Scaffolds Digest: Week 8
This post is a text digest of the new Scaffolds Podcast. To listen to the original, visit the following link: Scaffolds Podcast
Entomology Update with Monique Rivera
Today I will be talking with Dr. Michelle Heck. She works at the interface of plant disease and vector biology. And today we’re going to be discussing specifically her work on peptides to recap from last week when I introduced the idea of using peptides. Plants use peptides which are small molecules made up of amino acids that the plant uses to defend itself against both herbivores and pathogens. And now the interview.
Monique Rivera: All right. Hey, Michelle. So let’s jump right into this. You recently were awarded this $15 million grant to focus on the use of plant peptides for the control of citrus greening and citrus. So can you go over a little bit of what are the goals of that grant, and in particular, the focus on high throughput analysis?
Michelle Heck: Yeah, thanks. Great to talk with you today, Monique, about this. I’m part of a team that was awarded a grant in 2020 from USDA NIFA. And the goal of the grant, the major goal is to develop commercializable solutions for citrus greening disease. And so that’s a pretty big goal and an important one in research. There’s two types of research. You have “make it happen” research and “watch it happen” research. With watch it happen research, you set up a hypothesis and whatever your hypothesis was and you test it. If you get a result, you can publish it. But when you have a goal of finding a solution to citrus greening disease, it’s make it happen research. And it requires a sort of different approach and different mental framework to actually commercialize a solution to a major plant disease.
One of the major objectives of this grant is to identify bioactive peptides that target the citrus greening bacterium or the insect vector in this country, the Asian citrus psyllid. So there’s a component of looking for new molecules and sort of bioprospecting new peptides that could target these organisms and control their various aspects of their life cycle.
Then the next component is delivery. Right. Once we have peptides – and now we do have peptides and we’re not the only group who has peptides, there are other groups and other companies that are working in this space – the next critical thing is how do we deliver it? Right? How do we get a peptide into a citrus tree to control the citrus greening bacterium? Because the citrus greening bacterium lives in the plant’s vascular tissue, which is deep inside the tree and deep inside the leaves. And so it’s not economically feasible to make peptides at the scale in which you can spray them in citrus groves, nor is it sort of biochemically possible for topically applied peptides to penetrate into the phloem. So you need to have a delivery device. So one objective is focused on this bioprospecting and then another objective is focused on delivery.
Monique Rivera: Awesome. So how are you thinking this technology might be used outside of citrus,
particularly in other tree fruit?
Michelle Heck: Sure. We are very hopeful that the groundwork that we lay with this project and the research that we do with this project will be translatable to other vascular limited bacterial plant diseases. And so I’m thinking about Pierce disease of grapes or olive, quick decline, fire blight, a range of different organisms and plant diseases that we can target with these peptides. And so if the organisms can be cultured, the peptides that we find we could screen against the organisms. The citrus greening bacterium cannot be cultured, so we are very limited to doing those tests in insects, or in leaves, or in trees. If the pathogen can be cultured, the peptides that we find, we could send them to another group that might want to do the screening. If they can’t be cultured, then we are hoping to be able to use the delivery technology that we’re developing in our grant directly on these other tree species. That’s sort of where we’re going with that.
Monique Rivera: So last question. So how close do you think peptides are to being used in commercial agriculture? And are there some products already available?
Michelle Heck: That’s a great question. Yes, there are companies that are developing peptide based control solutions already. So Invaio is a company in Boston that has a license for the finger lime peptide that was published by Hailing Jin’s Lab at UC Riverside. That’s an exciting project I think would be great to sort of keep our eye on. And also there’s a company called Vestaron, they’re making insecticidal peptides that could be used to target various insect pests in agriculture. So for sure there’s a lot going on in that space. I hope the work that we develop will be able to add to those commercial solutions.
Monique Rivera: Michelle, thanks so much for talking with us today.
Michelle Heck: Yeah, thank you so much Monique. It’s really a pleasure. Happy to come back and talk about anything else in the future, citrus greening related or aphids or anything.
Monique Rivera: Awesome, thank you.
Pathology Update with Kerik Cox and Liga Astra Kalnina
So as for this week we have Hudson Valley and Long Island with weekly ascospore maturity reaching 100%, which means that the next rain event will discharge the remaining ascospores. So for Hudson Valley those are 5% and for Long Island those are 11%. This infection event is probably happening Saturday, May 20 and since ascospore release is lower, this might be a good week to apply a biological product.
As for the Capital District, there is somewhere between 35 and 50% of ascospores being discharged Saturday depending on where you are in a region and which station you are. So Friday would be a good time to apply a heavy hitter single site fungicide. Some good options include Aprovia, Tesaris, Merivon or Cevya. Cevya is really good if you also have rust, but there are other products you could use for single site fungicides.
So the Champlain Valley had an infection event happening this past Tuesday, but there is another apple scab infection event predicted for this Saturday with 25% of ascopores being released. Friday, May 19 would be a good time to ensure that the trees have been covered with a single site fungicide such as Aprovia, Tesair, Merivon, or Cevya.
As for fire blight, the risk of infection is very low, so take cultivar susceptibility and phenology into account if you’re making an application.
Protect your trees from this upcoming infection event from Scab either Thursday or Friday.
We’re now going to discuss some additional guidelines for fire blight management in new plantings. If you wanted to see our general maintenance guidelines, they’re up on the blog, they’re in the previous episode of Scaffolds. But what I want to talk about now is some additional things for young plantings. New plantings, one to two years old, maybe. Now that everything is dying down, it’s time to plant some new blocks. Soil is finally drying up and you can work it and maybe get some things in. So things to think about: If you can, when possible, get the fire blight resistant rootstocks. Yes, if the fire blight reaches the central leader, you’re going to want to pull the whole thing out. But what I’ve also found is that on the resistant rootstocks, the bacteria doesn’t move as quickly to the bottom and back out to the top of the plant, minimizing the time and the possibility of making that sprinkler system. For fire blight, I’ve noticed that plantings on susceptible rootstocks, the whole plant becomes systemically infected a lot more quickly. Even if you are planning to pull them, the resistant rootstock still can give you kind of a little bit of an edge.
Now when you get the trees, check your trees. Keep them nice, moist, and hydrated in your cold room and look at them, see if you see anything weird. If you think you see oozing or anything on any of the trees, it might not be bad to participate in our strep resistance survey and throw out the tree if it does turn out to be fire blight or if it looks too suspect. But you can also send it to one of us. You can check out our blog at blogs.cornell.edu/coxlab and then you can find the submission forms, you can send us samples, and we’ll check out any weird oozing you see on your young trees. Make sure it’s not strep resistant, make sure it’s not fire blight. But that can take so long that you might want to put that tree aside and be very careful with the rest of the plants from that individual box.
So once you get things going, immediately after planting, since you’re not going to be bearing on these trees, and about 14 days later, you can go ahead and make a low non-bearing copper application. And this is just going to protect the crop from any fire blight that might be moving or oozing on anything in your orchards at this time. We’re at the part where shoots might be sick and ooze, and this copper helps protect them. And also make sure that before you make that first application, let that soil settle. You don’t want that copper to pool around in the bottom of your roots and cause trouble. Now, once this has happened, I can’t stress this enough because I did this last year myself when we planted our own Evercrisp, scout the trees at seven day intervals for fire blight strikes. And normally I would say July 31, but last year I was doing it well into August and then September, as I still had fire blight in October. With the way our weather is behaving, you may want to scout your blocks every now and then, at least every seven days. Just send a person through to make sure you don’t see any fire blight strikes and get those trees out of there before they start spreading to other tissues. And if there is a hail event or any severe thunderstorm, it would be important to take a new look at it. You can use the NEWA tool to put in dates of severe thunderstorms and stuff and it would give you an idea about when you might see symptoms emerging and vice versa. Or if you go back in time. I had a big thunderstorm this week, put in that date and they might tell you you should be checking here, or this is around the time that you should be checking type of stuff.
Keep scouting at the end of season, mid-September, because sometimes we have a lot of hot weather in the fall and these things can be devastating. If you can, remove the flowers before they open. Fire blight likes to grow on an open flower, so if they start going into pink or tight cluster, that might be the best time to remove. And if you do blossom removal, try to pick the coldest day. We have a nice 55 degree weather day right now in the middle of May 17, so this would be the day to remove some flowers. Cold, dry weather is going to be better for flower removal. If you do it in hot weather, there could be enough fire blight in the area to cause trouble.
Okay, so let’s see. Once you get into bloom, you can use copper to manage fire blight. You don’t care about a crop, you just want to kill the organism and also observe all the label REIs and all that other stuff before blossom removal. Once you’ve removed blossoms, you can make your application to protect those wounds of the copper as well. So, if you get any other remaining bloom, you can just follow all the chemical management programs from our regular stuff as long as it’s non-bearing and it’s on the label. One of the things that we have been looking at for young plantings in both Michigan and New York is this idea of mixing perhaps prohexadione calcium and a little bit of Actigard. That combination really doesn’t really slow them down that much, but can kind of keep them from getting too far ahead if we get a lot of hot, wet weather in the fall. And right now we’ve seen that there’s been no impacts whatsoever on time to establishment with using that little program. That’s 2oz per 100 of prohexadione calcium mixed with 1oz per 100 of Acibenzolar-S-methyl, which is Actigard. And you can do this at Pink and Petal Fall, both for your young plantings, even though that Pink and Petal Fall is going to come at some crazy times, which you’ve been doing. And that’s been a fairly safe program for these really young trees that could be a little bit out of sync with everything else.
