Irrigation Webinar Series - Session3, August 4
August 6, 2021
This six session series focuses on irrigation topics such as irrigation management, irrigation efficiency, new and expanding irrigation projects and a weather and crop update.
Topics that will be covered each week:
- Past and forecasted crop water usage compared to rainfall for the last week and next week. (5 minutes)
- Ways to improve irrigation management and efficiency – Irrigation Specialist from MSU and Purdue (15 minutes)
- New and expanding irrigation considerations – Lyndon Kelley, MSU/Purdue Extension - Irrigation Educator (15 minutes)
- Updates on irrigation topics related to field crops, vegetable, fruit and ornamental crops by MSU and Purdue specialists and extension educators (15 minutes)
- Open Irrigation question and answer period (from chat or pre-submitted e-mail questions). Please feel free to email irrigation related questions to Betsy Braid at firstname.lastname@example.org before the programs.
Sessions will be held every other week on Wednesdays at Noon. They began on July 7 and conclude on September 15.
August 4 Agenda
- Monitoring leaf wetness duration to predict disease infection period– Dr. Younsuk Dong , MSU BAE Irrigation Specialist
- Irrigation water supply: how much water do I need? – Lyndon Kelley, MSU/Purdue Extension Irrigation Educator
- Irrigation of blueberries and other small fruit - Mark Longstroth, MSU Fruit Educator Emeritus
Okay, great. So my name's Lyndon Kelley. I welcome everyone to this irrigation Webinar put on by Michigan State University Extension. And Dr. Youngsuk Dong. He'll be our speaker, speaker today here a little later. I'm going to do the intro here, and my name's Lyndon Kelley. I work for Purdue Extension and MSU Extension split position, all on irrigation issues. So if you can see my screen, you're seeing, "Let's talk irrigation" and we hope to give you information that will help with both field crops, vegetable crops, or fruit crops, irrigation, situations. And coming up in the future, we've got some people from the ornamental industry that are going to talk about irrigation and the importance to the ornamental industry. This program is available- One of the easy places to find it is at a website that Dr. Youngsuk Dong maintains at Ag Engineering Biosystems Ag Engineering MSU. And the email or the link to that is there on the screen. Betsy I'm trying to find forward somehow. Click on your slides and click the arrow key, left or right arrow key to go foward. Click on that there you go, Yeah I clicked on the other screen. So we're going to talk about rainfall, Michigan and Indiana, are supplemental irrigation States. We tend to take the rainfall that comes during the season, add another quarter or a third of that volume usually, and meet, bring up the deficit areas that reduces our yields, that maximizes the natural resource. If you are on the last meeting, we were at a, a week following a week of rainfall that was so good that we actually, put water into the bank, into that soil reserve that we have this last week wasn't that good for most of us. And in a lot of cases, almost all cases, we've had a draw from the bank or add irrigation water. So if you received half an inch, you probably add, needed to add one inch. And if you received wanting one inch of rain, you probably needed to add a half inch or draw from the bank, the soil bank to meet that need. If you take a look at that, compared to the crop water use, if you are growing six inch grass, that's our reference crop that we look at both at the National Weather Service where we our graphic is from today or at the mauve stations, part of the enviroweather network here at Michigan State University, you would see that six inch grass used 1.3 inches of water last last week, 1.3 inches of water. But that's six inch grass. Very few of you are growing six inch grass. And so we're going to convert that. And so the examples we're going to give you are corn and soybeans. But Mark can talk a little later about fruit and other things too. But our two most irrigated crops, corn and soybeans. Corn, that 1.3 inches times our crop coefficient of 1.2. That means that it takes a 120, 20% more water to raise that corn for the water use each day for that corn plant than the six inch grass. And if you do the math, that means we needed about 1.6 inches. So that's how I got that 1.6 inches of need. Most producers are around sort of allowing the bank to deplete by about that water holding bank to deplete it by an inch. So if we get a one inch rainfall, we could capture it, hang on to it, make use of it. But beyond that, they're going to start irrigating. So that's that 1.6 that we'd need. And then we're going to be at this peak stage until beginning dent as far as corn. And it's pretty much to re-ron when we talk about soybeans. Same crop coefficient where at that peak use at least for a few more weeks here, up through full Seed. So in both cases we're going to need 1.6 inches. And later on I'm going to talk about volumes of water you need. Right now is the time when most of our crops are at their peak water use. It's the challenge to, for the system to keep up with the need. If rainfall does fall short in that we don't need. So next up is Dr. Youngsuk Dong. Dr. Dong going to be talking to us about some work he's doing that sort of related to irrigation. But it's a little bit more on the disease management side. It's this idea of leaf wetness and how we can monitor leaf wetness and help deal with disease. And it also lets us look at irrigation management and how we need to manage irrigation with a thoughtful eye to not promoting foliar diseases. All right. Well, thank you, Lyndon. And I'll share my screen. Looks good. Can you see now? Yes. Okay. So well, before I start want to just reminds the the website where you can find all the recordings for this webinar series. It's erg.MSU.edu/bae/water/irrigation. I believe Betsy put the link in the chat. So you can copy and paste it. Or you can go to MSU, you can just Google MSU BAE irrigation. Hopefully you see the first line for the website. Once you're on the web page, the irrigation website, you can click either one of the top irrigation webinar series or in the link to go to the page. Once you're in the page and the right photo that shows the page, you can watch all the previous videos and if you like to, want to just remind that quickly. So like Lyndon mentioned today, I'm going to briefly talk about how we can improve irrigation management to reduce the potential plant disease risk. And, and briefly talk about how we can monitor the field environment condition to predict the potential plant disease risk. So we'll firstly, so what conditions promote the potential risk of plant disease. There are three major parameters, which are the leaf wetness duration, temperature and humidity. So usually high humidity and longer leaf where the durations are the strong driver and favorable conditions for the plant disease. And many plant disease prediction models are based on leaf witness duration, humidity, and temperature. Well, here are some examples of what temperature and the leaf wetness duration and humidity that would promote the potential risk of disease. Whereas you see the temperature and leaf wetness duration humidity are the major factor for this. And the, for example, the average daily temperature between 75 degrees Fahrenheit and 85 degree Fahrenheit. With 12 hours of leaf wentess will promote grey leaf spot disease for the corn. I want to give you another exempt, for example, that is TOMCAST. So the TOMCAST weather timed fungicide spray program for, for, food tomato. This TOMCAST model was developed for use for tomato early blight. But has been adapted