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Hello folks. Today we're going to talk about the impacts of a changing climate on crops, weeds, and insect pests. Brief overview. We'll begin with a extremely capitalised summary of climate change. Then we're going to talk about phonology. Because that's really at the core of what I want to talk about today. We're going to focus on the impacts of changing temperature, not so much rainfall patterns. We'll use the example of bloom conditions in Michigan. Apples to talk about crops will talk about weeds and sort of a newer, faster, stronger perspective. And then we're going to talk a little bit about insect pests, pests, expanding ranges, and growth. Climate change is happening. At this point in our history, we have the data, we have the consensus. The source of climate change is almost definitely a change to our atmospheric chemistry. Usually preceded. This is really based on an increase in carbon dioxide, which results in a positive feedback loop with more water vapor going up into the atmosphere. And these gases hold infrared radiation. And it's really not that contentious point at this point, the vast majority of scientists and climate professionals agree this is happening and CO2 is at the heart. If we look at CO2 concentrations from a single point source. So this would be the Mauna Loa Observatory in Hawaii, beginning in the late 1950s when observations were started and ending in 2010, we've seen a nearly 25 percent increase in carbon dioxide in the atmosphere. Along with this, we've seen this increasingly rapid increase in temperature is really accelerating after the 1940s. The sort of periodicity of this temperature increase is the result of seasons in the north and south pole, but the overall trend is upward one. So the climate is warming. What does this mean for agriculture at large? What does this mean for pest management? Well, the science of phonology is probably the easiest thing to apply to questions of climate change and agriculture and Pest Management phonology simply put, is the study of periodic plant and animal life cycle events and how these are influenced by seasonal climatic and habitat factors. The convenient thing about our agricultural systems is that most of them are based off cold-blooded organisms, plants, microbes, insects, I guess reptiles and amphibians, and fish as well. None of them are capable of meaningfully generating their own heat for driving metabolic or biochemical processes. So what this means is their growth and development as individuals and as populations can be predicted if you have some idea of what's going on with the climate. So let's review this really quickly. The foundational thing that you need to remember when dealing with cold blooded creatures is that they are fundamentally different than us in the way they experience time. Warm-blooded creatures that are capable of generating their own body heat to drive metabolism, experience time in a very linear fashion and as warm blooded creatures, that's sort of our default when we think about time. This just isn't the case for cold-blooded creatures. Cold blooded creatures of whether plants or animals or microbes really experience time is a function of temperature. This is because the biochemical processes of say, photosynthesis, cellular respiration at a very basic level, but then biosynthesis of compounds, reproduction, everything else are dependent on temperature. These are chemical processes. They don't occur below or above certain temperature ranges. So for individual creatures, we can identify a minimum developmental temperature, optimal developmental temperatures, and we can also define temperatures at which point these processes start to break down. And the sort of culmination of all this from an organismal standpoint and a population standpoint is that if we're dealing with something that whose metabolism is Dr. by ambient conditions, we can predict their developmental rate. And by proxy, we can predict whole populations if we understand how individuals respond. But this brings up a big problem. So for us as warm-blooded creatures that experience time linearly, a linear calendar based around solely the orbit of the planet around the sun makes a lot of sense. For cold blooded creatures. It just doesn't. So the way that we can get around this problem or difference in the way we experience the environment is through the development of units that combine both temperature and time into a composite. And so this is the degree day that we talk about for growing degree days for crops or for the development of pest populations. The tricky thing about degree days is that no two creatures necessarily share the same developmental thresholds, either above or below. So to calculate degree days and understand how these creatures experience time as a function of temperature. You need to understand the lower threshold at which these creatures develop and the higher threshold. In Michigan. We oftentimes really just focus on the minimum temperature because we just aren't a very warm climate. We rarely get into the sort of 100 plus Fahrenheit degrees that you need to be in before most cold-blooded creatures start to have a lot of issues with protein denaturing and other, other concepts. But there is a maximum temperature and in some climates this is equally or more important than the minimum temperature. So the easiest way to model this, I would argue, is the use of degree days. And the easiest way to calculate a degree day is to take an average daily temperature and you subtract the lower developmental threshold. That if you do hit upper thresholds, you have to start thinking about that as well. But again, in Michigan, we just don't typically get there. So the easiest way to do this is if you just have a high and low temperature for a day. So theoretically if we had a daily high of a 100 degrees, a daily low of 50 degrees, and 50 degree lower developmental threshold. The way we would calculate degree days is simply by taking the average of this