Bloom stage: knowns and unknowns - part 1
I believe this year is setting up to potentially be a big one. According to growers I’ve interviewed, this could very well be the case with apples, cherries and pears considering how light the 2022 crops were compared to historical averages. That being the case, there are some important considerations to be made in preparing for the year.
First, apple fruit bud projections for the state are at 82%. This could likely lead to one of the bigger crops on record, in the last ten years. The challenge won’t be getting a big crop packed, but rather growing it uniformly and getting harvest completed in a timely manner. The fruiting buds look quite promising, but with that comes the potential reality of a big crop set. Big crops can be hard to size fruit adequately, finish uniformly and require more intentional nutrient management. You should therefore adjust your Nutrient Management Plan to address this most effectively.
Second, the plant canopy did not function properly last fall, with the abrupt change in weather and seasons. What effect that could have on this year’s potential, is anyone’s guess. I believe it will have an adverse effect, but to what degree remains to be seen. Now, please allow me to qualify that by saying, this is another good reason for collecting plant tissue samples in the fall. Fall analysis shows what got into the plant and provides a current nutrient inventory for Postharvest planning. I use fall tissue analysis as a guide for making fall applications.It is a good tool to confirm which nutrients need adjusting, as well as, verifying excesses and deficiencies, which are equally important and helps eliminate misapplications. Tissue analysis is a useful measure to ensure plants have adequate supplied reserves for dormancy, as well as, early spring growth and development needs. When everything functions properly under normal conditions, there aren’t many concerns with the plant canopy’s contents, because there is adequate time for nutrient translocation back into the plant. This past year that was not the case. This is why I believe there will be deficiencies this spring due to what is still locked inside the canopy that would normally be stored in the plant. I believe some of the contents of the canopy translocated into the tree, but only a small amount of the total. Therefore foliar supplementation will likely be necessary to maintain and/or improve yield levels, especially in terms of fruit quality.
Next, during dormancy, “leafy” trees need pruning, but are much slower to prune due to the visual hindrances caused by the leaves. The high hourly wage rate coupled with leafy, hard to prune trees and a high fruiting bud percentage, leads me to believe there is a high risk of a lot of “under-pruned” and overset trees going into bloom this spring. Trees that are overset require a good volume of stored reserves (energy and nutrients) to support the early growth and development until thinning the crop load is completed. The total volume of the plants’ stored reserves this season is uncertain at best. These resources stored in the “fruit-to-be-thinned-off” are lost in unproductive growth until thinning happens. These “spent” reserves reduce the total stored reserve volume available for the developing crop being grown. Timely thinning this year will be critical to lessen stored reserve waste. This is another reason foliar nutrient supplementation will likely be necessary.
Finally, most plant canopies did not defoliate normally last fall. There wasn’t the opportunity to transition through the necessary steps from actively growing to canopy defoliation. So, what are we to make of the leaves left behind that in many cases are still green with chlorophyll, at the leaf centers. I do not believe much of the secondary metabolite compounds and nutrients used to synthesize them were translocated into the trees and are still stuck to them. The plant secondary metabolite compounds, in the leaves, require ten times the photosynthetic energy to produce versus simple glucose. The first law of thermodynamics states that energy cannot be created or destroyed, it can only be transferred into other forms. The photosynthesized compounds stored in the leaves and the energy used to build them, are held unavailable until defoliation and decomposition occurs. This is assuming the leaves aren’t blown off the farm by the Yakima “breezes.” We can only speculate as to the total quantity of stored reserves inside the old canopy, but more importantly they are not available for spring’s needs and use. Foliar nutrient supplementation this spring can help reduce this potential deficit.
Last season, the apple industry was challenged with poor internal fruit quality. The fall of 2021 plant tissue values, from our company’s sampling archive, that were carried into spring of 2022, were comparable with the recent fall 2022 plant tissue analyses. Without adequate nutrient translocation from last season’s canopy back into the plant, what deficiencies could we potentially be facing in the coming growing season with all the aforementioned factors? What plans have you made to ensure this potential deficit is adequately addressed in your operation?
Educated guesses. This is something I practice based on facts that are available, at the moment. I collect data from various sources and analyze it with the goal of improving grower productivity and profitability.
For example, last season started out really cold, which delayed spring soil warming by 10 days (based on WSU AgWeatherNet Prosser data). This delay put additional demands on the plants’ stored reserves, which created some nutrient deficiencies and imbalances. During the summer, there were high temperatures in the final weeks before harvest, as Gala and Honeycrisp were finishing, which adversely affected fruit color and harvest quality. I believe the imbalances from the start of the growing season produced a deficient and therefore inefficient plant canopy. The canopy’s photosynthetic inefficiency was manifest prior to harvest where it was unable to produce the needed secondary compounds for finishing crops and maintaining fruit quality; i.e. carotenoids, anthocyanins, flavonoids, oils, resins, etc. Then, in the fall, the transition to winter conditions happened so quickly that the leaves “glued” themselves to the trees, effectively stopping nutrient translocation. With all this in mind, it’s important to remember that with tree fruit crops, we are always growing two crops. I believe it’s safe to say any or all of these factors not only had an adverse effect on the development of last season’s crop quality, but will also have a carried-over effect on this year’s crop potential.
Practical application. Here’s some information to help you check how your fields measure up. I once had an interview with a UC Davis plant pathologist. He shared with me some details about almond canopy research that had been done. In this canopy research, it was calculated there are 12,000 pounds of leaves per acre, in a mature, average producing almond orchard. With that information calculations can be made, as to the total pounds of nutrients stored within the canopy. Old apple orchards and high-density apple plantings have smaller canopies than mature almond orchards, but here are some interpretive analyses that can be made, based on this information.
An apple tree canopy is about one-third to one-half the size of a mature almond canopy. It is reasonable to use a value of 4,000-6,000 pounds of leaves per acre, for a mature apple orchard. I’ll use 5,000 pounds of leaves per acre for simple math. For younger orchards you could use 2,500 pounds of leaves as your guide. With that in mind, here is what is still (potentially) locked-in the canopy that won’t be available for use in the upcoming bloom and early stages of development. I believe this will be a significant factor in plants’ ability to perform productively early on, in what is setting up to be a big crop year; please plan accordingly.
Based on samples we collected, this past fall, from over a 1,400 acres apple sample group. Using 5,000 pounds of leaves per acre, multiplied by the average percentages of nitrogen, phosphorus, potassium, sulfur, calcium and magnesium, from the sample group, we calculated the values in terms of pounds of nutrients per acre “unavailable” in the old canopy. I think you can see this is a significant amount of nutrients that will have to be supplied, especially when you consider the foundational role “available” nutrients play in early season development. This is true for internal fruit quality, as well as canopy health. There is much “potential” held in the 2023 crop, but only those who are prepared with a Nutrient Management Plan that addresses these issues, will convert the “potential” into “actual” and come out with the competitive advantage. This spring, starting off with “plant-ready” nutrients and energy supplementation will play a vital role in your crop quality and yields at harvest.
Talk with your certified crop advisor for your best treatment options for your farm’s needs. Ask about “plant-ready” nutrient options and pure organic acids for supplementing potential deficits. If you don’t get the help or information you need, or you’d like a second opinion, you can email me directly from the link below with your questions.
Here’s to your crops’ success!