Finally, one last guideline I want to bring up is just make sure if you do get an infective tree in the high density orchards, get it out of there. And if you have any infections after planting, you can again send them to our strep resistance testing program. Check out the blog and that will get you to the area where you can begin to look at all our other articles and begin to find the sample submission forms, et cetera. All right, good luck this week. Let’s hope if you are doing any new planting soon that they go in smoothly.
State of the State with Anna Wallis
This is your weekly roundup of degree day accumulations and phenology from the major fruit production regions of the state. Information, as usual, is aggregated from the regional specialists, NEWA, and my own observations. In the Hudson Valley this week, fruit are just beginning to size. This week, most of the valley is reaching the thinning sweet spot, so pay attention to the carbohydrate model and the fruit growth rate model if you’re using them. Also, pay attention to recommendations from your regional specialists for specific considerations for this season.
In the Lake Ontario region, there seems to be quite a bit of separation between lake and inland sites. Inland sites are nearing petal fall, while sites closer to the lake are a little behind with still a lot of bloom. In general, it’s still a little bit too early to determine fruit set just yet. In Geneva this week, which is a little further inland than the other western New York sites, we’re even farther ahead. So earlier varieties like McIntosh were at Petal Fall on Monday, with later varieties including Honeycrisp still hanging on to quite a bit of bloom. Compared to the 20 year average, we’re a little bit ahead of normal. So the warm weather this past week seems to have caught us up, so to speak, after the cool weather during pink.
In the Capital Region this week, we’re into petal fall with some straggling blooms, especially on later varieties.
In the Champlain Valley, earlier varieties like McIntosh were near petal fall at the beginning of the week, and later varieties are still holding on to a bit of bloom.
Many of our favorite insect pests are active or will be soon. At this petal fall or fruit sizing window, keeping track of emergence and activity is really essential for successful management. So I’d like to do a quick review of what we’re seeing around the state and what’s best to do to predict when things will be showing up. In general, remember that to predict pest activity, we’re using phenology and heat accumulation. Insects are cold blooded, and respond to temperature increases. So we’re using degree days to measure heat accumulation, where heat units that are accumulated above a certain base temperature. Base 43 and 50 have been used historically.
Many insects that emerge earlier track better with the lower base temperature 43, including leaf rollers, leaf miners, and green fruit worm. For some of the later insects, it’s usually better to use the higher base temperature 50, and that includes things like codling moth. For Oriental fruit moth, it turns out it’s best to use base 45, so I guess there’s an exception to every rule. The average range of Degree Day accumulations for phenology and arthropod test events can be found in the Cornell Tree Fruit Guidelines.
As with most models, keep in mind that these are just general predictions. They’ve been accurate enough for effective management, so we know they’re useful to use. But it’s important not to oversimplify these really complex events. Many other factors can influence emergence and activity of pests, including solar radiation, wind, soil conditions. Wind, for example, could inhibit flight even if temperatures are sufficient for the pest to develop. Also, geographic features can play a role, such as latitude, elevation, location to other habitats like wooded areas, and proximity to bodies of water.
For the purposes of sharing verbal information, I’m going to continue to talk about Degree Day base 43, but know that in the show note tables there are both 43 and base 50 for reference.
So now a review of some of the pest activity that we’re seeing around the state. The first trap captures of OFM were reported in the first week of May in most of the state. A little bit earlier in the Hudson Valley, this was right about on time, maybe a tad delayed because of the cool weather at pink and at bloom. OBLR overwintering larvae have been active for a few weeks now, and we continue to see leaf rolling in places that haven’t been treated. Shortly after petal fall or by the beginning of June is the right time to be hanging traps to monitor for first flight. Rosy and green apple aphids have also been spotted throughout the state. Remember that there are many natural enemies of these pests that may also be present, so keep an eye out for some syrphid fly or lace wing larvae.
Plum curculio is likely to be out now, typically moving into orchards around petal fall. After a few warm nights and lots of moisture in the soil, we are continuing to monitor for fruit scars. These are typically found around 550 degree days base 43. San Jose scale is another insect to be monitoring for now. First trap captures were reported in the Capitol Region this week. This has typically taken place a little bit more than 500 degree days base 43. This week codling moth’s first trap captures were recorded in Geneva which is right on track. It usually occurs around 475 degree day base 43. Now I’ll give you a rundown of the degree day base 43 accumulations at NEWA weather stations throughout the state. Petal fall is usually in the mid 400s to lower 500s. As of the end of the day on Tuesday, 5/16, degree day accumulations were:
