1997USDA-ES Smith-Lever Competitive Grants Program
USDA-ES Smith-Lever Competitive Grants Program
Training on the biology, monitoring and control of walnut husk fly.
Principal Investigators: W. H. Olson, UC Cooperative Extension, Butte County; C. Pickel, UC IPM Project, Sutter/Yuba counties; S. Opp, CSU, Hayward
Objectives: Encourage clientele to adopt an IPM approach to walnut husk fly control by showing the Smith-Lever IPM video on Walnut Husk Fly Biology, Monitoring, and Control at Cooperative Extension meetings, conducting regional summer field meetings to demonstrate the techniques used in the video, and selecting regional demonstration plots to show the validity of the techniques illustrated in the video.
Develop a video evaluation form to document the video's usefulness
and provide each major walnut growing Cooperative Extension office
and IPM advisor with a complimentary copy of the video.
UC Davis risk assessment model for powdery mildew control in grapevines.
Principal Investigator: S. Gubler, Plant Pathology, Davis
Objectives: Promote the UC Davis Risk Assessment Model within the
Clarksburg wine grape growing group. Compare two blocks, one spraying
according to the growers' normal practice and one spraying within the
parameters of the model.
Biorational peach orchard systems.
Principal Investigators: J. Hasey, UC Cooperative Extension, Sutter/Yuba counties; C. Pickel, UC IPM Project, Sutter/Yuba counties; W. H. Olson, UC Cooperative Extension, Butte County
Objectives: Implement a Biorational Program for Peaches to Reduce
Pesticides in the Sacramento Valley and further involve PCAs in the
Pest management training for landscapers, nursery, and turf personnel.
Principal Investigator: C. A. Wilen, UC IPM Project, San Diego County
Objectives: Provide training/refresher lessons to pesticide applicators and PCAs to calibrate sprayers for pesticide application in landscapes (including turf), greenhouses, and container nurseries.
Demonstrate methods used to apply biocontrols in landscapes
(including turf), greenhouses, and container nurseries and how to
evaluate their effectiveness.
UC workshop on compost use for pest management in agriculture.
Principal Investigators: M. E. Grebus, Plant Pathology, Riverside; C. A. Wilen, UC IPM Project, San Diego County
Objectives: Train farm advisors in use and misuse of composts and the composting process for pest management in field, greenhouse, and nursery crops.
Demonstrate methods to assay composts for presence of pathogens and weeds, or for characteristics that may cause abiotic disorders.
Demonstrate how to assay composts for pest suppressiveness.
Development of a bilingual didactic and demonstration program in urban integrated pest management.
Principal Investigator: J. Klotz, Entomology, Riverside
Objectives: Translate into Spanish some of the UC DANR Pest Notes produced by the UC IPM Project relevant to urban pest control.
Develop a prototype Urban Pest Ant Kit consisting of slides, a
narrative, and samples of the common ant pests.
Evaluation of no-till tomato production systems.
Principal Investigator: J. Mitchell, Vegetable Crops, Davis/Kearney Agricultural Center, Parlier
Objectives: Evaluate the effectiveness of surface organic mulches
in reduced-tillage tomato production systems for suppressing weeds,
improving production efficiencies in terms of nutrient inputs,
providing optimal soil temperature regimes for crop growth, and
conserving soil moisture.
A comprehensive outreach program on integrated nutsedge management.
Principal Investigators: M. McGiffen, Botany and Plant Sciences, UC Riverside; D. Cudney, Botany and Plant Sciences, UC Riverside
Objectives: Compare and validate alternatives for nutsedge management.
Disseminate findings through field days, a day-long workshop on nutsedge management, newsletters, and nutsedge management guides for each commodity group.
Evaluate the success of the project with clientele surveys at the start and end of the project.
Encourage linkage among programs and institutions, including
participants from Cooperative Extension at UC Riverside, several
county offices, the UC IPM and Small Farms programs, PAPA, CAPCA, and
agricultural products companies.
Demonstrating weed management of yellow starthistle in Sierra foothill range and pasture.
