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| We’ve heard some great presentations today that form the foundation and pillars of an IPM program for codling moth management. I’ve been tasked with building the IPM roof over that framework by reviewing my approach to IPM in general, and codling moth specifically. | Title slide. Presentation title: Building the IPM Roof. Author information: Byron Phillips, Senior Horticulturalist, Wilbur Ellis Company. |
| I’ll do that by sharing some of the questions that I ask when building an IPM program, and how I might adjust tactics based on field observations. First let me say that I view IPM as a data-driven strategy but with site-specific tactics. | Slide titled “Approach to IPM” contains bullet points highlighting that it is data driven and site specific. |
| When building an IPM program I always start with pest biology. We know that insect development is absolutely tied to temperature. The length of time it takes to complete a phenological stage or a generation is temperature regulated. We have some very good models at our disposal to help us know where insect development is. Many codling moth models rely on synchronizing the model with phenology of field populations by setting a biofix. There’s some confusion around what determines biofix unfortunately. Is it first moth catch or is it first consistent moth catch over two or three consecutive nights? And in order to set a biofix, are traps checked every day or just once a week? Do you have an Azinphos-methyl resistant population that has a delayed emergence? These things could make a significant difference. The widespread adoption of mating disruption throws another wrinkle into setting biofix, at least when using pheromone lures. The current model from WSU uses a fixed biofix of 175 degree days from January 1 and synchronizes phenology from there. In other areas the fixed biofix varies depending upon latitude and altitude, and depending on the area can range from 175 degree days to 265 degree days. If you are not setting a biofix based on trap catch it’s important to select the model appropriate for your site. | An outline slide introduces discussion questions about codling moth development, degree day models, biofix selection, and variation in phenology across orchard conditions. |
| One of the questions that’s come up in recent years is whether there is a significant difference between in orchard and extra-orchard temperatures, and if that could perhaps be a reason why we sometimes observe flight curves that don’t line up with model predictions. Most of our weather stations are located outside of orchards and are not affected by things like canopy cooling effects of grass drive middles, irrigation, and overhead cooling. To look at this further, we installed two Atmos weather stations at a commercial orchard near Othello in 2021. One station was cited according to standard protocols established by WSU AGweathernet for tier 3 stations. The second was about 50 yards away, but was located in a tree row under the canopy of a mature, full-size granny smith block that was overhead cooled in the heat of the summer. You can see here some of the results comparing in-orchard and extra-orchard temperatures. Generally in the early season we found warmer days and cooler nights inside the orchard. Mid-season showed warmer temperatures outside the orchard as would be expected, and late season there was really no difference between the two. Bottom line though, for one year at one side at least, there was never more than about two days difference in counting moth degree day accumulation. Not enough of a difference to have any practical management implications. | A table and line graphs compare in-orchard and extra-orchard temperatures and codling moth degree-day accumulation across multiple periods in 2021, showing that that the differences between the sites were negligible in terms of codling moth management. |
| While we know that calling moth development is strictly temperature driven, there are other factors that could affect observed flight curves making them appear to deviate from the model. If mating disruption is effective, for example, we are likely delaying trap catch and we tend to hammer the early part of the codling moth generation with our material selection for petal fall leaf roller and thrip sprays and codling moth ovicides. This is almost certainly selecting out the early part of the generation in many cases. | An outline slide introduces discussion questions about codling moth behavior, including outside factors such as weather, mating disruption, and sprays. |
| Weather is another critical factor that affects codling moth behavior. For example, you could have fully developed codling moth adults in the orchard, but unless conditions at dusk are right, they won’t fly, and you won’t have trap catch. This is another reason we can have observations that don’t line up with model predictions. One of the things that having the weather stations in Othello allowed us to do was to go back and look at mating opportunities of the overwintering generation early in the season. If you just looked at temperatures at dusk in May, there were 11 evenings with temperatures warm enough for successful flight, female location, and mating to occur. | A line graph shows estimated codling moth mating potential in 2021 in Othello, comparing average dusk temperatures inside and outside the orchard over time. A horizontal line marks the lower temperature threshold for mating, showing that dusk temperatures fluctuate above and below this threshold depending on date and location. |