for carrots and asparagus. So as you're seeing the TOMCAST model, the table, the average temperature and leap wetness are the major factor for predicting the disease superiorly. So the, the, how the farmer is by using this model is when the disease severity value, accumulated, accumulated value reached, reaches to 15. That's the time they spray fungicide. So we know the environmental conditions such as temperature, humidity, and leaf wetness are the strong driver of potential plant disease risk. And the irrigation can contribute for that. So the frequent light irrigation application. So if you apply the small amount of application and more frequently, that can drive the plant disease, which extend the longer leaf wetness duration. And that results in favor condition for plant disease Just one thing I want to mention here is that this irrigation impacts will be more applicable for overhead irrigation system then the drip or a trickle irrigation because your drip irrigation system does not wet the leaf of the plants. But the overhead irrigation can be good source for extending the leaf wetness duration. This photo shows the importance of irrigation management. As it shows that the irrigated area is impacted by tar spot by which one of these is that Dr. Martin Chilvers and Bruce and we are working on. But as you see there is the irrigated area has an impact by the tar spt. So how can we manage irrigation to reduce the potential plant disease risks? Well, first we need to reduce the irrigation wetting event. So we suggest only irrigate when the application will increase it yield or quality. The one of ways to do this is using irrigation scheduling tool. So the irrigation scheduling tools can help make a better decision on when and how much to irrigate the field. And there are number of irrigation scheduling tools are available you can use to enviroweather network to find out the crops evapotranspiration. Or you can use the MSU Irrigation Scheduler program, which can be downloaded from MSU BAE irrigation website or you can use soil moisture sensors to schedule the irrigation. The second, when you apply water, use the big applications, which are good for next four to five days of water needs. The larger irrigation application definitely can reduce the number wetting events. There are a couple of things we need to keep in mind when we apply large application, well first make sure we have some room in the soil profile for predicted rainfall. So we don't want to apply irrigation to the soil to reach the field capacity. So field capacity means that the maximum amount of moisture that soil can hold after drainage. And second, we make sure we don't wet or push the water below the root zone. And third is the make sure we apply irrigation large enough while avoiding runoff. If you use irrigation scheduling tool, it will help to make a decision when and how much do you irrigate at, right amount and right time. So please consider to use irrigation scheduling tools and let Lyndon Kelley or me know if you have any questions on using the scheduling tools. So I just talked about just a little bit about how we can improve irrigation practices to minimize them potential risk of plant disease. So now I would like to briefly discuss how we can monitor the environmental condition, such as leaf wetness duration, temperature, humidity of your field, to predict the potential plant disease risk. Or in general, there are two different design of leaf wetness sensors. They are commercially available. The leaf wet sensors basically measure the dielectric constant of the sensor surface. So it detect the presence of water on the surface. So the bottom graph is the example, I believe, for instance, a data that using this sensor you can calculate the daily leaf wetness duration, which is useful information for understanding the potential risk of plant disease at your field. Well I just wanted to share some of our current work that we then that we are doing. We have been installing more than 70 sensor units in corn, soybean, potato, dry bean, asparagus, tomato field this year to monitor soil moisture and leaf wetness duration, temperature, humidity, and temperature to improve irrigation and disease management. I also want to share the LOCOMOS website that shows the time sensor data. And this is what a page that shows the TOMCAST model already embedded. So currently, we are testing the website and all the algorithm we put in the website. Make sure this other algorithm equation are working for the TOMCAST model. I just want to share that. And also we are working on the mobile app, what we hope to provide some more easy interface technology to the farmers. So to make, make more easier on the farmer when they want to see the data. Just go to the app and look at the data and make a decision based on this app or the sensor data. So with that, thanks so much for listening to the presentation. If you have any questions, you can put in the chat or email us, Lyndon Kelley, or me. Here's our e-mail address. So that I think Lyndon Kelley will be talking about irrigation water needs. Yeah, Youngsuk if I can. We'll have time for questions at the end. If there's anybody that wants to put anything in the chat, we'll try to get to that a little sooner if we can. I am trying to switch. So Mark, what screen do you see now? I see it in the edit mode. You just need to put it in presenter mode. Okay? You're going to swap out, your in your in presenter mode. We're seeing the next slide too. Right there. Yep, display settings. There we go. That's perfect. Okay. Great. Perfect would be one slide back. Okay. Thank you. I haven't every time I've had to swap out, I'm not sure why it doesn't why I haven't learned its system or it hasn't learned mine one or the other. Today we're going to talk a little bit about irrigation water needs. We're going to talk about sort of the maximum the crops can use and how you need to plan. And for that is your starting if you're either revamping irrigation system or are starting from scratch, how are we going to convert actual to actual irrigated acres? That's pretty much out for drip and trickle where we can have the advantage of not irrigating the areas that are not productive to irrigate. We're going to talk about factors for water loss, the historical water use, the soil reserve and how that makes a seed get by with less capacity if we have good enough soils. And then little bit about drought capacity. How long can your system go without rainfall to help supplement what you're doing? Downtime, we all figure that everything should work a 100 percent of the time, but in reality it doesn't. And then what do you do if you don't have enough water supply? If we take a look at crops and I've got up here, alfalfa, corn. field beans, soy beans and potatoes in the blue. If you look at them they'll peak with their actual crop water use between a quarter of an inch and three-tenths of an inch. And we talk about lumpers and splitters? For this case? We all want to be lumper. We want to build our system so that they have the capacity to meet the highest water needs for the crops that are going to be in our rotation. So a little bit of that is thinking about what crops are in your rotation, what you're going to grow. These tend to be some of the highest that we see here in the Midwest. Notice the alfalfa line is broken. As soon as you cut, the consumption of water goes way back. And then it inclines from that. We'll talk about that as a management strategy in the future. But potatoes is little lower than corn and soybeans, your field beans. But they're all between that quarter of an inch and three-tenths of an inch today. If we were going to think about that from a field crops standpoint