Principal Investigators: T. S. Prather, UC IPM Project, Kearney Agricultural Center, Parlier; W. Johnson, UC Cooperative Extension, Mariposa County
Objectives: Evaluate mowing, herbicide efficacy, and competitive mulches in starthistle management.
Provide growers in the Sierra foothills with information to
develop their own management strategies.
Biological Integrated Vineyard Systems (BIVS) in the central San Joaquin Valley.
Principal Investigator: M. J. Costello, UC Cooperative Extension, Fresno County
Objectives: Encourage production systems that replace inputs
disruptive to nontarget organisms or cause off-site contamination, by
using a "Biologically Integrated Vineyard Systems" (BIVS) approach.
The five main goals of BIVS are to establish a support network for
grower participants, establish an advisory team to help guide the
grower participants, establish a set of guidelines and goals for each
grower participant, monitor pests and natural enemies and estimate
yield and quality on acreage set aside under the BIVS program, and
demonstrate BIVS systems through field days.
Proper timing and growth form for the successful control of yellow starthistle using mowing.
Principal Investigator: J. M. DiTomaso, Vegetable Crops, Davis
Objectives: Demonstrate how to use mowing as an effective control strategy for yellow starthistle through proper timing and an understanding of the appropriate growth form.
Demonstrate the successful application of mowing, based on our
recent findings, in several heavily infested counties where this
technique is a practical and economic alternative to herbicide
Grower training for implementation of intensive vegetable crop farming systems using reflective mulches for virus disease management.
Principal Investigator: J. J. Stapleton, UC IPM Project, Kearney Agricultural Center, Parlier
Objectives: Plan, develop, and conduct an intensive, hands-on
short course and field demonstration of vegetable farming systems
employing plastic mulch and drip irrigation in the San Joaquin Valley
for producers wishing to use reflective mulches for virus and insect
management but not having experience sufficient to successfully adapt
the technology to their particular needs and conditions.
Validation of the monitoring system for timing fungicide applications to control shot hole disease of almond.
Principal Investigator: B. L. Teviotdale, Plant Pathology, Davis/Kearney Agricultural Center, Parlier
Objectives: Test the monitoring system used to determine need for fungicide treatment to control shot hole disease of almond.
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
Highlights: This is the fourth year the downy mildew disease
warning system based on morning leaf wetness duration (LWD) was
applied in commercial fields. At first it was based on observed LWD,
then we changed to predicted dew with mesoscale weather forecasts and
high-resolution weather forecasts. Now it can also deal with leaf
wetness from causes other than dew, such as rain or heavy fog. All
four years' results showed that the potential reduction in fungicide
spray frequency is 50% or more compared with conventional,
calendar-based schedules, especially in seasons with dry weather.
Clearly, a grower who uses fewer pesticide sprays to attain lettuce
yield and quality equivalent to conventional spray programs would
save money and be a stronger economic competitor.
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
Highlights: Hull rot disease of almond is caused by the fungi Monilinia fructicola and Rhizopus stolonifer. Infection occurs just before harvest during hull split when pathogen spores enter the almond fruit through the open suture. The ensuing infection causes a lesion on the hull and produces a toxin that is transported from the hull into the subtending spur and leaves. The nutmeat is not harmed but loss of fruiting wood compromises future yields. Many fruit attached to shoots and spurs killed by hull rot do not fall and become potential sites for overwintering navel orangeworm (Amelyosis transitella). Fungicides are not registered for control of almond hull rot and none are likely to be approved given the difficulty in reaching the target infection. Cultural practices are the only options available.
Recent investigations on the effects of deficit irrigation schemes
on hull rot and yield of almond trees showed that reducing the amount
of water applied for 2 weeks during early hull split substantially
lowered the incidence of hull rot without reducing yield. But in all
these previous experiments the inception and duration of the deficit
irrigation period was calendar-based. This was the first time we
attempted to use plant measurements to determine the onset (early
hull split) and duration (predawn leaf water potential) of the
deficit irrigation period. That we were successful in reducing hull
rot using this approach indicates that we should be able to alter
deficit irrigation to fit the needs of various orchards.