high and low. So a 150 divided by 2, which equals 75, and subtracting 50 from it. In this hypothetical day for a plant or a creature that had a lower degree day, lower developmental threshold of 50 degrees Fahrenheit, they would have accumulated 25 degree days Fahrenheit during this day. If the average temperature for that day was a 100? I'm sorry, if the average temperature for that day with say a 100 divided by 2, so 50, we would have accumulated 0 degree days. And what that would've meant is that basically from a developmental standpoint, no time really passed for that creature on that day, it, it was never warm enough for them to drive their metabolic processes forward and grow or reproduce or do whatever it is that there trying to do. And so this degree day concept is really important in the heart of how we understand how our crop plants develop. For, for example, this is a spring wheat degree day model from planting date. As you'll notice, this table provides planting dates and arrange. It also provides growing degree days. And really these growing degree days are a better predictor of when this wheat plant is going to hit its various stages. So, you know, from germination to tailoring to stem elongation to heading. And so if we understand the relationship between temperature and growth for a crop plant, we can make predictions about when it's going to be susceptible to a past, for instance, or when we should expect to harvest it. For pest management standpoint, when we're dealing with cold blooded creatures like codling moth, the primary insect pest of apples. If we have figured out their developmental thresholds and they're, and they're degreed a development. We can start to make predictions about when this insects population will be in various stages. So if we understand the time period over which these adults are, the, this is codling moth is largely an adult. Laying eggs are hatching. We can time pest management tactics to those stages, which means that we can have a much more precise way of managing this pest. Which means that maybe we can do less disruption to our agroecosystem and also maximize our benefit of pest management introduction, whatever it is. But knowing where this population is in time really helps us do that. So phonology, the science of phenology, allows us to predict crop and past growth. Because these are cold blooded plants and animals and microbes, they don't experience time linearly, they experience it as a function of temperature. So phonology lets us create things like plant hardiness zones. And one of the first places that I think you can really see the fact that the climate is warming is the fact that our plant hardiness zones are changing over the course of time. So this is a 990 map, a 990 USDA plant hardiness map. And this is a 2015. If you just look at Michigan, what you'll see is that we have shifted from a hardiness zone, ranging really from mostly 45 in the 990s to in the mid 20 tens, largely just 56. So over the course of just 15 years, the USDA has collected enough data to change the plant hardiness map and show that we are warming different plants, plants that would not grow in the Lower Peninsula of Michigan. So hardiness zones six plants now regularly grow in the Southern Lower Peninsula. So this has a huge impact on what we can grow agriculturally, on what weeds will grow. It has an even bigger impact on folks who are working in perennial cropping systems. And the reason for this is you can't just replant apples. For instance, once you've planted them, you're in it for a 25-year period. One of the reasons why we have so much for agriculture and Michigan really comes down to the Great Lakes. Water is very slow to heat and cool. Water also likes to absorb infrared radiation, which tends to heat it up. Having large bodies of water near you moderates your temperature. So for example, if the lakes freeze, it takes a lot of energy to fall them out. And that energy comes from, in part, heat derived off this landmass, this coastal landmass. So what this means is that you have a very gradual spring flip side. Once that water is thought out and say warmed up to a super warm 70 degrees Fahrenheit or something like that. Um, it, it will absorb a lot. It will, it, it will take a lot of loss of heat to to shift that. And so it will provide heat in the early fall and winter to this, to this belt as well. And so you can see this Temperature shift in gradient. Places near the lakes tend to be a little milder, a little warmer. And this is really good for perennial crops, which again, you can't change the planting date every year. Once it's planted, you're stuck, whatever that crop plants then I'll phonological pattern is. So this causes some real concerns for climate change in apples, in particular in Michigan. But to understand this, you need to understand a little bit about Apple phonology. So we're going to talk about dormant period. We're going to talk about early growth and then the sort of full on growing season for Michigan apples. So perennial plants like apples have a special problem when it comes to winter. You kinda don't want a lot of very tender high water content tissue out when it is maybe 0 degrees Fahrenheit out, that that water is going to freeze and it's going to damage your tissues and probably ultimately kill you. So perennial plants deal with this through senescence or dormancy. In Michigan, typically. This is largely driven by day length. This is what really tells a plant, Hey, we're getting close to winter. Days are getting shorter, but then it is further reinforced with temperature. So one thing we've seen is that full dormancy and our apple trees seems to be taking about a month longer than it used to. But dormancy itself is a complicated process that because the going into winter as a tree, you don't want to be late. Taken in all your, your green tissue before it starts to freeze because you're going to get damaged. But flip side, you want to wake up as soon as you can, so you can maximize your productivity. You also don't