This post a is text digest of the new Scaffolds Podcast. To listen to the original, visit the following link: Scaffolds Podcast
Monique Rivera Interviews Christophe Duplais
Monique Rivera: So today it’s my pleasure to introduce Christophe Duplais, who is an associate research professor here at Cornell Agritech. Today we’re going to talk about the mysterious black box that is adjuvants. So. Hello, Christoph.
Christophe Duplais: Hi, everyone. I’m Christophe.
Monique Rivera: Okay, so let’s hop right into it. So I think this is a big black box, especially because there’s a lot of different terms being thrown around and I don’t know what they mean. So that’s why I wanted to have you on so you can help us maybe try to start to understand this amazing plethora of products that you can potentially use. So my understanding is that there’s really three main categorizations so, nonionic, anionic, and cationic. So what do those terms mean? And there’s also surfactants, oils, nitrogen based fertilizers that can be used as adjuvants. And then there’s the terminology of stickers, spreaders, spreader-stickers, and penetrants. So how do we make sense out of this?
Christophe Duplais: That’s a lot. So the first thing you need to understand is that “adjuvants” means any products you add into the tank that helps the bioactive ingredients to be more bioactive. Basically, the adjuvants really help the products to be taken into the leaves. They help the droplets to be smaller. So there are different factors for the adjuvants to help the products.
The surfactants are part of being adjuvants. So the surfactants are adjuvants. Surfactants are pretty easy to describe. They are like soap. Basically, it’s a molecule that has a part of the molecule that is very water soluble and one part of the molecule is not water soluble. So what it forms, like soap, are little bubbles that can trap the fat inside. That’s how you wash your hands.
So within surfactants, there are three types. The non-ionic, the anionic, and the cationic. Which means that basically the tail I was taking about, the little part of the molecule that is water soluble, it can have a charge like, for example, hydrochloric acid or a sodium base, like these kind of things that are charged. When the molecule is charged it is very harsh. So that’s why most of the time we add non-ionic surfactants, because they’re way less harsh than all the other surfactants. So that’s why even the soap, we are using non-ionic surfactants. So humans, we use surfactants to wash our hands from the fat. So it helps to solubilize the fat into water. That’s what it means. The surfactants help to solubilize the fat into the water. And so when you think about your pesticide, any pesticide you have, basically they are not water soluble. When we synthesize them, they hate water. That’s why even when you buy them from the vendors, there are always surfactants to help them to solubilize into water.
Now, adjuvants have different functions. So adjuvants can be wetting agents, they can control the droplet size, which means that when you spray, you can have tiny droplets instead of like big coarse droplets going to wash out of your leaf. There is also what we call stickers or spreader-stickers that help when it’s like a very rainy day. You really want your product to stay on the leaf and not be washed out. There is also something we call tension surface. So, tension surface, when you see a water drop on the leaf, you can see that the shape can be a very half sphere. But because you want the product to be inside your leaf, when you change the tension surface, the drop size, the droplet can expand and have a better surface area with the leaf. So that’s why some of the adjuvants are helping to have a better uptake of the active ingredients into the leaf.
Monique Rivera: So basically, if you think about Movento or spirotetramat, we need a penetrant, that’s on the label. So a lot of times the label will indicate if you need an adjuvant. So, my next question is on oil. So that’s considered some type of adjuvant. Do you know why we would use those in mixes?
Christophe Duplais: So definitely you should always look at the label because if there is the mention of an adjuvant that should be used, it means that they already made pre-assays and it’s very relevant to use what they recommend. So always look at the label and make sure to use the adjuvants when listed, for sure.
Monique Rivera: So I guess my question is there is a whole section of work within these chemical companies called formulation chemistry. So if they need an adjuvant, is there any reason why they wouldn’t include that in the formulation?
Christophe Duplais: I think the company wants to sell the simplest product, and they know that growers are making their own recipe for the tank. So they want to probably let growers make their own tank mixes, or they don’t want to add too much themselves, because they know there are lots of products out there and they know that depending on the pH of the water, maybe the temperature, maybe the crops you are using, you need different type of surfactants for the same pesticide. So maybe they just don’t want to be in control of everything and make sure that there is room for improvement for each product.