Highlights: Our main goal in this second year of funding was to teach growers how to use a biofix and degree-day units to predict major events in the life cycles of citrus cutworm, California red scale, and citrus thrips. This year, we helped Avatel Corporation develop a user-friendly, relatively inexpensive temperature recorder (Harvest Guard). This equipment allows the user to input the biofix date and the lower developmental threshold of three different insect species. The recorder is placed inside the tree, and takes hourly readings of temperature and calculates the accumulated degree-day units. The LCD readout shows the accumulated degree-day units for each of the three pests. Thus the user can predict major events in the development of the pest and time sampling and control measures accordingly.
For citrus cutworm, this temperature unit in combination with a single pheromone trap per orchard to collect the male moths allows the grower to predict when the larvae will emerge. This is important because the soft microbial pesticides used to control this pest work best on the smaller cutworm instars. For citrus thrips, this temperature unit in combination with stick cards to detect the first appearance of adults can be used to predict when the nymphs will merge on the fruit. For California red scale, the temperature unit in combination with one pheromone care per 2.5 acres to trap first emergence of male scale can predict when crawlers will emerge and when subsequent male flights will occur.
We worked with 20 cooperators on the cutworm, citrus thrips, and
scale projects. We analyzed the data and sent summaries to 120 PCAs
and growers via FAX and 375 via newsletter. At the 5 field days 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 during 1996 based on their increased monitoring
and knowledge of the insects in their orchards. We worked closely
with a small core of cooperators and believe that 2 to 3% of the
growers and PCAs in the San Joaquin Valley altered their pest
management practices based on the information training we provide.
Many growers and PCAs are still unfamiliar with degree-day concepts;
however, now that they have a user-friendly temperature recording
device available there is increasing interest in the subject.
Highlights: We were able to use pheromone trap data to demonstrate which caterpillar species were potential pests in row crops. Black cutworm, variegated cutworm, and beet armyworm moths were trapped as early as the end of April, and western yellowstriped armyworms were trapped in August. Other species such as potato tuberworm, tobacco budworm, and tomato pinworm were rarely trapped during the study period, indicating that they were not potential pests during the cropping season. Weekly moth counts for nine worm species were faxed to about 20 cooperating row crop growers, crop consultants, and farm advisors during the growing season to stimulate interest and participation in this study.
A significant result of this project was showing that pheromone traps can be used to obtain biofixes for phenological models, thus providing a practical method to implement degree-day models in row crops. The moth count data demonstrated that the timing of moth flights for species such as variegated cutworm and beet armyworm was similar at different locations in the county. Variegated cutworm moths began a major flight in early June. The first flight of beet armyworm occurred in early May. Further analysis will correlate field sampling with degree-day calculations.
Integrated pest management techniques introduced through lygus control in strawberries.
Principal Investigators: R. Smith, UC Cooperative Extension, San Benito County; W. E. Chaney, UC Cooperative Extension, Monterey County
Project Summary: Lygus is a serious pest of strawberries in the Central Coast of California. Historically, control of lygus has been accomplished by treating the juveniles that attack the flowers of strawberries causing catfacing of the fruit making them unsaleable. The strawberry industry has seen a large influx of new-entry, Spanish-speaking growers who have a need for basic information on many aspects of strawberry production and specifically lygus control. A good understanding of the life cycle of lygus is essential to an effective control program. This project is creating a bilingual video that discusses in detail the life cycle of lygus as well as methods of sampling, threshold levels and control options.
Development of the video script occurred in spring 1996. Shooting
of all the footage occurred in summer of 1996. Editing and
translating of the script took place in fall 1996. The video is now
available through UC DANR Communication Services.
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
Project Summary: Alfalfa stands become increasingly susceptible to weed invasion as they age due to natural stand thinning. Growers frequently combat this weed invasion with an herbicide application; paraquat is generally used the last year since it does not carry over into the next crop. Previous studies have shown interplanting oats into alfalfa during the final year can effectively reduce weed invasion.