where I do most of my work. When you think about it, just in acre inches of water and pump capacity to cover that whole area. But luckily, a lot of the irrigation being developed for the fruit industry, the ornamental industry, and the vegetable industry is using drip tape and other systems that allow you to only water where your plants are and you're not you're not using or filling all of the space in the field. So we don't want to try apply so much water that we're wasting that between the rows. The classic example is Christmas trees. The, the year they're planted. If they're on a 10 by 10 spacing root systems only in 1% of the field. If you're using overhead irrigation, 99% of your water's not going where your plants roots are, and you're just watering the competition, the weeds. So there's, the math is up there, but basically the concept is to figure out where you're actually watering. And then the second important thing is to know that when you're using drip and trickle tape, that our water consumption is going to be tied to the light or photosynthesis area that's there. So we may only be watering or getting the soil wet in a band a foot wide. But if our blueberries have four feet of width that they're intercepting the soil, uh, intercepting the sunlight. Going to draw from that soil, the soil moisture needed for that whole four foot of width. That is drawing photosynthesis. Using the sunlight for photosynthesis and using water. So there's some rough numbers up there and then there's some, some raw numbers to help you figure out where you're at. A lot of times people will just tell me, well, it looks like about half of our field, like a watermelon industry and thinks. talked about maybe half the field at this time, portion of time is covered by water melons and the other half is bare earth. So they schedule their numbers from that point. If we look at that and say, well, what's that actually bring that back to it for in as far as planning purpose. Rough numbers or the the the easy planning numbers to remember is five gallons a minute. Pump capacity per acre is equal to an inch of water every four days. So if we say, well, look, we're using a quarter of an inch and we steam there at peak. At the peak, all of our plants have the ability to pull almost three-tenths of an inch. But for most producers, a quarter of an inch a day is sort of the planning and the economic point threshold where we can afford to. Build-to. And so if we look at that, 500 gallons a minute would be the capacity to put on an inch every four days or a quarter of an inch a day. If I'm a little bit shorter of that I'm down at three gallons per minute. It's going to be more like an inch a week. Back in the 70s and early 80s, my predecessor left me some presentation material. And when I looked at that, that was sort of the number that they shot for was an inch a week. And it works real well as long as we don't have these extended dry periods. And if you go into the extended dry periods, then we have drought issues, even though we've got irrigation investments made in the field. And then I need to make sure to say a lot of the vegetable industry, a lot of the contract plant industry, the seed industry, some of the other things that are contracted. They'd like to see seven gallons per minute because they don't want to have to see the system run seven days a week, 24 hours a day. They'd like to be able to see it be down for a day, day and a half out of each week. And to do that, you need to have seven gallons per minute pump capacity. At that point, even the 2012 drought, you could feed through and have almost a peak use for 30 days straight, still be able to keep up. So those are the numbers. If we're in overhead irrigation, if we are in looking for trickle irrigation, most producers are going to build up their number for the use by looking at how tight they want to irrigate. Do they want to have an irrigation line every four feet or every 10 feet times the length. And then work out from that point to get how much total water they need for that area. There's some numbers there to help you look at that. Probably important to know that not every bit of water that you pump actually makes it to the plant. And when I gave you the numbers for the plants consumption, that's the actual water that goes through the plant. We do some work with lysimeters and actually weigh that water going in, but we don't how the water that evaporates and is lost. And there's three forms that we see that loss take place. Runoff is an issue of the water going from one place to another. So there's an area and the field that lost water. In some cases it could be as bad as 30 percent. So if you look potatoes under this traveler irrigated or on a research plot, you see the water's running towards photographers feet, that water isn't in the field for the plant. So we, we can't assume that the plant has available all that water that ran towards the guy feet. Same thing when we look at center pivots and travelers and things. They are not totally uniform in their application. And we have a tendency to over water in some areas and underwater in others. So those over watering areas did not feed the whole field. And there'll be areas that are going to be light and showing drought stress at if we have extended drought or extended periods with no rainfall. And we'll need to add water to keep up with that lightest area. And then the, the one that you hear a lot of talk about, but it is pretty minimal in our area. Is this evaporative loss to the air that's the actual water loss of the droplet portions of the droplet as it flies from the sprinkler to the crop canopy. And that number is extremely minimal, mostly because of our high humidity in this area. Very, very low number should be the lowest priority in our systems. We don't want run off. We can do a lot of things to avoid runoff. Some time I'll talk about that. We want to stay as uniform as we can. So we want to build uniform systems that maintain them with a high factor of uniformity and evaporative systems yet we want to think about that to minimize evaporative loss, but those numbers are pretty small. When we talk about, well, how much is this, this number. Couple ways you could go back historically and look at it. A lot of work is done in looking at the 2012 drought, drought and whether we could have made it through that few years back, the banking industry was interested in knowing, could this guy have maintained high yields even during a drought situation? So we'll go back and look at those, that enviro weather tool is an excellent tool. In this case, we went to a site, Mendon and we looked at 2012 and how much water use was going on from July 1st through July ninth. In 2012 and that was in effect right during pollination. So people were talking about it and I look at those five days and we had 1.3 inches in that five days. And then the crop what needed 20 percent more than that because that's a grass reference number. So the crop you did 1.6 inches in those five days. So we're a little little over that quarter of an inch a day at that point. So you'd go back and look at the historical records for any of the places in Michigan that the enviro weather stations are, and their maps up there has been an excellent tool to help us work through planning processes. Let's us play that game. What if we had irrigation here in that year? How would it have went. The other thing we need to take into account, not all of us have the same soil type and some are blessed with a lot more holding capacity. What that holding capacity does is every time we have a major set of rainfalls in excess of plant water use, we rebuild that bank, that soil holding bank. If we have, we don't see