1996USDA-ES Smith-Lever Competitive Grants Program
Continuing Projects for 1996
Reports for Projects that Ended in 1995
VEGETABLES AND ROW CROPS
Validation of insect degree-day models in vegetable and row crops.
Principal Investigators: M. Cahn, UC Cooperative Extension, Sutter-Yuba counties; C. Pickel, UC IPM Project, Sutter-Yuba counties
Objectives: Conduct a preliminary study to validate existing insect degree-day models in vegetable and row crops cultivated in Sutter and Yuba counties.
Evaluate sex pheromone traps for determining degree-day model biofixes.
Correlate degree-day models with insect development stages in the field.
Weed control by interseeding oats or berseem clover into alfalfa.
Principal Investigators: W.T. Lanini, Vegetable Crops, Davis; D. Putnam, Agronomy and Range Science, Davis
Objectives: Demonstrate the feasibility of planting oats or berseem clover as an alternative to herbicides in established alfalfa.
Demonstrate the yield advantages and species composition of the oat or berseem clover/alfalfa mixture.
Implementation of a disease warning system for downy mildew of lettuce.
Principal Investigators: K.V. Subbarao, Plant Pathology, Davis; A.H.C. van Bruggen, Plant Pathology, Davis
Objectives: Update and validate a previously developed infection model for lettuce downy mildew using observed weather and high-resolution weather forecasts.
Develop methods to automate the input, retrieval, and dissemination of observed and predicted weather and of downy mildew forecasts.
Implement an automated forecasting system.
WESTERN GRAPE LEAFHOPPER
Incorporating Anagrus parasitism in the monitoring guidelines for the western grape leafhopper.
Principal Investigators: L.G. Varela, UC IPM Project, Sonoma County, R.J. Smith, UC Cooperative Extension, Sonoma County
Objectives: Validate a model using first-brood egg density and egg parasitism to predict second brood nymphal density to determine the need for insecticide applications.
WALNUT HUSK FLY
Video production of the biology, monitoring, and control of walnut husk fly (Rhagoletis completa ).
Principal Investigators: W.H. Olson, UC Cooperative Extension, Butte County; C. Pickel, UC IPM Project, Sutter-Yuba counties
Objectives: Develop an educational video on biology, monitoring and control of Walnut Husk Fly (WHF). The goals of this 20-30 minute video would be to teach: WHF biology; proper monitoring techniques; proper trap design; proper trap placement; proper treatment timing; and proper spray coverage for control of WHF.
Implementation of a forecast model for powdery mildew of tomatoes.
Principal Investigator: R.M. Davis, Plant Pathology, Davis
Objectives: Validate and implement a model that forecasts tomato powdery mildew epidemics based on temperature, relative humidity, and duration of leaf wetness periods.
Encourage growers to adopt the model by providing field demonstrations and by comparing forecast-based control with calendar-based fungicide applications.
Reduction of hull rot disease of almond trees through irrigation management.
Principal Investigators: B.L. Teviotdale, Plant Pathology, Davis/Kearney Agricultural Center, Parlier; D. Goldhamer, Kearney Agricultural Center, Parlier
Objectives: Validate experimental evidence that hull rot disease of almond can be reduced by altering irrigation practices during early hull split.
Commercial implementation of biological control of fire blight disease of pear.
Principal Investigators: R. Elkins, UC Cooperative Extension, Lake County; S.E. Lindow, Plant Pathology, Davis
Situation: In 1995 a new commercial biological control product, Blight Ban A506reg. (Plant Health Technologies, Inc.), became available for control of fire blight (Erwinia amylovora) in California. Because adoption of this product will be determined largely by its early success or failure, researchers and extension personnel felt large-scale demonstration plots were necessary to properly train both growers and PCAs in its use. Trials were based on knowledge gained from almost 20 years of research experience, most recently a successful large-scale trial in 1994.
Highlights: Although weather did not affect fireblight infection, and the initial shipments of Blight Ban A506reg. were largely impotent, the project successfully taught growers, applicators and PCAs how to use the material properly. This includes mixing procedures, application timing, safety precautions and need for repeat treatments.
The project also allowed us to demonstrate the usefulness of the simple flower assay to determine the presence of the biological control in flowers. While the initial shipments of the biological control organism were of lower titre than the label required, PCAs and growers were impressed that the status of biological control in the orchard could be so quickly evaluated in order to allow them to make management decisions; the participating growers are thus all willing to participate in further implementation studies of this biological control.
Five growers, representing 900 acres, and four PCAs (out of five who actively practice in Lake County) were trained to use A506 properly. The current estimated adoption of this practice in 1996 is between 75 and 100% of local growers and PCAs, depending on amount of product available. Pesticide use (i.e., copper and antibiotics) will decrease modestly at first, but use will potentially decrease by 50% as confidence in biocontrol increases.
Because commercial product was withdrawn early in the season, field meetings were not held. However, project progress and results were reported and discussed at monthly PCA breakfasts and with cooperating growers. Results will be presented at the annual winter pear research meeting in Ukiah and are currently being summarized for trade and peer-review publications.
Growers and PCAs have trouble using IPM methods of pest control because they take more time than pesticide application alone and they require the user to understand the biologies of the pests and natural enemies. Our goal with this project has been to improve grower/PCA understanding of degree-day units to predict emergence of citrus cutworm larvae and armored scale crawlers so that growers can more effectively manage these pests and reduce broad-spectrum pesticide use. For example, degree-day units can be used to predict egg hatch of citrus cutworm. Because young larvae are more susceptible to selective microbial insecticides than older larvae, predicting egg hatch and careful timing of microbial applications would increase the effectiveness of these pesticides. Microbials do not kill natural enemies and their use for citrus cutworm control will preserve the natural enemies needed later in the season for citrus thrips and armored scale control.
Highlights: Our main goal in this first year of funding was to teach growers how to use a biofix and degree-day units to predict major events in the life cycle of citrus cutworm and California red scale. For citrus cutworm the first male flight helps the grower predict that egg hatch will occur approximately 100 degree-days later.
The current technology for temperature recorders in orchards requires downloading to a computer so we performed this service for the growers. The growers collected the moth flight data by placing one pheromone trap in each orchard and emptying it weekly from March 1 until June 30. We also collected larvae by beating 20 trees each week onto a beating sheet in each orchard to verify that our prediction of larval emergence was correct.
For California red scale, the first male flight is a predictor for crawler emergence 550 degree-days later. Cooperators collected the male scale on two pheromone cards in their orchards every week from March until November and monitored crawler activity on sticky tapes. Intense sampling by the grower/PCA helped them to make better decisions as to whether an orchard needed a pesticide treatment and when to apply that treatment. We worked with 11 cooperators on the cutworm monitoring and 12 cooperators for the California red scale monitoring. In addition, for educational materials, we faxed the information we were collecting to 102 people and sent newsletters to 375 people throughout the San Joaquin Valley. At all five of the field days and workshops we presented our data and stressed how the information could be used to improve management of the pests.
Many of our cooperators chose not to spray insecticides for citrus cutworm or California red scale this year based on their increased monitoring and knowledge of the insects in their orchards. We were working closely with a small core of cooperators, and believe that 2 to 3% of the growers and PCAs altered their practices based on the information and training we provided. Growers who were able to more carefully time pesticide treatments based on the program required fewer treatments for control. For many of our cooperators, degree-day units were a foreign concept. As the growers and PCAs become more comfortable with the concepts, they will gradually incorporate them into their decision making.
Highlights: The field meetings had three parts. First, the local farm advisor talked about local pest management using live samples. Then the growers examined natural enemies from the natural enemy collection with microscopes. Orchard monitoring demonstrations were given including how to use traps and a presence-absence sampling plan for mites. Lastly, once the growers mastered the technique of using a hand lens, they were sent out into the orchard to monitor for mites and to decide if a spray was necessary. Most growers did not leave until they had seen a twospotted mite and a predator mite. Handouts were provided. Live samples of beneficials from alfalfa fields were available for growers to learn how to identify common predators.
IPM in San Joaquin Valley cotton: Survey of arthropod fauna.
