Pest Management Approaches for Raspberry Growers with Heather Leach


Well as beth was saying i applied for this say a graduate student grant to help support my master’s research And so a lot of the data i’m going To present is from that and so i know the talk says i’m going To focus on pest and raspberry but for those of you who work in raspberry Or other berry crops you know that slight losers aqua is the pests that we’re really talking about so my talk is really gonna focus on spotted wing drosophila and if you can’t hear me just give me some motion and all i’ll shout a little bit louder at ya So before you start talking about, spado in drosophila management i wanted to go back to Integrated pest management and really understand what that idea is and remember that you know that’s our ultimate goal is to use the best tools We have available to manage pests and the pest complex on a farm right so we know that there’s this combination of prevention of cultural control of physical control biological is also important and then we have chemical control when we talk about spotted wing drosophila we know that it’s really disrupted our pest management system So we are pretty much entirely reliant on chemical control and that’s you know that’s not our fault that’s just what we have available to? control this pest right now but as you can imagine this is not a great situation to be in right because if chemical control for some reason fails say you have resistance Or it rained or so you know something happens on your farm then you’re kind of sol there you know that we? We’ve got spotted wing drosophila that means you’ve got maggots in the fruit so really what we need to do is focus on these other control methods that we can use to help support integrated pest management on our farms and control this test So again i’m going to talk about these four branches of integrated pest management i’m going to talk about Physical first then we’ll go into cultural control and i have a lot, to say there and then we’ll talk briefly about biological biological control so you can understand what’s happening with research there as well So again i’m going To focus on physical control and with that comes exclusion netting and so we did a project in 2015 and 2016 looking at exclusion netting in both small structures and then and also in large high tunnel structures so what we want to know there is if we put exclusion netting on some sort of structure will it keep swd out of raspberries So i’ll start with that all skill study we did first And so what we did here there’s a lot of info here but basically we had plots that were untreated plots that were covered in this this netting structure plots that were only treated with chemicals so we had a Five, to seven day rotation of? Highly efficacious materials and then we had a combination so we had both netting and insecticide to see if that would help further reduce our infestation problems So what we can see here those are different sampling baits and then we have the average number of larvae that we have per gram So this white bar is that untreated and so you can see it’s really high if it’s not treated then you’re going to get infestation and that way what you see subsequently is this insecticide control this yellow bar and then that netting control that red and so what you can see is if you either put netting on or insecticides you get a reduction from that untreated control which you would expect but what we’re also seeing is that that combination treatment is Resulting in the lowest possible infestation so we know that these two methods are working together to further reduce infestation so this was data from 2014 when we jump in 2015 we sampled at a different time in the year here so we sampled in july and that’s you know when we don’t have as? many issues with spotted wing drosophila but i kept this up here because i want to show you that again we see high High a number of infestation in the untreated plots and then the same trend as before We have combination treatment resulting in the lowest possible infestation but what we also see here is this delay so you start to get infestation in these control in these treated plots not the Combination and then it’s not until a couple about ten days later that you start to see that infestation in that combination treatment so this is really important especially for raspberry growers to push fighter wing drosophila infestation as far as you possibly can and just give you a better better control of this pest and longer control so what we learned from that is that netting reduces swd infestation insecticides also reduce infestation but that combination provides the greatest control and we also saw that that combination Delays spotted bang by up to ten days So what we did from that data is decide to go big we wanted to understand what it would be like in commercial production So what we did is use exclusion netting on high tunnels so we did this in an organic System where we just had a little magnetic strip closed door and then we also did this in a conventional production system where a via these big barn doors that would allow for a tractor pulled sprayer to get in and out and on the inside of the tunnel it looks like this So you can see there’s this nice wall of netting here on the inside and then this is looking at the outside So we had these netted tunnels and then right next to that we had an open ton home we were just comparing infestation season long so What we found again that open tunnel or that kind of untreated tunnel was in that white bar and so this is as As the season goes on and the number of spotted wing drosophila we’re getting we see that in the open tunnels we get infestation much more we have a lot more spotted wing drosophila in the netted it’s suppressed we’re still getting spotted wing drosophila activity especially later in the season And it looks like there’s a you know you apply Insecticide sprays then you’re able to get control so what we found is that netting is Effective but you need to be on your game you need to be patching holes you need to also be spraying and making sure that they’re staying out of those situations Again i want to