want to wake up too early. Because if you wake up too early, say if you have a warm snap in the middle of winter like we have been having more and more of, you're going to wake up and then it's going to freeze again and you're going to get damaged. So they elegant way in which perennial plants like apples have dealt with. This is a two-stage dormancy. There is the Endo dormant stage, which is triggered by that short day length and maybe a couple of frost events. And then to break into dormancy, the plant has to accumulate chilling hours. These are almost like reverse degree days basically, instead of being over a certain temperature of the plant has to experience time under a certain amount of temperature. And this, you can kind of think of this as like a little timer. Basically the trees not going to wake up until it's convinced that winter might be over or coming to a close, and that's what ended dormancy allows. So after the trees accumulated enough chilling hours. And then switches to the second stage of dormancy, which is called Echo dormancy or it's said to be ecto dormant. Active dormancy then reverts and now the tree is looking to accumulate heat. Basically, it's okay. It's been cold long enough that winter is is probably coming to end. Now I want to gradually wake up and hopefully you don't put all my green tissue out after we're done freezing. And I can make apples if you're an apple tree. So E2 dormancy is released by warmth and heat. And really it's temperatures for most apple varieties, it's between 40 and 45 degrees Fahrenheit. That's the sort of minimal developmental temperature. So after ecto dormancy is released, the plant then starts putting green tissue on and eventually will through. So from premium blue to the fruiting. So if you want to think about apples during the spring, what we really worry about is having green tissue on the plant and then having a big frost event. And the interesting thing is that trees have further of all the sort of a, a natural resistance to these, this inevitable frost events by going through a gradual succession of waking up. And as trees wake up, they become more susceptible to frost damage. So what this table shows you is the the, how the end of Endo dormancy is broken and apples. And it shows you the temperature in Fahrenheit at which 10 and 90 percent loss of developing tissues is expected. So for silver tip for instance, which is the very onset of, of, of breaking dormancy. You expect to lose about 15 per 10% of buds if you hit 15 degrees Fahrenheit, but 90 percent if you hit 2%, that's still pretty chilly. If you go all the way to pink and beyond, what we see is you can have 90 percent loss at a fairly warm 25 degrees and you expect the beginning of damage at about 28 degrees Fahrenheit. The lesson here is that flowering plants and fruiting plants are very susceptible to frost damage. Vegetative growth is less susceptible to that. So what we've seen in Michigan over the last several decades is that growers and Central Michigan who are away from that band of sort of protected gradual climate change region on the coast are losing somewhere in excess of 30 percent of their crop to frost events in two out of three years. But then in 2012, we experienced a massive crop loss. We had 90 degree weather in March. The trees all broke dormancy very quickly and we got nasty frosts, which resulted in a 90 percent law statewide of apple production and a 98% loss in cherries, cherry trees move just a little faster than apples in terms of waking up. So in 2013, a now retired extension educator fish, while you're provided me with 30 years of green tip data and full bloom dates for block a Macintosh apples located near Sparta, Michigan, Michigan. So what he basically gave me was this really incredible dataset. This say, block of trees and the date at which first elongation of green tissue happen. So that very first break in, in dormancy and then full bloom, which is sort of the ultimate super susceptible stage to frost. And some really interesting trends emerge from this data. So what this figure shows you first is first green. So this is that, that first stage where you've got little sort of like green lamb years coming off the apple bud. And the way this data is visualized is by year on the x-axis, and then the day after January 1. So that this green tip evolved, this green tea, yeah, great tip sort of came out. And what we see here is a very obvious negative trend. And when I run a simple linear regression through this, I get a significant p-value. P-value telling me that there is a negative correlation between year and day green. However, I have very low predictive power. This model is not going to ever tell me when to expect green tip. But what it does tell me is that it's happening sooner every year. And the slope, or this decimal here, it tells me minus 3.6 days per year. So basically, Every, every year on average, we lost about a third of a day from beginning and 975 and extending through 2012. So to put dates on this, back in 1975, first green was happening usually around April 15th, sometimes earlier, sometimes later. But by the mid 2000s, we're seeing a bloom dates happening really around the beginning of April. This is what happened in 2012. So what does this mean philologically for the plan? Well, thankfully, for apple trees, even at green tip, buds are pretty cold hardy, so you really need to get down below 18 degrees Fahrenheit Before you see a lot of damage. And we don't see a lot of 18 degree nights in March or April. So usually we're okay. It's not until you get to 15 degrees or below that we expect a lot of damage. However, when we look at full bloom, we get a much scarier picture. So again. Same type of visualization on the data here. And what you see is again, a significant p-value. What this means is that we can conclude that there is a correlation between the later year and an earlier full bloom date. And this time we're losing about a quarter day per year. So every year since 975, we're hitting full bloom in this block