Principal Investigators: P.B. Goodell, UC IPM Project, Kearney Agricultural Center, Parlier; E.E. Grafton-Cardwell, Entomology, Riverside/Kearney Agricultural Center, Parlier
Situation: Cotton insect pest management has been well understood and IPM is considered well developed in San Joaquin Valley cotton. However, since approximately 1990, insect problems have resulted in an increased use of insecticides. This may be due to a number of factors: shift in cotton varieties; more aggressive pest management early season as a result of improved Lygus action thresholds; development of insecticide resistance in aphids and Lygus; shift to more pyrethoid insecticide use, especially early and mid-season for Lygus and aphid management.
In 1994, a wide area of the San Joaquin Valley suffered the worst insect pressure in 20 years, based on the reported insecticide use. In 1995, the situation continued to worsen. Insecticide use has gone from one to three applications during the mid-1980s, to four to five applications in the past 2 years. There is widespread concern that the cotton industry is getting back onto an insecticide treadmill. This concern is expressed by cotton producers, PCAs,m and agchem dealers. More dollars are being spent for insect pest control, which is adversely affecting the economic sustainability of the industry.
This project proposes to establish 16 sample sites located in Kern, Kings, Tulare, Fresno, Madera, and Merced counties that will be followed throughout the season. In addition to site selection based on geography, sites will be selected so that half are managed by PCAs who tend to use a calendar approach to pest management and half who use sampling and economic thresholds as a basis for pest management. Cooperators will include a diverse group of producers from conventional to organic. Baseline information about cotton producers and PCAs' attitudes about IPM will be compiled using a survey
Insect, mite, and plant data will be collected weekly as well as pesticide history. This information will provide substantiation for pest pressure during the year. The arthropod numbers will be reported at monthly cotton production meetings (May-July), through media outlets (Mite Fax), and through the toll-free hotline. Interpretation of the data to provide useful pest management information will be done by the PIs.
Highlights: The data set collected during the summer needs extensive analysis. It does provide a solid baseline for the arthropod population dynamics in 14 cotton fields throughout the San Joaquin Valley. We noted differences in the diversity of arthropod fauna through time and location. We noted very similar aphid flight patterns over a wide area. Weekly faxes were provided to cooperators and PCAs.
Information from these plots as well as general field observations were provided to over 1,500 growers, PCAs, and other cotton industry officials through 10 field production meetings. The total acreage that was impacted by these meetings is estimated at 500,000 acres. A one-page fact sheet on the management of late season aphid was provided to meetings and as a part of farm advisors' newsletters. Weekly updates were provided to Mite Fax (subscription list estimated at 1,200), a privately sponsored weekly providing overviews of the current insect pest situation. In addition, the Cotton Insect Hotline was maintained during this period with twice monthly updates.
The 1995 season was one of the roughest in memory. Beginning with Lygus outbreaks, aphids followed which required repeated applications of insecticides. Beet armyworms, cabbage loopers, and spider mites became important secondary pests and the latter caused as much damage in some areas as any cotton pest. The industry recognized that cotton production practices must change in order to return to less reliance on insecticides and to return to more IPM methods, especially indigenous biological control. This terrible pest situation has provided an unprecedented educational opportunity for IPM to be demonstrated to an entire generation.
The 1996 educational process will begin with a year-end review of 1995. It will consist of a facilitated workshop in which a consensus building process will strive to identify the key problems, the causal agents, and management guidelines to reflect the new reality of pest complexes. The participants will present an important team building process. From these meetings will come the recommended insect management guidelines for 1996 as well as research and extension priorities.
Developing a weed seed and seedling identification manual and an expert system for weed seed and seedling identification.
Principal Investigators: T.S. Prather, UC IPM Project, Kearney Agricultural Center, Parlier; R.F. Norris, Vegetable Crops, Davis; C.L. Elmore, Vegetable Crops, Davis
Situation: Weeds normally are controlled early in their life cycle, from the seed to early seedling stage. Development of monitoring programs, threshold models, and prescribing postemergent herbicides all require identification at these early stages to be most effective. Currently, there is no manual for California's weeds that focuses on the seed to seedling stages. Pest control advisers have expressed interest in seedling identification and welcome the idea of a new manual and computer identification program.