point out the delay so the first catch in the open tunnel happened in late june and then the first catch we had in the netted tunnel happened in late july so again this delay is really important if you notice this first catch is almost at the end of summer harvest so There’s a potential here to keep? larvae out of your raspberries for the entire part of summer harvest if you have summer producing rice berries so that’s a really good advantage here with many as well We also found again that it reduces infestation across eggs larvae and adults again we’re still getting Because we’re still getting some swd found in those netted tunnels so it’s not perfect overall we found about a 75% reduction with netting and i will say that other people are trying netting across the us and in europe and they are having really good luck some are not having to spray any insecticides at all if they’re able to keep you know everything patched keep their door closed in fields so the next thing i want to talk about moving on to cultural control is understanding our landscape that surrounds our and if there’s alternate hosts and what we can do about those and how those alternate hosts will affect spotted wing drosophila populations So again in michigan and wisconsin is very similar we have these farms with a lot of wood lots and then we have in those? wood lots a lot of different wild raspberry wow black berry honeysuckle a lot of different fruits and spotted wing drosophila will use those fruits So what we did is a study in 2016 and in 2017 to understand surrounding blueberry what wild hosts are there what are they using and what’s available to them and then does the presence of those hosts increase the severity of spotted wing drosophila and also the onset and so what i mean by that is if you have number of swd by time without hosts you would expect this general population growth where you see first early catch in the spring and then it goes up in the summer potentially with post what you might see this is hard to see here but you might get an earlier catch and then a result in A higher population so that’s what we were looking at we wanted to see if that was true or not, so again as i mentioned if you walk around the edge of a farm there’s a lot of other hosts that you can you can pick up so this was me walking around the edge of a blueberry farm and just looking at other fruits that i could i could collect So this is clearly a problem this is something that’s probably not sprayed because it’s against the label to spray and it’s also probably teeming with swd So we’re getting the support of swd populations and we’re trying to understand what we can better do about that So we know that spotted wing Drosophila like a lot of wild hosts and so here’s a list going down of what we found this is by no means a comprehensive list they will utilize a lot of different things but this is what we found surrounding michigan blueberry crops and so this is organized also By the seasonality of this so in the late part of the season we get a lot of american pokeweed autumn olive dogwood crabapple some of those late fruiting sees late fruiting varieties In the early part of the season we get blackberry raspberry and then honeysuckle now i want to focus on that honeysuckle because honeysuckle fruits before blueberry fruits so there’s that potential that honeysuckle could help build up spotted wing drosophila populations and then move into the blueberry so again we were testing that and what we did is basically sample those so again this is hard to see but here is a Honeysuckle bush and if you look really closely you can see little red fruits and then here’s that blueberry crop so again they could potentially Hang out in this honeysuckle build up populations and then go over to the blueberry crop so what we did is sample those honeysuckle basically what we did for 2016 and 2017 Is collect the honeysuckle that was their monitor adult populations and also monitor the larvae in the blueberry crop So this is our basic setup so we worked at six different blueberry farms in west michigan and what we had these white white circles mean Blueberry crop that was surrounded by a non hoe so something like an oak tree or a pine tree something they can’t reproduce on and then we also had sample sites that were within the woods there these green green circles indicate blueberry crap that was next to honeysuckle And then again those stars indicate where that honeysuckle is on that farm and then we also had sample sites in the interior of the farm so we’re just trying to understand if there’s this localized effect of that honeysuckle on the blueberry following drosophila populations So here’s another farm with the same setup again these green indicate That honey where that honeysuckle is and i was what indicate being non host areas so i’m going To show you a quick video Hopefully you’ll be able to see this okay but this is a heat map as we go throughout the season starting in june Okay and you’ll start, to see some blue dots here that’s indicating spotted wing drosophila presence and you can start to see that red come in and if you notice that red is really focused where those honeysuckle bushes are so this is really giving us a good indication that honeysuckle is impacting populations if you also notice while you watch that that we found swd all throughout the farm but they are more severe in those areas so again we’re we’re being told here that spotted wing drosophila behavior is affected by some honeysuckle Production so now i’ll show you the numbers what we are finding so if we look at s dvd activity adult Activity so what we found in the traps if we just look at the woods here we found that overall this green line is where the honeysuckle is we have a higher population In the honeysuckle compared to that non-host and this is throughout the season here if you look in the crop it’s a little bit messier So again we have throughout the season and the number we see so that green line still remains on top so that Crop next to the honeysuckle and then that blue line is the interior and somewhere in the middle there is the crop non-host So that means a blueberry that’s adjacent to something that’s not a host i’m so i’ll show you those numbers that we just look at season-long averages 2016 is on the left and 2017 is on the right we had very different pest pressure here throughout these different years i don’t know if you guys also had really big problems with swt this year but if you notice our average year was around 40 to 50 per trap and then 2017 it was around 3, to 400 so really really bad years for us but what we found again is that honeysuckle overall has the greatest number of spotting drosophila adults and then anterior has the lowest and this was especially apparent in 2017 but what we also found is that that crop honeysuckle had significantly more spotting drosophila activity than that anterior or the non host If we look at infestation that’s again a little bit messier but that green line is the number of spotted wing drosophila larvae we see per fruit And so what we see is that initial infestation does occur greater near the crop honeysuckle Near the blueberry adjacent, to the honeysuckle As, we get later into the season that trend kind of disappears i think what’s happening there is that one spot i mean just awfully Populations get so high here they start to spread out, to the rest of the farm Again season-long averages we’re seeing that the blueberry adjacent to the honeysuckle has significantly more Infestation compared to the interior of the crop it was not Significantly statistically different from the crop mix to the non-host but we’re still seeing this trend and are still seeing a higher higher number of larvae so this is telling us that yes alternate hosts do affect swd populations and this probably means we should be managing them in some way right It’s hard to say what that management is and we’re still going To be working on this neck year to understand if it’s worth it to go out there and remove that honeysuckle or those alternate hosts But i think the more important takeaway here is walk around the edge of your farm and understand what’s out there Because that’ll help you detect those hot spots and understand where spotting drosophila populations are going to come in from if you’ve got a big Stand of raspberries or a big stand of honeysuckle i would say it’s probably worth it to remove that out especially if you’re already going out there this winter and doing some pruning Next i want to talk about harvest frequency with raspberries so again staying on that cultural control theme so understanding if increasing our harvest frequency can decrease infestation that we see in raspberries so i’ll go over this kind of quickly but basically what we did in 2016 and 2015 was To have raspberry plots there are either harvested every day every other day or every two days and we just took all those fruit from those samples and looked at its following drosophila larvae and what we found here the average number of eggs or larvae we see and eggs first and second and stars and then third in stars so if you harvest every day or every two days you get a significant reduction compared to when you harvest every three days, for each of these life stages And i also want to direct your attention to this third and stars so this is probably this you know the smallest infestation you’re thinking that doesn’t matter as much But really that’s the most important because those third end stars are the ones that aren’t visible to the naked eye So we pop open the fruit and you can see that little worm going inside so you can potentially get complete Eradication of that third instar larvae when you harvest every day or if you harvest every two days you get Significant reduction so again i think that harvests raquin see if you’re able to you know provide the labor this is probably the best thing we have aside from chemical control so i’d really think about whether or not you can employ this on your farm and i also want to talk about sanitation practices really quickly a lot of our growers in michigan were removing their waste fruit but then they would say leave it in the bucket next to their farm and we’re kind of thinking that that’s probably not the best thing to do right because spot a wing drosophila will come out and then go back into the crap and just reinvest so we want to suppress those adult populations as much as we possibly can So what we did is a bagging study just to understand how long it takes for those larvae to die once their bags So we bagged this waste fruit something like this and we found that if you leave that bag and in the sun for 32 hours 99% of the larvae are killed really i think it’s incredible that 1% of the larvae will still survive after being pegged for 32 hours and the hot sun But well we also found that clear bags will get hotter than black or white bags so i’d recommend using clear bags so you have that greenhouse effect and kill them a little bit faster there I also want to talk a little bit about pruning practices and understanding how that can reduce infestations so i’ll talk about this in blueberry and in raspberry and so what i mean by that is just basically opening up that canopy making it so you’re changing that microclimate and you’re making it less hospitable for spotted wing drosophila To lay eggs and to like hanging out in that area you’re also going, to increase spray spray penetration by doing that So what we did again bradbury’s on the top and blueberries on the bottom so what we did here is have what we called a grower standard where it was we thought what the standard practices were for pruning and then we had treatments where we pruned more than that so we removed even more in case of raspberries we removed all flora canes And then we had 25% less pruning where we left a lot more material In the canopy and we just looked again at infestation season long when we talk about Raspberries we might see a numerical difference when you prune more compared to less pruning but We didn’t see any? statistical difference i think part of that is because we were on a v trellis so that means the fruiting wall is already on the Outside so most of the infestation and the but what’s going on and the canopy is already on the outside so it’s not really important what’s going on the inside and