Monique Rivera: So do you think it’s necessary to use an adjuvant with sprays?
Christophe Duplais: I really think that some adjuvants are very important. Those that control the droplet size are very important. Those adjuvants will control the tension surface to have a better penetration into the leaf tissue are absolutely important. There are some that I’m questioning, like the spreader-stickers, what we call stickers. I’m questioning the efficacy of those. And that’s one thing we’re going to test, actually, in the next growing season.
Monique Rivera: So how do you know what adjuvant to use with what product? So let’s say you have a pesticide, right? Let’s say it’s a pyrethroid. Is there any special consideration that you would give other than the label to decide on maybe potentially adding an adjuvant?
Christophe Duplais: I don’t think there is a specific rule. I feel like for each type of molecule, there can be a different type of adjuvant that can make it work better. For some molecules, lots of different adjuvants can make it work better. And that’s why I think that we, as extension specialists and researchers, should do the work, because there are lots of combinations where different adjuvants are going to have the same effect, which can improve substantially the activity of your pesticide. But in some cases it might not be very useful, or in some cases can even be detrimental. So it’s hard to predict which adjuvant should be used for any type of molecules, in my opinion.
Monique Rivera: Yeah, so obviously we use adjuvants for a lot of different reasons. Right. And so for the entomology side, we’re using it to control insects and say, Kerik Cox is using it to control diseases. Do you think there’s a difference in approach for the two?
Christophe Duplais: Maybe not. You don’t want the fungal strain, the fungal pathogens, to get inside the leaves. So the infestation requires the pathogen to get inside the leaf, and for the insect, they are feeding on the leaf itself. So you need the product to be inside the leaf, not on the surface. And that’s why all the penetrants, the wetting agents that helps the uptake of the molecule through the leaf, are very important. And I don’t think we should expect any differences between adjuvants that are used for insecticides or for fungicides.
Monique Rivera: Okay, so maybe I’m going to round it out with, like, a couple of fun questions. This is really your first job working in agriculture, right? But you’re an organic chemist.
Christophe Duplais: I’m totally an organic chemist. Like the black matter of synthesizing molecules, you can name it “mixing them in a pot”. It’s not cooking, but it’s kind of like this.
Monique Rivera: Yeah. So we’re really lucky to have Christophe here at Agritech. So what are your plans to investigate adjuvants?
Christophe Duplais: The first one I want to really test is the efficiency of these sticker adjuvants that claim that when there is lots of rain, the molecules stay on to the leaf. We’re going to survey most of growers in apple orchards, making sure which of these sticker adjuvants they are using. And then we’re going to test them all. And with Kerik we’re going to do something very simple. We’re going to take a few pesticides/insecticides, mix with different combination of these stickers and spray that in the field. And then we’re going to mimic the rain and wash out the plant, and then we’re going to quantify, using heavy analytical chemistry, how much less of the pesticide/insecticide is still in the leaf with different treatments. So we’re going to really see if there is a need of using the stickers or actually if you don’t use stickers, if you still have the same concentration of the pesticide even after a big rain. My goal is try to make sure that you don’t have something in a tank that is not useful and not worth the money you’re going to have to spend to protect your field.
Monique Rivera: Yeah. So I feel like no one else is really doing that work. And I read that here in the US adjuvants are unregulated, but in Canada they are. So if you were to regulate these, what would you do? Would you require efficacy testing maybe?
Christophe Duplais: Efficacy testing, maybe also, like I know that there are very few studies right now on pollinators. These materials are not toxic. Right? They are not toxic, but when you think about organosilicone, these kinds of wetting agents are kind of heavy. So for some pollinator to be exposed to the pesticide plus these adjuvants can be very detrimental for the pollinators and all insects in general. I don’t think they have a toxicity per se, but I’m sure there is some adverse effect that we haven’t tested yet. Not for humans. But you will not eat soap, right? And so that’s the same idea here. You don’t eat soap, but probably for the bees, not great to be tasting flowers with lots of organosilicone inside.
Monique Rivera: Yes, absolutely. So hopefully we’ll be hearing more from Christophe in the future. We’re really looking forward to hearing about all your adjuvant work because no one else is doing it because it is not fun work. Anyway, thanks so much for being on the show today, Christophe. We will probably be having you on again sooner than later.
Pathology Update with Kerik Cox
Okay, Kerik Cox coming at you with pathology updates for this week’s scaffolds. I think last time we talked a little bit about a week of heavy rains, plus what to do about the various summer leaf blotch diseases such as apple blotch, formerly known as Marssonina, leaf blight, and some of these other things, maybe some glomerella, some frog eye leaf spot. I have seen a little bit of frogeye out in the area and I think we also talked about a pretty heavy rain week and sort of finishing any last residual scab you might have with one of the stronger fungicide materials. And we talked a little bit about how starting the summer program, maybe that third cover with one of the single site fungicides, an SDHI, QoI, or a DMI, or some kind of wild mix of one of any number of them. Usually it’s SDHI, QoI, or even the DMI with a little AP in there can be pretty good.
And now what I want to do is sort of creep into the idea of the summer fruit diseases. But before we do that, we are in a unique possibility as we have a highly motivated apple scab research student. You might have heard from her, Liga, and she’s already picked up a couple of growers who have had some scab issues. And if you have scab in your area and want us to take a look at it, we’ll start it this summer and look at it into the fall so that by next year you would know if you had any resistant issues. We have opened up what I like to refer to as the disease sample submission form for apple scab. What you’ll want to do is collect nice sporulating, velvety lesions. Don’t pick the burned out ones, Take about 50 leaves, put them in a paper bag and you can priority mail them to us. Don’t put them on the dash of your car. Apple scab loves to get killed. But if you want to find out more about how to do it and where to submit some apple scab samples, you can go to https://blogs.cornell.edu/coxlab/ And you just go down to the middle page and click on the link that says disease submission forms and you’ll quickly find one for apple scab. We’re still doing fire blight samples as well. Don’t do powdery mildew, that’s a little more complicated. One day we’ll get another graduate student interested in powdery mildew. So we’ve updated the forms. It tells you how to label the bag. Providing all the information that it asks will really help us identify whether or not you have a fungicide resistance problem, or if it rained a lot.
And speaking of raining a lot, looks like next week we got a lot of intermittent rain again. So it’s not really a big week for summer diseases here, particularly on your developing fruit. But who knows, maybe next week might be the time. And we talked about that timing being a little bit later as we go through extended periods of drier weather. Or it might rain a little bit and it might bake off immediately, not providing a lot of hours of leaf wetness. And your cover intervals, now that you’ve really hit them hard to clean up a lot of things, probably could be creeping into that 14 to 21 day interval or the 10 to 14 depending on how much summer disease problems you’ve had. It looks like next week we have a bit of rain starting Friday all the way through next Tuesday, so maybe a little bit over the weekend but it’s going to be hot and it could bake off.
But then the question is what do I do? Now we’re moving into that period where we could have extended drought and if you sort of followed along last time and decided to sort of end your scab season strong with a really strong SDHI-QoI material, right, that sort of 3rd-4th cover, whatever you happen to be putting in there. Now I think you can sort of relax a little bit.
What are our summer fruit diseases? Well, we have the flyspeck/sooty blotch, a classic disease that does not change the taste of the apple, but will have your apples thrown out of the fresh market just as easily as anything else. Now, one of the other more challenging problems if we get warmer, wetter weather, you could run into the bitter rot, and then sometimes you can run into the black and white rot caused by botryosphaeria. In some instances a little bit of lenticel damage, even from the captan you’re using to try to protect against these diseases could cause enough injury in those cells to start what looks like a little bluish dead area on part of the fruit. And it could be some sort of botryosphaeria infections that failed to take off.
Now a lot of these things are latent infections, and so that means that with a nice fungicide you put on at first and second cover and petal fall, those are cleaning a lot of the infections up. They’re happening earlier. Extended fruit wetness after petal fall allow these sort of latent infections, and then they can kind of emerge and become problems later. Now for most of the summer you’re fine. It only isn’t until you get those fall rains, we’re probably going to go through a drought period, and then we’ll pick up the fall rains right at harvest. And then what ends up happening there is you just get a little drop of an herbicide from a late application. Or maybe a bird decides, I’m going to go peck a hole in your fruit. And then the bitter and black rot and white rot are all there to cause trouble. And then these things, if you have a latent infection, meaning it happened earlier because you didn’t hit it hard enough as you were finishing off the season, you could have these things just emerge in storage and you are wondering what did I do wrong? What did I not spray enough over the summer? It probably means you didn’t clean up enough of those latent infections early on.
Now there’s even the dreaded moldy core which is bunch of fungi that happened to infect during really wet weather at petal fall, and that’s something you don’t want to see. It can be confused with things like callus core, which is just an overdevelopment of callus tissue in there, but the person buying your fruit doesn’t care if it’s actual fungus or callus tissue, they’re just going to throw it out.
So hopefully last time you sort of ended your season strong. Now you can relax a little bit as we go into these drier periods and extend things out a little bit for the flyspeck/sooty blotch, the bitter rot and the white rots until we start getting later in the season. Now, for the most part, if you’re really worried about the heavy fruit diseases, particularly the bitter rots, that could be pretty strong on the eastern part of the state, particularly in Hudson Valley and Long Island. Always going to be a really big problem in organic production because you can’t really finish strong with a SDHI, QoI, or a DMI, or some mix of the two. Those aren’t really allowed and they’re going to be kind of challenging. I’ve got some product recommendations to try to keep those down as well. And this will be some of the same products I recommend for kind of getting through this sort of dry summer period before you get to the fall. Best things you can do for these is hit them hard at petal fall and those first couple of covers as you creep into the summer, particularly if you have wet weather like we did all last week. And then you can extend the intervals up and you want to save one of your SDHI, DMI, or QoI fungicides for that last single site fungicide application before harvest to make sure that the fruit go in clean, and then when someone pulls them out, they’re not covered with fly speck/sooty blotch or bitter rot, or black rot, or some of those other things.
The best things to do for these things is just like we talked about last week for those early leaf diseases like apple blotch (formerly known as Marssonina) was hit that second cover, even third cover, window that you’ve already moved into and dealt with. And now, as we move into this sort of late period, if you get like an inch or so of rain, one of the better programs that Dave Rosenberger and I used to recommend was a low rate of captan with a low rate of phosphorus acid.
Now, all that being said, in these light periods, you may have a variety that doesn’t take well to captan, and Ziram may not be an option as well because you can’t export the fruit or we may lose it as well in the US. There’s been a lot of EPA chatter about that as well. So what does one do? The one thing that’s tricky about captan is you don’t want to use it in really slow drying conditions. It is phytotoxic, and if it gets inside the cells, it can injure them enough. And maybe the variety you have in question has very sensitive lenticels and could lead to one of those botryosphaeria infections we talked about. Other options, let’s pretend like you’re not going to go for those. Or let’s just say you have an organic orchard and you’re like, oh, I got to get through this period as well. Some of the products I really like to use, I like the Double Nickel LC, any of the liquid bacillus products. I’ve had excellent luck also with Howler. Some of these newer bacillus products, particularly if they’re portable or if they really, really mix well, can be something to really get you through the sort of intermittent warmer weather where we’re not really going to be hitting these long, wet, cold periods for, for sort of the summer disease as they can move through well. I’ve had good luck with Polyoxin D Zinc products. If you think about it, maybe there’s a little bit of the old zinc in here helping out the situation. And these are all the things I’ve mentioned thus far. I believe we’re safe for organic production and can kind of help you creep through until you can use that last single site fungicide in the fall. I’ve used Ozo a lot. I’ve had good luck with this. I just noticed it had a specific label for New York, for fly speck/ sooty blotch and all the bitter rots as well. In this particular instance, what we want to do is as we move through this thing, we start hard, we finish really well with your single sites, give them a kind of a break. You can either do the captan/phosphorus acid, low rates of both, or you can try some of the various biologicals that I mentioned to try to get to that last period where you can finish strong with one of those SDHI, usually SDHI/QoI combinations that has a very low PHI. And you put that on towards the end when things start getting cold and wet again. And hopefully it’ll keep all of your fruit clean in storage all the way to next June at this time.
I think that’s all I’ve got to say for this week. Have a fantastic week and good luck next week with a little bit of rain that I see throughout the week.
State of the State with Anna Wallis
Now for the state of the state, your weekly roundup of Degree Day accumulations and phenology from the major fruit production regions of the state. Information aggregated from regional specialists, NEWA and my own observations.
Last week: lots of rain early in the week, but then returned to hot and dry.
- WNY ~3.28” in Geneva, as much as 3.5 in some places, other places ~1”
- ENY about 0.8-1.7” depending on location
Nearly 200 DD43 over the past week across the state, which is significant, irrigate where possible, things will dry out quickly with high ET Demands.
Continue to see frost damage – fruit cracking, frost rings, other fruit marking, calyx end of fruit, lopsided fruit. Thinning and June drop mostly finished. Easier to evaluate now.
We’re continuing to track DD base 43 as an indicator of insect activity. Both DD43 and 50 are summarized in the table in the show notes. You can also find average range of DD accumulations for phenology and arthropod pest activity in the Cornell Tree Fruit Guidelines Table 7.1.4
As you know DD since Jan 1 isn’t the best predictor of all apple pests, so we encourage you to use the models in NEWA that correspond to each pest.
Here are a few things that are active now:
OFM is between generations in most of WNY and Northeastern NY, beginning second generation soon in HV.
CM in WNY first flight is winding down, second generation will begin soon. In the HV nearing the end of the window.
OBLR flight is continuing throughout the state, trap captures increasing this week in Geneva and other WNY sites. For blocks with a history of this pest, an application targeting larvae should be timed at about 350 DD base 43F after first sustained trap catch, then again in about 2 weeks. In the Hudson Valley, the larval emergence is predicted sometime this week, so first applications are likely going on or will be soon. In the rest of the state, trap captures continue to increase, and larvae will be present early July.
Mites are present in orchards now. Sampling procedure in the Cornell Guidelines Figure 7.1.4 Sample 20 leaves (4 from each of 5 trees) and inspect top and bottom with a hand lens. Determine presence/absence on each leaf and use the schematic to determine if a treatment is needed.
Rosy and green aphids also continue to be active throughout the state.
WAA has been reported in many locations throughout the state. Particularly on pruning cuts, inside canopy, lower. Not much increase from last week, possibly due to rain?
SJS is another insect to be monitoring for now, crawlers are typically active at about the beginning of June. We haven’t had significant reports of this pest yet in WNY, but it is active in the HV. But you can be monitoring for them by placing black electrical tape or double sided tape around branches just above active infestations.
Apple leaf curling midge has continued to pop up in some locations across the state. This is a relatively new insect that has become significant in the Champlain Valley and Ontario, so it is important to pay attention to. Kristy Grigg-McGuffin from OMAFRA has been doing some work on this insect and there is a great webinar recording hosted by the ENYCHP:
https://www.youtube.com/watch?v=bnSqoYIj7kk
In terms of diseases, we continue to see quite a lot of Powdery mildew this week. We’ve continued to see natural fire blight infections (not inoculated for research), in places that had infections last year, keep an eye out. Scab primary infections are present in places that were unmanaged or it slipped through. Entering infection periods for summer rots, thanks for the overview from Kerik and Liga this week on that.
And finally, here is the rundown of the DD base 43 accumulations at NEWA weather stations throughout the state. As usual, they’re also in the show notes for you to reference later.
As of the end of the day Thursday 6/22, DD accumulations were:
