Scaffolds 2024 Digest: Week 17
On this week’s episode of Scaffolds, I talked to doctor Rebecca Schmidt-Jeffris. about biological control in tree fruit. Kerik talks biopesticides and bacteriophages, and Anna gives us our state of the state update on degree day accumulation and trap captures.
Monique Interviews Dr. Rebecca Schmidt Jeffris
Monique: Okay, so today I’m here with Rebecca Schmidt-Jeffris. She is a research entomologist in Wapato, Washington, at the USDA facility there. Hello, Rebecca.
Rebecca: Hi, Monique. Glad to be on.
Monique: I also wanted to add that Rebecca is the editor in chief of American Entomologist, a magazine that mostly just entomologists read, but is a very cool thing to be doing.
Rebecca: Yeah, no, it’s really fun, and it’s really different to kind of have that fun, the fun version of science writing as part of my day to day.
Monique: Yeah, it’s a totally different way of viewing, interacting with an audience, for sure. But what I really wanted to talk to you about was biological control in tree fruit, something that you are absolutely one of our top experts in, and ask you about some of the work that you’re doing. In particular – I’m interested in – you guys are doing drone releases of different types of predators. And what has been your experience with that, and what do you think the promises for the use of biological control agents in this manner?
Rebecca: Yeah. So the predator we’ve done the most work with drones is a mealy bug destroyer, which is a smaller kind of solid black with the orange head lady beetle. People don’t realize right away that they’re just another lady beetle because they don’t have the characteristic red with black spots. So with those, drones do not appear to be very promising. And that’s my caveat, you know, really, anytime I’m talking to folks about doing drone releases, is that most of our experience, the exception of one trial we’ve done this year, which I’ll talk a little bit more about, has been with those mealy bug destroyers. We’ve done a little bit with minute pirate bug, which is an Orius species, and then we’ve done some work with lacewing eggs. So for the first two things, I think the reason we’ve seen results that don’t make me super excited is those are both insects that fly in the life stage that you purchase them in. They are adults. They have wings. And so when you release something with wings above the tree canopy, its inclination is to fly and fly farther, far, far away. Those are also just two organisms. We haven’t had luck with establishing an orchard post release anyway. So it’s a little hard to compare drone versus ground releases when you find, like, two individuals post release in the ground treatment and zero individuals post release in the drone treatment. You know, does that really mean anything? Where we’ve done lacewing eggs, we’ve also not seen great results. I think that’s the artifact of, it’s an egg that doesn’t really stick to the leaf, and so it just sort of spills right off post release. But I said, we’ve got a caveat to that is, we did do one trial this year where the first set of releases we did with the drone was lacewing eggs. We saw the first time where we didn’t find any lacewing larvae post release. And in that case, it was in either treatment. I think the loose eggs and the drone eggs just don’t seem to hang out in the tree canopy. They fall out. But when we tried it again we did it comparing a drone release and a ground release with lacewing larvae, and there recovery rates on the larvae were pretty equivalent in the drone to in the ground. So at bare minimum, for getting those larvae into the trees, the drone seemed to have worked on that.
Monique: So what were you targeting on the ground in terms of pests with all these different predators? They’re such generalists, but I was wondering if there’s anything in particular that you were looking for them to be active on.
Rebecca: Yeah, so with the mealybug destroyers, it’s. It’s pretty clear because it’s in the name. targeting mealy bug. So we get both grape and apple mealy bug in orchards out here in Washington. The growers get really frustrated in organics in particular, because conventional products don’t even work very well. So you get a sense of how well the organic products work for mealybug control. So you get a lot of fruit marking, especially because those mealy bugs will jam themselves into the calyx and then get some honeydew fruit streaking for the Orius. That was the original trials. We were looking to see if they had any promise for controlling pear psylla. They don’t appear to, at least at the rates that we tested. The Orius species that’s commercially available is native to the east coast of the US, but has never been found in our neck of the woods. So I’m assuming it’s not a happy climate match for them. So there’s that added little caveat, too. And then with the lacewings, most of our trials have been looking at aphid control, although we did do some in pears to see if they could put a dent in pear psylla. And the answer, once again, appears to be no.
Monique: So one interesting thing about Rebecca is that she was a postdoctoral researcher here at AgriTech with Brian Nault. So she does happen to know a bit about the climate differences between where we are and the west coast. So when it comes to biocontrol, I think on the east coast, there might be this overall sense of a little bit of disinterest in it, where it seems like on the west coast, and even when I was working in California, like, there’s an extreme interest in this. So could you talk about maybe why this is, why is there such a negative outlook on the east coast in terms of biocontrol?
Rebecca: Yeah, there’s one big thing and one small thing, I think the big factor is humidity, humidity, humidity. So I also did some work on vegetable entomology in Charleston, South Carolina, and it was the same thing where it was really hard to incorporate biocontrol into research, where you have bio control agents that are sensitive to at least one of the fungicides that absolutely has to be applied or the crop will die, in the case of vegetables. So when you’ve got a spray program that requires a fungicide to go on, minimum, once a week, in most cases, there’s a lot less room for fungicide sensitive natural enemies to attack. And then in the case of augmentation, if you’ve got to spray something after spending quite a bit of money on a natural enemy, than you wasted money kind of twice that way. So that makes augmentation in particular really difficult. And that kind of brings up the smaller reason, which is if you’re trying to do an augmentation program on the east coast, you’re typically working with smaller acreage crops, with a few exceptions. So you don’t have a grower that’s got this massive level of acreage and this huge operation that might have some capital to throw around and investing and trying out and develop an augmentation program, whereas that’s definitely true here in the west coast, where we do have folks that have been kind of playing around with it for maybe a decade and have kind of narrowed into what works for them. Yeah, we’re just so much drier. So the fungal pathogen pressure is a lot lower.
Monique: So definitely the diseases drive the program here. But I was wondering if you had any thoughts about tree fruit in particular, apples on the east coast and the use of biological control agents. There’s a lot of talk about Aphelinus mali, which is the wasp that attacks woolly apple aphid. There’s no commercially available source. And I don’t know if you guys have worked with that at all in Washington.
Rebecca: Yeah, so we do have A mali out here in Washington, too. It can be really, really abundant, especially in certain organic orchards where they’ve, you know, gotten a nice cold. And you can go back to old shoots. You know, I’m talking like two to three year old wood. You’re sampling for aphids for that season, but you’re seeing just mummies, mummies, mummies, mummies from, like, the last one to two years just piled up on top of each other in some of these orchards. But, yeah, we don’t have a commercially available source out here either. And that’s really been the challenge for us for augmentation. We have a lot of large scale organic orchards that are willing to pay the price point that these insectaries have for their beneficial organisms that they are rearing and selling. But a lot of what is commercially available is not suited to our climate. Or it’s just somebody wants an aphid parasitoid. But the aphid parasitoids that are on the market are for aphid pests that exist in greenhouses. There’s nothing specific to apples that are available. I also get a lot of questions about, you know, is a commercial insectary ever going to rear Trechnites insidiosus? Which is the parasitoid for pear psylla. And my answer is no, probably never. One. It’s very, very difficult to rear pear psylla in culture just because they tend to take out the trees that you have them on before you get them all the way through. And it kind of tends to be smaller scale research stuff. But the big one is, in order to be willing to put in that investment into basically rearing a new organism, creating new stock, the insectaries would have to see that they’ve got a really good base of who’s going to be purchasing from them. And the pear acreage just doesn’t justify it compared to what they get from all the greenhouses in North America, where they can be a little more generalized with what they rear. Just focus on greenhouse pests.
Monique: Are there any other things your lab is working on in apple that you think might be worth discussing?
Rebecca: Yeah, so we, in addition to augmentation, and this is kind of just across the board, is we look at conservation, and conservation always plays in with augmentation. Like, it’s no good releasing something if the environment you have isn’t suitable for where you’re putting it. You’re just throwing bad money after bad money. So what we have been primarily working on in that aspect is looking at the integration of pesticides with augmented natural enemies, both in the context of conventional pesticides, as well as starting to look a little bit more at organic pesticides, in particular at organic pesticide compatibility with lace wings. But really across the board, that’s the big push that I get from growers is looking at specific chemical combinations with natural enemies, especially as new chemicals get registered in tree fruits, is, “what about this one”? Is this one compatible with the natural enemy that we typically release as part of our program?
Monique: And are you seeing that the newer compounds are having better compatibility, or do you think that that is not true?
Rebecca: It’s really hit or miss. I think the newer compounds tend to always be better than the old, old stuff. So we’re talking like, you know, the most of the pyrethroids, of course, the organophosphates, the carbamates. Then within the newer materials, there’s always going to be variation in whether or not something is broad spectrum or very selective. So there are new compounds for caterpillars. Those tend to be quite a bit more selective than newer compounds that hit piercing/sucking pests, just because to get that suite of pests, you’re usually going for a broader spectrum compound.
Monique: Well, that’s awesome. And thank you so much for joining us today.
Rebecca: No problem. Yeah, it’s been a blast working with these basically little tiny, wonderful little biocontrol agents, and we just hope to basically do the best for them when we put them out.
State of the State with Dr. Anna Wallis
Anna: And now for the state of the state, your weekly roundup of phenology and degree day accumulations from the major fruit production regions across the state. As always, I’m Anna Wallis with the New York State IPM program, and I’ll be sharing information aggregated from the regional specialists as well as my own observations. As was forecasted, it continued to be extremely hot in most places across the state and very humid, with highs in the upper 80’s to 90’s and overnight lows remaining in the 60’s to upper 70’s in most places across the state. Heat advisories continue to be issued in the Hudson Valley and in other locations with a real feel of up to 100 degrees in some places. So just another reminder to stay hydrated, replenish electrolytes, and be looking out for each other in these heat waves.
We’ve continued to see sporadic rainfall across the state again this week, with more dramatic differences this week. In some places, less than a tenth of an inch of precipitation was recorded over the past week, and in other locations more than three inches. Most of the storms that brought some of the precipitation occurred in the middle of last week around Wednesday. Also some rain on Sunday evening, and then we had some more rain Monday evening in some parts of the Hudson Valley and other parts of the state that are not reflected in the weekly rainfall that’s reported in the show notes. The US drought monitor, which is a tool that you can access online that we’ve linked in the show notes again shows that there are some spots in the northeast that remain on the dry side with the category abnormally dry. You can see that on the map online in yellow, but most places across the state are not at risk. Most of the abnormally dry locations are across Wayne county, most of the county, as well as a few isolated locations in counties in the Hudson Valley, including spots in Columbia, Greene, and Orange county. So it’s just a good reminder to be looking at it for irrigation, especially for trees as fruit starts to ripen and continues to size, and for young trees.
Looking at the forecast for the rest of the week and into next week, forecasted weather early in this week continues to be excessively hot, with a break in the weather toward the end of the week. The six to ten day forecast looking at the NOAA Climate Prediction Center is forecasting above average temperatures to normal temperatures with normal precipitation amounts. And then the eight to 14 day outlook from the NOAA Climate Prediction Center forecasts a return to hotter than average weather and wetter than average weather, and that outlook continues in the long term forecast for the rest of the season for hotter and wetter than average for the months of July, August, and September.
Phenology across the state now, as we’ve said for the past couple of weeks, we’re closer and closer to terminal bud set on apples, and fruit continues to size and color really well. People are getting cover sprays on in between the rain and wind events. It continues to be a fairly compressed phenology across the state with the early sites in the lower Hudson Valley maybe a week ahead of some of the later sites like in the Champlain Valley. Phenology and pest events seem to be fairly similar between the Capital Region and Geneva, and some of the lake sites in western New York are fairly similar to some of the Champlain Valley sites. In the Hudson Valley, most apples are at terminal bud set, although with all of the rain in the past couple of weeks in isolated locations, we are still seeing some new growth on some varieties. Fruit is continuing to color and size really well. Cover sprays are being applied in between rain and wind events. With the early season and the excessive heat, we are anticipating an earlier harvest than average. So at this time make sure to be paying attention to your PHI’s, your pre harvest intervals, and making sure that you’re applying materials according to those labels. Most sweet and tart cherry harvests are completed at this time in the Hudson Valley and wrapping up in other parts of the state. Plums, peaches, and nectarines are all in harvest now, especially the early varieties and berries, including blueberries, raspberries, and other berries are ripening quickly in the hot weather and still harvesting.
Now, looking at some current and upcoming pest events, apple maggot is probably the pest that is most on people’s mind at this point in the season. We are continuing to catch apple maggot on traps across the state in monitoring locations. In many locations we are only catching one or two per baited trap, which is not quite at threshold, while in other places we are well over threshold in known problem areas. And this is consistent with what we know about this pest. It can be very sporadic and site dependent. So just a reminder that we monitor for this pest earlier in the season with yellow sticky cards for the adult emergence. And then more commonly or later in the season, around the beginning of July, we begin looking at red sphere traps coated with tanglefoot. And that’s looking for those ovipositing females as they’re getting ready to lay eggs in the fruit. So if you’re using a baited trap with either ammonium acetate or some kind of pear or apple essence, the baited traps, the threshold is five flies per trap. And if you’re using an unbaited trap, it’s one or two flies per trap.
Codling moth is another insect that we’re paying close attention to now. We’re ending or tapering for the second generation of the moth flights. And in the Hudson Valley, we’re beginning the hatch of second generation eggs. So that is predicted at 200 to 250 degree days base 50 after your second generation biofix or the first moths in this generation that would be caught in traps. You can also estimate that timing based on the first generation biofix. And so that would typically be around 1200 to 1250 degree days base 50 after the first generation biofix or the first generation first mods. So that application timing is beginning now in the Hudson Valley and will happen pretty soon afterward in other parts of the state. Remember that if you had excellent control of the first generation of codling moth in your orchard, you’re likely to have lower pressure in the second generation. But if you’re surrounded or nearby any abandoned orchard or unmanaged wild hosts, you are likely to have insects moving in from the outside. So it’s important to be staying covered during the second generation. Especially important for codling moth management is to be rotating chemistries. This insect can be endemic in the orchard, if any survive. And so making sure to rotate chemistry so that insects don’t develop resistance to the tools that we have available.
Obliquebanded leafroller trap captures are tapering at this time across the state with very low trap captures in most locations. The insects are getting quite large at this time, so it’s too late to be applying an insecticide targeting larvae of this insect.
We are also continuing to see European red mites and two spotted spider mites. In some locations we can expect more activity and faster generations with the really high hot weather that we’ve been having, particularly in dry, dusty situations.
Woolly apple aphid is very active at this time. In the past couple of weeks, we’ve seen colonies increasing and moving quite aggressively toward the leaf axils in a lot of places where we’re scouting.
We continue to also see Japanese beetle activity, brown marinated stink bugs, second generation nymphs active now, and apple leaf curling midge in a few locations in different parts of the state where we know that there are problem areas. Leaf hoppers are also present in some locations where they’re not being managed.
Looking at diseases, fire blight continues to be relatively tame across the state from the reports that we are getting. There are some known problem areas in New York where it has been a severe problem in the past, and we have reports from outside of New York state where fire blight has been a really severe problem. So fingers crossed that we continue to have that disease under management this year.
Scab lesions continue to be reported in sort of unexpected places this year, so keep looking out for infections so that you can be managing secondary as necessary.
Powdery mildew continues to be fairly severe in some places. Again, related to the really hot, humid weather that we’ve been experiencing.
Other summer diseases are becoming more prevalent at this time. A little bit of sooty blotch and fly speck showing up, as well as some fruit rots are definitely present in some areas, and we’re starting to see more of the yellow leaf spotting symptoms from marrsonina, glomerela, and necrotic leaf blotch at this time. This is normally when we would expect more of this to be showing up and they can be a little bit tricky to differentiate. So if you want help with identification or diagnosis, please send your photos to your regional ag specialist or fruit specialist so that we can help you with diagnosing those disorders and diseases.
A quick reminder that we’ve had two virtual orchard scout trainings this year. The first was prebloom and the second was post bloom, and recordings for both of those trainings are now available on the New York State Integrated Pest Management YouTube site. So if you’re interested in viewing those, we’re including the links to those videos in the show notes. Janet van Zoeren, Mike Basedow, and I provided detailed instructions on monitoring and scouting and identification for significant orchard pests, and so that included things like mite sampling, internal lep identification and thresholds, a review of plum curculio injury and management, woolly apple aphid, apple maggot, apple leaf curling midge, stink bugs, and spotted winged drosophila, among other pests.
And now here are the current degree days in the major fruit producing regions of the state. Throughout the season, we’ve been aligning this information with previous work done by Art Agnello to McIntosh phenology and degree days base 43. So now, from January 1 through July 15, the current degree day accumulation base 43 is: in Geneva, 2239; in Highland at the Hudson Valley Research Lab, 2413; in Clifton Park, 2260; in Peru, 1961; in Medina, an inland site, 2167; Appleton North, a lake site, 2016; Fairville, an inland site, 2122; and Williamson, a lake site, 2141. Again, those tables of the degree day accumulation and upcoming pest events are included down in the show notes.
That’s all for this week, and good luck until next week.
Phenology & DDs for NY NEWA Stations from 1/1 – 7/15
Station || Stage || DD 43F || Rainfall (in)
Geneva || fruit sizing || 2239 || 0.15
Highland (HVRL) || fruit sizing || 2413 || 0.08
Clifton Park || fruit sizing || 2260 || 0.09
Peru (Forrence) || fruit sizing || 1961 || 2.41
Medina – Inland || fruit sizing || 2167 || 2.05
Appleton North – Lake || fruit sizing || 2016 || 3.11
Fairville (The Apple Shed) – Inland || fruit sizing || 2122 || 2.01
Williamson (DeMarree) – Lake || fruit sizing || 2141 || 1.73
*all DDs Baskerville-Emin, B.E
Upcoming Pest Events
Pest/Phenology Event || DD Base 43˚F || Approx. Date
Apple Maggot Traps Set Out (in orchard) || 1-Jul”
ERM Sample – 5.0 mites/leaf || 1-Jul
Comstock mealybug tape traps set out || July 1 (ENY), July 15 (WNY)
OFM – 2nd flight starting || 1180* ± 136* || 29-Jun ± 5 days
OBLR Summer Gen. 1st Sample || 10-Jul ± 5 days
STLM Summer Gen. 1st Sample || 9-Jul ± 7 days
RBLR – 2nd flight starting || 1367 ± 105 || 29-Jun ± 6 days
AM – 1st catch || 1509 ± 285 || 4-Jul ± 12 days
Lesser peachtree borer – peak catch || 1234 ± 470 || 25-Jun ± 19 days
STLM – 2nd flight peak || 1563 ± 207 || 6-Jul ± 8 days
Codling moth – 1st flight ending || 1557 ± 262 || 6-Jul ± 12 days
Peachtree borer – peak catch || 1579 ± 465 || 7-Jul ± 19 days
Lesser appleworm – 2nd flight starting || 1768 ± 339 || 14-Jul ± 12 days
OFM – 2nd flight peak || 1450* ± 147* || 11-Jul ± 9 days
American plum borer – 2nd flight starting || 1850 ± 290 || 16-Jul ± 11 days
RBLR – 2nd flight peak || 1721 ± 232 || 13-Jul ± 7 days
San Jose scale – 2nd flight starting || 1804 ± 170 || 15-Jul ± 8 days
Codling moth – 2nd flight starting || 1887 ± 313 || 20-Jul ± 13 days
Dogwood borer – peak catch || 1611 ± 226 || 8-Jul ± 10 days
STLM – 2nd flight ending || 2167 ± 177 || 28 Jul ± 8 days
American plum borer – 2nd flight peak || 2290 ± 285 || 1-Aug ± 8 days
OFM – 2nd flight ending || 2044* ± 233* || 31-Jul ± 7 days
*Base temperature for OFM 45F
Virtual Orchard Scout Training #2
https://www.youtube.com/user/NYSIPM
Berry Pest Monitoring Network – NEW Blog!
https://blogs.cornell.edu/berrypests/
Quick Guides for SWD Management
https://fruit.cornell.edu/spottedwing/management/
https://fruit.cornell.edu/spottedwing/
NOAA NWS Storm Prediction Center
https://www.spc.noaa.gov/
U.S. Drought Monitor
https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?Northeast