on average a quarter, a quarter of a day faster. So let's look at this again. So early on May 17th, That's that's when we expected to see full-blown later on. Well, may too. So by and in fact, in 2012, we saw much earlier than ME second. So what's the problem with this? Well, the problem is, is that if we go to the other end of the developmental spectrum of, of apple bloom development, you can see that we're only winter hardy to 25 degrees at best. And if you have a frost event, you're almost in Michigan, you're almost definitely going to get below 28 and likely 25 degrees. And in fact, very often in Michigan, our last frost date below 25 degrees is sometime in the first two weeks of May. So the problem here is that the trees are accumulating key over a long time period, and this results in a reduced resistance to frost damage. But frost events themselves are very chaotic. They're determined by more local conditions. And even a half hour at say, 20 or 25 degrees Fahrenheit is going to cause you a very appreciable loss. And so in 2012, as I mentioned earlier, we lost 90% of our apple crop. And this is really because we were blooming in mid April. And we got a series of very typical for Asper US extending through the first week of May. So unless you were exceptionally lucky and just had a really nice microclimate, you lost all your apples. So, you know the first question always that as well, when we look at data like this is this is just okay, well maybe this is just Michigan and Michigan special and it's and it's a problem. Well, that turns out not to be the case. There was a paper published in 2010 in Japan by these two researchers. And essentially they found very similar patterns in, in northern Japan. So for me as a researcher, this meant that, well, maybe I don't have something to publish here because someone's already done a better job, but also was a little scary. So what these researchers found was a very similar loss of days per year. They actually did this over 6, six orchards and Japan over a very similar time range. So in this case from 75 to 2005. And what they found was that to green tip, they lost about a quarter day and to full bloom about a quarter day. The really unnerving thing about this is that the slopes for all of these lines are not statistically differentiable. So what this means is the pattern of loss of time. Even though the individual day might be different between these orchards. It is the same across all these orchards. And furthermore, when I did a similar analysis with the Michigan data, what I found was that we couldn't disentangle our rate of change for either of these events either. So this very much suggests that we are seeing this shift in perennial crops on a global basis, which means that this is a global climatic problem. So how do we deal? Well, you can't just replant and apples. Modern high density planting costs anywhere from $15 thousand if you're really cheap to $40 thousand per acre to establish, your break-even point is usually projected to be around year six or seven. Your expectation typically to be profitable is that you're going to get at least 25 years of productivity out of that planting to justify that huge capital expenditure. So you can't really do that. You can't switch variety. So you have to try to modify the environment. And there are two real options of the traditional option for dealing with frost is using frost protection, usually done by moving air. And traditionally this has worked, okay. The other approach is to delay balloon by manipulating the microclimate. And the idea here is to slow the break from ecto, from ecto dormancy. So you want to try to keep that plant as long as possible on those early breaking dormancy stages so that the more vulnerable ones don't get exposed to for us. So how do when machines work? Well, when machines were great, under certain circumstances, when machines work great when you have an inversion, this is when you have what I would call a shallow frost. So you have cold air that's trapped under warm air and this happens pretty frequently and it was in the old days, sort of our frequent source of a frost injury. The basic concept is really simple since you know, you have this warm air above the cold-air, all you have to do is set up a wind current that pulls warm air and pushes cold-air up. And so, and that's what these giant windmill machines, these machines do in orchards. However, if you have a, if you're frost is not a shallow inversion like this, but it's actually a massive cold front, which is typical of the frost we get earlier in the season. When machine is it going to do any good, There's no warm air to draw from, essentially. So when machines allow us to respond to mild frost events and they can save us a crop when irradiation freeze happens, but they're not good for an egg effective for you. So when you have a miles deep front of cold air over your orchard. So in this case, what we can do is delay bloom, and it's been shown time and time again in multiple regions of the world that you can use evaporative cooling, too cool plants during that dormancy braking phase and delay balloon. The problem is, is that you're using a half an acre inch of water per hour to do this usually. And that there's a variety of irrigation technical problems as well as plant health issues that they go into, into that process. So wind can save you during an actual frost event. As a 50-year history of US many machines on the market. But you really have to understand the topography of your ground and where you're likely to get those shallow inversion freezes and not a big advected freeze water, you can actually avoid frost. And it may be that you can use this for summer cooling if you're running into high temperatures that damage or fruit in the late season. But there's a hi, water requirement for this. But what are the costs? This is the best comparison I can find. Unfortunately, it was done back in 1980, so it's 970, $980. I've actually converted this to, I think 2016 dollars just to show you. But the