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Monique Rivera Interviews Kerik Cox on The Current and Future State of Disease Management in New York

So this week on Scaffolds, I’m going to interview Kerik Cox.

Monique Rivera: So let’s get right into it. So, one of my questions that I was hoping to get a fun answer from you on was, what do you think is the current state of apple diseases in New York, and how do you think things have evolved since you’ve started in your position?

Kerik Cox: Okay, that’s a good question. Still, even after 200 plus years, fire blight is still there. And I think if anything, it’s gotten a little more intense. It’s getting this hotter weather that we’re having after petal fall due to a second question we’ll talk about later, but I think the fire blight is actually getting a little bit worse, even though we’re having more tools.

Monique Rivera: Even with scab? Do you think scab is also worse?

Kerik Cox: I think scab is going away, I think slowly. And when I first started, by the time the summer scholars arrived, those are our undergraduate researchers who come to Cornell every year, we had scab falling off the tree, and now I can barely see it in my filthiest, biggest, ugliest, most non-high density orchard trees that I have.

Monique Rivera: So what do you think is driving that?

Kerik Cox: I think it’s the heat. I think it’s the change in the heat, the warmer weather earlier. I know now that if I drive to the Eastern New York Fruit School and I’m not in a blizzard, it’s going to be a bad scab year.

Monique Rivera: Oh, man. Okay, that’s interesting. I never thought of it like that. Are there reservoirs of that in the environment?

Kerik Cox: Yeah, I think the problem is also is that the leaves with the warmer weather, the leaves are probably degrading faster, and that’s how scab survives. That’s my thought on that. And then with low inoculum, we’re just not seeing it.

Monique Rivera: It’s just too hot. I mean, it kind of makes sense with a fungus that you would need a cooler, wetter environment. So launching into the climate change question, so do you think obviously this uptick in Fire blight and its intensity is due to climate change and those weather patterns, but what do you think is going to be the ultimate outcome here? Can we do anything with different varieties, possibly, to help with this increase?

Kerik Cox: Yeah, I think that’s a good idea. I think picking varieties, I mean, you’re obviously going to want to pick for storage, color, and consumer taste preferences. But within those, if we could steer our way to things that were not incredibly highly susceptible. I think we need to do a little more assessment on the various new releases, regardless of what program they come out of, to be able to differentiate whether or not it’s because we’re all planting young trees in a bunch of really hot years, or we have something that’s truly highly susceptible. And if you could steer away from some of those. Sadly, some of the ones that fit the three categories of storability, color, firmness, and taste often are some of the ones that melt the fastest.

Monique Rivera: So what about the shift to high density? Do you think that’s played any role in disease pressure?

Kerik Cox: I’ve noticed that the smaller the size of the tree, the more heavily devastated and the faster fire blight seems to spread. In the Memorial Day Fire Blight Massacre of 2022, we noticed that we nearly lost all high density orchards and our high density plantings in Geneva. However, the plants that we dump fire blight on that are more 300 TRV trees to the acre, they’re back and they recovered, but the smaller high density sized trees just get wiped out.

Monique Rivera: Do you think tree age plays a role?

Kerik Cox: I think it helps a little bit, but I hate to say it, I still think keeping them in that small size, when the diameter of that trunk is under 10cm, and even a mature high density orchard doesn’t always have the thickest trees. I think age probably matters a lot, but for the most part, I think it’s a little bit of cultivar susceptibility and how long they’ve been there before they get their first real big fire blight.

Monique Rivera: So this is kind of off topic, but what do you think about immune priming when it comes to apple diseases? If you had that stress factor ahead of infection?

Kerik Cox: Yeah, we’re using it a lot with the acibenzolar-S-methyl or Actigard type stuff. We have a lot of natural products that are doing those, and those growers are already doing them. They’re trying to prime. And we’ve been pushing priming as early as pink, so that by the time the flower infections occur at bloom and stuff is moving through the system, that system is primed as much as possible by the time we hit that petal fall, really hot, thinning weather. The nice thing about the priming, it works best in a small tree, but the fire blight migrates fastest in the small tree, so it’s a trade off. It might help, but it might not save the day every time. If the weather is bad enough.

Monique Rivera: So where are we going to end up? What’s the future of disease management that you’re studying? What do you see as the next phase?

Kerik Cox: The next phase? I think a lot of things are moving away from the single site synthetic type chemicals, including the antibiotic type things. Everything that’s a carbon ring is being replaced slowly with interests in the biological and biopesticides. We’ve lost ziram, captan is not really allowed in many countries, and streptomycin is on the way out. I see streptomycin being one of those things where we get one application a season, kind of like the old Lorsban thing, until it finally goes away. But I think it will all be biological type materials, minerals, probably a little bit of copper, until it goes away. But mostly biologicals attempting to be streptomycin, but less refined, which is essentially what many of them are.

Monique Rivera: Okay, interesting. So that’s it for this brief interview. Next week, maybe you’ll interview me?

Kerik Cox: Yeah, I’m hoping so.

State of the State with Anna Wallis

 This is your weekly roundup of Degree Day accumulations and phenology from the major fruit production region of the state. As always, this information has been aggregated from regional specialists, NEWA, and my own observations.

This week temperatures have cooled off just a little bit compared to the 20 year average. Degree Day accumulations in Geneva have fallen a little bit below average for this time of year, and Degree Day accumulations in the Champlain Valley are actually close or even slightly ahead of western New York sites. That’s especially true of lake sites, which are a little bit behind inland sites. It continues to be dry in most of western New York, while some locations in eastern New York received about a quarter of an inch of precipitation on Tuesday. Unfortunately, this included storms and hail in some locations.

We’re also continuing to get reports of some frost damage observed in many places, including frost rings, cracked and lopsided fruit, which are easier to see now that fruit is sizing. A great place to find more information about severe weather events and weather outlooks is on the NOAA National Weather Service website. We’ll include links to a few places in the show notes for you to find more information. This includes the Storm Prediction Center, which provides information about storm watches and severe weather reports. Also the Climate Prediction Center, which includes short, medium, and long term forecasts for precipitation and temperature. It includes the next 48 hours in the upcoming week, two week outlooks, and monthly and seasonal forecasts over the next two weeks.

In most of New York, temperatures are expected to be near normal or above average, and precipitation continues to be below or near normal for this time of year. Most of the state is at the tail end of the thinning window at this time of year. Cell division in fruitlets is taking place from petal fall to about five to six weeks after bloom. This has a direct effect on the potential for fruit size, so it’s really critical to maintain adequate water. We’re continuing to track Degree Day base 43 as an indicator of insect activity. As I’ve said in the past, both 43 and 50 base temperatures are used historically and are summarized in the show notes, but I’ll just talk about base 43 for the purposes of the podcast. You can also find an average range of Degree Day accumulations for phenology and pest activity in the Cornell Tree fruit Guidelines table 7.1.4.

Here are a few things that are active now.

Plum curculio is still active in most locations in western New York and northeastern New York, but near the end in the Hudson Valley, we found more scarred fruitlets in apple, pear and cherry across western New York this week. They continue to be active from petal fall until we reach about 308 degree days base 50. Using the NEWA model, you can enter your petal fall date and it will predict the Degree Day base 50 accumulation for the next five days. The model also generates petal fall dates based on degree days. Using those dates, western New York sites are approaching 200 this week and predict it to be in the low 200s by the early part of next week. Keep covered for at least another week.

In the Hudson Valley, Degree Day 50 accumulations are beyond 308, and in the Capital area, many places are beyond this threshold or will be so by the end of the weekend. There’s also a table in the show Notes summarizing Degree Day 50 accumulation, and the petal fall dates generated by the NEWA website.

OFM first flight in most of the state is nearly over, and we’re beyond the window for management based on Degree Day accumulations.

Codling moth numbers in Geneva and western New York continue to increase this week. In western New York, this week is likely the best time for a material targeting larvae.

OBLR first trap capture was recorded in Geneva and western New York and the Capital Region this week. Be sure to have your traps out now if you’re monitoring for first flight.

Rosy and green apple aphids continue to be active throughout the state. They appear to be very active in some places this year.

We’re also beginning to find woolly apple aphid in hot spots this week. It’s been reported in many locations throughout the state.

San Jose scale is another insect to be monitoring for now. Adults are typically active at about this time of year. We haven’t had any significant reports of this pest yet.

More apple leaf curling midge has been reported in the Lake Ontario region in isolated locations. As I’ve said before, this is a relatively new insect that has become significant in the Champlain Valley and Ontario, so keep paying attention to it.

Our first dogwood borer adult moth captures were recorded last week in Geneva, and the flight is continuing. This insect would be a good candidate to consider using mating disruption for this year. It’s a little bit too late to get that out, but it’s best to get ahead of the population before it gets established, and you might want to consider it for a future year.

In terms of diseases, we’re continuing to see quite a lot of powdery mildew this week due to the hot, dry weather. We’ve also heard the first reports of natural fire blight infections in places that had infections last year, so keep an eye out. Scab primary infections are also visible in places that were unmanaged or where it happened to slip through.

And finally, here’s the rundown of Degree Day based 43 accumulations at NEWA weather stations throughout the state. As usual, they’re also in the table in the show notes for you to reference later.

As of the end of the day, Thursday, June 7, degree day accumulations were: