Bernardita Sallato, WSU Extension reviews factors contributing to bitter pit in WA and targeted management at North Central Washington Tree Fruit Days.
Text Transcript with Description of Visuals
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| Thank you Tianna for the invitation. This is a topic that I really enjoy sharing with you all, and like Tianna said this is not only my work but I’m trying to share as much information as I have gathered in my now 18 years of research in in this topic. | Bernardita stands at a podium on stage with a microphone. View switches to title slide presentation. Presentation title: “Bitter Pit in WA ‘Honeycrisp’. Author information: Bernardita Sallato C, Tree Fruit Extension Specialist – IAREC, Washington State University. |
| Okay, so we’re gonna talk again about bitter pit. And this is just a symptom, the way we see it, and you’ve probably have heard of different ways that we call this symptom depending on the variety and depending on the species. But mainly bitter pit is allocated to apples, you all have probably seen this in Honeycrisp, but it also happens in many other varieties. We have seen others, such as cork spot, cork spot is a kind of like a bitter pit in pears, but we call it cork spot because of the symptoms that develops in pear. Also some of us believe that this is also the same problem that we have in WA 38 called the green spot; its just another way of showing up the symptomatology. And this is a cellular deficiency, and I was just hearing a talk by Dan Donahue from Cornell, he was speaking an hour ago in another meeting that that is very true and I will quote him: sometimes when we talk about calcium deficiency we need to be very clear, especially for all of you growers, that the deficiency is not a lack of calcium or a deficiency of supply. And I’m gonna go into that topic now of course in more depth. This is a deficiency that happens as at a cellular level. | Slide titled “Bitter pit” appears with three images of disease symptoms in fruit. The first shows brown spotting on the skin of a Honeycrisp apple, the second shows brown spotting on the flesh of a pear, and the third shows brown spotting on the skin of a WA 38 apple. |
| So I’m gonna show here, this is the symptomatology that we are more familiar with. And you can see that what is happening actually in the cellular wall is that the membrane that holds the cells together becomes leaky and it breaks and that’s what’s become for us, visually, as bitter pit or oxidation and necrosis of the tissue. So these are the main conditions that will lead into that symptom that we see in the cell walls. | Slide appears with a photo of brown spots and pitting on the skin of several apples as well as a microscopy image of the plant cell wall. |
| Now why it’s so complicated, is because calcium not only has that role of structure that keep the cells together. So that role that we call this structure is where calcium is binding what I draw here in red. This is the middle lamella and that holds the cells together. | Slide titled “Ca role” appears with the subheading of “1. Structural”. It contains a drawing of two plant cells. The space between the two cells is highlighted in red to show the location of the middle lamella. |
| But also calcium is here around the membrane of the cells, which is another form of calcium that I will explain in the next slide what it does. | The area around both cells and along the top and bottom of the middle lamella is highlighted in green to show the location of calcium. |
| But in the structural role is where we see that it fails, especially in some more susceptible varieties, and creates this leakiness and bitter pit. | A microscopy image of two plant cells appears, degradation of the membrane that holds the cells together is visible. |
| Now the second role, also being related to calcium, in bitter pea development, especially later in the season, is this role of calcium in the cell membrane. Which is some available calcium that is kind of floating outside the cells and is reactive to signals. What it means is that, when we have a problem like heat stress, light, shade, deficiency, insect damage, or any environmental impact into the fruit, the calcium is a signaling element that goes from the cell membranes inside the cell to make a reaction. And so that’s why we call it a signaling element. | Slide titled “Ca role” appears with the subheading of “2. signaling” which contains a diagram illustrating calcium movement within a plant cell in response to internal and external signals such as ripening, stress, insects, and light. |
| Now once the reaction is done for example having (indistinct), or having a thicker layer, or having a protein development for example, then the calcium needs to go back into the vacuoles and it becomes non-mobile non-active. When this process happens later, and we don’t have enough calcium available, this soluble calcium can reduce our deficiency of calcium in the cells and it could also lead to that leakiness and the development of bitter pit. So those two roles are related to bitter pit development. Now this, in a way, explains why, when we evaluate calcium or total calcium in the fruit, we don’t always see a good correlation with bitter pit. And that’s because we are evaluating all these forms of calcium, including the calcium that is not active or important for us for the cell wall. So that’s why total calcium is not a very good indicator. | The calcium signaling slide updates to include additional microscopic images showing calcium localization and structural effects within plant cells. |