much capac soils being irrigated. But when we Oshtemo, is the state's most irrigated. Soil, Bronson's up in the top three. And if you'd look at those, if I had 24 inches of rooting depth, I'm going to hold 3.3 inches of water holding the plant capacity that's available to the plant in the Bronson soil there I can hold 3.5 inches. But if you have Spinks sand or spink sandy loam, your whole inch short of that. a third less of the holding capacity. So every time we refill that capacity, your shorter and closer to the line that you need to be able to irrigate than the other people are. So they're bringing that into the factor. So that that sort of brings us to the point where we're going to talk about this drought capacity. This comes up when people invest in irrigation equipment and then they don't achieve the higher yields that they were hoping. And we have this discussion about what, what could be done to bring that up or if they actually have the capacity of water to run the equipment. A year after drought, we see a lot of irrigation equipment go in areas where our water supplies are questionable, be able to supply those things. And really the water supply is the heart of the unit. If that heart of the unit, if that does not keep up with the rest of it, it's the limiting factor about being able to keep up. So here's a case. The guy's removing three-tenths a day that's sort of that peak that we seen. During that drought period in 2012. He has available water holding capacity of three inches. He can apply an inch every five days, so he's a little bit short. As a good manager, he doesn't start irrigating until the water. The first inch of water has been used that allows him to to take any rainfall that comes in and make use of it. If you look at that in about 20 days because his deficit is a tenth of an inch a day water, the plants are removing a tenth of an inch more than he can put on. He can run 24 hours a day, seven days a week, in about 20 days. Those crops will still be showing reduction in yield because he doesn't have the capacity to, to work there. And then the question is, uh, especially when you talk to the bankers and people that's, that lend money for these systems. They'll say, Well what else happened? And there's always a story about what, what kept you from pumping coming out of the 2012 crop year, a major drought. I asked a number of producers, we had a 150 producers at a corn soybean meeting in a Michiana area. We asked them survey data and we asked them what were the things that kept you from running as much as you want? And if you needed to irrigate 24 hours a day, 30 days in a month, do you think you would be able to keep up? And these are all pretty seasoned growers. And the answer was about 10 percent downtime. So they thought out of 30 days, they could keep it running 27 days, about 10 percent of the time had to shutdown for one reason or another. And they cited a number of things. Equipment wrecks. here we have very good in equipment companies that help us get up. But your pivots down and you want to run it, you're going to be lucky if you can get it back up in three days. Improved, something as simple as a tire repair. If you notice that pivot there, that it's carrying its tire on a channel around, on a chain across the field. It, you have something as simple as that. You lose a day or so, just getting that repaired and then the neighbors air conditioning system is up there to remind me to talk about brownouts. In a lot of areas our electrical system is fragile enough that when people come home at four o'clock, we see the four o'clock or five o'clock brownouts happen and that shuts systems down. We actually have producers. They have systems that are designed to shut down and check their equipment and then restart at eight or nine in the evening to keep the irrigation equipment going. Last but not least, we see a lot of producers that they're in good shape when they have the first pivot, the blue pivot up there. There. That first pivot they could put an inch on every three days. Everybody's happy. Contractors want to rent that fields to use it. They add the second pivot, same water supply, and now they're down to an inch every four days. Now, when it's at peak use, somebody's got to keep it running a 100 percent of the time. But of course they're making good money, so they add the yellow pivot, the third pivot. Now they're down to an inch every five days and now even running 24 hours a day, somehow we got to decide where we aren't going to get the water, where, what crop or what part of the farm isn't going to get watered. And so that takes me to my last slide, tells Mark to give Mark a little warning. He's up next. What do you do if you don't have enough water, well you diversify the crops. So that we're have apps that have different peak uses on or a low use versus a high-use. So a low use one, maybe a sacrifice crops. So that works out but doesn't make us the maximum amount of money. We could stagger planting dates. In general, people don't like that because there's a, tends to be in most of our crops an ideal date. But we know that by staggering planting dates, we can move the peak water use time around by a couple of weeks during that July, late July, early August time standpoint, we can move that peak water use. We can have a sacrifice crop and that's the crop that you're not going to water when we're short. Um, I say that and people say nobody does that, yes, that happens. It's when the potato company says, we will take three quarters of that pivot and you can plant the other quarter to something else because your water supply isn't sufficient enough to water the whole pivot, the whole area. So we'll take three quarters of it and you will have to sacrifice that other chunk when that happens. The other things that tend to be sort of wasteful as far as water, you could start early and bank water, we said earlier, good producers, going to let the crop uses that first an inch water after the profiles been filled so that he always has a little bit a capacity to take on rainfall. If you don't have capacity, then you need to start right away and use that inch as your so you can bank water ahead. And then if he had forage crops, you remember back from our first slide, the alfalfa didn't use much water that day or two after it was cut. So I can actually cut the crop, reduce it's water intake for the next week or so. And by staggering those, I can have parts of the field that are the fields that are using the same water supply at their peak use and add a lower use. So those are all systems to try to get by on a lower supply than you need. And then the crops actually need. I don't think we see any questions here in the chat. So that takes us to the fruit man, Mark Longstroth. Mark is, I guess recently retired, I guess is the way to say it. He's an Emeritus educator with Michigan State University, but we called him back to make sure we glean some information from him about what the fruit industry in irrigation. Mark, How can I help? Yeah, I think I'm getting there. Okay. All right. All right. I was going to talk about Small Fruit irrigation and actually I'm going to focus on blueberries. That's the one I'm most familiar with. About 80 percent of michigan blueberry acreage is irrigated. And I spent a lot of time coming from an Inner Mountain West where it doesn't rain very much. I knew an awful lot about irrigation before I started. So I'd like to review about how the plants use water. A lot of growers have the mistaken impression that the that the plants actively take up water and that's not the case. Evaporation is what pulls the water out of the soil. The soil was where the water is, and the plant is a conduit that's carrying it