blueberries however we did see a strong effect here is if you have some amount of regular pruning we get significantly less larvae than if you just leave the bush so i think this is more take this as a reminder to keep your pruning practices making sure that you’re clearing out any any basically opportunity for spotted wing drosophila to have that nice heat and humidity that it likes The next thing i want to mention with cultural control is talking about ground floor management so again this was a trial done in blueberry And this is the same concept or trying to like manipulate microclimate and understand how microclimate is gonna change with these different Treatments so we had blueberries that were covered in woodchips blueberries that were covered in weed fabric? we had a bare ground treatment and then buckwheat treatment it turns out that entomologists are not very good at growing cover crops Yeah, so this is more of a bare ground treatment as we go along here So again we’re trying, to understand if ground floor management can reduce larval infestation When we look at the interior part of the canopy we don’t see a significant difference across these treatments but we do see this numerical difference with weed fabric this is kind of what we expected weed fabric is gonna get really hot it’s also gonna allow potentially kill those pupae that are dropping out of the fruit it’s gonna kill them because that weed fabric is so hot On the exterior of the canopy is where we saw that Statistically significant difference so we know that we can at least save for sure’s wheat fabric is having some effect we also found overall lower infestation of spada wing drosophila on the exterior part of the canopy again that’s just telling you about their behavior they prefer to be on the inside part of that canopy where they nice and protected compared To the outside but weed fabric did have that strong effect of reducing Infestation so again this was done on a small small farm small trial so we’re gonna go big this year and try to Convince some growers to put this out on their new plantings and see if we could have an effect there? so basically i have this list of things we can do for cultural control so that includes exclusion thatting scouting your landscape for alternative hosts increasing your harvest frequency remembering the sanitation practices and then utilizing weed fabric and maintaining your regular process so this is a long list of things and not all of these might work for your farm but some of them might So the idea here is that we’re starting to build up a different control method so if you kind of look at this listing and think about what you can take home and potentially use on your farm i want to talk briefly again about biological control so i’ll go over what native natural enemies might be controlling spotted wing drosophila populations right now and then also just give you a brief update on Classical biological control so going over to south korea and china where spotting drosophila is native to and then trying to introduce new natural enemies there So in that Ground floor management trial we also did a ground predation study to understand if predation was different in these different habitats So we again have that buckwheat treatment the wood chips the bare ground and the weed fabric If you squint on that weed fabric you might be able to see these little orange dots there those are sw d pupae so what we did is put pupae out For two days and then take them back in and basically see how many were damaged and also trap the trap the ground predators that were there and in a trap and understand who’s there who might be controlling spotting just awful of qp from that So this is a picture of an intact pupae and when we left him out in the field for a couple of days this is what
We found so we found pupae that obviously had these little munching marks so we know that there is some sort of predation Going on out there we’re still not sure who entirely is responsible for that i decided to share this kind of fun photo again it might be hard to make out but here we have an ant carrying away a Fruit fly and its mandibles back to its colony this happens pretty often in the fall especially when spotting drosophila populations are so high so again we are seeing that there is predation going on but not, very much of it and It’s sort of the same story when we talk about Parasitism so for the past two years we’ve been conducting a survey of? understanding what parasitoids are out there that might be controlling spoda wing drosophila so we’re finding that when we’re trapping of almost half of our collections our fruit fly Parasitoid so that’s good we’re at least on the right track there But when we look at parasitism rates in the field they’re less than 2% and that’s consistent across different states as well so it’s consistent in new york in north carolina and california where other researchers have To these studies So really this just points to the fact that we need help we need biological control we need something to be able to release So that brings me to classical biological control so again releasing natural enemies into michigan or into wisconsin To control spotting drosophila populations so there’s a group researching group out of uc berkeley who’s gone over to south korea and china Basically spent a bunch of days in the field try to look for Parasitoids and then bring them back to the us and a quarantine facility and so what we can do there is evaluate those parasitoids and understand what other fruit flies did they attack are they really good at attacking spotted wing drosophila in order to get that permit to release them, so about nine months ago we submitted a permit to release two larval parasitoids that are pictured here so they attack first and second in stars of spotting drosophila larvae and they’re pretty good at it that permit was denied and that was about three months ago that it was denied but this group is really hopeful to address those concerns and get that permit Resubmitted so it’s not gonna be this year that we’re gonna get Parasitoids but it might be the following year so i just want to give you an update that we are you know we are working on classical biological control and trying to get something released that might might help us out there and then i wanted to put in a plug – if you’re interested in a biological control and want to learn more about it in the framework of spotting drosophila management there’s a free webinar good bugs vs. Bad happening on february 23rd So there’s a link here you can register but if you’re interested in it See me afterwards and i can i can hook you up with that And then lastly i want to talk about chemical control because obviously that’s what we do for spotted wing drosophila management for the most part So i want to give you an idea of what growers in michigan are using to control spontaneous afla and raspberries So here we have the different classes of insecticides so The neonics are inbred pyrethroids are in that blue color organophosphate mouth i own is in that yellow Spinosa and biologicals are in that green and gray so in conventional and you pick operations we’re seeing pretty consistent selection of materials and you pick carries a little bit more malathion because it has that short residual and there’s more biologicals being used again because they have that short brief residual time but overall we’re seeing good rotation with conventional and you pick control and pretty good options when we go down to organic control we already know that it’s really hard to control spotted wing drosophila in organic management but again most growers are using in trust I was surprised to see in the past two years we’re still having a lot of reliance on pi ganic? We’re finding that delegate is that better auteur grande evo i’m sorry i grant Evo is a better rotation partner with entrust so if you are an organic grower i recommend using grande Evo over pi ganic because paganica does flair those mics and cause other issues So i want to walk you through a couple of spray programs just To show you what works for us and what didn’t work actually for these growers so i’m going To set these up all in the same way so here we have the infestation the average number of lardy we see per fruit capped at five which five is a lot of larvae and fruit and then we have the season as it goes this white bar is the number of larvae we see and then these little rain clouds indicate rain that was over half an inch So i just want, to show you this is an example of a spray program that was first started too late so you can see they didn’t start until august and they did an application of brigade infestation was already really high but that application did bring it down ten days later they followed it with malathion Again that interval is pretty long but they’re starting to again they go back in five days later with brigade two days later with the application of math phi and following that rain bringing spotting drosophila populations down six days later with delegate and then 19 days they finished off the season with another application of brigade So what we’re finding here again is that they started too late and their intervals were irregular and just too long But the nice thing you know what i like to take home from this graph is we had Infestation levels up to four and five larvae per raspberry that’s really high infestation but what we are learning is that if you shorten your intervals and apply appropriate materials you can bring that down So i think that’s that’s something that you can take away from that? looking at another spray program we start the application early with malathion six days later with grand devo 3 days grand devo six days malathion three days grant devo four days delegate three days Grand, devo and a tank mix with the sale and that’s when that spray program ended i think what happened here is this grower sprayed himself out this is a lot of applications but they worked they were able to keep spotted wing drosophila larvae low We didn’t see that infestation grow until we got that rain period so that last application actually lasted a pretty long time but this again was a good spray program and you’re using Materials that wash away clip quickly so this was this particular farm was a you pick so they’re interested materials that are only going to last a few days And then the last program i want to show you is kind of what i see is the cadillac method if you’re not using any other of these cultural control methods that i presented earlier and So if you go through this you can kind of? see that they’re rotating their materials really well they’re using tight intervals and they’re loosening their intervals when they can so when they have a gap in the weather they can loosen but when they it starts to rain again they starting to tighten their intervals and we get really successful you season-long control here this is an intense spray program but again it’s a really good example of using good materials season-long and rotating those materials to avoid resistance so again i’ve kind of talked about these four branches of integrated pest management and what works with us in michigan and what we’re seeing cultural control is more and more important i think and i you know kind of created this list for you of things that you can do on your farm again this is a long list and hopefully some of it will work for you hopefully you can take home some of this on your farm So i think i’m optimistic about claude oh he was awful of control we’ve only talked about spotting drosophila long term i think We’re starting to bring the balance back by no, means have we fixed this problem or created ipm on farms yet But i think we’re you know we’re continuing to try and we’re getting better and better at it so i want to thank the folks that worked on this especially our summer hires and the field technicians that we have Grower collaborators i wouldn’t be able to do it without the gar collaborators so for those of you who work with researchers It’s super helpful and it allows us to get this great data so that we can then present it to you And i of course want to thank the sare program for inviting me here to give this talk But, also for the opportunities allowed in the grant funding you

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