Scaffolds 2024 Digest: Week 19
This post is a text digest of the Scaffolds Podcast. To listen to the original episode, visit the following link: Scaffolds Podcast on Spotify
On this week’s episode of Scaffolds, I talked to Dr. Kelsey Tobin, a postdoctoral researcher in my lab, about a new ambrosia beetle that we’re finding attacking apple. Kerik talks to us about leaf blotch diseases, and Anna gives us our state of the state update for the week.
Monique Interviews Dr. Kelsey Tobin; Discusses Ambrosia Beetle
Monique: Today I’m here with Dr. Kelsey Tobin, who is a postdoctoral researcher in my lab here at AgriTech. Hello, Kelsey.
Kelsey: Hey, Monique.
Monique: So today we’re going to talk about ambrosia beetles. Kelsey is an ambrosia beetle expert, and we have a new species of ambrosia beetle in town, so to speak. So I guess I want to start out with, could you tell us a little bit about how we first discovered that this additional species is attacking apples?
Kelsey: Yeah. So I got to the area in January, and there had been a couple of potted apple trees from last season that we had pulled out and saved because they looked like they were infected with fire blight, but we also noticed ambrosia beetle entry holes at some of the branch junctions on these trees. And so we’d left them out and did not put them in cold storage, just left them out outside and decided to dissect them one day to see if we could find these beetles and how many beetles were in there. At the time, we were expecting it to be the black stem borer, but when we were dissecting them, we found a couple of adults and a lot of larvae in these trees. And we know that black stem borer overwinters as adults. So finding these larvae were an indication that it was not the black stem borer. And we did some molecular work and got a positive identification from the larvae and, also from the adult beetle that we found that it is a new species, Anisandrous maiche.
Monique: Thankfully, Kelsey came here, having done her entire PhD on this species. So I think that was a lucky happenstance in this case. So my next question for you is in particular, you know, we know about black stem borer. We know black stem borer attacks apples. What is so different about Anisandrous maiche that may have differing implications for their attacks on apples?
Kelsey: So one thing that is interesting to me is this overwintering as larvae, I think that has some implications for maybe some temperature development that we might want to look into and how broadly this species will be able to establish. If it requires some sort of cold, chilling temperature, maybe its range will be limited by areas that can reach that cold temperature. But, yeah, it’s kind of a species that’s starting to pop up not only in apples, but in other ornamental orchards and plantings throughout the United States. And so I think in the coming year or two, we’re going to learn a lot about this species, but, yeah, that’s where our work is headed.
Monique: So maiche is invasive. When did it first get to the United States?
Kelsey: It was first found in an ambrosia beetle survey in, I believe, 2009 in Pennsylvania. And at this point, it’s probably been confirmed in 12 or 13 states, mostly in the eastern US.
Monique: It’s also possible, right, that this could have been previously mistaken for black stem borer, right?
Kelsey: Yeah. These two beetles are nearly identical. They do require microscopes to be able to distinguish between the two ambrosia beetles in general. So their features are also very small. Yeah. So that’s when I was in Indiana during my PhD, that was the case, was it had been there for probably longer than we thought, but we’d just been misidentifying it for a number of years.
Monique: And in terms of when we see Anisandrous maiche flight, how does that compare to our black stem borer flights?
Kelsey: Over the past couple of years, the black stem borer has had an early, early spring peak in around May, a large peak, and then followed by a smaller second peak in July. We start to see Anisandrous maiche flying, probably like early June, mid-June. But then their flight is more prolonged, where we’re getting high weekly captures throughout most of the rest of the summer. So we’re still catching upwards of 20 to 30 in each trap, still right now in almost August. So I think they have a longer, more protracted flight throughout the season.
Monique: I also think in New York, what I’ve heard, generally speaking, talking to growers, is that they think that the ambrosia beetle issue is resolved. And last week, I was asked by a consultant and the Palmers at Reality Research to visit this farm in western New York that had a bunch of fire blight, but also a bunch of ambrosia beetle attacks. And we think that the damage and the decline to the trees is multifactorial, meaning that it could be, you know, the original tree stress happening. It could be the fire blight bringing in the ambrosia beetles, but either way, they’re there. And so I brought back a bunch of trees and samples to Kelsey, and we confirmed that, yet again, we’re finding maiche in apple, and this would be so easy to mistake for black stem borer.
So I guess the next thing I think we should talk about is where do we think we are with management? So, currently what’s happening is, if there’s a problem, and like I said, folks say that this is a resolved issue you know sort of user error, if you have, you know, bad tiling and flooding in your field, that this is going to solve the ambrosia beetle issue, is to correct those sort of tree stressors. But I will say that when you have an attack, the decline on the trees, especially if they’re young and they’re newly planted, is going to be extreme, and it’s going to be fast. So, I think that talking about this as an issue that is over, resolved, is great for the people that don’t have the issue, but the people that have the issue, I think it’s quite tragic. So, I think, now where we are with management is that there’s the idea that you can have a regional trap line and you can kind of track the flights of ambrosia beetles because they’re way too difficult to identify on your own. So, you could have a trap out, and if you were trained, and maybe that’s an idea, something we should do, maybe we should put on a workshop to train people on ambrosia beetles. But I think that, you know, figuring out where we are with management. So, again, like I said, the trapping, peak flight there is the application of a pyrethroid. But we’re still not really sure how this actually affects them, if that actually prevents attacks. Because even if you time it, that initial peak flight, if this other species continues to fly and there continues to be stressors, then you may have additional attacks that you’re unaware of timing sprays for. So what do you think we can do to innovate in terms of managing these guys? Because once they’re in the tree, we don’t have a lot of good solutions.
Kelsey: Yeah, that’s a great question. So we’ve been working on this push-pull experiment. These ambrosia beetles are primarily attracted to ethanol, but we’re also interested in identifying other compounds that might help us improve our trapping techniques currently. But we also have identified some really strong repellent compounds. They’ve been repellent in the lab, and also we’ve started to test those in the field to see if we can essentially just push the beetles away from these commodity plantings. And we have just wrapped up a multi-state experiment using verbenone as the push and ethanol as the pull to lure them into traps and kill them. We have tons of traps and beetle ID that we’re still going through, so we don’t have any results to report on that currently, but next year on scaffolds, we’ll report those findings. So that’s one thing that we’ve been working on, is just trying to improve the trapping and also try to manipulate where these beetles are actually going instead of attacking the trees. We also know that they feed on fungus and not actually on the tree itself. So, we could look into testing some fungicides that might knock back that traditional symbiont that they feed on, and then they would theoretically not be able to feed and complete their life cycle that way. So that’s another avenue that we could look at. Yeah, just trying to identify these behavior-modifying compounds and trying to control the populations, mostly with trapping.
Monique: Yeah, so that is one approach is mass trapping. If there is an issue or if you have a particular block that keeps getting attacked, we will see what happens with this push-pull. I know Art Agnello was working on that a bit with this product called Splat before my time, and I’m not sure he was doing that in potted trees, so not exactly the same as what we were doing in an actual field that was experiencing attacks, we’ll see what the results come out as. But I think this is one of the more difficult pests to manage if you do have a problem. The insecticide recommendations I don’t think are clear in a lot of ways, because you’re spraying to try to time for the flight. And I do think that this is one of those insects that probably was residually controlled by chlorpyrifos or applications of diazinon, but no longer are those products really in our arsenal. So I think that we have a charge ahead of us to try to figure out some additional ways to control these guys. So I want to thank you so much, Kelsey, for being on the podcast today, and hopefully we’ll bring you back on again soon with some results.
Kelsey: Yeah, that sounds good. Thank you.
State of the State with Dr. Anna Wallis
And now for the state of the state, your weekly update of phenology and degree day accumulations for the major fruit producing regions of the state. As always, I’m Anna Wallis with the New York State IPM program at Cornell and I’ll be sharing information aggregated from the regional specialists and my own observations.
Last week we had more heat and humidity across the state, with highs in the eighties [°F] in the Hudson Valley and the Capital Region, slightly cooler in the Lake Ontario region and the Champlain Valley, with highs in the upper seventies and low eighties. Overnight low temperatures were consistently in the fifties and sixties across the state. We’re hoping to have some more cool overnight low temperatures over the next couple of weeks to help with fruit color. We’ve received considerable rainfall across the state over the past couple of weeks, which is good news because the rainfall has replenished soil moisture in most places. This is in stark contrast to other parts of the northeast, including Virginia and West Virginia, which is currently under a severe drought, and parts of Vermont and other parts of New England that have had excessive rainfall over the past few weeks. So most of New York is in a good place with precipitation at this time. We had a little bit more rainfall early last week, although surprisingly little accumulation, with less than a quarter of an inch recorded in most NEWA weather station locations. A few isolated locations had up to three quarters of an inch of rain.
Looking at the forecast for the rest of the week and into the next couple of weeks, the six-to-ten day outlook from the NOAA Climate Prediction center is still forecasting above average temperatures but near normal precipitation, and the 8-to-14 day outlook is slightly different, with northern parts of the state, the Champlain Valley, Franklin, and St. Lawrence counties near normal conditions for temperatures. The Lake Ontario and Capital Region are expected to be just slightly above normal conditions. And in the Hudson Valley, we’re expected to have above average temperatures. Across the state we’re expected to have slightly above average precipitation. In the longer term forecast from the middle of July through the middle of August, the NOAA Climate Prediction center is again expecting hotter than average temperature.
Looking at phenology across the state now, most apples are at terminal bud set or approaching terminal bud set. We’ve said this for the past couple of weeks, but we’re still seeing some new growth in different places and varieties, especially with all of the rainfall. Fruit is continuing to color and size really well as we approach harvest, and we’re expecting an early harvest. This is no surprise to anyone, but we are encouraging people to get out and be looking at fruit sooner than you would normally. As we approach harvest, various predictions are being made about harvest dates for this season. Craig Kahlke and the Lake Ontario region with the Lake Ontario Fruit Team published some predictions and degree day accumulation comparisons for 2024 as compared to other seasons and historical averages. And Craig’s predictions indicate we’re ten to twelve days ahead of averages in most of the Lake Ontario region. Using degree day accumulations from the Climate Smart Farming tool at Cornell, which provides seasonal degree day accumulations as well as 15 year averages and 30 year normals, we are about seven to ten days ahead of average across most of the state. So needless to say, we are expecting an early harvest and we’re encouraging people to get out and look at fruit earlier than later. In the Hudson Valley, stone fruit is now picking with lots of peaches and plums coming into harvest. Apples are continuing to color and size very well. The very first apples in the lower Hudson Valley with varieties like Pristine and other early varieties are just beginning harvest this week. In other parts of the state, in the Lake Ontario region and the Capital Region as well as the Champlain Valley, things are looking about a week behind that, if not a little bit more in cooler locations.
Now looking at some upcoming pest events. Apple maggot is the focus of many pest management programs at this time. We are continuing to catch apple maggot across the state with heavy captures in unmanaged or abandoned locations. We did see some increase in captures last week in both the Lake Ontario region and in the Hudson Valley. Trap captures continue to increase in many places where we know there is a high population and significant pressure. But in other locations, we don’t have any trap captures at all or we have very low trap captures that have been consistent over the past few weeks. So it’s important to continue paying attention to your location. Remembering at this part of the season, we are using red spheres coated with sticky tanglefoot, and those traps are capturing the ovipositing females. The threshold for those traps again is five per baited trap, which would be baited with an ammonium sulfate or a pear or apple essence. And for unbaited traps, the threshold is one to two per trap.
Codling moth second generation larvae are also a pest we’re thinking about right now in the Hudson Valley. The second generation larval emergence is happening at this time. And so this is a good time for insecticide applications targeting larvae. In the Lake Ontario and Capital Region, we’ve seen an uptick in trap captures indicating the second generation emergence. And the model is predicting that the larvae will be emerging at the end of this week or early next week, so that would be a good time for an insecticide applications targeting those guys. And in the Champlain Valley, we’re also seeing an uptick in moths this week in traps. And so perhaps at the end of next week would be a good timing for targeting the larvae of the second generation there. We are getting a number of reports of internal lepidopteran feeding across the state this year. So this can be codling moth. It’s easier to identify that insect because it prefers to feed on the seeds. So codling moth will tunnel directly to the center of the fruit and feed on the seeds, which are rich in nitrogen and a good nutrition source for that insect. You can also find oriental fruit moth and lesser apple worm tunneling into the fruit, although those insects may not feed directly on the seeds, but just tunnel toward the center of the fruit. It’s important to be identifying which pest is affecting your fruit if you do have any damage. That way you can be targeting your insecticides for next season to the appropriate pest. During this second generation larvae emergence when we’re targeting insecticides, remember to be rotating chemistries for the second generation compared to what you use for the first generation. This insect can be endemic to the orchard, so it’s important that we change up the things that we’re using against the insects so we don’t develop insecticide resistance in the population.
Obliquebanded leafroller trap captures continue to be very low. No trap captures this week in a number of locations and very low trap captures in other locations. So right now is not a good time to be putting any insecticides out targeting this insect for management.
We continue to see European red mites and two spotted spider mites in isolated locations. This can cause bronzing and feeding on the leaves, which is caused by the rasping of these insects feeding on the chlorophyll. We’re seeing a little bit more activity of aphids at this time. Often we have a flush of green aphids at this part of the season, more likely in a dry year when these insects are looking for a moisture source. We’re also continuing to see woolly apple aphid active in many locations, although management over the past couple of weeks has suppressed populations quite a bit, in many locations. Stink bugs continue to be active. We are in the second generation of many stink bugs, including brown marmorated stink bugs. So those nymphs are now moving into fruits and starting to feed on fruit. Often they jump over from an adjacent crop, like soybean or corn. So be paying attention to that in your area. If you’re using a trap to be monitoring for this insect, we recommend that you’re placing it on the edge of the orchard so you know when it’s moving in. If you’re using a tedder trap, a black pyramid trap, the threshold is ten per trap per week, and if you’re using a clear sticky panel, these have a similar expected detection of the first insects, but they tend to be lower counts, and so we recommend three to four per sticky panel per week. We’ve seen very little feeding in apples at this point in the season, just a little bit in isolated locations. We’ve also seen a little bit of feeding on peaches, which can show up as cat facing or dimples in the fruit, although this can be caused by other plant bugs as well.
Moving into diseases, just a reminder, we continue to see scab lesions pop up in some unexpected places this year, so stay on top of that and look for secondary infections that could continue to be affecting leaves and fruit at this point in the season. We continue to see powdery mildew. We’ve also seen a little bit less of this after all the rain. Powdery mildew can’t survive in freestanding water, so we know that’s been suppressed a little bit, especially in locations that have had high rainfall over the past couple of weeks. But it could take off again in the really hot, humid conditions that we’re expected to have over the next couple of weeks.
At this point in the middle of the summer, we know that sooty blotch and flyspeck and fruit rots are the focus of disease management programs. Look for bitter rot and Botryosphaeria. So bitter rot you’d be a bit of recognized by orange fruiting bodies and concentric circles on the fruit in that rot circle. You can cut the fruit in half through that lesion and see a v shape if it’s bitter rot as well. We’re seeing quite a bit of frog eye leaf spot or black rot or Botryosphaeria in some locations, and those lesions look like defined circles, brown that are depressed on the leaf lesions. And then in the center of those lesions you can see black fruiting bodies, and so that’s a way to identify frog eye leaf spot or Botryosphaeria.
We’re also starting to get more reports of yellow leaf spotting that could be caused by Marssonina apple blotch, glomerella and necrotic leaf blotch. So if you’re interested in getting help with diagnosing those, please send us some pictures. We’d be happy to help. Kerik also did a great review of these disorders and diseases in last week’s podcast, so we encourage you to review that. And he has a great video on his blog and website that you can use to help you diagnose any problems that you may be having in your orchard.