up to the atmosphere. So evaporation from the leaves actually pulls water out of the soil into the plant and evaporates it. And that's how the plant takes up the water and the nutrients, the fertilizer we apply, and also uses that water with carbon dioxide in the air to make sugar and power its growth. So I talk about irrigation. We talk about how much water is the plant using. And Lyndon had the example of the corn and soy beans that are actually using more water. And reference crop of six inches of grass that I often use because many of the fruit crops have a soft soil but grass strips in between for equipment. How much water can the soil hold? And Lyndon and gave us an example of several soils and I use them in this talk. How much water can a system apply over a period of time? As Lyndon was just pointing out, you know, you're constrained by your pump capacity and how much area you need to cover and how quickly you need to be back. And then how much rain have you received If I received rain and my soils are saturated, I can quit irrigating for awhile. But if I haven't received any rain for three or four weeks, I've probably been irrigating for two or three weeks. And in blueberries and, and a lot of the fruit crops. I believe the soil should be recharged before the soil capacity is 50 percent of the available water capacity has been used up, especially with blueberries. It probably should be even higher than that because blueberries are not very efficient users of water. So this is when the blueberry plant or any other perennial crop is using a very minimum of water. It has essentially no leaf surfaces to evaporate water. And the only thing that's drawing water into the plant is the fact that starches had been converted to sugar and then water is flowing in going to these new growing points and puffing them up simply from the osmotic pressure of sugar in the water. That this is maximum demand. What we're seeing right now, the plant is fully leafed out. The photosynthetic machinery is moving as quickly as it can and will be using as much water as the plant can pull out of the soil and evaporate through the leaves. And if they can't maintain the stomates of the leaves open, then they'll shut down and that shuts down photosynthesis and that reduces growth. So these are monthly water use figures for blueberries for the months of May, June, July, and August. And you can see the, the, the monthly use in May is very little. That's when the plants begin to leaf out. Actually start leafing out in April and May we're getting good shoot growth. And by June were using the plants are almost completely leafed out. They've set a crop and are a touring the crop. In July, we're maturing the crop and the crop is being harvested. And then in August, not only does, do the days get shorter, but the demand on the plant isn't nearly as much. But you can see over on the far right, is the daily use maybe two tenths of an inch, pardon me, two hundredths of an inch in May, not very many leaves in June, a tenth of an inch in July, almost two tenths of an inch. And then in August it's back down to below the figure that it was in June. And so generally, from my point of view, we have to be able to replace either on a daily or a weekly basis in the blueberry field or the strawberry fields or the raspberry field, the water that was used that previous week. So here's a soil profile of blueberry root s.ystem And so blueberries have a relatively shallow root system, 18 to maybe 24 inches at depth. Strawberries and raspberries have similar root systems. Now the only part of the root that's very efficient at absorbing water are the new right, white roots, where structures that restrict the movement of water in order to conserve water within the plant haven't really formed. So water can move pretty easily in and out of the root, tips and where the roots are woody. There's very little movement of water. So essentially it's just the new white roots that have formed in the last week or two that are the ones that take up water. And blueberries have an exceedingly small root system for the size of the plant with comparison to lets say like an apple tree or a grapevine that have a large, well distributed root system. Blueberries have a very shallow root system. It doesn't extend that far from the plant usually. And also last but not least, they lack root hairs so they don't have quite the surface to absorb water as any other, many other plants do. So we have talk about soil water storage. Water plant use, a evapotranspiration and precipitation. And so we know how much water the soil can store. We know how much water we can estimate or we can go to enviro weather is where I usually go and figure out how much water the plants are using and get an estimate of how much water they will use for the upcoming week. How much rain have we received, Is there a chance of rain? And then we make up the rest in irrigation. So here's some of the soil textures. Lyndon had a table up showing similar values. An awful lot of our blueberries and strawberries. And indeed even raspberries are grown on sands, are sandy loams. They only hold about one to two inches of water per foot of depth. So since the sandy soils don't hold an awful lot of water and we're using a fair amount of water. Remember, during July, we were using about two tenths of an inch of water a day. If we're going to irrigate before we get to 50 percent soil moisture to recharge the soil so that the plant doesn't run out of water. Every day. We're going to have to irrigate about every five days. And so here we got two inches of water in the soil profile with weekly water use beings 12 hundredths of an inch in May. And so the soil holds enough water for 16 weeks. So essentially it may have to water once every eight weeks. That's not very often. They usually, Most blueberry growers will do their first irrigations in may, soon after bloom, when they've got a fair number of leaves coming on. And we know that demand is high. But you can see we go from having to water occasionally in the month to having to water every ten days. It's twice in two weeks. By the time we get to July, we're down to the point where we have to water every five days in order to maintain the soil. At least 50 percent the capacity of the, of the soil for water to maintain no water deficit in the plants. Then in August it falls off. And I hit the problem that a lot of people have is once I finished harvesting the fruit, I don't need to irrigate any longer because I've harvested the strawberries or I've harvested the blueberries. And generally, I find that very shortsighted. I want to maintain the plant health going into the fall. I'd like to stay. I want that plant plant fat, dumb and happy as we go into the fall. So I want to maintain adequate irrigation. Blueberries, strawberries, and indeed raspberries are all making fruit buds for next year in the fall. And if that plant is water-stressed in the fall, I will be looking at a reduced crop next year. And in fact, we do see that in blueberries when we get a very dry fall, almost always, unless the fields are well maintained and irrigated, they have a lighter crop. So here's my my go-to answer when people say, How often do I need to irrigate? And I say, well, hey, you got to water every other week in June, you've got to water every five days. In July, you have to water every three days. And in August you have to water every week and you'll Well, when do I stop? And I said sometime in September when the fall rains begin, you can cut off your irrigation. Out west we like to give a crop. We like to recharge the soil one last time because we didn't know how much rain we were going to get in early fall. But in general, we don't need