Highlights: The project has received 2 years of funding. Our training programs focus on hands-on identification of weed seedlings. These programs target growers and PCAs; this year we have trained 360 people statewide. We continue to photograph our seedlings, using UC Photographer Jack Clark's expertise. The quality of our slide set is excellent, and these slides will be incorporated into future training sessions. Our first year slide collection includes slides of 40 weed species at three stages of growth. In the second year we expanded that collection to 90. A working computer program will be completed this fall and added to as we collect more data. In addition, we continue to grow seedlings for use in educational programs in the coming year.
Implementation of a postharvest control strategy for codling moth in pears.
Principal Investigators: R.A. van Steenwyk, Environmental Science, Policy and Management, Berkeley; R.A. Duncan, UC Cooperative Extension, Sacramento County; W.O. Reil, UC Cooperative Extension, Yolo-Solano counties; S.C. Welter, Entomology, Berkeley
Situation: Codling moth (CM) is the key insect pest of pears. Control of CM in pears has relied on repeated applications of Guthion. Heavy reliance on Guthion has resulted in the development of Guthion-resistant CM and the outbreaks of a number of secondary pests, such as pear psylla and spider mites. These secondary pest outbreaks require additional insecticides for their control. Alternatives to the repeated use of insecticides for CM control must be found if pears are to remain an economically viable crop in California.
Pear harvest is completed from mid-July through mid-August. After harvest a large number of unharvested fruit remain on the trees. Since insecticide use is terminated 3 or more weeks before pear harvest is completed, the unharvested fruit allows for a rapid increase in the CM population. The majority of CM larvae that complete their development in the unharvested fruit before the end of July will enter the pupal stage and emerge as adults. However, larvae which complete their development in the unharvested fruit in early August will begin to enter diapause. Nearly all larvae that complete their development in the unharvested fruit by the end of August will enter diapause. If the postharvest population of CM can be suppressed before mid-August, then the diapausing population would be largely eliminated.
Highlights: This is the first year of a project to demonstrate to pear growers and PCAs the potential of postharvest CM control in suppressing next spring's overwintering flight. In the Suisun Valley, fruit removal is the most cost-effective means of postharvest CM control because of the open tree structure and low number of trees per acre (70 to 110 trees per acre) . Fruit removal cost was about $30 per acre. Fruit removal reduced the percentage of CM-infested fruit by over 90% as compared to the unstripped portions of the orchards. Next spring CM overwintering flight will be monitored in the stripped and unstripped portions of the orchards with an anticipated reduction of 50 to 75% in moth flight by the stripping treatment. Pear growers and PCAs who attended our field demonstration meetings were impressed by reduced CM infestation in stripped portion of the orchards. If the overwintering moth flight is reduced by 50 to 75% next spring, then fruit removal should be widely adapted next year.
In the Sacramento Delta, an insecticide application is the most cost-effective means of postharvest CM control because of the closed tree structure and high number of trees per acre (150 to 300 trees per acre). Insecticide application cost was about $45 per acre. Postharvest insecticide treatments suppressed CM infestation but treatments were applied too late to eliminate infestation. Insecticide treatments were applied about 1 week after the beginning of egg hatch of the second peak of the second CM flight. The delay in insecticide applications was the result of the late registration of Lorsban (August 3) and the late harvest completion date (August1 to 8) in relation to the CM flight. Lorsban was the insecticide of choice because Lorsban exhibits negatively correlated cross-resistance to Guthion-resistant CM.
Grower acceptance of the postharvest insecticide application was tremendous, with over 500 acres of pears treated with Lorsban. A large number of growers treated their entire acreage with Lorsban and it was difficult to find growers willing to leave 20 acres untreated for our comparisons. Six pear growers (those willing to leave 20 acres untreated) and all but one PCA in the Sacramento Delta directly participated in our demonstration project.
Next spring, the CM overwintering flight will be monitored in both the treated and untreated portions of the orchards. If the overwintering flight is suppressed by the treatment, then next year most of the pear acreage in the Sacramento delta should be treated postharvest with Lorsban.
Implementation of an IPM scouting system in ornamental crops in California.
Establishment of a regional network for weather monitoring/disease risk assessment for grapes.
Principal Investigator: D. Gubler, Plant Pathology, Davis
Situation: Grape powdery mildew and Botrytis bunch rot are serious diseases of grape. Fungicide programs have not been effective in most cases because of poor timing of applications. Risk assessment models allow for better timed fungicide applications and therefore better disease control.
