N management
Experiments with vegetables.
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Manifold system utilized in drip irrigation experiments. |
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Collection of soil solution sample from an experiment
evaluating irrigation and N rate combinations on a
sandy soil. |

Irrigation study on young citrus evaluating slope and
head to border ratios on water application, efficiency
and uniformity.
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Evaluation of a pressurized system on young citrus. |
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Development of efficent flood irrigation practices
for citrus. |

Soil analysis in laboratory
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