Pest Management Evaluation
for the Almond Industry
Pest Management Alliance
(Attachment #1)
Contract Number: 97-0264
Chris Heintz, Principal Investigator
Director of Research, Technology and Education
Almond Board of California
May 15, 1998
Prepared for California Department of Pesticide Regulation
Disclaimer
The statements and conclusions in this report are those of the contractor and not necessarily those of the California Department of Pesticide Regulation. The mention of commercial products, their source, or their use in connection with material reported herein is not to be construed as actual or implied endorsement of such products.
Acknowledgments:
Prepared by:
The Almond Board of California
1150 Ninth Street, #1500
Modesto, CA 95354
209-549-8262 (phone)
209-549-8267 (fax)
This report was submitted in fulfillment of DPR Contract
Number: 97-0264 for the "Pest Management Evaluation for the
Almond Industry Pest Management Alliance" under the
sponsorship of the California Department of Pesticide Regulation.
Work was completed on May 15, 1998.
Table of Contents:
Almond Pest Management Evaluation abstract page 5
1. Summary of pest complexes and key pests page 6
2. Summary of pest management practices page 7
3. General review of reduce risk pest management practices page 11
4. PMA challenges page 13
5. Innovations in pest management methods page 14
6. Potential barriers to adoption of reduced risk methods page 14
References page 16
Appendices..see Appendix #1 and Appendix #2
Almond Pest Management Evaluation Abstract
Almond Pest Management Guidelines have been well documented by the UC Statewide IPM project and are available in the manual IPM for Almonds with current information via the World Wide Web.
The Almond PMA has identified those UC IPM recommended practices that have the greatest potential for reduced pesticide risk. These include: dormant OP spray alternatives for PTB (Bt sprays at bloom) winter sanitation and an early harvest for control of NOW with rapid pickup to avoid ant damage (no in-season OP sprays), and the greater use of economic damage thresholds for decision making about when to use OP or other conventional sprays for any pest.
Additionally, barriers to adoption of these practices are identified. Most solutions include grower outreach and education in the use of standard UC IPM recommended reduced risk practices. New reduced risk practices for the control of scale, ants, and diseases will be investigated by UC Cooperative Extension and coordinated by the Almond Pest Management Alliance (PMA.) If the industry as a whole can significantly reduce the risks of OP use, there may be less likelihood of the regulated elimination of all OPs for almond production.
1. Summary of information about pest complexes, key pests (primary and secondary), regional/geographic variability of the pest pressure, affects of different management systems on pest complexes.
Navel Orangeworm (NOW), Peach Twig Borer (PTB), San Jose Scale (SJS), ants and webspinning mites (two spotted and Pacific spider) mites have the greatest potential for economic impact on the almond tree or crop. Control of NOW, PTB, SJS, and ants are the main uses of organophosphate pesticides (OPs) in almond production. As identified by UC IPM, alternatives to OP control of these pests exist, and greater widespread use of these alternatives is a main goal of the almond PMA.
Shot hole, brown rot and anthracnose are major almond diseases. Few reduced risk alternatives are available for these pests. However, a forecasting model has been developed for shothole on almonds to predict disease occurrence. Although new research by UC Cooperative Extension is investigating possible alternatives to current fungicides, these trials will be integrated into PMA demonstration plots.
On January 5, 1998, the U.S. Environmental Protection Agency (EPA) issued a Section 18 specific exemption that permitted almond growers to use Break(tm) EC (propiconazole) to combat anthracnose disease. The Section 18 allows for 94,000 acres of almonds, within specified counties, to be sprayed with the fungicide. A very important component of the Board's research program has been the studies on various fungicides effective in protecting almond orchards from the anthracnose disease.
These major pests and diseases of almonds are well described in the Almond Pest Management Guidelines from the UC IPM Pest Management Database. A hard copy of these guidelines, which includes descriptions of the pest, types of damage, cultural, biological, and chemical controls with application rates and timing, and guidelines for when to treat, is attached as Appendix #1.
The guidelines are meant to be used in conjunction with the UC ANR publication #3308 IPM for Almonds, which is in the process of being updated at this time. The next section on geographic variability is to supplement the Almond Pest Management Guidelines.
