Project No.:              04-CP-01      

Project Leader:       Carolyn Pickel, UCCE Sutter/Yuba Cos.

Cooperating Personnel:  J. Connell (UCCE Butte Co.), M. Viveros (UCCE                                                                         Kern Co.), R. Duncan (UCCE Stanislaus Co.), W. Bentley                                                          (UC-IPM Kearney Ag Center)

Description

Ongoing regional projects located in Butte, Stanislaus and Kern Counties each focusing on reduced risk pest management programs for that region’s specific pest pressures, and extension of these successful techniques to California almond growers.

Introduction

In 1998, The Almond Pest Management Alliance (PMA) was initiated by the Almond Board of California with funding from the California Department of Pesticide Regulation to evaluate the possibility of reducing the pesticide inputs in California Almonds.  The PMA is a cooperative effort among the industry stakeholders including the Almond Board of California, the Board’s Environmental Committee, the Almond Hullers and Processors Association, the University of California Statewide IPM Project, University of California Cooperative Extension, PCA’s and growers, CA Department of Pesticide Regulation, and U.S. EPA Region 9.  With increasing funding from the Almond Board, the PMA was continued (in Butte and Kern Counties) for a sixth year, 2004, to document that high levels of rejects seen in 2003 were not due to increased pest populations attributed to less spraying.

The regional projects demonstrate and evaluate reduced risk pest management methods in local orchards, and use intensive monitoring to reduce the possibility of damage to the crop. The alliance has been able to track pest populations, damage levels, and economic data over several years to examine the long-term effects of reduced pesticide inputs.

Education and outreach is also a major component of this project.  Each region has conducted field meetings and dormant-season workshops, complete with hands-on training and demonstrations. The PMA is publishing “Seasonal Guide to Environmentally Responsible Pest Management Practices in Almonds” a decision guide that includes information to help almond growers make environmentally responsible pest management decisions year round without decreased yields or increased reject levels. There is information on how to manage almond pests by first considering environmentally friendly and low toxicity materials. It also gives guidelines and threshold for situations where growers may need to use a broad-spectrum insecticide. This information is based on University of California research and results of the Almond Pest Management Alliance (PMA). In addition, the almond PMA’s newsletters contain updates on the regional projects and detailed information on implementation of reduced risk pest management systems in almonds.

Accomplishments

1.                  The “Seasonal Guide to Environmentally Responsible Pest Management Practices in Almonds” is based on what has been learned from the six years of PMA work and is specifically geared towards reduced risk pest management orchard systems.

2.                  Reduced risk practices appear to be controlling the pests below economic damage levels. The PMA has demonstrated that a dormant insecticide is not always needed, and that often there is no additional crop damage with zero sprays.

3.                  Almond growers have reduced dormant applications by 77% from 1991 to 2000 reported in an analysis of the Pesticide Use Report. In the report written by DPR, this was primarily attributed to the Pest Management Alliance.

4.                  Grower/Cooperators in the Almond PMA have made an unselfish commitment to continue to study reduced risk programs by remaining in the PMA for up to six continuous years.  These growers can lead by example, encouraging others to implement reduced risk systems.

5.                  Meeting attendance is increasing as growers look to the PMA for guidance in the transition to reduced risk pest management. Growers are interested in reduced risk practices and continue to be proactive, as shown by increasing participation in outreach activities that emphasize reduction of broad spectrum pesticides in almonds.

Butte County Site 2004, Year 6

The Butte County site is an ongoing demonstration of the long-term effects of orchard pest management with reduced pesticide inputs. Intensive monitoring is used to track pest pressure over the years and to reduce the possibility of damage to the crop. Monitoring continues to show that reduced risk practices appear to be controlling the pests below economic damage levels.

The 49 acre orchard is divided into four treatment blocks which have been followed since 1999.  In 2001, an untreated check was added.  In 2004, three secondary treatments were added in an effort to avoid the worm damage seen in the 2003 crop.  The treatment blocks are as follows:

No insecticide treatments have been applied to the PMA I block since 2001 (except for a section treated with Clinch ant bait in 2003) and the PMA II block has been without insecticide sprays since 2002.  The Oriental Fruit Moth pheromone was applied to the two blocks during the third and fourth flights, determined by trap catches and degree-day forecasting.  The timing of the hullsplit and dormant treatments were determined by the grower.  Fungicide treatment and weed management was the same across the whole orchard.

Monitoring

Traps: This trial has been monitored for peach twig borer, naval orangeworm, web spinning mites, San Jose scale adult males, and San Jose scale parasitoids (Encarsia and Aphytis), and in 2004 Oriental Fruit Moth traps were added to each block.  Degree days for each of these pests were calculated to determine biofixes and to provide treatment timing for those in the area who might need it.  The weather data and degree day modeling available on the UC IPM website http://www.ipm.ucdavis.edu/index.html, used in conjunction with actual trap catches helps to identify the biofixes during the season.

Shoot Strikes: The upper portion of the canopy was inspected for shoot strikes (SS) at the beginning of PTB generations.  Shoots with damage were clipped with a pole pruner and split down the center to verify presence and identification of larvae. When larvae were present, they were identified, but if the strike was already vacated, no attempt was made to determine whether the damage was done by Peach Twig Borer or Oriental Fruit Moth.  In most seasons, including 2004, few if any shoot strikes were ever found, making the high level of strikes found in 2003 unusual.

