Electromagnetic induction surveys
THE UNIVERSITY OF ARIZONA
COLLEGE OF AGRICULTURE AND LIFE SCIENCE
Entomology and Integrated Pest Management  Plant Pathology  Plant Science

Soil & Water

Irrigation & Water Quality

 

Entomology and Integrated Pest Management

Program Description - John Palumbo

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.

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.

Melons grown under drip
Melons grown under drip irrigation.

  Whitefly damage on melons.
Whitefly damage on melons.
  Whitefly nymphs on melon leaf.
Whitefly nymphs on melon leaf.
Impact of whitefly feeding in fall melons.
Impact of whitefly feeding in fall melons.

 

  Spray deposition on melons
Spray deposition on melons
  Applying imidacloprid to lettuce ( preplant).
Applying imidacloprid to lettuce ( preplant).
Pelleted lettuce seed on shaped bed.
Pelleted lettuce seed on shaped bed.

 

  Whitefly nymphs on lettuce.
Whitefly nymphs on lettuce.
  Whitefly nymphs on lettuce.
Whitefly nymphs on lettuce.
Effect of whitefly feeding on lettuce.
Effect of whitefly feeding on lettuce.

 

  Yellow sticky trap on lettuce.
Yellow sticky trap on lettuce.
  Sampling lettuce for lepidopterous larvae.
Sampling lettuce for lepidopterous larvae.

 

Beet armyworm feeding on lettuce.
Beet armyworm feeding on lettuce.

 

  Spraying insecticide on broccoli.
Spraying insecticide on broccoli.
  Effect on whitefly feeding on cauliflower.
Effect on whitefly feeding on cauliflower.

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.

Lettuce drop
Lettuce drop

 

Downy mildew on lettuce.
Downy mildew on lettuce.
Downy mildew on broccoli.
Downy mildew on broccoli.
Cantaloupe powdery mildew.
Cantaloupe powdery mildew.

 

Phytophthora on chile pepper.
Phytophthora on chile pepper.
P. parasitica on sweet orange Yuma Dogwood tree.
P. parasitica on sweet orange Yuma Dogwood tree.
Coniophora brown
Coniophora brown
(wood root).

 

Ganoderma.
Ganoderma.
Drip Irrigation with constant moisture under tree.
Drip Irrigation with constant moisture under tree.
Hendersonula on citrus.
Hendersonula on citrus.
Pistachio severe septoria leaf spot.
Pistachio severe septoria leaf spot.

 
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 industry’s 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.

Potted citrus rootstock seedlings.

 

  Spraying K and Bin a attempt to reduce granulation in navel orange.

Spraying K and Bin a attempt to reduce granulation in navel orange.

  Spiral girdle around young lemon trunk.

Spiral girdle around young lemon trunk.

Lemons under clean culture.

Lemons under clean culture.

 

  Lemons infected with brown Heart wood rot.

Lemons infected with brown Heart wood rot.

  Lemon rotstock  trial.

Lemon rotstock  trial.

Young lemon in irrigation trial.

Young lemon in irrigation trial.

  Valencia oranges under clover and native weed cover crop

Valencia oranges under clover and native weed cover crop.

   Color formation in lemon retarded by application of GA.

Color formation in lemon retarded by application of GA.

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.

Field plots used in N management Experiments with vegetables.

 

Manifold system utilized in drip irrigation experiments.

Manifold system utilized in drip irrigation experiments.

Collection of soil solution sample from an experiment evaluating irrigation and N rate combinations  on a sandy soil.

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.

Irrigation study on young citrus evaluating slope and head to border ratios on water application,  efficiency and uniformity.

 

Evaluation of a pressurized system on young citrus.

Evaluation of a pressurized system on young citrus.

Development of efficent flood irrigation practices for citrus.

Development of efficent flood irrigation practices for citrus.

Soil analysis in laboratory

Soil analysis in laboratory