The purpose of this project was to improve adoption of this management practice. Seven field or indoor meetings were held in which interseeding of grasses or berseem clover were discussed. The average attendance at these meetings was over 50, composed of growers, pest control advisers, and farm advisors. The option of using berseem clover or grasses for interseeding allows growers the flexibility to produce forage for different markets while still reducing herbicide use. Counties where this practice has been demonstrated have shown an increase in adoption. It is estimated that 10% of all alfalfa fields are currently being interseed with grasses or legumes (clovers or alfalfa).
A 25% adoption rate is feasible for this practice, which would
reduce herbicide use by 250,000 pounds.
Developing Spanish-language grape pest management notes to train vineyard foremen and supervisors.
Principal Investigator: L. G. Varela, UC IPM Project, Sonoma County
Project Summary: Early detection of pest problems affords an opportunity to select among a larger range of preventive and control measures. Well-trained workers can provide the grower with the prompt pest detection needed for the effective use of alternatives to pesticides. They can also provide crop managers an additional resource for keeping track of impending problems and monitoring pest management practices. Knowledge of IPM principles increases farm workers' effectiveness and provides them with an important skill that will help with their personal career advancement. The widest possible dissemination of IPM methods should result in reduced use of pesticides and a stronger protection of the environment.
Since 1992 I have presented 19 workshops, 13 in the north coast counties and 6 in other wine regions of California. A total of 460 foremen and supervisors have been trained representing 94 wineries, vineyard operations, and growers. A total of 16 handouts in Spanish have been produced. Spanish-language Grape Pest Management Notes will aid trained foreman to train their crew (which changes each year).
If each foreman trains an average of five workers, an estimated
2300 farm workers would be trained by the conclusion of the project.
In addition I have developed a protocol for the workshop so that
Spanish-speaking farm advisors or vineyards managers can teach the
workshop themselves to their clientele.
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
Project Summary: Currently, growers in the north coast tend to spray the first grape leafhopper brood, fearing that low to moderate first brood nymphal counts will translate into nymph outbreaks during the second brood. First brood insecticides are also preferred because the leafhopper hatch is more synchronized, and thus easier to control. Similarly, growers may spray below the action threshold during the first brood because of uncertainty as to the ultimate size of nymphal hatch. If insecticide is delayed until the second brood it would allow time for parasites to inflict maximum mortality on leafhopper eggs, increasing the probabilities that an insecticide would not be needed.
As early season egg parasitism increases, there is a corresponding decrease in the number of nymphs found on leaves during the first brood. In addition, the degree of parasitism could also be used to predict nymph densities in the second brood and thereby predict the potential need for insecticide applications to protect the crop.
This was the first year evaluating the impact of the parasitic
wasp Anagrus on leafhopper nymphal density. In all fifteen
sites monitored, parasitism reduced nymphal populations from the
first to the second nymphal brood, making it unnecessary to spray for
grape leafhopper. When parasitism begins early during the first
brood, leafhopper populations will be controlled by the parasitic
wasp. We trained 60 PCAs, growers, and vineyard managers to identify
parasitized grape leafhopper eggs. On average these people manage 300
acres of vineyards, representing 20% of the total north coast grape
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
Project Summary: More than 50,000 acres are affected each year between July and October by walnut husk fly (WHF). WHF is a major pest in most of the coastal region, and in Sutter, Yuba and Stanislaus counties. It is a sporadic pest in most all other walnut growing regions of California. It is primarily a pest of late-season walnut varieties such as Hartley, Franquette, and Mayette. These varieties currently make up approximately half of the total walnut acreage. WHF is also a problem on backyard walnuts and is found in rural and urban residential areas (parks, roadside, etc.).
Although tools and techniques have been developed to help growers and pest control advisers monitor WHF, these tools and techniques are not being used to full advantage. For example, even though growers have attended many educational meetings they still use the wrong trap, use traps without the proper lure, place traps in inappropriate locations, and don't monitor plant-based signs of WHF. Further, growers fail to understand the biology of WHF. These failures cause growers to treat repeatedly (up to six times) often with poor results.