take-home is that when machine will cost in terms of installation cost and installation of heaters to add two to heating and in your ability to mix warm air around a $1000 an acre time averaged over ten years. Sprinklers. If you have irrigation in place, the, the estimated cost is 500 today, if you have to add it, then that's going to add to the cost. However, wet feet and access to water are major issues with using sprinklers. Having talked about how climate change can have a massive impact on a perennial crop, we're now going to shift gears and talk a little bit about weeds, which are a more general problem in agriculture. The thing to recall is that climate change really presents a double-whammy for weeds. Gotta increase growing degree days because of the increase in temperature we're experiencing. So this means that there's more heat and light available for them to go through photosynthesis. But the other issue is really carbon dioxide. Recall in photosynthesis, plants uptake CO2 from the atmosphere to drive that process. That's where the carbon that they fix into their roots in the soil eventually comes from it all comes from the atmosphere. So when there are higher concentrations of carbon dioxide in the atmosphere, this can have fundamental impacts on which plants do better. So the first thing that this change in atmospheric chemistry and degree day availability has visibly done is it's changing the range at which weeds that we have to deal with exist in. Could x2, which is an invasive weed from Asia, is a great example of this, could see was initially brought into the Southern United States by the Army Corps of Engineers as an anti erosion tool. It's an incredibly fast-growing vine. It comes from Asia where it's actually a somewhat important food plant. Kudzu starch is important in Japanese culture, for instance. And very quickly it's sort of develop this legendary status in the southern United States. This image here shows you could zoom covering up entire trees. It's sometimes called mile a minute. We'd it grows incredibly fast. I mean, almost visibly. Another important problem that kudzu poses for us in soybean growing regions is that good is an alternative host for soybean rust and invasive fungal disease of soybeans that evolved the soybeans in Asia. So could do as a reservoir host for this problem, for this, for this problem disease. And kudzu, while traditionally we've thought of as a South Eastern weed, is now starting to expand into the southern midwestern states. So kudzu is expanding its range. And some work by Harold Zika at all suggests that this is really due to increases in the minimum temperatures experienced in or in the Midwestern United States. So this work focuses on Illinois. If you look at this in 970 one, this little contour line basically shows the northern extent of where kudzu was detected. And it really just includes the southernmost portion of Illinois. In 2006 when folks surveyed this, again, this line to move significantly northward. If we look at average This days of the year in Illinois from 1970 to 2005, what we can see is that shortly after the 990s in the early 2000s, the coldest day and the year has crossed this minus 15 degree line. So this really suggests that a warming climate, in this case, moderating very cold winter temperatures, is allowing a weed to expand its geographic range. And if we look at a plant growing degree day map, you can see this just in terms of USDA hardiness zones. Look at an annoying, it's a dark green which would be growing area of five in 990 in 2006. It is largely a six. Kudzu is following our plant hardiness maps very well. So in addition to expanding range and dealing with new weeds that we may not have a cultural context with climate change and also can make weeds grow faster. Recall, plants fix carbon from atmospheric carbon dioxide. The more carbon dioxide you expose many plants to, the faster they will grow. The warmer it is, the faster they will grow. So a question that Zika and his team asked in the early 2000s was, how can we test the impacts of increased CO2 and heat on plants? And they came up with this genius design idea using urban heat islands. Something we've known for quite some time, is that large amounts of concrete and lack of natural services leads to increased heat in urban areas, as well as a slowed down, cool down effect. So basically there's more heat being produced from heating and automobiles and everything. There's more capacity to hold that heat and the surface, the surfaces themselves to hold on to heap. So what this guy and his team did was they set up a two-by-two meter plots in a gradient in Barrow. And beginning in, on the same logic, longitudinal grid, latitudinal grid, beginning out in rural areas, going into suburban areas and then going into deep urban areas. They then went to the rule area, scraped soil, scraped soil out of all their plots, and then filled it with a parent soil from the rural area. This standardize the soil series at the top of the soil and more importantly, the weed seed bank in that soil. They then observed what happened over the course of years. So the first thing they wanted to maintain, the first thing they wanted to show was that there was indeed a change in CO2 as you went into this gradient into Baltimore. And in fact, what you find is at the time of this study, back in the early 2000s, at the farm or rule area, they average 386.2 parts per million carbon dioxide. In the park suburban area, they had about 400, and in the city they had 455. Coincidentally again, just cross bore 18 molar Mauna Loa Observatory. So this is kinda getting us a glimpse of the future of a non urban area. They did the same thing for temperature. And what they found was that average daily temperatures over the growing season where 18 degrees centigrade and the farm, 19 degrees in the park and again, 20.7 degrees in the city. So moving along a latitudinal gradient. So the same amount of incident solar radiation is hitting these places. And ofcourse this replicated set of