Dormant spur sampling: Spurs are collected before the growing season begins, most recently on Jan 15, 2004.  Spurs were taken from each treatment block and inspected for mite eggs, predatory mites, San Jose scale, parasitized SJS, and European Fruit Lecanium crawlers.  Counts were tabulated to determine if levels are increasing or decreasing and if the treatment threshold for any of the listed insects had been reached.  This orchard has had evidence found in the dormant spur sample of parasitism of the San Jose scale and also of the European Fruit Lecanium.

Mummy nuts: Twenty trees per treatment block are surveyed for mummy nuts.  This can be done at the same time as dormant spur sampling.  Mummy nuts are counted to make sure there are less than an average of two per tree.  The Butte cooperator routinely shakes the entire orchard to remove mummies.

Damage At Harvest

At harvest, 100 almonds were randomly collected from each of five trees in each of the treatment blocks for a total of 500 per treatment.  Nuts were inspected for damage, and an attempt was made to identify the insect which had caused the damage.  It is difficult to distinguish OFM from PTB worm damage to the nut, if no larvae is found, damage is classified as “PTB/OFM”.  Percent damage to each treatment block was calculated. The Harvest Damage Table is expressed in percent damage.

Percent Insect Damage at Harvest, 2004

The high levels of worm damage seen in 2003 were not repeated in 2004, even in the unsprayed treatments, which is encouraging.  We will continue to monitor for these insects, including OFM, for 2 more years.

Kern County 2004, Year 6

The Kern County PMA project focused in 2004 on three objectives:

1.  To determine injury and economic level of San Jose Scale in almonds.

2.  To determine the effect of a barley cover crop on ant control.

3.  To determine the feasibility of mite control using predatory mite releases.

To accomplish the first objective, we eliminated the San Jose scale infestation in all plots of the old PMA projects.  Some of these plots were heavily infested with San Jose scale since they were not dormant sprayed for four years.  Yields were drastically reduced due to San Jose scale infestation in 2003.  This year, yield measurements were taken to determine yield response after San Jose scale was eliminated.  These treatments will be followed for 2 more years.

Mario Viveros, UCCE Farm Advisor, Kern County, outlines results of the PMA project at the annual Almond Board Conference, Dec. 1, 21004.

To accomplish the second objective, an experiment was established in areas with and without a barley cover crop.  Ant control using bait products can be severely affected by other food sources available to the ants. The results are being analyzed at the time of publication.  They will be available at the almond conference.

To accomplish the third objective an experiment was established to determine the efficacy of Agri-Mek® , Acramite® , Summer oils and predatory mite releases on webspinning mite populations and their damage.  The results of this experiment are being analyzed at the time of publication.  They will be available at the almond conference.

Stanislaus County 2003, Year 5

2003 was the fifth and final season for the Stanislaus County PMA trial.  Because reject levels were very low for all pest management regimes, a fourth, “untreated” program was added in 2001.  Each pest management program was replicated three times within a 120 acre Nonpareil orchard west of Modesto.  The treatments are:

1)                 Grower’s Standard Practice: (fairly common in the Northern San Joaquin Valley).

¨      A dormant application of Asana^® (a pyrethroid), 6 gallons of oil, & 8 lb. Kocide^®.

¨      A May spray with an organophosphate (Lorsban).

¨      Lorsban for ant control.

2)                 Soft Program #1:

¨      A dormant application of copper & oil (no insecticide).

¨      A “bloom” spray of Confirm^® at ~ 30% PTB emergence (piggy-backed with fungicides).

¨      A May spray of Success^®.

¨      Clinch^® (Abamectin) bait for ants if monitoring deems necessary.

3)                 Soft program #2:

¨      A dormant application with oil only.

¨      Two “bloom” applications of Bt (@ ~20% PTB emergence & ~ 80% emergence).

¨      Two May sprays of Bt (300-350 & 450-500 DD after biofix).

¨      Esteem^® bait for ants if monitoring deems necessary.

4)                 “Untreated”:  only mites and ants are controlled if necessary. 

¨      No dormant copper, oil, or insecticide application.

¨      No bloom insecticide applications.

¨      No May or hull split sprays.

¨      Esteem^® bait for ants if monitoring deems necessary.

Overwintering nuts (“mummies”) were removed and destroyed in all treatments to reduce overwintering naval orangeworm.  Cover crop management, fertilization, and fungicide treatments were the same for all treatments other than no dormant copper was applied in “soft program #2” and the “untreated” areas.

Insect Damage at Harvest

Overall insect damage has been very low and there were no significant differences among treatments. Although there was no difference in pest pressure or insect feeding damage at harvest among treatments, there was a significant cost difference.  From an economic view point, there is no incentive for growers to use reduced risk materials like Success, Confirm or Bt. If a grower needs to apply dormant oil for scale control, it makes better economic sense to apply something for PTB at that time.  If a dormant oil spray for scale is not necessary, a grower may choose to apply one of the reduced risk materials at bloom for PTB if necessary.  Of course the least expensive program is one where no insecticide is applied.  However, few growers may choose to take that risk.

(Information presented in 2004 Proceedings of 32nd Annual Almond Industry Conference, Dec. 1-2, 2004)