Weed pests are well covered in the Walnut Pest Management Guidelines, of which a hard copy is attached as Appendix #2.
Geographic variability of pest pressures.
Arthropod pests
The southern fire ant and the pavement ant are significant pests particularly in the central and southern San Joaquin Valley. The southern fire ant is considered the most damaging, where it occurs. The pavement ant is found primarily in Northern California. Citrus red mite can be a problem on the eastern side of the San Joaquin Valley. Tetranycid mites: pacific mites prefer hotter, dustier areas (South San Joaquin Valley), while the twospotted spider mite and the strawberry mite prefer cooler areas. However, all three can be found in the same orchard at the same time. The naturally occurring parasites of San Jose Scale (Aphytis and Prospetella spp.) are less prevalent in the Southern San Joaquin Valley than in the Northern and Sacramento Valley, although recent observations indicate that Prospetella ssp. may become more prevalent when conventional pesticides are not used in the San Joaquin Valley.
Disease pests
Brown rot is worse during rain or fog at bloom. Therefore brown rot is a bigger problem in northern growing areas. The same is true of shot hole. Fungicides that are effective for controlling these diseases must be applied preventatively before a rain but a model developed to forecast shot hole incidence is available for validation and could help reduce sprays for this disease.
2. Summary of information about current pest management activities/practices including pesticide use, biological controls, cultural controls, costs and efficiency of controls. Describe how biological, cultural, mechanical, and chemical methods are currently integrated.
Current almond pest management guidelines are well covered in the attached (Appendix #2) hard copy of the Almond Pest Management Guidelines from the UC IPM Pest Management Database.
The information which follows is provided as an example of alternative practices used by a small group of almond growers in California. This information is provided as an example of what some growers are doing to reduce the risk of pesticides. The data is taken from Biologically Integrated Orchard Systems (BIOS) grower surveys conducted in 1996 and compiled by BIOS staff. Growers enrolled in the program were interviewed and asked about their pest and disease control programs. There were 53 growers in five counties who participated in the survey.
Conventional treatment information was taken from chemical and non-chemical control methods for the major pest on almond in California. Data is from the 1996 Pest Management Survey Database. The top three chemical used for each pest or disease are included along with the pounds of chemical applied. These figures are taken from DPR’s Pesticide Use Report for almonds in California, 1995. The pounds applied figures are a total of the chemical applied to almonds and are not pest specific.
Peach Twig Borer (PTB)
Sprays for PTB can be applied during dormancy, growing season, or at hull split. Conventional treatment uses a spray of oil and an organophosphate insecticide to control PTB during dormancy. When used during the dormant period, the spray kills overwintering PTB larvae, but can also kill many of the beneficial insects and mites in the orchard. Over 90% of the surveyed growers applied no dormant insecticide spray.
Bacillus thuringiensis (Bt) is a caterpillar stomach poison that is very selective and effective on both PTB and Navel Orangeworm (NOW). Bt sprays have been proven effective through field trials for control of PTB. Used during bloom in place of a dormant spray treatment, Bts are widely accepted. The drawback to using Bts is that spray timing and good coverage are critical. Forty two percent of surveyed growers applied Bt sprays for control of PTB.
In addition, many surveyed growers are also releasing Trichogramma wasps, which parasitize PTB eggs. Thirty-two percent of surveyed growers released Trichogramma in their orchards to aid in PTB control. Other common orchard predators that can decrease PTB levels are lacewings, assassin bugs, minute pirate bugs, and gray field ants. These predators were found in cover crop sweeps conducted in many BIOS orchards.
Pheromone mating disruption has been shown effective as a replacement spray for OPs and pyrethroids for controlling PTB. There are some problems associated with the use of pheromones. Pheromones are currently applied by hand with plastic dispensers. This is not only labor intensive and expensive, but also leave some room for error. There is need for a spray applied formulation. Cost is another factor inhibiting growers from using pheromones in place of broad spectrum sprays. At an estimated two to three times the price of an OP spray, many growers cannot afford to make the switch. Pheromones cost about $65 an acre, compared to $25-30 for an OP such as Diazinon or Guthion. (Agribusiness Fieldman, March 1996, page 4).
Conventional treatments for PTB used by California almond growers included the following chemicals: Methidathion (Supracide) 67,000 pounds applied, Permethrin (Pounce) 10,181 pounds applied, Malathion 433 pounds applied.
Navel Orangeworm (NOW)
Good orchard sanitation and early harvest are two key factors in controlling NOW. The majority of surveyed growers (72%) used some form of winter sanitation. Many of the growers in the program who did not winter sanitation had a substantial amount of natural mummy nut removal due either to weather or birds.
Several parasitic wasps are currently being studies for their effectiveness in controlling NOW. These include Goniozus legneri, Trichogramma and Pentalitomzstix plethorica. Forty-four percent of surveyed almond growers released Goniozus and /or Trichogramma for NOW control.
Conventional treatments for NOW used by California almond growers included the following chemicals: Chlorpyrifos (Lorsban) 153,781, Methidathion (Supracide) 67,000 pounds applied, Permethrin (Pounce) 10,181 pounds applied.
San Jose Scale (SJS)
Most surveyed growers found they can effectively eliminate the use of dormant sprays. However, this reduction does raise some concerns about an increase in San Jose scale in almonds.
UC IPM Regional Entomologist Walt Bentley found in his 1996 BIOS and comparison orchard study that the level of scale was low in both the sprayed and unsprayed BIOS orchards. What was unexpected was the abundance of Prospaltella and Aphytis (two key San Jose scale parasitoids) in the BIOS orchards.
He feels these two parasitoids are having a dramatic impact on reducing San Jose scale populations in almond orchards. Elimination of the dormant spray allows more beneficial insects to survive and thrive to combat San Jose scale in the orchard.
Conventional orchard systems apply an insecticide spray during dormancy to control prevent flare-ups of San Jose scale. If a dormant spray is not applied, a spring spray during emergence can be used.
Conventional treatments for SJS used by California almond growers included the following chemicals: Diazinon 235,433 pounds applied, Chlorpyrifos (Lorsban) 153,781 pounds applied, Methidathion (Supracide) 67,000 pounds applied.
Mites
Growers have proved that, by carefully controlling irrigation and minimizing dust through the use of cover crops, they can control damage from Two-spotted and Pacific spider mites. Several predator species also help regulate mite populations. About 20% of surveyed growers used a chemical spray to aid in controlling mites.
Conventional treatments for mites used by California almond growers included the following chemicals: Propargite (Omite) 254,767 pounds applied, Fenbutatin Oxide (Vendex) 25,693 pounds applied.
Pavement Ant/Southern Fire Ant
Several surveyed growers applied an OP spray for ants. In some cases they were able to spot spray or use less than 100% coverage.
Conventional treatments for ants used by California almond growers included the following chemicals: Diazinon 235,433 pounds applied, Chlorpyrifos (Lorsban) 153,781 pounds applied
Brown Rot/Shothole/Fungal Diseases
Almost all growers in the BIOS program as well as conventional growers apply a chemical fungicide spray. Many growers used copper spray alone or in combination with other chemical products like Rovral, Benlate or Manex. At the present time the only alternative to conventional sprays for the control of fungal diseases are cultural controls. BIOS growers use careful monitoring to evaluate disease levels and to time spray applications most effectively.
Conventional treatments for fungal diseases used by California almond growers included the following chemicals: Maneb 500,012 pounds applied, Captan 279,954, Iprodione 156,945 pounds applied.
Herbicides
Herbicides are applied in almond orchards to control understory vegetation and to create a clean orchard floor at harvest. Sometimes this procedure is termed "chemical mowing." Most BIOS growers have changed the type and amount of herbicide they are applying, using materials that are less persistent in the environment.
There are two main types of herbicides, which can be applied to the entire orchard floor, tree row or to the area at the base of the tree. Pre-emergence herbicides applied in the fall or early winter kill weed seedlings as they germinate. The BIOS program discourages the use of pre-emergence herbicides, which can pose problems in the environment since they can persist in soil for a few months to a year or more and leach into ground water. Simazine, a widely used pre-emergence herbicide and a known ground water contaminant, has been targeted by the US EPA for reduction in California.
