Season 7, Episode 4 - April Freeze

Don is joined by Kari and Shan this week to discuss what happens what a spring freeze doesn’t just “nip” buds. Shan highlights what to do after the frost: how to sample across a block, cut buds to spot real freeze damage in the reproductive tissue.

Kari gives an early fire blight heads-up as warm weather accelerates bloom, plus a smart “minimal spray program” mindset for blocks that lost fruit to winter injury.

Frost Protection Strategies: https://extension.psu.edu/frost-critical-temperatures-and-frost-protection

Critical Temperatures: https://extension.psu.edu/orchard-frost-critical-temperatures-for-various-fruits

Host: Don Seifrit
Speakers: Kari Peter, Shan Kumar

Photo Credit: Faith Miller

Music Credit: “The Raven and the Swan” by Josh Woodward is licensed under a Attribution 3.0 United States License. Courtesy of FreeMusicArchive.org

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Flight Seasonalities of Main Fruit Pests During the Growing Season

Transcript

Welcome And What’s Ahead

SPEAKER_02 0:07

Alright, everybody, welcome back once again to the Dr. Tree Fruit and Don podcast. I'm Don Siefer. I'm here with Dr. Carrie Peter. Say hi, Carrie.

SPEAKER_00 0:14

Hi there.

SPEAKER_02 0:15

And Dr. Sean Kumar, say hi, Sean. Hi, everyone.

unknown 0:19

Dr.

SPEAKER_02 0:19

Krawchak is not with us this week, but that's alright. It is April 7th, the Tuesday. We've got a couple things on the schedule, some big things on the schedule to talk about. So I which one of you guys is going first?

SPEAKER_00 0:36

I'll let Sean go first because yeah, that will be a good segue for me. So, Sean, you take it away.

Peach Bloom Frost Risk And Thinning

Apple Stages And King Bloom Damage

SPEAKER_01 0:43

After you sounds good. Thank you guys. I just wanted to give a phonology update and then we'll talk specifically about uh some stuff. But I wanted to talk about peaches first, and then we'll move into apples. And so peaches, especially in Adams County, depending on the variety, they are close to full bloom or anywhere in the bloom cycle from like early bloom to 50% to 90% bloom, depending on the variety. But a lot of varieties are close to full bloom. And uh uh talk about the elephant in the room, it is the frost that we are all hoping that it doesn't do too much damage. But uh on the Freck uh uh uh weather station, it shows that it can go uh to as low as 2625 uh Fahrenheit, and so at that time it can do some damage uh to peaches, it's only going to go there for a few hours, so hopefully the damage is not damage is not too much, and hopefully the forecast is actually what it says says it is because that is also a concern. It could go a little bit lower, it can be a little bit higher, uh, and so that really depends. And then the temperature in your own orchard is very dependent on the location, uh, like elevation and the uh all all of that can change the temperature, the actual temperature in your own particular blocks. So that's features some that is something to be concerned about, especially with the frost that's coming up. And so, any frost protection mechanism you have, if you have windmills, if you have uh frost fans, if you have anything like that, uh this is the time to use it. And uh the other thing I wanted to mention was uh it'll be good for the peaches to wait and see the damage that has happened and then think about thinning because peaches you can thin with a seed uh uh right from pink to petal fall, and so there's a wide range of time which at which you can thin, and so most of the peaches are uh close to full bloom or at full bloom, so there's still a couple of days uh at least to the end of the week until you can apply thinners. So once the frost is done, uh it's uh it's expected uh uh later this night or early Wednesday morning, and once that's done, uh what you can do is to uh harvest uh uh st harvest stems with some uh with some flowers, or and then you can wait for a day or wait for 12 hours or something like that to then check for damage because that'll make sure that the damage is seen rather than doing it immediately. You can also do it immediately, it'll give you a good idea as well. But it's better to wait a couple of hours to make sure that the damage can be seen and then uh cut into the buds uh longitudinally, and then open it up and see uh whether the ovules, the style, where you whether you see damage, and then you can estimate damage. You can take about 50 buds or 75 buds and uh uh look at them and see what the damage percentage is, and then make a decision about uh how you want to thin. And so your thinners for peaches could go sometime on Thursday or Friday, depending on the damage that you see, uh uh damage that you see on your peaches. Uh, ideally, with the frost and with the damage that the frost is going to bring, I think going with the lower rates of a seed will make much more sense. And so once you've evaluated that extent of the freeze damage, you can apply anywhere from 10 to 20 ounces of the product per 100 gallons of water in an acre. And so 10 to 20 ounces that's 300 to 600 ppm. So you can use a lower rate 10 ounces if you see a lot of damage, if not, you can go up to about uh 15 ounces of the product per 100 gallons per acre. That's sort of the meat middle rate. So to go in when uh there's not that much damage, but you still need to thin. Uh so uh the middle rate of 15 ounces would be good if you see damage that is more than uh 40 to 50 percent. Uh you would still need to thin, but you maybe not do not need to thin as much. And so that that is the time when you can use a low rate, 10 ounces of the product. Uh and uh you can thin and try to get that to closer to the number that you want, so that you your hand thinning can be made easier. Uh so uh if you have for peaches, we want around 10 to 15 percent of the crop to have a full crop. Uh so as long as we have that at the end, I think we'll still have a good crop, but hopefully the frost doesn't do too much damage to the peaches. Uh, there's a lot of ways growers have been uh doing stuff in order to save their peaches. I know there's a few orchards uh especially that are close to the city, uh, that sometimes even start fires to save peaches. And while that is a very, very arduous and difficult task, uh it does help to increase the temperatures and then uh save peaches. You can use frost france, frost dragons, uh, and also use irrigation as well, uh, or overhead sprinklers, overhead irrigation to sort of uh also help with uh reducing the damage from the frost. We are looking at testing a few products that I'll talk about when we move on to apples. But as far as apples are concerned, uh we are at uh for we'll start with Adams County. Uh most of our uh apples are at anywhere from uh loose cluster to turning pink, so early pink, like uh uh so for example, like pink lady, you can kind of see early pink, and most other varieties they are at loot loose cluster, so in between tight cluster and pink, and so uh that's where a lot of the varieties are at Adams County in Berks. Most of them are a tight cluster again. Some of the early varieties, like Pink Lady, we can kind of see a little bit of pink, and then uh we are firmly in tight cluster in center center county, and and so uh there is a potential for damage of the kings, especially ones that are showing pink with the temperatures that we are seeing. So uh apples are something to also check because based on whether the king is alive or the king is dead, uh our thinning strategies will vary based on that. So it's important to understand uh how your varieties are doing and to understand if the kings survived after the frost. And so, similarly for peaches, I think with apples, you can uh you can check them by cutting not longitudinally into the bud, uh the flower bud, and then uh check if you have damage to the reproductive parts, and that's easily seeable. You'll see a brown or black sort of uh uh ovule style or pistol or those damaged reproductive parts, and so I think that uh it'll be easy to tell. And again, you can't just do a few and then decide because it's highly variable depending on the location on the tree, and also whether it's a spur or a terminal, because the terminals are usually a little bit more exposed, and so it's important to try to get around 50 to 100 pods and then do an estimation for you to get a clear idea of how much damage, how much damage you've seen. And uh for apples, we are uh and then based on the damage, then we can plan our thinning strategies as to whether we need to do blossom thinning or we don't need to do blossom thinning, and again uh try to deploy all the strategies you have for frost protection because this is uh going to be one of the major frost events this year, and uh we forecast it to go as low as 20 uh 25 in Adams County. Uh, I know in Bedford, in the new Parish weather station, it shows it can go as low as 22 Fahrenheit in Center County as well. Our forecast shows that it can go as low as 22 Fahrenheit, and in different locations, based on your elevation, based on your uh uh orchard location, uh the temperatures could vary, but those are uh those are temperatures that can cause damage, so it's important to make sure you understand how much damage has been caused, and that can easily be done immediately after, so you don't have to wait till bloom. Uh, the other thing I want to mention is uh some folks can sometimes harvest branches and put them in water. So that uh I would advise against doing that to check for uh whether the buds have damage or not, because sometimes things can bloom, uh, but the inside parts it can be a fake bloom, for example. Sometimes you see that in peaches where the bloom can be very showy, but when you check inside the flower buds, the reproductive parts are not viable. So uh uh so similarly, you might see that when you put them in water and wait for them to bloom. Instead, try to use a blade to cut the uh buds longitudinally and check whether there's damage. And so um that's that. And if you have any questions, let me know. But otherwise, that's where we are at, phenology-wise, and uh uh that's a suggestions for thinning, mainly for peaches. Yeah.

SPEAKER_00 10:20

Um so it it dawned on me that on our website, the Penn State Extension website for fruit, we do have an article about orchard frost critical temperatures for various fruits. So I will make sure, or I should say, I'll have Don make sure that this is like linked in the description of this episode, uh, because it's a good reminder as far as understanding the critical temperatures and the bud development and like at 10% kill and 90% kill as far as what's the the temperature. And uh if the according to this, if the forecast comes to fruition, we are going to have a knockback, some early thinning, it looks like, um, from this event. But this is I I think people need to sort of mark this week down on their calendar because I feel like every year we always have some kind of major cold event this week. It's always the first full week of April. We had it last year. I think it was on April 6th that last year. It was a very similar situation.

SPEAKER_01 11:26

Yeah, Carrie, I just want to mention that we have an article coming out in uh about an hour or two that also has that information about the seas and the frost. And so hopefully you can check that as well if you need uh if you need to. There will be a Penn State uh alert or I forget what Fruit Times alert or something like that.

SPEAKER_00 11:47

Oh, perfect.

SPEAKER_02 11:51

Cool. Sounds good. Thanks, Sean. And yeah, that will definitely be linked. Uh and ideally folks are getting our emails, uh, probably with a bunch of other emails, but at least that email. Uh Carrie.

Apple Powdery Mildew Spray Plan

Peach Rusty Spot And Brown Rot

Fire Blight Prep Before Bloom

SPEAKER_00 12:04

Well, yeah, uh speaking of alerts, you will be getting hopefully a disease alert either today or tomorrow. I don't know if it will be in time to have both of these articles um together in the same email. We we shall see what happens. Uh but anyway, uh so right now uh we have just emerged from kind of a wet early start to April, a wet uh late um, or I should say the end of March. It was pretty wet. So we did have an apple scab infection event over the weekend and also last week. But now we're in a stretch of dry. And so we've got lots of dry weather, at least for the next week, at least to maybe next Wednesday. That's how far I see into the forecast that is posted online that dry weather may extend even further. So this does not mean we can take a step back and relax and thinking, ah, we don't have anything to worry about. Remember, in the winter we talked a lot about powdery mildew. We are in the happy zone for powdery mildew disease development, and we are at the right stage in many of the areas of bud development of when control starts. Uh so for apples that is at tight cluster, and I know there a lot of the listening area is at tight cluster. We definitely are in tight cluster, probably early pink down here in Adams County. And then for peaches, it's going to be at petal fall, and we may be at petal fall by the end of the week for some varieties. Um, so for peaches, that's rusty spots. So, first let's talk about apples, tight cluster. So, even in light of this weather event that's coming up this evening or early tomorrow morning with the frost freeze, powdery mildew is still going to be a concern because we're going to have temperatures, it's not going to suppress the disease. It's just maybe we'll delay it a little bit. Um, but the spores are active and trees need to be protected because for apples, it is those shoot tips, it is those initial plant tissue that's emerging from the buds. That is going to be where primary infection is going to occur. Flowers can be aborted as a result of primary powdery mildew infection. So it's important to take this infection event, which is going to be multiple days, seriously. So we've talked ad nauseum about powdery mildew at Hershey and during the winter meetings. So everyone should be primed for this major event. But as a reminder, let's talk about management for apples. So I still encourage, even though this isn't a major scab infection period, still be tank mixing with uh a mangazeb, a rain fast mangazeb, because you never know. It's going to be hot later in the week, early next week. And so that may spur some thunderstorms, which it won't take very many wetness hours to trigger another scab infection event. So rain fast mangozeb, three pounds to the acre, and then have tank mix it with a product that is strong for powdery mildew. What could that be? It could be sulfur, and I recommend micronized sulfur, some micronized sulfur. And I would say because of this stretch of dry weather, use eight to ten pounds per acre and maybe on the higher side. You could tank mix it with axios, that is great against powdery mildew, that's a frac group 52. You've got some frac 3s like Sevilla, Rally, Sonoma, Rhyme, Procure. These are all strong against powdery mildew. You have some unique modes of action like Torino and Gattin, which are also strong against powdery mildew. For organic management, probably micronized sulfur might be your best bet, but you could also be thinking about potassium bicarbonate. That also works. Also, eco swing works against powdery mildew as well, but not against scab. But since we are in you could probably get away with it or for organic control just by focusing on powdery mildew. So for folks that may not be at the tight cluster phase, you can still be conservative during this time period. Um still be thinking about scab, but you could just, you know, I get a jump start on powdery mildew control. So right now, I would do mancozeb and sulfur, micronized sulfur, uh, as far as doing a good control measure. Um scab spores are low, but powdery mildew is high, and sulfur is excellent against powdery mildew. Okay, now moving on to stone fruit, particularly peaches and nectarines. We are at bloom pushing petal fall, maybe for some varieties. I know even here at Frex Farm, we have some varieties that are really charging forward along. There's some varieties that, as I joke, need an invitation to bloom that are still pretty tight and aren't blooming, and then some varieties that are in the middle. But petal fall will be approaching for peaches and nectarines, and petal fall starts for rusty spot control. And as a reminder, in contrast to apple, rusty spot only affects the fruit, or this powdery mildew of peach only affects the fruit. So we need to make sure that on very vulnerable varieties that you've got adequate protection at petal fall, shuck split, first cover, and second cover. This is the time frame when you control for rusty spot. You don't need to go beyond that. Um, that research was done at Rutgers, Dr. Norman Malansa did it, and he narrowed it down to those four sprays that are necessary. And so, just as a reminder, cultivars can vary in susceptibility. So, what are we talking about cultivar-wise? So, low susceptible cultivars to Rusty Spot, the examples are Gloria, Snow Giant, Red Haven. Moderately susceptible, this would be Messina, Desiree, John Boy, Suncrest, Jersey Glow, Rare and Rose. And I know this because I have Rare and Rose. Those that are highly susceptible, Bounty Jersey Queen Autumn Glow. So those are just some examples of varied varieties, a variation of varieties that vary in susceptibility. So it's something to be mindful of when you're controlling for the disease. So to be managing for a rusty spot right now, I guess at Petalfall, this is what you definitely want to be uh thinking about. And this is going to happen probably this week or early next week or over the weekend. So there's a lot of options for rusty spot control. Number one, sulfur, you know, micronized sulfur. And why I keep stressing micronized is that a little goes a long way with micronized as opposed to yellow jacket, goes on a little more evenly. Um, again, and considering this is an extensive dry period, I would be focusing on the higher rates of about eight to ten pounds per acre. But you can also use other products. Your frac threes like Rally Sonoma, Indar, Aureus, Sevilla, Quash, uh, your frac group three and nine, like Inspire Super, your Frac Groups Three and Sevens, that's Luna Flex, Luna Tranquility, Frac Group 7 by itself, Fontelus Miravus Tacerist, Frac 11, Flynnextra, then your Frac 7 and 11s like Marivon Pristine and Luna Sensation. Um, for organic options, sulfur is great. I've tested Pro Blood Verdi, which works pretty well, and you can also use potassium bicarbonate, which is also effective against powdery mildew and peaches. As far as other organic options, I'm in the process of testing those this year, and hopefully I'll have more data to share next year. Even though we are at bloom in some areas for peaches, we also think about brown rot. You can be conservative with brown rot blossom blight control right now because no rains in the forecast, uh, especially of extensive rains, but be on alert because again, we're expected to have some pretty high temperatures over the weekend early next week. This is going to move trees along, and we may have a pop-up thunderstorm that would give us enough wetness hours to make brown rot happy. And so in this case, uh again, focusing on powdery, mildew, rusty spot, control at petal fall, but blossom blight, you could again be conservative because the conditions really are not um uh optimal. Um, but again, there's still a risk. So you've got iperdiome products like Roverall Meteor, uh, you can use this through petal fall, Topson M works, captan works, sulfur works as well, micronized sulfur. Uh, and so if you have a protracted bloom, which this may occur because next week it looks like after a string of 80-degree days, it drops back down into the 60s. So some folks may be in this weird zone where we may have a protracted bloom and we may have some wetness events during that time, not sure. Um I the forecast doesn't go beyond, I believe, next uh Wednesday. Uh so you can tank, you can rotate with other products, your frac threes, nine, seven, and elevenths, but just be mindful of what you use during bloom when it comes time when it comes time to managing for brown rot during the pre-harvest period, and that's the three weeks leading up to harvest. Uh and as just as a reminder, as your iperdione, your captain, and topsin, these aren't very effective against rusty spot. So don't be thinking that you can kind of get a two bangs for your one buck as far as control. Um, if you do want to do that, sulfur would be your best bet. Um, sulfur will control for brown rot and for rusty spot. So just be mindful of. The products you're using and make sure that they are effective, really against Rusty Spot right now. Um, so uh as far as um the last thing I just want to mention, because of the bud stage we are at with Apple and things, we've got a stretch of 80 degree days, which is probably going to move things to bloom very quickly. Where I will talk about probably fire blight next week, but what can you do in the meantime, especially with the warm temperatures coming? Um, the closer you get to like full pink, you could be thinking about adding in a plant defense solicitor to your tank mix, something like Actigard that needs a couple days to kick in before full bloom. Um, you've got a bunch of other different plant defense solicitors out there, um, like uh Lifeguard and I would say regalia, but I've had mixed results with regalia. Um and another product that I do I will mention because even though it's not registered as a pesticide, it is a actually foliar fertilizer, but I do see some plant defense properties with it, and that's um a product called Neutrophyte Magnum. Um it's it's a 2016 or 24016, they're the same product, depending on where you're located. I know that sounds unusual, but this is a um this is a potassium phosphite, and potassium phosphates are known to have plant defense properties. Um however, this one in particular is not labeled as a fungicide, it's a it's a foliar fertilizer, um, but it does have some promising um aspects to it. And I'd be remiss in not mentioning it just because of how consistent my results have been working with it. But I just need to emphasize this is not a pesticide in controlling fire blight, but it does have some kind of plant health benefits when it's used during the time when fire blight is active. So that might be a sort of a disclaimer as far as when using this product. There are some other products out there that I can't really um uh give my endorsement yet because I haven't worked with it um yet, but hopefully through this season I am will test them. We'll have even more products to be able to share with you for the next coming season to try to really kind of tighten up, um button up the uh fire blight to control um during such a weird time, especially when we have a protracted bloom or dealing with trees that have rat tail bloom and such. So, but I will say this is that folks need to be starting to be on alert for fire blight come this time next week, um especially if the conditions turn out to be the way they're forecasting with warm temperatures. Um but it remember we do need a wedding event. Um, so that is something that also has to be in the forecast. But the warm temperatures and if it's blooming, that's really gonna jack up the reproductive potential of any bacteria that finds itself in flowers as the bees are pollinating. Um so just something to be on guard, definitely be on guard in the in the next 10 days. So that's that's it for me for my update. Um there's any other comments, questions, but there will be an update um hopefully coming out within the next 24 hours from Penn State Extension.

Minimal Sprays After Crop Loss

SPEAKER_01 25:25

Hey Carrie, I have a question. Yes. Um so our particular block of peaches, we actually lost a lot due to the winter damage.

SPEAKER_00 25:33

Yes.

SPEAKER_01 25:33

And so we expect little to very little peaches. So basically, what are some things that we can get away with with not spraying?

SPEAKER_00 25:41

So that's an excellent question. I'm glad you brought that up. So um, for folks that got really nailed by the cold temperatures this year, um, you may be prone to not just do anything, save some money. But I advise against that. What I do advise is to have a very minimal spray program. Again, captain and sulfur is really all you need. Um, the disease you do have to worry about is bacterial spot because that will still go to the leaves. Uh so that is still something you need to be mindful of depending on the vulnerability of particular cultivars you may have and the bacterial spot history. If you don't have bacterial spot, you don't have to worry about really anything. Just stick with a very minimal fungicide program to keep any inoculum lurking about suppressed. Um, because it's usually during these off years, if people don't spray, you can get a high inoculum buildup and you could be really nailed next year. So that's why I just really encourage folks just to still do basic maintenance fungicides just to keep that, keep down the inoculum in the orchard. Uh for bacterial spot, though, if you do have uh vulnerable varieties, still stick with, I would say, uh, you know, do oxyte um during the dry time, or I should say do oxy tet really during the wet times. Um, and then during dry times, maybe a low rate of copper. And I will come when it comes time, petal fall will be the time when um petal fall shuck split is when bacterial spot management occurs. So I'll be sure to mention options, um, low rate. We've talked about very low rates of copper that is 0.5 ounce to one ounce of metallic copper per acre. So this is a significantly reduced rate. Um, Norman Lancet figured this out um at Rutgers. I always talk about this every year. Um, and this is you can you can use this safely, it will cause some phytotoxicity, um, but not enough to stress out the tree. Um, but you will get disease management control for varieties that are vulnerable. So you still need if bacterial spot, that's the disease you really have to worry about. That's the disease that still affects leaves. But all like fungal fruit rots, rusty spots not going to be a problem, brown rot's not gonna be a problem. Any ro is not gonna be a problem. So but come this fall when the leaves fall, you're still gonna have to worry about peach leaf curl because that is another disease. But you don't have to worry about peach leaf curl until the fall or late winter next year.

SPEAKER_01 28:14

Awesome. Thank you.

SPEAKER_00 28:15

Yeah, thanks for asking that. That's a good point.

SPEAKER_02 28:20

And we have announcements.

SPEAKER_00 28:23

Oh, yes, we do. Thank you for that. I'm so I'm so you were locked in. I'm in the zone. I'm in like the disease management zone. Yes, we have announcements. So um spring meeting update. So we have uh a few more locations to announce, but just to give you the rundown of our spring twilight meetings for 2026. So Tuesday, April 28th, this will be in Lancaster County, and it's going to be at the Masonic Village Orchard in Elizabethtown. Uh and all these meetings, with the exception of the last two, are going to be from 6 till 8 p.m. Uh Wednesday, April 29th, it will would will be Adams County, but we haven't secured a location yet for Adams County. Thursday, April 30th, this will be in Franklin County, and it will be at Harlan Hesses Orchard, which is in Waynesboro. Uh and on Monday, May 4th, uh, this is the uh this will be in Columbia County, so this is the Central Susquehanna Northeast meeting. This is going to be at OHF Orchards in Bloomsburg. On Tuesday, May 5th, this is our Southeast regional meeting, and it's going to be in Delaware County, and this is Lynn Villa Orchards in Media, Pennsylvania. On Wednesday, May 6th, this is our Western PA meeting. It's going to be in Lawrence County, and it's Dawson's Orchards, and it's going to be in Enon Valley. And then on Thursday, we have a double header. Um, so we will be on Thursday in the morning, we're going to be in Erie County, and we're going to be at Birch Farms Country Market. And this will be from 10 to 12 p.m. And then we're going to drive down the same day to for the Appalachian region meeting. And that's going to be held in Bedford County, and that will be at Boyer Orchards in New Paris, Pennsylvania. And this will be from 5 30 to 7 30, a little bit earlier, and this will help the specialists who've been on the road for two days get home before midnight. So that is the goal for that. So that is the the latest for the spring meetings. And I believe they are in process of getting up on C Vent. I think. I'm not sure if that is live yet, but once that occurs, I'm sure Don will post the link uh at when we have it.

SPEAKER_02 30:43

Yep, that actually reminds me I have to go do a test right now. So we're gonna finish this up and then I can get those things online. Alright. So thank you guys for jumping on here for giving the updates. I will try and get this edited pretty quick because this is pretty timely.

SPEAKER_00 31:02

Um and then we'll just week because I'm sure we'll have more exciting things to discuss in a week. Uh because Mother Nature definitely is keeping us on our toes this year. We went from winter to summer, essentially with no spring.

SPEAKER_02 31:23

She always does.

SPEAKER_00 31:24

Yeah, yeah. There's been no easing into this season.

SPEAKER_02 31:29

All right. Well, thank you guys again. We'll get this rolling, get this edited, and hopefully get this online pretty quick. So say goodbye, everybody.

SPEAKER_00 31:37

See you later. Good luck.

SPEAKER_01 31:39

Goodbye, everyone. Good luck with the frost.