IPM information currently exists to do an adequate job of monitoring and controlling WHF. Much of this information is in print form and has been presented at numerous meetings held for walnut growers and PCAs. A new approach is clearly needed to train clientele. With the proper use of existing monitoring tools and an understanding of WHF biology, adequate control of WHF can be achieved in most cases, with two or fewer pesticide treatments.
An educational video with information on biology, monitoring, and control would be a new educational approach to reach clientele which could be evaluated in 1997.
The completed video will become available in 1997 to anyone who
wants to borrow, rent, or purchase it. It will be shown at numerous
Cooperative Extension walnut commodity meetings in 1997. We
anticipate it being shown in at least six meetings to an audience of
500 to 700 people. This video will provide clientele with the latest
information on walnut husk fly control and will teach growers proper
treatment timing, which should reduce the frequency and number of
pesticide applications made against this pest.
Implementation of a forecast model for powdery mildew of tomatoes.
Principal Investigator: R. M. Davis, Plant Pathology, Davis
Project Summary: Over the last 3 years we have developed a forecast model based on prevailing environmental conditions that predicts when pesticide applications are needed for the control of powdery mildew of tomatoes. The purpose of this project was to validate and implement the model and encourage growers to adopt the model by providing field demonstrations.
Six demonstration experiments were established in Yolo County
processing tomatoes and San Joaquin County fresh market tomatoes.
Microclimatic information was collected at each site. Some fields
were sprayed using the model forecast recommendations and others at
calendar-scheduled intervals--every 14 to 15 days after the middle of
bloom. Untreated controls were also included. Based on preliminary
data, the number of fungicide applications (for a year like 1996)
could be reduced by one to three sprays using the forecast model to
time application. If applications were cut in half from the current
level, the fresh market tomato industry would realize a savings of
$263,030 and the processing industry $544,220.
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
Project Summary: Fire blight disease, caused by the bacteria Erwinia amylovora, is the number one disease of pear worldwide. Controls include sanitation (cutting out overwintering cankers) and chemical (antibiotics and copper). Erwinia amylovora has developed resistance to the main antibiotic, streptomycin. Also, the future of antibiotics in agriculture is uncertain as they are now feared to invade animal systems, hastening resistance in human pathogens. The newly registered biological control agent, Pseudomonas flourescens strain A506 (Blight Ban A506reg.), has been shown to reduce frost injury and russet caused by various bacteria living in the orchard.
1996 was the third year of Smith-Lever funding. Impact on russet and frost control are still being evaluated. Four commercial orchards were treated, involving four growers and four pest control advisers (out of five active in Lake County). In addition, 50 growers and others attended a July field meeting to hear preliminary results. There was commercial use of BlightBan A506reg. on about 4,000 acres in Lake County in 1996, or 80% of the acreage (one to three applications).
In the demonstration orchards, treatments reduced the number of antibiotic applications 50% (from about 12 to 6). Reduction in the remaining commercial acreage has yet to be calculated. Historical results have shown a 50% reduction is very feasible. In addition to the July field meeting, results will be presented in the annual California Pear Research Reports, distributed to 100% of growers and at annual industry-sponsored research meetings in Sacramento and the north coast (Lake County in 1996).
The impact of a successful biological control program is positive
economically, environmentally, and socially. In May 1996, local
applicators were tested for allergic reaction to A506 by the
University of Cincinnati; results have yet to be released. The use of
naturally-occurring agents is now the main focus of both public and
proprietary research programs. If 1996 data on frost and russet are
positive, wider use may be expected in 1997.
Project Summary: Many growers and PCAs are unable to identify pests, their damage, and beneficial insects. Without this basic knowledge they are unable to conduct monitoring necessary to successfully use IPM techniques such as sampling and degree-days. Growers need to know how to use a hand lens and where to buy them to use the presence-absence sampling for mites in almonds. Educating growers on basic insect identification in the field is the first step toward improving IPM adoption and reducing pesticides.
The field meetings had three parts. The local farm advisor talked about local pest management highlights with live samples. Then growers used microscopes to examine natural enemies from the natural enemy collection. 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 on mite sampling, predator identification, how to purchase hand lens, and on using degree-days.