The second type of herbicide is a post-emergence herbicide which kills the weeds on the soil surface on contact. BIOS encourages program participants to utilize the less persistent post-emergence herbicides (like Roundup and Goal) which do not remain in the soil for a long time. About 80% of BIOS growers rely on these two herbicides almost exclusively.
BIOS growers are reducing not only the use of pre-emergence herbicides, but are also greatly reducing the amounts of herbicides they apply. Rather than uniformly spraying the entire orchard floor, many are using a strip treatment of herbicide in the tree rows to prepare the floor for harvest. The 1996 survey asked growers if they had reduced the width of this treated strip since joining the BIOS program. One-third of all growers have reduced the width of the strip they treat with herbicide and many indicate they use less herbicide at each application and still get a clean orchard floor at harvest.
Costs and efficacy of controls
The main goal of pest control is to increase economic profit for the grower and to reduce the risk of pest damage. The decision to use or not use a particular pest control method should be based on a cost benefit analysis. The expected increase in dollar return when using a treatment is then compared to the cost of treatment. When treatment benefits are greater than the cost, only then will treatment be economical. Using a cost benefit analysis is also helpful to decide which type of pest control to use, when multiple types of pest control are available. The most effective treatment may not be the best, because it may cost more for the amount of control it gives.
Cost benefit analysis can be a valuable tool to reduce pesticide risk. Usually, by the time a cost benefit analysis is done, a pest problem is already perceived. A cost benefit analysis can be used to "check" that a control measure should be used. Without a cost benefit analysis a pest control strategy invariably will be used. With a cost benefit analysis, there is a chance that the control measure will not be used. Cost benefit analysis can help reduce the number of unnecessary pesticide applications.
UC IPM has simplified the cost benefit analysis for growers by establishing "control action guidelines" or "treatment thresholds" for some pests. Control actions guidelines are well defined for NOW, ants, mites, and San Jose Scale. For diseases, weeds, nematodes, and vertebrates, the guidelines are currently less well defined. If control action guidelines are strictly followed, often times pesticide sprays are not needed.
It is difficult to put a precise dollar figure on the economic benefit to be derived from this proposed work plan. However, the most recent data suggests there is significant potential for economic benefit both to the California almond industry, as well as to the general public.
In an article in the Sept-Oct. 1990 edition of California Agriculture, Dr. Zalom notes, "The almond insect IPM program has resulted in an estimated $4.1 million reduction in pesticide costs." This figure was arrived at by comparing a 1985 grower survey versus 1981 survey. That analysis showed a 24% reduction in spraying pesticides as part of growers' routine worm control practices. Data showed growers who sprayed used an average of 1.43 sprays per acre. The average bearing acreage between 1982 and 1988 was 387,000 acres. The 24% reduction on sprays has meant a reduction of 124,614 acre-sprays per year. At a cost of $32 per spray, this meant a direct savings in input costs to California almond growers of over $4 million. According to the analysis, this added up to an estimated benefit of $12.8 million, including an increase of $8.7 million in revenues resulting from increased salable production and a decrease of $4.1 million in pesticide costs.
Similar types of savings can be reasonably expected to result from the type of pesticide reduction strategies being proposed by the Almond PMA.
3. General review of pest management options to be considered that meet overall objectives to reduce risk.
The following UC IPM recommendations are low pesticide risk practices with high efficacy. These UC IPM recommendations could be emphasized in outreach to increase their adoption.
Control of Navel Orangeworm (NOW)
UC IPM recognizes that pesticides are not very effective at controlling NOW (IPM for Walnuts, IPM for Almonds, Biological Control in the Western United States.) The most effective way to prevent economically destructive populations of NOW is with good winter sanitation, an early harvest and a rapid pickup of nuts from the ground. The definitions and thresholds for good sanitation and early harvest are well discussed in IPM for Walnuts, IPM for Almonds and will not be repeated here. Usually no pesticide sprays are needed with good sanitation, early harvest, and if the orchard is at least 1/4 mile away from other sources of NOW infestation.
Control of mites
Mites can be controlled with a dormant oil spray. OP insecticides do not control mites. See the Sab Jose Scale section for special considerations when eliminating the dormant OP spray. Avoiding the use of pyrethroidsecticides for other pests is important in mite control because of the effect on predatory mites.