quadrats, they're able to show that, yes, urban centers have higher CO2, higher temperature. They're giving us a window into the future. If we keep warming up, if our climate continues to warm and have more carbon dioxide. So what was the result of this? Well, I'm not going to show you any any means and standard errors because I don't really need to. This was very clear data. This is one year weeds growth at the farm and in Baltimore. Same parents Soil, same weed seed bank, same day, same research technician standing next to these two-by-two meter plots, look at the difference in biomass. So essentially, weeds are going to grow much faster as we warm things up, as we increase carbon dioxide. Interestingly enough, subsequent work done by this group showed that successional change actually moved faster in this system as well, would be species came to dominate the system faster than they did in these, in these rural areas that were also left them undisturbed. So we can deduce that new weeds are going to move and follow climate. That weeds are going to grow faster and plants in general are going to go for Aster as CO2, CO2 concentrations go up and temperatures go up. But there's some more nuance that we can think about. So this was a review article also done by this because group. And what they basically figured out was that higher levels of CO2 are likely to favor C3 plants. More than C4 plants recall. Plants that undergo C3 photosynthesis are adapted to moisture cooler environments. And C4 plants are adapted to hotter, drier environments. The causal relationship there is that C4 plants are able to close their stomata and undergo dark photosynthesis without evapotranspiration occurring whereas CP plants cannot. So one of the questions that they asked in this review paper was, how will this affect crops versus weeds? And as you often will find an agroecological research, it really depends on the comparison. So here's just a very simple table that summarizes across a variety of work that ask questions along these lines. And it's sort of summarizes what we think. What we think is likely to happen as we continue to warm and gain more carbon dioxide. So in these comparisons, we had grasses, a C4 group of weeds versus alfalfa, a C3 crop, read or pigweed, a C4 plant versus a soybean. A C3 crop, red root pigweed. Again, again, sorghum, so C4 it and see for lambs quarters versus soybean, which is S3, again, C3, deadline versus alfalfa, also C3, C3 though, leaf versus sorghum, S3, S4 and dandelion planting mix against AC for a week. So let's look at what happens. Well, what they found in these studies, across these studies is that S3 always wins in this competition, there's always a selective advantage to C3 plants when carbon is increased in these environments. So regardless of whether it's the weed or the crop, the C3 always wins. However, in a fair fight. And these increased carbon environments, the We'd always wins. Basically. Read, we read root pigweed be sorghum. So a S4 to S4, lambs quarters, bead, soybean, and dandelion beat alfalfa C3s to C3s. So a final area of the disk has research team looked at was the concept of stronger weeds in response to temperature and carbon dioxide. So the basic research question here is, will weeds be more resistant to management under a changing climate? And this was another sort of genius experiment. Basically what they did was they grew Canada thistle in little greenhouses outdoors under either ambient CO2 or future CO2, where they added 300 parts per million. So they added quite a bit of CO2 to these systems. I mean, this is hundreds of years out if we continue on our, on our current course. But some very interesting results emerge. The other thing they asked and this, you might notice there's really heavy. We'd cover here and very low we'd cover here is they added an herbicide. So they planted candidate vessel and then they sprayed it with round up on half the plot and not on the other plot. And this picture gives you a pretty good feeling of what happened, a failure of weed control under the increased CO2 concentration. So here is some numeric data from this because I think it really helps. So canada of this all grown under elevated CO2. In the blue, you've got herbicide treated. In the green, you have untreated normal CO2, elevated CO2. And the really sort of disturbing thing about this data is that we elevate CO2. Canada fissile becomes resistant to glyphosate, the active ingredient in Roundup. So this means that are very ability to manage weeds maybe negatively impacted by this changing atmospheric chemistry. As CO2 concentrations go up, it changes the way in which Canada thistle can mount a defense against the early cidal activity of glyphosate. So what can we do about this? Well, the first thing we can do is really pay attention to invasives. And this point actually probably plays across taxa. Invertebrates as well as vertebrates, as well as plants and microbes. As the climate changes, new creatures and plants are going to continue to move into areas and they're going to pose us with new challenges. From a weed management standpoint, if our tools become less effective, we may need to pay more attention to wheat management strategies like 0 C drain, intensifying, cover cropping and rotation practices, and avoiding vacant German germination microsites, maybe a big part of this. It may also be important that we return to more rotation practices if herbicides do indeed become less effective because of climate change. Then finally, we're going to need to continue to think about what crops are going to be competitive with weeds, not only in the present, but in the future as temperature and CO2 levels continue to increase. So beware of the C3 plant advantage under high levels of carbon dioxide. So we've talked about crops, we've talked about weeds. Now we're going to talk about insect pests. And the theme here is really again, expanding ranges and growth. So like plants, insects are cold blooded. Increased temperatures equal a changing and from our