to do that here in Michigan. So I'll talk a little bit about water measurement. And Lyndon gave you an acre inch. And so that means the two tenths of an inch, which is about the amount of water that we're using on a hot July day is about 500 or pardon me, 5 thousand gallons. And if I've got my blueberry plants out on that acre and I've got them planted four feet by 10 feet. Then there are 1244 blueberry plants to the acre. And each plant should be using about 4 and a third gallons of water a day. And this pretty much agrees with some work that was done out of Canada with a lysimeter where they would add water to potted blueberry and measure the change in weight every day. And they were getting 18 liters of water, which is about 4.5 gallons of water a day for a mature blueberry bush. And so if you've got a one inch shortage of water in the plant is, then the plant is short, 22 gallons. And so this accumulates over time. I took a slide out of this presentation. And so it showed a graph of fruit growth, where the fruit grows very quickly after bloom. Where the fruit or the flower which is going to become the fruit, is growing very quickly by cell division. It's making more and more cells. And the number of cells is doubling every day or two and it's really growing quite fast. And then the rate of growth falls off. And it doesn't grow very fast because there's not an awful lot of cell division going on anymore. And the Plant organ is transitioning to cell expansion. And so you see a, another peak in growth as all the cells begin to expand as they grow and get filled up with water. And so generally I have people that don't worry too much about irrigation after bloom, which I think is the most critical time because you need to have plenty of water and the plant needs to be in really tip top performing shape in order to make as many cells as possible in the young fruit. And they think that it's important at the end to pump up the cells that you have and make them big. And so that strategy works. Almost invariably the fruit is soft. So I want to talk a little bit about irrigation types. In blueberries. Trickle is becoming more and more popular. It's cheap, but it's big. Drawback is it doesn't have really large application rates. Sprinklers are very, very common. They're expensive. More and almost all of them here in Michigan are solid set and they have the ability to put on a lot of water maybe eighth to a tenth of an inch an hour and quickly catch up. And the fact that we can do that during bloom. Overhead sprinklers are also used for frost protection, where we can put water over the plants before it freezes. The water freezes. We keep putting water on it. And as long as we keep the ice wet, it stays right at the freezing point of water, 32 degrees and the flowers are not hurt until we get about 28 degrees. Unfortunately, because we're using irrigation systems that only apply a tenth to an eighth of an inch. We won't be able to apply enough water when the temperature begins to get down below about 25 degrees depending on the wind. And then the ice dries out. And so we get more cooling, then we get protection. And so I generally recommend to growers that they not even turn on their irrigation systems unless they have open bloom or in the field to protect the open-loop them. Because the plant before that can usually withstand virtually any cold temperatures below 23 degrees. There is a little zone in there just before bloom when we probably can't protect with overhead sprinklers and we'll see damage. We would see more damage if we turn the overhead sprinklers on. So trickle irrigation, Lyndon talked about it a fair amount. Here's a trickle irrigation blueberry field with a single drip irrigation line. And generally, what most growers use are two lines. They may start out with one line, but pretty quickly they'll go to two lines. And you need to know, I'll ask growers how much water they put on and they'll get a faraway look in their head because they had never really sat down to figure out what the application rate is for their system. When we talk about wetting fronts, different types of soils. So if I'm using a sprinkler, I'm wetting the whole surface. Clay tends to absorb an awful lot of water and it doesn't, water doesn't move very quickly through clay, it absorbs an awful lot of it. And so we'll see relatively small wetting front in sandy soils like we have if you have trickled emitter and this one example of real irrigations, a pretty good example of trickle irrigation. We can over irrigate. If I had a blueberry with only two feet rooting depth here, then I've over irrigated. So Youngsuk had talked about measuring soil moisture content and talked about worrying about over irrigating. And so if you're irrigating sandy soils, you always want to check and make sure that you're not over irrigating, especially with the trickle system on sand. It's very easy to over irrigate and have deep cones of water penetrating and not have really good irrigation in-between. Which is another reason why many blueberry growers go to two lines with the emitters spaced about 12 inches part. So there's usually an emitter about every six inches and which covers the plant. Also in blueberries, we have to worry about water quality. Here's a comparison of that trickle irrigated field. We went out there because the grower was complaining that his blueberry seem to get worse and worse the more he irrigated. And here's trickle irrigated field. I would ask the grower, well, so what's the pH of your water? And they didn't know that, so you should know the pH of your water. In fact, it's a good idea if you're growing a specialty crop to have a pretty good idea of what your irrigation water is. Blueberries like acid soils with a pH of five. And this grower was irrigating with hard water with a fair amount of Carbonate. So pardon me, calcium and magnesium bicarbonate, pretty hard water. And so every time he irrigated, he was adding, he was raising the soil pH of the water and raising the soil pH of the soil. So here's an example of a grower that has a small-scale irrigation system. And the blueberries, his irrigation water was at seven, had too many bicarbonates of calcium and he was actually injecting muriatic acid, sulfuric acid. He started out with concentrated sulfuric acid and went to 60% sulfuric acid and 30 percent sulfuric acid. In order to get the right mix, cause he was metering in an extremely tiny amount and he couldn't get a pump that was accurate enough to put in a small quantity they he needed to be able to irrigate with a pH of about 4.3. And since his pH was higher than we actually wanted it, it was very good to be able to irrigate with this acidic water and the grower was completely happy. It just took him a year to figure out the system. So again, the the right pH water onto the system, I think. And so those are the those are the take-home messages here. In general, during the hottest parts of the year, blueberry plants can be using about four gallons of water a day. But you need to adjust that compared to how much rain you've gotten and what the actual evaporation evapotranspiration is? I think that's it. Are there any questions for me? Yeah, There was a question for you Mark from and that is what is the best way to maintain roots white or healthy in blueberries. What are some of the factors that really cause issues, I guess? Oh, yeah. The best way to do it is to maintain soil moisture so that you get good soil growth. I mean, not good soil growth, but a good root growth. Root growth starts out pretty quickly in the springtime, and then it tends to fall off as they're competing with shoots. And then it will pick back up in the summertime. But the best way to encourage white roots is to maintain the soil. At I like to say, blueberries like the soil moist. They don't like it wet, but they, but they can't stand it dry. So you really want to maintain the soil at about 50 percent of available field capacity or higher the whole time. And that will maintain a healthy root system. And you're still going to run into the fact that the stomates will probably shut down in the middle of the day simply because their roots can't absorb water fast enough to maintain evaporation through the stomates of the leaves. Yes, I understand. The other thing that we wanted to cover, at least I'm always curious about, I know every time it looks like it's going to rain I see. our grape growers in the neighborhood here, out putting on fungicides and sometimes insecticides in that mix. So is there big differences between using trickle and and using overhead and having to reapply. I mean I guess. Yeah, I mean essentially, for an awful lot of plant diseases we'll use fungicides as a protective and put them on before a rain rather than as an eradicant, trying to stop the infection afterwards. Trickle irrigation is really nice in the fact that it doesn't wet the leaves. And it's really popular in raspberries. It's not very popular in strawberries. Virtually all strawberries are overhead sprinkle. And we see more and more blueberry fields going in that have both overhead sprinklers, solid set and trickle irrigation. And this is for two reasons. One is that they use the overhead system for spring frost control and early season application. But they're using the trickle irrigation system not only for irrigation but also for fertigation, Where they'll be spoon feeding fertilizer in with trickle irrigation. And also due to food, food safety concerns and microbial contamination. If you're pumping out of an open pond, you need to test the water for bacteria. Essentially they're looking for E. Coli and establish what type of bacterial population you might be sprinkling over the plants. Now I've spoken with blueberry growers who run packing plants and do microbial testing of the product that they bring in and go out. And they say in general, overhead sprinkled fruit is cleaner than the than the trickle irrigated fruit because it's being washed once or twice a week. And truthfully the bacteria don't survive very long on the surface of the, of the crop. But we do have concerns, especially in blueberries with overhead sprinklers and some of the fruit rot diseases where as Youngsuk had talked about minimizing leaf wetness. How can we irrigate the crop and minimize the amount of time that it's wet in order to reduce the incidence of disease or to avoid washing off an insecticide. And so it's a very clever little game they play where oftentimes they'll irrigate and go right in right after and spray and then come back about two or three days later and pick and then irrigate and spray and pick on about a three or four day schedule. And certainly there's plenty of challenges out there, trying to keep the Especially I guess what the insect pests out there so that you can have them clean boxes for them, right? Yeah, it's a big deal with the other. Lyndon had given the example of irrigating just the just the row. And that's a good example to use when you're using blueberry plants. And you'll go back and you often tell people to use a factor of 0.3 or 0.44, since you're only irrigating. the row. And if you've got one of these double systems and you're using overhead sprinklers, you're going to irrigate everything and so the soil is wet most of the time. And then you're going to go in there with a heavy tractor pulling a heavy sprayer or with blueberry harvester. And so you get an awful lot of problems with running. So that's the other advantage of these dual systems where I can apply water either way it needs to be applied. And when I don't want water in the row middles, but I do want it in the plants because I'm going to drive machinery in the row middles. But I want the plants to have adequate water. I can irrigate with that system. That's fantastic. Yeah. Expensive. And yes, that's true. Are there any other questions for Mark, out there? Mark, Could you expand on using that trickle irrigation system as the, as the feeding system for the fertilizer. How, how often and do producers that have that available to them do they do more of a spoon feeding or micromanagement of the nutrients there? Yeah, they do. In general, we recommend, their, that are generally putting in most of the macros: nitrogen, phosphorus, and potassium. And they'll start putting that. They will break that out into say, 10 discrete applications. They'll put on all the nitrogen in pain irrigations. And I generally tell him, don't Don't do that before or pardon me. Let's me start over, or they'll, they will put the fertilizer in with their regular irrigations from when they start irrigating until about the beginning of July. And then after July, we don't want to keep spoon feeding nitrogen. We want the plant shoot growth to slow down and make and stop because that's where the fruit buds are going to be next year. But then they will also have magnesium and potassium in the, in the system later in the season for maintaining fruit growth. And so essentially they, they've, instead of putting on one or two soil applications, they're giving the plant just a little bit. And their fertilizer use efficiency is much greater than a soil application because it's directed right to the crop you want. And it's kinda spoon fed. They will come back in and do leaf analysis to try to fine tune that whole thing. But generally, systems where their trickle fertigating, you see almost twice as much growth in the blueberries as you would if they were simply grown in the old way. That's neat. I, I'll have people scoff at me that say, well, the irrigation allows us to use the other inputs to our area a very, very efficiently. There was a study done with labeled nitrogen and, but I don't have a study comparing the two. I could probably find one. But for surface application of nitrogen, only 40 percent of the nitrogen ever showed up in the blueberry plant. Whereas if you were putting it right where the white roots where your use efficiency would be much, much greater. Are you guys dealing with sulfur deficiency issues? Not yet. Because of the fact that we're trying to maintain an acid soil, any growers will put on a 100 pounds of sulfur every year just as a maintenance. And if the soils are generally if the soil pH is above five, we recommend ammonium sulfate as the nitrogen source because it's the most acidifying fertilizer. And so we're, we are supplementing with sulfur but not because we need to yet. That's, that's neat. It's the opposite of what us field crop producers. As we add sulfur, we're adding, we're going to have to add more lime. And so we often measure the two in opposite ways. It's like okay, for this much lime I put on this much sulfur and backwards. So I know the, the, the acidifying rates of fertilizers very well. The other thing that happens is that blueberries don't like chloride. So they don't like potassium chloride, but they really like magnesium, potassium sulfate. So most of our fertilizers that we use in blueberries are either phosphates or sulfates if they're salts. Great. Any other questions? Bruce, do you see anything else for as far as questions for Mark or anyone? I don't at this point, So, are you going to talk us through the RUP. That's a good question. And I guess maybe Betsy, if you're still there, can you can you talk about the process, the RUP seminar code currently, guys, I have a problem with my Outlook somehow because I'm not getting I didn't get email with the link for this. I had to have my secretary send me one real quick to be able to do that. So thanks Missy for doing that, but so I'm not sure what's going on with that. And unfortunately, I was the one that sent the RUP request, so I'll have to check with with Antonio, give him a call to a follow up. That doesn't mean anything except that we just need to get that similar code to be able to do that to you. It talks through the process of what they need to be able to send to you. So I put a link into the chat for everyone, I will ask my email in case anyone's having trouble pulling in data from that chat. But basically you'll click on that link. The first couple of things are just survey questions is kind of see and gets him back on, you know, what you're thinking on the irrigation webinar series so far and today's session. And then it will ask if you're interested in receiving credit for today's presentation. Once you've completed that, I will get that information prepared with the seminar code that Bruce gets and we'll submit those details to MDARD for those credits. So just go ahead and click on that survey, fill that out and include your license number and how you want those credit applied and we'll get that taken care for you. Fantastic. Thank you so much. If you have a problems, our email addresses either probably be better if it came to me or Eric or Bruce but any RUP questions, please let us know and we'll work through those. If there's any other questions. We'd be glad to take them if if not Dr. Dong , last week, I've heard one discussion after another about the whole tar spot issue. And I know you've been working with Dr. Chilvers and Dr. Tilanco on a project using your leaf wetness sensors, correct? Yes. Yep. Can you tell us just a little bit about that and what you're hoping to accomplish. Yes. So maybe I'll just share what what we do what we're working on right now for next year. So the one study, Dr. Marty Chilvers, It has comparing two different hybrid and comparing different population this so we, we've been discussing exactly location where we want to monitor for us right now, but we will be comparing how different population of corn and the different hybrid will be related to the disease severity, especially for tar spot So yeah, that's some ongoing project. Will continue monitoring. Hopefully we'll share some research in the fall or later in the winter. Yeah. Yeah. Yeah. Lyndon can I throw a just a quick comment out there too, so they're a little bit drier weather that we've that we have had here over this last week in Southwest Michigan should help us a little bit in terms of not having as much disease pressure. So we had initial tar spot found in fields in Southwest Michigan up to two to three weeks ago. But there's not very much out there yet. It usually, it takes a week to 10 days to be able to get spores going again. So if we get a return to wet weather and saturated conditions, then I think we would expect to see more tar spot to blow up. And in all honesty, a lot of times that does seem to occur in like the third or fourth week in August is when we really start to see a lot of signs of it. So it's important, to scout early and keep an eye out for the initial symptoms. Because once you get those lesions in, in the plants, in the field, then it's just a matter of time before they actually start to, to produce spores and really push the infection rate up. So it's good to catch them when there's, there's very few. per plant and try to make your applications with fungicides then if you're going to. Could you review for us scouting protocol for that? Where do you look? Well we've had pretty good success, at least finding initial lesions towards the outside edge of fields. It doesn't make a lot of sense in some respects that we see him there except the fact that, that I think a lot of the spores are coming from infected residue. So it was a corn on corn field then you've already got residue in your field. But if it was a rotated field than a lot of times those spores are released from soybeans or potatoes or whatever other crop that had corn residue in it. And so if you scout along those edges in places where there's pretty good airflow even though it may dry that we had to kinda what conditions here a couple of weeks ago that were foggy and wet and raining all the time and that kind of exacerbates that that challenge. And so even areas that you would think the leaves would dry out quickly may not simply because the conditions were so, so moist and damp. And the other thing that goes on in terms of later in the season is, of course we had these kind of these heavy morning fogs and we have a little bit of that this morning, I think probably anybody was reasonably early can see that there's the extended leaf wetness associated with those too. So we seem to be getting those about a week to 10 days earlier than we normally do this year. So I guess that'll depend a little bit. We're going to get warmer temperatures here and, and, uh, continue drying. So maybe that will, will reduce that too. But so I think the discussion about those leaf wetness sensors in the canopy is really important to understand when you likely have challenges with tar spot. Can you review what the tar spot looks like? The early lesions. Yeah, the early lesions are really kind of a dark brown color. It almost looks like if you've got a small mole on your arm, you know this a little bit of a raised bump there and they can have a brownish, yellowish tanish halo around them there. So normally we see those lesions that are extremely dark. You know, the kind of coalesce and really look like somebody just splattered oil on your corn leaves. That's not really the initial symptoms. Initial symptoms are often much more subtle and a pretty small. So it's important to just kind of take out either a good pair of glasses if you're old like me and your eyes are, are kind of, eyesights a little challenge or to look out. Or maybe even don't think you really necessarily need a magnifying glass, but you do need to look a little bit more closely at those leaves for kind of raised brownish bump. There's also a lot, some look like felt there. There's insects that lay or not lay, but they, they have frass on those leaves. And so sometimes if you do that, you can rub that off real easy with your finger or your thumb. Whereas true tar spot, lesions really kinda goes through the corn leaf itself. But they're pretty small. They do kind of look like a fly speck initially when they when they are found in the field. Okay. Any other questions? Okay. If you need to get a hold of us, please email or call if you have RUP questions or if there's anything we can help with help you with in the irrigated area. I'd be glad to to respond to your email or or take your call. We need to thank Betsy, for getting this all pulled together for us. Mark and Eric, local agents that are there backstopping us. Our speakers. Mark Longstroth coming out of retirement for today to talk to us. Our young professor, Youngsuk Dong, talking to us about leaf wetness sensors. And our next meeting is the August 18th, at Noon be sort of the same discussions we've had before, but a little bit of emphasis on the ornamental industry. Anything else anybody wants to say? So the, the, the speakers for next week, because Lyndon is going to be down at a field day in Purdue, will end up being Ron Goldy will talk a little bit about trickle on vegetables. Nikki Rothwell, will talk about trickle in sizing fruit from some research she did at the north northwest station up in Traverse City area. And then Tom Fernandez to talk a little bit about ornamentals. More specifically. Look forward to have everyone there. All right, Lyndon. Fantastic thank you. Have a good day.