| However looking at other factors that can affect codling moth flight, those opportunities were reduced substantially. There was no rain in May so that wasn’t a factor, but when we looked at wind speed during those dusk hours there was a huge impact on flight. With wind factored in, there were really only four opportunities for successful mating to occur. Those happened to be on four consecutive evenings the second week of May. There was one additional opportunity the end of May, but by then mating would have been delayed for so long that success rates were likely very low. The reduced and delayed mating opportunities would show as a delayed flight curve, deviating from model predictions. | Blue circles are added on the line graph highlighting the five actual opportunities for mating based on weather conditions. |
| Monitoring is a critical component of any pest management strategy. For codling moth, that means trapping. Trap placement is really important. I see a lot of blocks where only corners are trapped. Unless you have a history with the block that would indicate corners are enough, this practice leaves to block vulnerable to internal populations as well as border immigration. If you only trap corners, you’ll only catch on corners, and this could lead to poor decision making based on incomplete information. What type of trap will you use? Codling moth trapping has evolved from the old molasses and vinegar bait traps, to black light traps, to Wing traps, to Delta traps, and now see, even some camera traps are being used. Does trap type influence codling moth catch? Our treatment thresholds were developed using wing traps. Most of our current traps are Delta traps and trap catch between those two types is similar. Camera traps have a different opening than wing traps or Delta traps. Does that make a difference? For me, we don’t know enough yet to rely on camera traps. What about trap density? Our thresholds are based on one trap per two and a half acres. I’m comfortable with one trap for five acres. I would bet that our industry average is closer to one trap for 15 or 20 acres, and I think that gets us into trouble sometimes. Which lure will you use? How do you correlate trap catch and treatment thresholds among the different lures? What are the new VOC lures really telling you? They’re great at monitoring presence, but I don’t think they can necessarily be used to evaluate effectiveness of mating disruption. Regardless of lure type, in mating disruption blocks, I like to use a few strategically placed 1X lures to tell me if I have any gaps in pheromone coverage. | Slide outlines key considerations for codling moth monitoring, including trap placement, trap type, trap density, and lure selection. Images of the different trap styles are displayed along the right side of the slide. |
| As I mentioned trap placement is an important consideration. The photo on the left here is a heat map created from trap counts from a block that was only being trapped on the corners. We knew there was immigration in the northeast corner of the block, but I wasn’t convinced that was the only source. We deployed traps on a one acre grid across the entire block and discovered that there was an additional pressure source on the western border that wasn’t known or suspected. And we also showed that there was no pressure coming from the bin pile in the southeast corner of the block, which was a bit of a surprise. Intensive trapping like this can help identify both internal and external pressure and lets us manage accordingly. On the right is a photo of an unfortunate placement of a codling moth trap in a tree. While this location is beneficial for the trap checker riding through the block on a four-wheeler, it’s not good for catching codling moth. Traps need to be placed in the tops of the trees. | Slide contains two photos, on the left is a heat map of codling moth pressure in a specific block as outlined in the audio. The photo on the right is of a codling moth trap which has been placed far too low on the tree, around 4-5 feet off of the ground. |
| The first thing I consider when deciding on mating disruption is the number of point sources per acre. I’m a firm believer that the more point sources you have, the more effective mating disruption is. I prefer to use 400 passive dispensers per acre. Research has shown that 400 is more effective than 200 or 300, but you don’t get any additional control when you exceed 400. So 400 is my target. About the only exception to this for me is that, given labor costs, if I have a block with no or very low pressure, I’ll probably hang 400 passive dispensers on the borders and perhaps use aerosol emitters internally. Other things to consider when designing a mating disruption plan include things like block size and shape, topography, potential gaps in coverage from recently removed or grafted trees, and dispenser life. Are you using 150 day dispensers or 180 day dispensers, that can make a big difference late in the season. Finally, think about dispenser placement. Like traps, these need to be hung in the upper part of the trees on branches stiff enough so that they won’t bend down to the ground when loaded with fruit, like in this photo. I also don’t like seeing dispensers hung on trellis wires, and there really is no need to hang them on newly planted trees two feet off the ground. | Slide titled “Codling Moth Mating Disruption” contains 5 photos of improperly placed mating disruption. The first two photos are of mating disruption hung on trellis wire in the orchard rather than trees. The third photo is mating disruption hung on the end of a branch which is bending down towards the ground due to fruit load. The last two photos are of mating disruption hung on very small and newly planted trees. |