These meetings were attended by 165 growers. Only a few PCAs
attended the meeting. The meeting held with Punjabi translation was
attended by progressive growers in the East Indian community. Farm
advisors are disappointed with attendance at the summer "hands-on"
field meetings. There are several fundamental problems that
contribute to lower attendance; it is difficult for growers and PCAs
to attend meetings in the summer, and with the increased use of
synthetic pyrethroids, growers and PCAs cannot benefit from the pest
monitoring and management techniques.
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
Project Summary: This was the second year of this arthropod survey in cotton in the San Joaquin Valley. While the data set still requires extensive analysis, the 2 years provide very different views on pest management. In 1995, insects and bad growing conditions dominated the season. In 1996, good early growing conditions provided an excellent start to the season and insects required very few treatments. However, areas of the San Joaquin Valley varied in their insect pest fauna and pressure, and our sites reflect these differences.
Information from these plots were provided to over 1,500 growers, PCAs, and other cotton industry officials through ten field production meetings. The total acreage that was impacted by these meetings is estimated at 500,000 acres. 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, information was provided to CE's Cotton Insect Hotline with weekly monthly updates.
The 1995 season was one of the roughest in memory. It was followed
with a year-end review. This facilitated workshop resulted in
developing a consensus that identified key problems, the causal
agents, and management guidelines to reflect the new reality of pest
complexes. The results of these meetings were general insect
management guidelines for 1996 as well as research and extension
priorities. These guidelines and the data collected in 1995 were
presented during winter production meetings. Insect pest management
tactics were substantially changed in 1996 because of this project
and subsequent meetings. There was a definite change in philosophy
among key PCAs and growers in their pest management approach to key
pests such as lygus and aphids.
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
Project Summary: Our training programs focus on hands-on identification of weed seedlings. These programs target growers and PCAs; this year we trained 353 people statewide and will train another 200 to 300 in fall 1996. We continue to photograph our seedlings; the quality of our slide set is excellent. 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. In the third year we added an additional 30 species and filled in gaps in our photo collection where some plant developmental stages were missing.
The computer program has most of the data for over 100 of the
species entered and the program will be tested this fall and winter.
Data will continue to be collected until a manual is presented for
publication. Text descriptions have been developed for nearly all
species that will be included in the manual.
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, Environmental Science, Policy and Management, Berkeley
Project Summary: In the Suisun Valley, fruit removal is the most cost-effective means of postharvest codling moth (CM) control because of the open tree structure and low number of trees per acre (70 to 110 trees/acre). Fruit removal in 1995 reduced the overwintering CM flight in 1996 by over 70% in traps placed in the center of the orchards and by over 50% for all traps as compared to the companion orchards where the fruit was not removed after harvest. In 1996, a number of growers practiced postharvest fruit removal at the same time or shortly after commercial harvest. The removed fruit were then sold as juice pears. This practice paid for the cost of fruit removal and removed about 70% of the fruit as compared to companion orchards. We will determine the CM infestation in the remaining fruit over the next 3 to 4 weeks. Next spring, CM overwintering flight will again be monitored with an anticipated reduction of 50 to 75% in overwintering moth flight.
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/acre). Insecticide application cost was about $45 per acre. In 1995 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 and the late harvest completion date in relation to the CM flight. Lorsban was the insecticide of choice because it 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.
In 1996 the cooperating growers and PCAs were extremely pleased by the suppression of the overwintering CM flight. However, our data did not show a significant reduction in the overwintering. This was because the six growers who were willing to leave untreated areas chose to leave the area with little or no CM infestation while treating areas with known CM infestation. This biased our data to be less favorable to postharvest insecticide application. In 1996 all orchards with significant CM flight during or shortly after harvest were treated with Lorsban or Penncap-M. Penncap-M, like Lorsban, also exhibits negatively correlated cross-resistance to Guthion-resistant CM.
We estimate that about 1,000 acres were treated this year. We will determine the CM infestation in five to six treated orchards and untreated companion orchards. In the spring CM overwintering flight will again be monitored with an anticipated reduction of 50 to 75% in overwintering moth flight.