New York researchers study pheromone disruption
In 2005, fruit growers in New York state’s Lake Ontario fruit region began to notice significant worm infestation in apples. Codling moth (CM) was identified as the predominant pest. A survey conducted at processing apple receiving stations in 2007 recorded more than 300 truckloads of apples with CM and other larvae, detected from almost 80 growers in western New York; damage peaked in 2008, to almost 400 truckloads of infested apples from 110 growers.
New York growers had little experience with the use of pheromones for mating disruption of CM, and had only two classes of insecticides to address these insects: organophosphates and pyrethroids. Growers also had little understanding of the critical timing of insecticide applications under these high populations. Funding from the Northeast Center for Risk Management allowed a demonstration of “area-wide” mating disruption on 150 acres of relatively contiguous orchards typical of western New York apple production, with four main growers and a consultant who worked with the growers from 2008 to 2011.
Growers and project leaders collaborated on best spray timing and insecticide choices. During the first season, however – as technology in pheromones was developing – labor was limited to install hand-applied dispensers at a rate of 200 per acre – so it was limited to 10 acres. Therefore, these processing growers opted for sprayable pheromones. The subsequent season, however, most pheromone products used were the “Puffer” dispensers that would spritz aerosol pheromone in the tree tops – hung at a rate of 1 per acre – which reduced the labor required. The Puffers maintained a consistent, effective plume of pheromone, which is not accomplished using sprayable formulations susceptible to weathering with rainfall. Isomate TT was also installed at 200 per acre in a 20-acre section (2009-10), but no differences in performance were detected.
We gathered spray records and costs related to codling moth control and conducted a partial budget analysis, which showed an increased profit of high-yielding, high-value apples going to processors, and reduced damage. After the third season, a net present value analysis was conducted in high-pressure orchards, with and without the use of mating disruption, to get these pests under control.
The cost of planting a new orchard ($6,800-$13,000/acre), whether for fresh or processing, is significant, therefore the price growers receive for their fruit and the marketable yield is critical in determining whether a grower will recoup his investment. Under low prices, a new processing block will take more than 30 years to recoup the investment, while it commonly takes 15 or more years for a new fresh block.
We compared how net cash flow was affected for the three years (years 11 through 13) following the initial year (year 10) of the codling moth infestation for both treatments, using mating disruption against a more traditional chemical approach. This comparison did not consider the time value of money. We also compared how the two approaches affected the overall profitability of the orchard using a discounted cash flow, the accumulated net present value of profit at a 5 percent discount rate by year 13. This method takes into account the time value of money. Two processing varieties, Cortland and Idared, were compared at two yield levels.
This project demonstrated a significant reduction in moth trap capture, as measured by the seasonal total number of adult moths captured in pheromone traps. The number of moths caught in pheromone traps was reduced in the second season by more than 90 percent. Although oriental fruit moth (OFM) was not a major pest in this project, the trap numbers were significantly reduced after the pheromone for OFM was included in the Puffer formulation in 2010 and 2011.
Growers have increased reliance on more accurate insecticide timing models relative to weekly trap reports. They have learned that controlling the first generation will increase the success of control of later generations and prevent worms in fruit at harvest. Trap networks have also consistently demonstrated an extended flight of the first generation under heavy populations, and a third insecticide application for the overwintering moth flight is necessary to prevent late first-generation egg hatch.
Growers have learned to use more effective insecticides for these pests, with low environmental and worker risk and reduced reliance on less effective pyrethroid and organophosphate insecticides. The New York Department of Environmental Conservation registered Assail for use in 2005, Calypso in 2006, Delegate for the 2009 season and Altacor late in 2009. The addition of these new, but expensive, insecticides played a large part in improving control of internal leps, where growers were able to get good spray coverage.
Where growers are struggling with control of CM and OFM, resulting in lost fruit value and loss of market, the addition of mating disruption pheromones was shown to be beneficial and to increase profitability – when other necessary strategies of control were in place.
By Deborah I. Breth, Alison De Marree, Cornell University