Integration of Microbial Pesticides in Pome-Fruit Production in the Pacific Northwest

View the project final report

• 2009 annual report

Commodities

• Fruits: apples, pears, general tree fruits

Practices

• Pest Management: biological control, biorational pesticides, field monitoring/scouting, mulches - killed, weather monitoring

Codling moth (CM) remains the most significant insect pest encountered in pome fruit production in the Pacific North West. Mounting evidence suggests that the CM granulovirus (CpGV) and other microbial-based pesticides (spinosad, Bt and entomopathogenic nematodes) now provide effective and safe methods for managing CM and other orchard pests in the region. Since 2003, for example, CpGV and mating disruption alone have successfully controlled CM in a 7 acre organic orchard located near the Yakima Agricultural Research Laboratory (< 1% fruit damage despite repeated re-infestations). To date, the adoption of CpGV and other microbials is largely limited to organic producers. Historically the availability of cheap and effective broad-spectrum organophosphate insecticides (OPs), notably Guthion (azinphos-methyl), has provided few incentives for conventional growers to switch to reduced-risk pest management programs. This situation is changing; the Environmental Protection Agency has announced that Guthion will be phased out by 2012, with permitted application rates reduced starting 2008 [http://www.epa.gov/oppsrrd1/op/azm.htm]. Consequently conventional growers in the Pacific Northwest (PNW) are facing a shift to new insecticide products. Although new tools for controlling insect pests are available, there will be a transitional period as growers adapt to new products and chemistries. We believe that microbial pesticides have a role in this transition. In 2002 applications of CpGV were minimal in the PNW; in 2003 approximately 6,000 acres were treated; by 2006 over 86,000 acres were treated including some conventional orchards. The future potential is illustrated by Europe, where CpGV is now used on 100,000 acres, with this usage mostly in conventional agricultural production where it is effectively used in combination with other soft methods such as mating disruption (information from Rob Fritts, R&D, Certis/Advan, USA and Don Thomsom, R&D Biotepp Corp). By contrast, although research shows that entomopathogenic nematodes may be used for post-harvest control of overwintering CM in the orchard, this method has not been widely adopted, largely because this technology is unfamiliar and operational use strategies for nematodes are different from other insecticides. In the USA, significant questions about how CpGV, nematodes and other microbials can be effectively adopted and integrated in conventional agriculture remain. Our proposal represents a strategy to evaluate the success of microbial pesticides for control of CM and leafrollers. We will work with organic growers who rely extensively on such products and with conventional growers who may include microbials (mainly CpGV) within their normal spray programs. Reasons for the latter approach include worker health or environmental concerns, resistance management and short pre-harvest and restricted re-entry intervals associated with microbials. In addition, we will establish baseline data on CpGV susceptibility in CM to that will allow monitoring of the threat of resistance (which has been confirmed in Europe) and continue specific lines of research to improve the effectiveness of current commercial formulations of CpGV through formulation and testing of adjuvants. In addition to on-site interactions, our outreach plan includes organizing a series of lunch time grower meetings with the theme of ‘Reducing reliance on OPs.' In temperate climate, diapausing cocooned codling moth (CM) larvae make up 100% of the population. Control of this stage of codling moth would reduce or eliminate damage by first generation codling moth in late spring and early summer. Entomopathogenic nematodes (EPNs) are good candidates for their control in the cryptic habitats used for larval overwintering. The two predominant limiting factors for EPNs are adequate moisture and temperatures below 15°C. Our research will include the use of anti-desiccant agents in mulch and on tree trunks to demonstrate improvement in larvicidal activity of Steinernema carpocapsae and S. feltiae for CM control. The need for alternatives to fumigants such as methyl bromide for quarantine security of exported fruit has encouraged the development of effective fumigants with reduced side effects. The endophytic fungus, Muscodor albus, produces volatile compounds that are biocidal for several pest organisms including plant pathogens and insect pests.

Conduct research to:
(a) Evaluate CpGV as a replacement for one or more sprays with chemical pesticides. At some sites, growers will include microbial pesticides in a block or section of orchard that is otherwise managed without any microbial interventions but that has similar pest pressure (determined by pheromone trap catches). Comparisons of these adjacent sites (see methodology) will help us determine how successfully CpGV may be integrated into more conventional pest management practices.
(b) Obtain baseline data of efficacy of commercial formulations of CpGV to facilitate resistance monitoring among regional pest populations. Given the usefulness of CpGV, it is important to conserve its efficacy. CpGV-resistance has now been confirmed among CM populations in Europe that have been exposed to frequent CpGV applications for a number of years. It is therefore prudent to gather broad information on baseline susceptibilities of a wide geographic range where CpGV is presently applied. These baseline data will allow any suspected cases of field resistance to be quickly confirmed so that resistance management strategies can be adopted.

Conduct demonstration trials at our experimental orchard near Moxee.
We will utilize experimental orchard blocks, comprising 1A ‘Golden Delicious’ and 1A ‘Delicious’, heavily-infested with CM and leafrollers to compare three spray programs: 1) ‘organic microbial’, 2) ‘contemporary conventional’ and 3) ‘CM mating disruption alone’ (control). CM pheromone dispensers (MD) will be applied throughout all blocks. The objective will be to compare efficacy of each approach in terms of pest control efficacy and secondary impacts on non-target organisms.

Improve the stability and effectiveness of CpGV and spinosad under operational conditions through formulation (lignin- and particle-film based adjuvants).
This objective continues several years of research into potential adjuvants that may be used to improve the effectiveness of current formulations of CpGV. In addition, we will continue to provide technical assistance to the commercial companies producing CpGV who are experimenting with modified or improved formulations. For example, in 2007 we compared experimental freeze-dried formulations of CpGV currently in development at one of the manufacturing plants with their current commercial material in laboratory and small-scale field tests.
Disseminate relevant information such as optimal application strategies or issues of concern regarding secondary pests through specified outreach activities

Monitor the effectiveness of operational spray programs including microbials (chiefly CM virus) in apple and pear orchards.
Locations included for monitoring are sites under both organic and conventional-management practices that may or may not include organophosphates. While the former may rely heavily on CpGV, spinosad and Bt, the latter may include infrequent use of microbials. Our monitoring strategy and the biology of CpGV and Bt will allow us to estimate their relative contribution in pest control program (see below). Where possible, we will monitor sites under organic transition programs.

Evaluate the effects of anti-desiccant agents in mulch and on tree trunks for improvement of larvicidal activity of Steinernema carpocapsae and S. feltiae for CM control.

Determine the effects of M. albus volatile organic compounds on codling moth adults, neonate larvae, larvae in infested apples, and diapausing cocooned larvae in simulated storage conditions.