perspective, increased geographic range. It also means that insects are developing faster, faster past development can mean more generations. It can also mean invasive. Being able to set up shop where in the past they had to migrate in. And it can also change pest synchrony with crops and both now and natural enemies. So there's been some really excellent work thinking about expanding ranges of insects, working on the corn earworm or Helio at this Zia. At the moment, helium, this Zia is a migratory pest. And the Northern United States, like kudzu, cold winter temperatures in the Northern US, keep this pest from essentially setting up a local base of operations. So to understand this, we have to talk a little bit about the lifecycle of the corn earworm. In, in the Fall. Corn earworm in the Southern United States go to the ground and pupate in the soil. They will then begin to cycle up in the Southern United States as soon as there are plants to eat, they're very polyphagia. They don't just eat corn, so there's lots of things for them to build their population on. And then in June and July, adults are blown north on storm fronts into the Northern United States, where they become a problem in corn production in the northern Midwest. The degree day accumulations required for each stage are presented here, both in Fahrenheit and degrees centigrade. This is a base 50 degree day model. And it's important to restate that this past is a migratory pass in the northern United States. So in Michigan, for instance, it's very rare for corn earworm to overwinter in Michigan. It just gets too cold in the winter. They can't survive the cold temperature in the soil. So defend ba at all in 2008, applied knowledge of corn root worm, geographic distribution and phonology to create this, this following chart. So this was from 1961 to 1989, the latest data they used in this study. And this shows a heat map of the number of years where there were suitable overwintering conditions and where those were located for helium, this CSEA. And so what you see here, if we look at Michigan, is maybe one year between 961 in 1989, as you move further south, there's more and more suitable years for over-wintering of this largely subtropical pests. They projected forward based on at the time current projections for what temperatures would be like between 20772099. And you see a much different picture. So essentially, Michigan has now become someplace where more than half of the potential of 24 years, this pesky to overwinter and in fact, this pest is beginning to overwinter in the much cooler. A Dakotas, Minnesota, and Wisconsin. So the problem with this is that wherever this pests over winners, it's pressure is much, much higher. And this is simply just a function of geometric increase. The more generations this pest has in a year, the faster it can build to epidemic populations. And compounded, of course, is the problem that if there are, there is more heat in the South, you're going to have more generations down there as well. So every time you hit 872 degree days, base 50 Fahrenheit, you're going to have a new generation. So let's just do a quick thought experiment to think about the possible consequence of this. Now if one female lays a 100 eggs, I'm on average half of them are going to be female. And so in the first generation, you're going to have 50 females from a single female. In the second generation, you're going to have 2500 females. If these all survive. In the third generation, you're going to have a 125 thousand females and the fourth generation, 6,000,250 thousand female, so on and so forth. So having this past overwinter in Michigan means that rather than only having one or maybe two generations, we're going to have at least three, maybe four generations. And this is going to put our corn crop, it in a much bigger jeopardy than it's experienced in the past. So here's just two additional generations. Population density by time in generations. So we can also hypothetically see impacts on pests were already dealing with. So I'd like to turn attention now to codling moth. So codling moth, this is also a base 50, base 15. So base 50 Fahrenheit centigrade degree day model codling moth take about a 1000 degree days base 50 to go through a full development from egg to adult. Now, codling moth can survive Michigan winners because they're fairly cold tolerant and they use a dye applause stage to do this in the late larvae. This, uh, whether or not a given codling moth larvae goes into diet, pause is determined by daylight. So if a codling moth larvae experiences a day length of less than 15 hours at any point in its time as a larvae, it's not going to go to POP and adult stage, which would then lay eggs and infest more apples. Instead, they're going to go to sleep for the winner. Kinda like hibernation. So let's think about that, how this plays out, increased temperature or degraded accumulation versus day length. So this is a 20 year average through I think 2016 degree day accumulation for Central Michigan. So, you know. Starting with a April 1, which isn't a bad, but it is a slightly early bio fix for codling moth. So currently we have about two generations per year. And the reason for this is that this second-generation, by the time it hatches, we're already past 15. We're already past a less than 15 hour day. So all of the larvae hatch here are, are going to pupate instead. So what would need to happen for us to hit a third-generation? Well, two things, probably. First thing is our bioethics would have to become earlier. And as I showed you with trees earlier, trees are in fact developing their sexual parts which become fruit earlier. So there's a real possibility for that. The second thing that's going to have to happen is this second generation is going to have to get at least some of its larvae through before that 15, our day length window. So here again is that, that hypothetical degree day accumulation for codling moth. And what I've done is just added three degrees on average per day or five degrees per average