Highlights: An environmental monitoring system coupled with disease risk assessment models for grapevine powdery mildew and Botrytis bunch rot of grape was established in 22 vineyards in Napa County, 7 vineyards in Sonoma County, and 14 vineyards in Kern County. In addition, two private systems covering 14 vineyards in Mendocino and Napa counties were installed.
Weather monitoring equipment was purchased from Adcon Telemetry using funding from UC IPM. Equipment consisted of a base station which was placed in UC Extension offices in Napa, Sonoma, and Kern counties. Grape growers in each county were asked to contribute to the project by purchasing field monitoring equipment which transmitted environmental data to the base station via radio telemetry. Individual growers then retrieved weather data directly from the base station by modem.
Disease risk assessment models developed at UC Davis Plant Pathology for powdery mildew and Botrytis bunch rot were incorporated using Adcon software which could interact with weather data to allow growers to make educated decisions on whether to apply fungicides for each disease. The powdery mildew model is based on pathogen biology rather than disease increase though the later is a direct function of the former. Powdery mildew epidemics have been documented to occur when temperatures in the range of 70° to 85°F occur for 6 or more hours for 3 consecutive days. The temperatures allow for pathogen reproduction at 5-day intervals thus resulting in extreme disease pressure. The risk assessment model simply records 20 points for each day when conducive weather occurs. When the index reaches 60 to 100, growers shorten fungicide application intervals. When temperatures are not conducive, the model subtracts 10 points, when the index is 0 to 30, growers were asked to stretch spray intervals. On the day of application, growers enter the information into their PC. This zeroes the index and takes into account the normal intervals for the product used, i.e., sulfur dust 7 to 10 days, sulfur df 14 days, or DMI 17 to 21 days. Depending on temperatures, the model then will keep the intervals as they are or will allow growers to stretch dust to 14 days, sulfur df to 17 days, or DMI to 21 or more days.
The Botrytis model predicts infection periods based on leaf wetness duration at given temperatures, which will allow growers to spray only when needed.
Results in 1995 showed clearly that regional weather networks can function to aid grape growers in decision making regarding fungicide applications. In 12 vineyards where fungicides were applied for powdery mildew according to the model vs. a standard program, the model saved two to three applications and resulted in better disease control in every case. Table grape growers did not want to trust the model this year but after using it they have assured us that it will be used in 1996. The Botrytis model was validated in three vineyards in 1995 with success and we anticipate greater adoption in 1996.
Trials were established in Watsonville, Oxnard, and the Southcoast Field Station to evaluate treatments aimed at eradicating overwintering inoculum and effects on delaying disease onset. Treatments were: (1) pre-plant dip using the DMI fungicide Rally; (2) removing all green tissue from transplants; (3) maintaining a disease-free nursery. These treatments were compared to a control treatment. All treatments used plants obtained from a heavily diseased nursery plot. Plants were planted in treatment blocks at each site and monitored for disease onset.
Results showed clearly that disease onset was delayed for 4 to 8 weeks when plants were maintained disease-free, or when plants were treated with Rally before planting, or when contaminated tissue was removed prior to planting. Disease increase was slowed in treatment plots and occurred only as contamination from adjacent nontreated plots.
Using clean plants in fruit production fields may result in the saving of 2 to 3 fungicide applications for the control of strawberry powdery mildew simply by delaying the onset of disease.
Demonstration of integrated pest management concepts for fly inspectors and other regulatory personnel.
Principal Investigator: N.C. Hinkle, Entomology, Riverside
Situation: The state of California has over 26 million caged laying hens, making it the number 1 egg-producing state in the country. The six counties having the highest numbers of caged layers (Riverside, San Diego, San Bernardino, Stanislaus, San Joaquin and Merced) account for over 90% of the state's production. With encroaching urbanization, many of these egg ranches are experiencing increasingly severe regulatory constraints, especially regarding nuisance flies. Both county health departments and vector control districts have jurisdiction over these facilities. Unfortunately, many of the inspectors have no background in biology and little appreciation for integrated pest management concepts.
In order to encourage producers to use cultural techniques that are compatible with existing biological controls and minimize pesticide usage, we recognized the necessity of including fly inspectors in the equation, to ensure that their recommendations did not conflict with the poultrymen's IPM strategies. By providing inspectors with background and appreciation of the various IPM components, we drew them in as participants in developing mechanisms for managing pest fly populations.
Highlights: The scheduling of this project was particularly timely in that this year the California Egg Quality Assurance Program initiated its Vector Control and Biosecurity component, emphasizing suppression of arthropod pests in egg production facilities. In addition to the targeted poultry producers, these sessions were well-attended by representatives from vector control districts and county health departments, thus reinforcing the training they had received at the Smith-Lever sponsored events.
Implementation of a complete mating disruption program for oriental fruit moth and peach twig borer in cling peaches.
Principal Investigators: C. Pickel, UC IPM Project, Sutter-Yuba counties; J.K.Hasey, UC Cooperative Extension, Sutter-Yuba counties; W.H. Olson, UC Cooperative Extension, Butte County
Situation: There are two key insect pests in the cling peach orchard system, oriental fruit moth (OFM) and peach twig borer (PTB). Commercial products for controlling OFM have been available since 1989. About one-third of the growers have been using OFM pheromone for control but the number of growers using the program has not expanded much because they still had to spray for PTB. In 1995 the first commercial PTB pheromone product became available.
Highlights: This is the first year of this project. There were 16 cooperators: 10 in Sutter/Yuba and 6 in Butte counties with 155 acres in the program. The funding helped purchase PTB pheromone for the cooperators to keep the costs comparable to a standard spray program. Growers kept track of application costs, which ranged from $7 to $24 per acre per application. This provides the opportunity to help growers with high application costs to lower them. Growers with a paired grower standard keep records on applications of sprays in that standard to compare with costs of using mating disruption; this data is still being collected. Growers in the program represent 1000 acres and would like to use the program on more acres, once they know it works. They represent about 10% of the cling peach acreage in this region, with a potential reduction of 1900 a.i. lbs of insecticides. This program is now going to expand to other cling peach growing areas in the state with a $35,000 grant to the Cling Peach Advisory Board by the EPA.
Host status of plant species to parasitic nematodes: development and release of a PC and Mac database.
Principal Investigators: B.B. Westerdahl, Nematology, Davis; H. Ferris, Nematology, Davis; E. P. Caswell-Chen Nematology, Davis; R. Sloan, Nematology, Davis
Situation: Nematode management for economically important crops has been centered on the use of nematicides for more than 40 years. Alternative management of plant-parasitic nematodes requires combinations of tactics including selection and temporal and spatial arrangement of crop-plant or cover-crop species and cultivars to reduce nematode numbers and damage. Information regarding the host status of plants to many nematode species is available in the literature; however, a current, accessible compilation of the qualitative and quantitative information on nematode-plant interactions is not available.
Highlights: We have been developing the database, using support from a variety of funding sources, since 1991. As of October 1995, there are 38,682 records from 96 countries. The entries include information on 6,140 plant taxa identified at the genus, species, or variety level and 801 nematode taxa identified at the genus, species, or race level. That information has been extracted from 4,747 articles published over the last 90 years in six journals that deal primarily with plant-parasitic nematodes and in widespread reports assembled in earlier compilations of host records. The extractions are not yet complete and there are data in several other important sources that need to be assembled. We currently estimate that 50% of the available data has been extracted from the available literature.
Assisted by a professional programmer, we have developed a "user-friendly" FoxPro interface with the database for PC users. The database allows selection of nonhost crops and determination of the availability of resistant cultivars for species and races of plant-parasitic nematodes. It allows selection of cover crops that are nonhosts to resident plant-parasitic nematode populations. It provides capabilities of rapid search of the available knowledge base for novel species of crops or cover crops that warrant testing in a cropping systems in relation to their effect on resident nematode populations. Customized screens allow the user to search for host status, resistance or damage levels by crop or crop type, and by nematode species or group of species. The screens also allow the user to establish filter conditions for host status, plant susceptibility and tolerance, geographic region, climate and soil texture conditions, study site, date of report, and data quality.
Nemabase Version 1 is in final testing by UC IPM staff prior to release. Initial advertising has been done by distribution of brochures during demonstrations of the database at national and local meetings. A considerable number of requests have already been made. We plan to continue development of the database, depending on our success in soliciting funds, with periodic update releases.