| Okay so what I want to do here is to show in what stage we can manage this calcium availability in that cell level. So first of all we need to understand how it works in a normal process. Start from the soil, whatever calcium we have available in the soil is taken up by the roots, especially the root tips, and it’s moved up into the plant by the xylem. And this is very important to understand, because that means that calcium is not a very mobile element inside the plant. Xylem also only goes upwards, not like phloem that goes both ways, and it has a limitation when the fruit matures. I’m going to explain that later, and so it’s driven by transpiration and by the capacity of the xylem to move and sustain that exchange capacity similar to what we see in the soils. | Slide titled “Ca – Root to Fruit” appears which illustrates calcium transport from the soil, to the roots of the plant, and up to the fruit, showing that calcium moves upward through the xylem with transpiration rather than through the phloem. |
| Another key point in this is that, when we are developing that cell wall and that membrane, this happens earlier in the season where we have the cell division. It doesn’t happen later, because later what happens in the fruit while it matures, is that the cells start to enlarge. So increasing size but not increasing in numbers of cells. So we don’t create more cells later in the season. So this is the stage that has been mentioned many times in the past by researchers, this is the time that we have to target available calcium in the soil, adequate root health and growth, and avoid competition in that transpiration. | A line graph is added to the root to fruit slide which plots fruit calcium content from flowering fruit set to harvest. There is a sharp increase in calcium uptake from flowering fruit set to 6 weeks after fruit set, and then a leveling off as the fruit grows. |
| What really causes this is really this multifactorial and that’s why it’s so complicated. In the same talk that I mentioned before, Dan Donahue, where they measure 45 different factors and they found that 25 factors are actually impacting bitter pit development. So that’s why it’s so complicated. But at the end, what is happening? We know that is a genetical factor that’s why we have varieties that are more susceptible than others, and especially related to the longevity of that xylem that is bringing that calcium into the fruit, and the reduced ability of that membrane that I showed in the signaling portion to retain that calcium. So it’s a genetical component that is mostly related to this stage which I mentioned before, not to the root growth, its more related to that transpiration and movement of the calcium into the fruit. | Slide titled “What Causes Bitter pit?” appears with a picture of apples growing on a tree. A bullet point list outlines that three big factors for bitter pit are genetics, reduced xylem functionality, and reduced calcium binding capacity. |
| This is just to show the same, where it started in the 90’s, that was the first thought of this xylem functionality. But then it was proven in 2004 by this researcher that that was the cause in apples, and this is just to show this. ‘Catarina’ is a susceptible variety similar to Honeycrisp, and you can see that in 40 days after full bloom the xylem starts reducing the functionality compared to a ‘Fuji’ that, in their location, is not susceptible to bitter pit. And we have proven, we have seen this over and over, because it has also shown some staining and differences between ‘Gala’ and ‘Honeycrisp’, so this seems to be the main factor. | Slide titled “Fruit Ca uptake” presents research data showing that fruit calcium uptake decreases over time after bloom and that cultivars more susceptible to the disorder lose xylem functionality earlier. |
| What happened also is that, while we cannot put calcium into the fruit later in the stage, (after 40 days after) what happened? We still can gain other nutrients, especially nitrogen, potassium, and magnesium, because those elements are mobile and they can go into the plant and the fruit through the phloem. So we can still increase the level of these elements, and thus, we can change the balance, nitrogen to calcium. | A slide presents research data in the form of two line graphs showing that fruit calcium concentration changes over development and is affected by its balance with nitrogen, potassium, and magnesium. |
| So what can we do to mitigate this problem that is genetic? We’re probably not going to solve it completely in a susceptible variety, but there are some things that we can focus on. So I divide this in four stages: in the soil, the roots, the transport to the fruit, and at the cellular level later in the maturity. | Slide titled “How can we mitigate?” appears which contains a bullet point list of the 4 stages mentioned. |
| So in the soil, we have to secure that we have levels above four. Normally I will show a chart of the levels that we have found in Washington, but with this amount in the soil we have sufficient to supply what the plant needs to grow. Now in a very sandy soil like this one in this image, is very easy to supply that if we have good irrigation that doesn’t leach the calcium. But it’s very easy to supply because we can put it there when the roots are growing. And it’s just a matter of adding the fertilizer that is needed; like for example, a calcium gypsum which also provides sulfate which are normally low in sandy soils too. So just keep up with the calcium requirements in the soil. Also we have to focus on the balance with other nutrients because we know that if we have too much potassium, magnesium, or even ammonium, those can compete with the uptake of calcium if they are in large quantities; especially for potassium. And we know that there are many soils here in Washington with high levels above this number here which seems to be adequate for ‘Honeycrisp’. And the ph., of course, above 8.5 we can start having some… we have enough calcium, but not necessarily available. But also it’s not ideal for general root growth. So if we keep this up, we should be fine in terms of calcium availability. | Slide titled “1. Soil Ca – Availability” appears with an image of soil layers in which the sandy layers are clearly defined by their lighter coloration. A bullet point list highlights key factors in availability including ensuring that soil levels are above 4 meq/100g, ensuring cation balance, and that the pH is in an adequate range. |
| In a more clay type of soil where we have maybe sun in the top, but then we have a layer that is preventing adequate drainage like Tianna mentioned before, that can prevent the health of the roots. So that’s also a problem we have to be focusing on. Look in the profile of your soils and avoid those stages of excessive water and lack of oxygen because that would prevent root growth. | A different image of soil layers appears showing layers of compacted clay within the soil. |
| Now this is very simple to show that, in the soil, if we do have root hairs, the movement of calcium into the plant is passive. That means it doesn’t require energy and is very fast and effective. | Slide titled “Ca availability” which shows an illustrated diagram of a root tip, showing how nutrients move from the soil to the root hairs. Calcium primarily reaches the root through mass flow, moving with water toward roots as a result of demand by plant transpiration and growth. The diagram also shows diffusion, where nutrients move from areas of high to low concentration, which is shown as the main path for potassium and phosphorus. |
| So the movement from the soil, which the calcium normally is around the clay layers, and will move with water into the root hair. | Camera view switches to Bernardita speaking at the podium |
| So those are two components that are fundamental early in the season. Again we need to have adequate root growth and health, but also we have to have moisture because otherwise calcium doesn’t go into the plant. | View switches back to the slide titled “Ca availability” with aforementioned diagram. |
| This is a chart of more than 260 soils that I’ve been working on in collaboration with growers where we have the levels of calcium. In white is the level that I consider adequate, so you can see how much are above adequate levels. These ones here are normally associated to very sandy soils, but this area probably is easier to manage in terms of you can add calcium quite easily in the soil. | A bar graph of calcium levels in 260 soil samples appears. The y-axis is the calcium level in meq/100g and ranges from 0 to 28. A horizontal white line at 5 shows the adequate level of calcium. The majority of the samples sit above this line, with a few samples sitting below. |
| But this overlay that we put here is the levels of potassium that we have in our soil. So when we have adequate levels, this range of very adequate levels of calcium, when we overlay the potassium levels, this red line is the maximum level of potassium we should aim for. So all the soils here that you see that are above this line are preventing the uptake of calcium. And that’s where we have to focus, not in adding more calcium, but just to control the levels of potassium that we have in our soils. | Another bar graph is overlayed on the calcium level graph showing the potassium levels in the soil samples. The y-axis is the potassium level in mg/kg and ranges from 0 to 800. A horizontal red line at 250 shows the maximum adequate level of potassium in the soil. Many of the samples sit above this line, with a few sitting below. |
| So this I kind of listed the priority what I will be doing. So first of all for those areas that are low in both, in potassium like here and low in calcium, is easier to just supply what is needed. And you can rely on the tables that we have provided in our webpage of adequate levels of potassium and calcium. | The number one is drawn on screen along with an arrow pointing to a soil sample on the graph which is deficient in both calcium and potassium. |
| But second I will focus on those areas that we have excessive potassium. Which are everything that is above this red line those orchards, especially those that are inadequate levels of calcium. But levels of above 500 is way too much and probably this is preventing the uptake of calcium. | The number two is drawn on screen above soil samples on the graph which are high in potassium and low in calcium. |
| And third we have to think about this area here where we have very high levels, above 15 normally. This means in most cases that the soil has calcium carbonate and probably this relates to high pH and the layer of caliche in the soil. Also in many cases, we have lack of drainage because of that caliche and so the problem there is more related to that lack of drainage and infiltration of water rather than nutrients. | The number 3 is drawn on screen above soil samples on the graph which are high in both potassium and calcium. |
| So if we think about we solve the problem in in calcium availability in the soil we have to focus on the root growth. And this is important because calcium is passively going into the plant only when we have root tips. When the roots develop this layer here, kind of in light blue, that’s a casparian layer that prevents the entry of calcium into the xylem which is down here. So only through the root tip that doesn’t have that layer the calcium goes there very easy and very freely. So if we don’t have the root tips that you see early in the season, we don’t have that passive uptake of calcium. While other nutrients like nitrogen and potassium can be taken up by not only the root tips, but the more mature section of the roots throughout the season. And we need to consider that because sometimes we don’t have root tips for example in the middle of the summer. But we are irrigating, we are overhead cooling, we are putting water, and the plant is up-taking potassium and nitrogen together with that water. So we can create that imbalance while we no longer are taking up calcium because we don’t have root tips, but also we don’t create more cells at that stage. | Slide titled “2. Uptake – Root tips” which contains 3 microscopy photos of root tips in the soil as well as an illustrated diagram of the tip of a root where we can see calcium molecules entering. A bullet point list outlines that calcium is taken up by the root tips, that the process is passive, and that it occurs via mass flow. |
| This is to show, of course this vary between location, but it’s very standard that, in most cases, the root growth starts right after we have shoot growth. So the first shoot growth you see in the top here, this is shoot growth and fruit growth rate, both start before we have actually root growth. And that’s because they rely on the reserves from the previous year. So I draw here the line where, in this chart below, we see that the root growth start growing after we start that process of cell division. So the earlier we have that root growth, we will have more supply but initially actually the plant relies on whatever is in the plant as a reserve, especially for nitrogen. | Slide titled “Uptake – Root tips” which contains three plots: fruit and shoot growth rates, root emergence and turnover, and soil/rock respiration. The graphs show that shoot and fruit growth begin earlier in the season than root growth. A bullet point lists highlights that shoot growth begins in early May, but roots do not begin growing until the end of June when the temperature is around 15 degree Celsius. |
| This is a trial that we did in collaboration with Stemilt and Washington State funding support, where we are evaluating: what can we do to improve or accelerate root growth? So we have been trying different, maybe not very practical measures, but we have a black tarp, this is a plastic non-permeable cover, a control, and extend to see if we can manage that temperature. | Slide appears containing photos of the three different methods tested in the orchard. The first image has a black plastic tarp covering the ground beneath the trees, the second has a clear plastic sheet, and the third has a white plastic sheet. |
| And we indeed changed the temperature quite a bit especially early in the season we were able to improve and accelerate that root growth with the clear plastic in the root zone, while with the extend it was actually delayed. This might not be a bad thing especially in very hot years, because in our case we are working with ‘M9’ which is actually susceptible to high temperatures in the soil. But in any case, our trial was to evaluate if we were able to improve root growth and see what that impacted in terms of the plant. | A line graph shows soil temperature over time from late April to early August for the four surface treatments: control, white sheet, black sheet, and clear sheet. The clear treatment shows a consistently higher temperature than the other treatments from early May to late July. The white treatment shows a consistently lower temperature than the other treatments over the course of the trial. |
| I’m not going to show all the results because I have a lot of other things I want to show, but overall we observed, but only on one year this was in 2018, that the clear also reduced the levels of a bitter pit only at harvest. And we have no difference between the storage and the control. But there was there was something there so we are continuing to evaluate whether higher temperatures in the soil can help us to improve that root growth early in the season, because we do believe that it could be a limiting factor especially in cold years. | An additional bar graph appears on screen showing the percent of bitter pit incidence for each of the four treatments both at harvest and in storage. The only noted difference is that the clear treatment significantly reduced the levels of bitter pit at harvest. |
| Okay so we have adequate levels of calcium supply, then we provide good root growth and healthy roots. So the third stage and this is probably the most relevant one because it relates to that xylem timing that we have to put that calcium into the plant, relates to the movement of calcium from the roots to the fruit and to that fruit in development, fruit in cell division. So remember xylem is one direction, it’s bringing the calcium into the fruit, driven especially by transpiration. So early in the season we do have transpiration from the fruit, but later when the fruit is developing the cell walls and all that, the fruit no longer transpire. So we have a window opportunity to have calcium into the fruit. There’s also other research that show that the seeds from the fruit are a driving force of calcium to get into the fruit. Which makes sense because at the beginning we have to think, and this is the second theory that moves between concentration, that early in the season when we don’t have leaves or big leaves transpiring. How does it move? And we don’t have root growth early when the cell division starts, so how does it move? The other theory from Bangerth in 79 shows that it moves from a differential of concentration, from high to low concentration. So there’s two forces that are taking the calcium into the fruit. Now that’s why there’s a couple of research that show that a early thinning can prevent the uptake of calcium into the fruit and have increased levels of bitter pit if we thin too early. That has another other consequences too. | Slide titled “3. Ca Transport to Fruit” appears which contains a bullet point list highlighting that the xylem is one directional and that calcium transport to fruit is driven by transpiration and potentially by a differential in concentration. It also highlights that plant growth regulators, seeds, and thinning timing can all impact calcium transport. |
| So what we have to do, and this is probably where we have more tools to manage this, is to we need to manage vigor in our orchards. We have seen that the most related condition to bitter pit in Washington is the excessive vigor. So we have to manage crop load. Vigor and crop load go together, I cannot separate those two. Shoot to fruit ratio is the same. When we have too much vigor, we have reduced number of seeds early in the season, so that can prevent the uptake of calcium. We have more GA coming from the shoot growth, and GA is known to inhibit the uptake of calcium into the fruit and also will create more shade that also has led to bitter pit. And we know that we will have more nitrogen and potassium demand with high shoot growth and that can lead also to oversized fruit, also leading to bitter pit. So all these factors that all relate to vigor are the way I feel that we need to manage bitter pit in our orchard. | Slide titled “Excessive vigor” appears in which a bullet point lists the mentioned factors related to vigor which can be risks for bitter pit development, including more nitrogen and potassium, oversized fruit, and more shade. |
| I want to show here some of the factors that are related to vigor, for example you all know that the ‘B9’, this is a work from Dennis Robinson in New York. ‘B9″ is a lower vigor rootstock and has lower levels of bitter pit compared to, for example, a ‘G41’ that have higher levels of bitter pit, right? And that’s the same for the rest of the rootstocks in general. A dwarfing rootstock has less bitter pit compared to a more vigorous rootstock. | A line graph titled “Geneva Rootstock trial, New York” shows bitter pit incidence across multiple apple rootstocks, The x-axis lists rootstock types and the y-axis shows bitter pit incidence. Several rootstocks show higher incidence than others, with B9 highlighted as an example of low incidence, and G41 being highlighted for high incidence. |
| The same was shown by Lee Kalcitz in his work with Nadia Valverde. They also showed that more dwarfing rootstocks, M9 and B9, have less bitter pit compared to a more vigorous rootstock. | A bar graph of probability of bitter pit incidence across several rootstocks is shown. The M9 and B9 rootstocks are shown to have less probability of bitter pit incidence than the other rootstocks tested. |
| And the same with Musacchi’s work and more vigorous rootstock, more bitter pit. So we will learn more about the rootstock influence, but that’s pretty much very standard. | A bar graph titled “Incidence (%) Bitter Pit by rootstock in 2019” appears in which percent of fruit with bitter pit across several rootstocks is shown. The rootstock G41 has the highest rate of incidence, while G11 and G969 are highlighted as having low incidence of bitter pit. |
| In terms of nitrogen management, we also know, and this is ‘Cosmic’ and ‘Honeycrisp’ from my data in my lab, and this is for more references but we can see that the demand of nitrogen and calcium and all most of the nutrients in ‘Gala’, which is known to be less susceptible to bitter pit, is higher compared to a ‘Honeycrisp’. In general ‘Honeycrisp’ doesn’t like to have high levels of nitrogen, so these are the standard we should be following in terms of demand for ‘Honeycrisp’. Its lower than a less susceptible variety. | A table appears outlining the macronutrient extractions in apples of four different rootstocks. The Honeycrisp variety is shown to have the lowest demand for nitrogen at 0.7 while the Gala variety has the highest demand at 2.6. |
| According to Cheng in 2021, he mentioned also that the foliar values for ‘Honeycrisp’ should be lower compared to a standard. So between 2 and 2.2, and, in terms of potassium, 1 and 1.3. Slightly lower than what we use for the other varieties. Another point that he made that I think is very important is that we need to collect the samples before we see this typical ‘Honeycrisp’ chlorosis. Which will be a little bit earlier than other varieties. | Text appears on screen of the results of a research study showing that the nitrogen requirement of Honeycrisp is 2 to 2.2 percent versus 2.5 percent, which is standard. The potassium requirement of Honeycrisp is shown to be 1 to 1.3 percent versus 1.9 percent. |
| Crop load, we see that there is a relation. Its not a very strong relation in most cases, but there is a relation where, especially when we are in the very low crop load level, if we are in this very low crop load, below the three fruit per trunk cross-sectional area, we see that we increase the levels of bitter pit. | Slide titled “Crop load” appears with a picture of an apple growing on a tree and a scatterplot showing that low crop load tends to increase bitter pit incidence. The x-axis of the plot is crop load in fruit number by tree cross sectional area, and the y-axis is the precent of fruit with external bitter pit. The graph shows a higher incidence of bitter pit as crop load is reduced. |
| And this has also been proven by Lee Kalcitz here. Dan Donahue shows also that application of PGR which is inhibiting GA’s and growth, improve or reduce the levels of bitter pit when applied at pink. And of course that relates to reducing the vigor of the shoots. | Slide titled “PGRs GA inhibitors” shows a graph of bitter pit incidence measured 45 days after treatment across several plant growth regulator treatments. The x-axis lists treatments including a thinned control and multiple Prohex applications, the y-axis shows bitter pit incidence. Each treatment is represented by a point with vertical error bars. Three values are highlighted with colored circles: 44.4 percent incidence in the control, 57.8 percent for one Prohex treatment, and 25.6 percent for a Prohex pink treatment. |
| Another work, and we are copying this here in Washington in a new project, is the application of an Apogee later in post harvest. This author, Amarante from Brazil, they showed that they reduced bitter pit levels with this application of Apogee later in the season prior to harvest. I’m going fast because I have one minute. I have to stop. | Two bar graphs appear showing the percent incidence of bitter pit and the index of bitter pit across 5 treatments. The treatment with the lowest incidence and index of bitter pit is circled on each graph, which is ProCa PH. |
| So that’s in the process of cell division where the fruit starts to grow. This is the fourth stage, which is what happens after, when we no longer can put calcium into the fruit and because there’s no more cell division, no more cell development. So what do we have to prevent? In this case we think that the fruit enlargement, we have to prevent that oversized fruit and we have to prevent the uptake of nitrogen, potassium, and magnesium because they continue going into the fruit via phloem. Oversized fruit, we know that you growers know that about Honeycrisp, its very big. But we also have to prevent the stress because the stress can lead to bitter pit. And ripening is another process, during ripening naturally the plant needs to reduce the level of calcium to become good for the seed development. That’s not our goal, but calcium levels will reduce in the ripening process as a natural process. | Slide titled “Fruit enlargement” appears with a picture of apples growing on a tree which have brown spotting on the skin indicative of bitter pit. A microscopy photo to the side shows the degradation of the attachment of the plant cells, and a bullet point list highlights that nitrogen, potassium and magnesium go to the fruit via phloem, and that excess size, stress, and ripening are all factors in bitter pit development. |
| Okay so this is another PGR, and this is thinking about the later stage to prevent stress where, these authors have shown, de Freitas also from Brazil and the same group. They showed that Red Chief which is a susceptible variety with bitter pit, they reduced with the application of ABA later in the season. We are copying this too, we are trying to evaluate this later application of ABA in ‘Honeycrisp’ to see if we can reduce the levels of bitter pit. And in this case they show also the increase in the ratio of potassium magnesium in the control compared to an ABA treatment. | Slide titled “Plant growth regulators PGRs” contains photos of two sets of apples. The first is the control which shows brown spotting on the skin, indicative of bitter pit. The second is the ABA treated, which does not show spotting. A bar graph to the side shows that potassium, magnesium, and calcium levels were lower in the ABA treated apples when compared to the control treatment. |
| This is my work. You are the first ones to see this now, I’m going to present it next week in the Washington Tree Fruit Research Commission review, that we did see in one of the two trials that we are evaluating, that the ABA later in the season pre-harvest did reduce bitter pit levels at harvest and in storage. | Slide titled “WA ‘Honeycrisp’/M9-337 – 2021” contains a bar graph showing percent of bitter pit incidence, at both harvest and in storage, across 4 different treatments. We can see that the ABA treatment significantly reduced the percentage of bitter pit in both harvest and storage. |
| Okay so with that I’m finishing. A just overall message to start with the soil, to secure these levels of above four, it should not be a complicated task. To prevent the antagonism with potassium in particular. Promote root health and moisture and temperature early in the season. Prevent the excessive vigor, this is key, this is fundamental in our region because we have a lot of potential for growing shoots. We have the best conditions to grow trees here in Washington so this could become a problem actually for this disorder. And finally prevent, or do everything that you can to prevent, stress conditions. | Slide titled “Summary” contains list of key points for reducing bitter pit incidence. |
| Great, thank you very much. Let’s give her a big round of applause and we have some questions. | Camera view switches to Bernardita speaking at the podium |