per day to it. So you can think of a generation happening every 1000 degree days from bioethics, which again, we're just going to set as April 1st. And so let's take a look at this. The next thing we have to think about is when do we have a 15 hour day? Now the nice thing about day length is that it's not changing in response to climate. It really has to do with the angle of the earth and where you are on the sphere. So this is probably going to be pretty consistent from year to year. Pretty much always that 15 hour day happens right around the 22nd of July. So our first generation of codling moth comes out from overwintering and lays eggs here. For the second-generation to emerge. It happens here at about 1500 degree days. And what we rapidly see is that under current conditions, this entire generation is not even emerged before our 15, our day length. However, when we add even three degrees, this shifts and suddenly you have the potential for another generation of codling moth. And so perhaps we're going to see another generation. The issue with this again is geometric increase every generation we add, adds the potential for a vastly increased pest population. The other issue for apples is that the time you really don't want to have your apples infested by a worm that bores into the fruit is right before you harvest it. And in fact, in other parts of the country that are ahead of us in terms of temperature, there is precedence for this problem. So Hitchcock historical data from California walnuts, another host of codling moth, shows that this has been happening. There's increased codling moth flights between 950 and 2000. There protect their projecting up to seven flights by 2099. So what this map shows and 950, where you were expected to have 0 to 1 fly, it's one to two flights all the way to six to seven flights. And as you can notice, there's one little stretch here where it's hot enough to get five to six flights per year. In 2 thousand, we've already seen the expansion of 34 generations in the Central Valley. And the prediction is by 2040, 120, 60. We may have six to seven generation and that, that one hotspot. And we're going to see more 56 generations in these areas. Again, the problem here is the more generations and insect pest has, the more its capacity to rapidly explodes its population is. And for a direct pests like this, the more, more, more exposure your mature crop has to this, that the worse off you're going to be, the more losses you're going to see. So what are the pest management consequences of this? Well, expanded range means that we're going to always have to be looking for new past. Global trade has been bad enough. But addition to new, it's truly novel pests that are truly invasive. We should always be consistently looking south and saying, okay, a 100 miles South to me, what is causing people a lot of problems in this crop that I am currently growing. Because it's quite likely that within our lifetimes, we're going to see a migration of those pests up north. The other problem is the greater numbers of generations. This means more damage. It could also lead to more phenotypic, to less phenotypic predictability. One of the nice things when you're dealing with a pest like codling moth that typically only has two flights per year, is they stayed pretty to Saint distinct. They don't overlap very much. When you get to a third, fourth generation, what you find is a lot of overlap. And the challenge that, that presents us when we're using phonology to guide pest management is suddenly you can have multiple stages of a past, present all the time. So it really reduces your ability to target a particular stage. So again, if you're applying an oocyte like an oil, if you have eggs all the time, that means you've got to apply oil all the time. You can't just target when one of these generations has a nice cluster of eggs in time for you to target. Likewise for larvicides or adult decides. So what can we do about this? Well, aggressive monitoring, we need to pay attention to what's coming across the ocean, certainly into this continent. But we also need to be looking south and thinking about what's going to start migrating north as our climate changes and becomes more favorable for things that either have a low tolerance for freeze or have longer degree day accumulation requirements to complete a generation. We also need to rethink our phenological models. This is something that we really don't do enough of any way. Phenological models are only good as the data you use to calculate them. So phenological models developed on data collected under a different climate are not going to provide you as good timing information as one's collected under the current climate. And I think maintaining on-farm habitat to support biological control is only going to become more important. The more homogeneous we have, we make our landscapes, the more pest pressure we're going to see pests are, are selected early colonizers species. They like homogeneous environments. It's what they are. It's fits their strategy of reproduction. The more broken up we can make our landscapes, probably the more resilient they're going to be. Something we really should be thinking about anyway. But in the face of additional generations of insect pests, this is only going to become more important. So I did a little bit of data analysis and support of this talk with the Apple phonology work for Michigan. But really, the vast majority of work that I've talked about is comes from giants who shoulders I am privileged to stand upon. Some of these folks include Dan herms who was with Ohio State University. Louis discovered recently retired from USDA ARS. Feels while you're at who actually recently retired from Michigan State University as a longtime extension educator and ICC labelling of the University of California. I can't say if IQ is still there or not. Thank you very much.

2021-SS-ENT479-Ag and climate change

From Matthew J Grieshop April 6th, 2021  

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