Control of Peach Twig Borer (PTB)
PTB can be controlled with two or three well timed bloom applications of Bt, dormant applications of insecticides or in-season applications of insecticides. Dormant sprays of OPs can be eliminated for control of this pest. See SJS section for special considerations when eliminating the dormant OP spray. Pheromone mating disruption, an available but somewhat immature technology, can also be used for PTB control.
PTB treatment is most effectively controlled in the dormant period (reduces the population by over 95%). Use of Bts has been effective at pinkbud or popcorn flower development and a second spray at full bloom. Timing is critical if these treatments are to be effective.
When using pheromones for in season control of PTB growers achieve optimal post bloom control of PTB by applying treatments between 400 and 500 day degrees after the flight begins.
Control of San Jose Scale (SJS)
Control of SJS is difficult. A dormant spray is the preferred treatment and spray coverage is very important. A phenology model and pheromone traps are available for monitoring and predicting the biological events of SJS. No treatment thresholds exist at this time.
Though non-chemical options will work for most pests under many conditions, they are often more expensive and more difficult for growers to use. Therefore, growers will tend to spray as long as it is possible for them to do so. Also, sometimes the best options to prevent damage is a pesticide application when conditions simply do not favor the use of an alternative. This proposal will help in the search for good alternatives that are economical for growers.
A dormant OP spray is the most effective control measure for SJS. New research by UC IPM Regional Entomologist Walt Bentley shows that in some areas SJS will be controlled by natural biological control and the dormant OP spray is not needed. There is also building evidence that lower populations of SJS can be controlled with a dormant oil spray alone. This is ongoing research and no final recommendations can be made at this time. Monitoring and inseason sprays are also possible for SJS but these can result in undesirable nontarget effects. Research on lGR's and other as yet unregistered insecticides for SJS is underway. Research on San Jose scale is vital to the almond PMA because SJS is the only pest controlled by a dormant OP spray that does not have a low pesticide risk alternative.
New reduced risk management practices to be incorporated in this proposal are covered in section 5.
4. PMA challenges
The above information demonstrates a wide variety of insect and mite pests attack almonds in California. Some are present and do damage in all almond-growing regions throughout the state, while for others damage potential is limited. Almond growers face many challenges of insect pests and almond diseases. They must balance the production of an economically viable crop with environmental, regulatory, human health and technical issues. The following is a discussion of some of the pest management challenges facing growers.
a) Getting growers to implement UC IPM practices on their farms. Utilizing an IPM system requires that growers know and understand the pest pressures facing the orchard. Careful monitoring, working with a local farm advisor or PCA and networking with neighboring growers are essential elements of a good pest control program. Many growers feel they do not have the time and effort it takes to implement non-conventional IPM practices. Some of these practices are also more costly for the grower. Therefore, they tend to rely on more traditional management practices and possibly the advice of a PCA.
b) Growers lack confidence in utilizing new alternative methods. They need to be reassured that other farmers are being successful implementing these methods. The greatest barrier will be to develop confidence in these new practices. Growers will develop confidence by seeing these practices in action, talking with other growers, and through support from UC researchers. They will then have the knowledge they need to make more risk free decisions.
c) Growers are afraid they will have to sacrifice quality and thus the economic benefits associated with a low incidence of insect damage. The premiums paid to growers are based on the percent of insect damage. If growers lose the use of some key chemicals and are not able to effectively manage pests, they will not remain profitable.
d) Educate growers to use a cost benefit analysis for their orchards. Using this type of analysis will help growers analyze whether the cost of spraying is paid for by the increase in return.
e) Educate growers about reducing the off site movement of OP and other pesticides. Provide information on alternative practices which may reduce OP usage, including information on pesticide mixing and loading, container handling and equipment cleaning. Educating growers to adopt "Best Management Practices" remains a constant challenge.
f) The threat of FQPA eliminating some of the tools needed by almond growers. If California almond growers can implement a reduced risk strategy including decreased pesticide risk in the water and food supply and increased worker safety, there may be less likelihood of the elimination of all OPs for almond production.