| Sterile insect release has been used for several years now in British Columbia as well as a few other places around the globe. Its use in Washington has been growing the last few years, but I’m still uncertain as to its effectiveness in our conditions and it’s significantly more expensive than mating disruption. If you’re thinking about trying it, be aware that, when sterile moths are released, they will flood traps; both yours and your neighbor’s. One of the disadvantages of using camera traps is that they can’t distinguish between sterile moths and wild moths, so you’d still need to do that manually. These are heat maps of trap catch in a block that used sterile insect release last year. Sterile moth catch is on the left and wild moth catch is on the right. It doesn’t appear that sterile releases reduced wild capture in the southwest or northwest corners, but I don’t really know that trap catch is necessarily a good way to evaluate sterile insect release effectiveness. | Slide titled “Sterile Insect Release” contains photos of two heat maps of trap catch in a block using sterile insect release. The map on the left is of sterile moth captures and the moth on the right is of wild moth captures. |
| There are several predators and parasitoids that will attack codling moth, but biocontrol of a direct pest that we’re trying to manage to zero just isn’t practical on a commercial level. Entomopathogenic nematodes have been researched for years, initially as a bin treatment in the packing house and now as a trunk and soil treatment in the fall. I just haven’t seen these be very effective under field conditions especially given their temperature and moisture requirements. I’m also starting to think that we may be developing some resistance to the granulosis virus. If not resistance we are certainly seeing control slipping in the field especially where it’s been used on a weekly basis all season long. I’ve seen as many as 20 applications of granulosis virus in a season with no reduction in trap catch or fruit injury. | Slide titled “Biocontrol” contains a photo of spider on a web which is suspended between two plants. To the left is a list of several biocontrol approaches for codling moth. |
| Studies have shown that predation provides a higher level of codling moth control than parasitism. And I’ve seen some good predation by spiders especially in the fall and winter when banding has been used. In this photo on the left every one of those coding moth hibernacula was inhabited by a spider, and all of the larva had been consumed. | Two images appear, on the left is a photo of many codling moth hibernacula on a corrugated cardboard band. The hibernacula have been inhabited by spiders. On the right is an image of an adult spider on the leaf of an apple tree. |
| I think the bigger consideration for biocontrol when planning codling moth programs is the effect of control tactics on natural enemies of other pests. This means knowing both acute toxicity as well as sub-lethal effects of any pest control products applied, and making applications when natural enemies are less susceptible, such as early in the season or when parasitoids are inside their host. Unfortunately, we still don’t know enough about the biology and ecology of most of our natural enemies to always be able to make well-informed decisions. I’ve been asking for this for almost 20 years now and we’re still lacking adequate information. | Slide titled “Biocontrol”. Text on the upper potion discussed biocontrol considerations and limitations. Along the bottom are several images of natural enemies, including a brown lacewing adult, a lady beetle larva, and lacewing eggs. |
| There are several cultural management tactics available to us, including things like pruning to improve spray penetration, thinning to remove clusters, and orchard sanitation. Even the planting system can affect codling moth behavior and control tactics. If trees have smooth bark, that forces codling moth to overwinter in the ground rather than on the tree. Raking the debris out of weed strips in the fall will disturb these overwintering sites and provide some level of control. Of course if a grower has mulch down, or is using mow and blow, raking really isn’t an option. But that might be a place where a fall application of nematodes might be effective. Plus the mulch provides an environment that’s suited for nematode survival. Tree banding can remove a lot of codling moth from the orchard, but comes with a significant labor cost, so probably isn’t practical unless populations are very high. If banding is used, they need to be removed and destroyed no later than pink stage the next spring. | Slide titled “Cultural Control”. Text to the left discusses cultural control options and limitations. To the right are two photos of codling moth larvae inside corrugated cardboard bands. |
| There are also some exclusion tactics available for use, but in most cases the labor costs to install them are prohibitive. One exception to that might be drape net. Other cultural practices that should be part of an IPM program include scouting for abandoned blocks and any feral trees in the area, cleaning up potential overwintering sites like brush piles and dumps, and not bringing bins into the orchard directly out of CA storage in IPM programs. | Slide titled “Cultural Control”. Text to the left further discusses cultural control options and limitations. To the right are three photos. The first and second are of unmaintained orchards, one with a great deal of fruit seen on the trees. The third image is of an area in which culled fruit has been dumped next to an orchard. |
| I view chemical intervention as a secondary tactic that supplements other tactics that are used first, not as the primary control measure. In the case of codling moth, chemical intervention supplements mating disruption. We’ve gone through a dramatic evolution in chemistries available to us for codling moth management in the past 15 years or so. Our old programs that were based on organophosphates actually provided a pretty stable pest management system. Those broad spectrum products were effective across a wide range of pests, worked on contact, and were effective against all life stages. So timing wasn’t as critical. The newer chemistries usually target specific life stages such as egg or larva, usually need to be ingested, and require much more precise timing. The change in chemistries destabilized our old IPM system, in particular the removal of OP’s and replacing them with something like spinetoram, resulted in significant flare-ups of woolly apple aphid and two-spotted spider mites. The flip side of that though, is the almost complete disappearance of other pests like Lacanobia, white apple leafhopper, and western tentiform leafminer. | Slide titled “Chemical control” contains a bullet point list outlining chemical control options, advances, and limitations. |
| The point is that there are several things that should be considered when deciding on which new chemistry to use. After efficacy, which should always come first, the most important consideration for me, is the effect of a product on natural enemies. WSU’s Decision Aid System has some really helpful information about this. As you can see in these screenshots on the right, that information alone to me is worth the cost of the subscription. We also need to balance resistance management strategies with both the effects on natural enemies and with MRLs for export markets. We use a lot of oil in our industry as an ovicide in our codling moth programs, but there are times when a sticker or a UV blocker would be a better fit than oil. One thing that really bugs me about our codling moth control programs in recent years is the overuse, or for me, any use of Lambda-cy. I understand it’s effective against all life stages, and I understand it’s cheap compared to the other products available, but it’s just so extraordinarily disruptive of IPM that I cringe when I see how much of it we’re using. | Slide titled “Chemical Control” contains a bullet point list further outlining considerations that need to be made in chemical control programs including residual activity and effects on beneficial insects. To the right are example screenshots of the Decision Aid System showing information on pesticide effects on beneficial insects. |
| Finally, there are some socio-economic factors that I consider when approaching pest management. Every tactic we use comes with an associated cost. Does the tactic generate a positive return on investment? If it doesn’t, then we should look at other tactics. What is the economic profile of the grower and/or the block. I like to use these three general classifications shown here when designing pest management programs to fit the economic circumstances. This helps me to optimize the use of available tactics, given the constraints of resources and operational conditions. | Slide titled “Socioeconomic considerations” contains a bullet point list outlining economic considerations as well as three colored bubbles outlining the categories a grower or block could go into. The first bubble is for orchards that have low cash, insufficient labor, high pests, and are not profitable. The second is for orchards that are middling in those categories and are breaking even. The third category is for growers who have adequate cash and labor, low pests, and a profitable orchard. |
| That’s all I have. Hopefully I’ve left you with a set of questions and considerations that can help with the design of an IPM strategy for codling moth specific to your blocks. Thanks for hanging in until the end of the summit. | Conclusion slide shows a house shaped diagram labeled “IPM at the roof. Vertical pillars beneath the roof represent different management strategies such as biological and chemical controls. The foundation blocks are labeled with supporting elements such as monitoring and predictive models. |
| Music plays | Credits for talk and video production roll. |