We also start to see more decline at this point in the season, which there are lots of reasons for tree decline to happen and collapse. We often see it around this time as trees are approaching harvest and trying to support the crop, in addition to whatever other stresses that they’re under. This could be related to cold damage, it could be related to moisture, nutrition, or some kind of pest complex. Dr. Jason Londo and his student Ken at Cornell are doing some work to try to characterize decline in apple orchards across the state. So we are asking you to report any decline that you may have to an extension specialist or you can do it through the anonymous survey that is available through many of the regional newsletters, and also a link is included in the show notes of this podcast.
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 related to McIntosh phenology and degree days base 43 Fahrenheit. Current degree day accumulation from January 1 to July 29 included in Geneva, 2637; in Highland at the Hudson Valley Research Lab, 2844; in Clifton Park, 2684; in Peru, 2349; Medina, an inland site, 2548; Appleton North, a lake site, 2403; Fairville, an inland site, 2510; and Williamson, a lake site, 2582.
As always, this table of degree day accumulation is in the show notes, as well as a table of upcoming pest events taken from table seven one four from the Cornell guidelines. That’s all for this week, and good luck until next week.
| Phenology & DDs for NY NEWA Stations from 1/1 – 7/29 | ||
| Station | DD Accumulation | Rainfall (in) |
| Geneva | 2637 | 0.13 |
| Highland (HVRL) | 2844 | 0.32 |
| Clifton Park | 2684 | 0.15 |
| Peru (Forrence) | 2349 | 0.26 |
| Medina – Inland | 2548 | 0.71 |
| Appleton North – Lakeside | 2403 | 0.36 |
| Fairville (The Apple Shed) – Inland | 2510 | 0.20 |
| Williamson (DeMarree) – Lakeside | 2582 | 0.12 |
Phenology & DDs for NY NEWA Stations from 1/1 – 7/29
Station || Stage || DD 43F || Rainfall (in)
Geneva || fruit sizing || 2637 || 0.13
Highland (HVRL) || fruit sizing || 2844 || 0.32
Clifton Park || fruit sizing || 2684 || 0.15
Peru (Forrence) || fruit sizing || 2349 || 0.26
Medina – Inland || fruit sizing || 2548 || 0.71
Appleton North – Lake || fruit sizing || 2403 || 0.36
Fairville (The Apple Shed) – Inland || fruit sizing || 2510 || 0.2
Williamson (DeMarree) – Lake || fruit sizing || 2582 || 0.12
*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
ERM Sample – 7.5 mites/leaf || 1-Aug”
Cherry fruit fly traps in || 1-Aug
San Jose scale – 2nd flight peak || 2312 ± 174 || 3-Aug ± 9 days
Apple maggot – peak flight || 2394 ± 247 || 6-Aug ± 10 days
Codling moth – 2nd flight peak || 2327 ± 349 || 6-Aug ± 13 days
RBLR – 2nd flight ending || 2419 ± 273 || 7-Aug ± 10 days
STLM – 3rd flight starting || 2420 ± 196 || 6-Aug ± 7 days
Comstock mealybug – 2nd gen. crawlers emerging || 2429 ± 195 || 8-Aug ± 12 days
OBLR –2nd flight starting || 2413 ± 201 || 7-Aug ± 9 days
OFM – 3rd flight starting || 2275* ± 290* || 9-Aug ± 9 days
Lesser appleworm – 2nd flight peak || 2607 ± 463 || 15-Aug ± 23 days
RBLR – 3rd flight starting || 2715 ± 214 || 19-Aug ± 10 days
STLM – 3rd flight peak || 2755 ± 222 || 19-Aug ± 9 days
OFM – 3rd flight peak || 2625* ± 137* || 27-Aug ± 12 days
*Base temperature for OFM 45F
Apple Tree Decline Survey
Apple decline research is hindered by an incomplete understanding of where it is occurring and what its symptoms look like on different rootstock/scion combinations. Please consider taking this survey, even if you haven’t observed apple decline in your orchard blocks! Your participation will help drive research focus in the right direction and aid in the creation of informative extension documents. https://forms.gle/NpRkDEZmTB6EPUh98
Virtual Orchard Scout Training #1
https://www.youtube.com/watch?v=OtyOWCL1Q2A
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