5. Innovations in pest management methods
The formation of a Pest Management Alliance (PMA) for almonds is a new and innovative approach to the development of reduced risk strategies. This proposal process brings together many difference facets of almond production and creates a forum for discussion and a method of outreach and education for use of alternative pest management practices.
Through the combined efforts of the Alliance - the Almond Board of California, Almond Hullers and Processors, the University of California and CAFF - the project will provide growers with needed information and implement a system for effective grower outreach. The project is a collaborative effort and assembles a highly credible team to address the risks associated with pesticide use. Through the media, direct grower contacts, field days and demonstrations and farmer to farmer interchange, the Alliance will spread the word about reduced risk practices and the use of alternatives.
New applications that will be considered as part of this proposal include the following:
a) Assessing the impact of older OPs and new IGRs on parasites of scale. Both of these types of chemicals are readily available and the efficacy will be tested. The new products have the potential to eliminate the use of OPs for scale in some cases.
b) The relatively low level of scale parasites in Fresno, Tulare and Kern Counties is also a concern to the growers and farm advisors in these areas. There is speculation that long-term use of OP sprays have reduced the parasitoid populations. Studies will be set-up in these areas to look at the issue and comparisons made with orchards where there is an abundance of scale parasites. This study too has the potential to eliminate or reduce the number and type of sprays used to control scale.
c) Fungicide trials being conducted in Madera County will help in the search for alternative fungicides. Currently, there are no good substitutes for use in combating common fungal disease like Shothole, Brown Rot and Leaf Blight. This work has the possibility to reduce or eliminate the use of chemical sprays for fungal control.
d) Ants and mites are a major problem facing growers in many of the almond growing counties. Ant control plots are being set-up which will compare use of an OP, pyrethroid and IGRs for ant control. Four replications of nine different treatments will be implemented. Alternative approaches to the mite problem are also being tried using qivermectin and horticultural oils.
6. Potential barriers to adoption of reduced risk methods
a) The cost of materials and of their application may pose a barrier to the implementation of reduced-risk practices. In many cases, the cost of a reduced risk application such as Bts may be more expensive to apply than a single OP application. Usually multiple, well-timed Bt applications are required for control. This may involve more time and labor than the single OP application.
b) In some cases there is a lack of effective reduced-risk alternative available. For example, one barrier is the use of chemical fungicides for treatment of conditions like Brown Rot, Shothole, and Leaf Blight. At the present time there are no other options available to growers for control of these fungal conditions. Current trials are being carried out with biological products which could replace chemical fungicides, and this work will be incorporated into the PMA’s demonstration projects.
c) The availability and implementation of reduced risk methods and IPM practices needs to be more widely publicized. The lack of grower awareness presents a barrier to their adoption. Actual grower demonstrations, grower panels, and farmer to farmer interchange can inform growers and help relieve their concerns about having adequate pest control when using an IPM or reduced risk alternative.
d) The structure of the Pest Control Advisory (PCA) industry poses another barrier to the adoption of reduced risk alternatives. The almond industry has been slow to utilize consultants who are not employed by farm supply companies and who tend to be strong proponents of reduced risk alternatives. The costs of hiring a PCA employed by a dealer are hidden since growers pay only for the chemicals and not for the monitoring services. Independent PCAs have to charge growers up front for their time and many growers are hesitant to take on the extra payments.
e) Tradition plays an important role as a barrier to the adoption of reduced risk alternatives. Changing grower practice is difficult when growers perceive a risk to their livelihood if they lose quality and yield. Growers need to be shown that they can reduce costs, use alternatives, and still make a profit.
References:
UC Pest Management Guidelines for Almonds (UC DANR, Pub #PMG1)
IPM for Almonds (UC DANR Pub. # 3308)
IPM for Walnuts (UC DANR Pub. # 3270)
Almond Production Manual (UC DANR Pub. #3364)
Biological Control in the Western United States (UC DANR Pub. # 3361)
Publications
Division of Ag and Natural Resources
University of California
6701 San Pablo Ave.
Oakland, CA 94608-1239
(510) 642-2431
fax (510) 643-5470
World Wide Web sources
For almond arthropod and disease pests see the almond section at:
For almond weed pests see the walnut section at: