In the last SoilMatters – Bloom Stage: Knowns and Unknowns Part 1, I discussed the amount of nutrients that are potentially tied-up in last season’s canopy and unavailable for spring growth and development needs as well as reasons why foliar nutrient supplementation will be necessary. I believe these are significant factors going into 2023 with the high fruit bud projections. A plan to fortify fruiting parts early in the growing season, starting as early as “Tight cluster” or “First white,” will improve trees’ ability to carry out each of the stages of the Pollination process more effectively. The crucial detail is nutrient derivation source to reduce phytotoxic risk and ensure efficient uptake. 

Nature is dynamic. Every system, process or function operates in a very precise manner. Nature’s design uses nutrients as the raw materials and carbohydrate energy as the fuel source, for combining them into different configurations in order to build healthy and productive organisms. In plants, this is quite noticeable at different stages in the growing season, but especially in later winter, when they start awakening and buds begin swelling. This is an early signal that bloom stage and canopy development are just weeks away. As dormancy concludes and new growth begins, the primary energy source fueling these processes are the plant stored reserves. These Reserves are photosynthetically-based compounds, which are stocked up during the previous growing season. They are meant to adequately supply the plant for the early growth and development needs until the soil warms sufficiently for nutrient release to begin. Despite wintertime soil limitations, foliar applications with the right forms of nutrients can supplement and fortify early development processes, like Pollination activities. In fact, the greatest limiting factor to Pollination success is nutrition. Therefore, it should go without saying, the fertility selections you make at this stage will significantly complement or hinder the efficacy of each part of the process. Selecting the right nutrient formulations for the plant’s current condition is a vital consideration in order to stimulate a productive response. 

Each stage of plant development requires certain nutrients for a productive growth response. Key stages like bloom, cell division, crop retention, canopy and bud development all have different nutrient needs that must be addressed effectively, in order to maintain plant health and productivity. At bloom stage, use care in applying fertilizer, specifically nitrate-nitrogen, as it is readily absorbed and easy to supply more than is needed, thus causing a nutrient imbalance, at an important stage. I have not found nitrate-nitrogen to be essential for improving blooming activities. Talk with your crop advisor for best treatment options for the needs of your farm. This season, with the “glued canopy” issue from the fall and high fruit bud percentages will make your Nutrient Management decisions all the more critical to ensure a productive growth response rather than one that’s overly vigorous.

Where to Start.

A general guideline to follow is the PNK Rule of Neoteric Agriculture, which states, “Start every crop with phosphorus, grow the crop with nitrogen and finish it with potassium.” Based on that premise and with consideration to the current conditions facing us in California and Washington, selecting “plant-ready” orthophosphate will be in your best interest this spring. Using a pure formulation with low heavy metals will benefit foliar spray applications greatly. This is simply due to the fact that in California, the majority of the crops are coming through an historically wet winter with saturated soil and anaerobic rootzone conditions following three consecutive years of drought. This is a lot of stress to manage in addition to growing marketable crops.

In eastern Washington, tree fruit growers are dealing with “glued canopies.” A delayed spring 2022 start due to unexpected April winter conditions, extended the growing season through late November and into early December. Then in a few days time, the autumn weather conditions shifted rapidly to winter freezing conditions. This resulted in leaves that “glued” to the trees and the abscission layer was unable to develop. In the process, much of the nutrient inventory and photosynthetic compounds in those leaves were locked inside.

Under normal conditions there would be time for the nutrients (stored in the liquid parts of the leaf cells) to translocate into the parent plant along with disassembled carotenoids, anthocyanins, flavonoids, etc. as well as the energy used to synthesize them. With this process being “short-circuited,” there is a good likelihood that spring deficiencies will happen.

Some of the worst parts of this “glued” canopy problem are:

1. There is no way to know when defoliation will be completed.

2. There is no way to be sure the leaves, when they senesce,  will stay on the farm or be blown away by the high spring winds.

3. By the time these first two factors are answered, most likely the early stages of development will be completed and it will be too late to affect the current crop. 

4. High fruit bud percentages will require more resources than are stored in the plant inventory and therefore be inadequate based on the current conditions

5. Supplementing with “plant-ready” forms of nutrients will be important this spring, both for soil nutrient supply as well as foliar applications. 

Careful nutrient management will be the smart play this year. If Washington also experiences late spring weather, like California, many of these effects could be magnified due to inadequate stored reserves, delayed soil warming and lack of soil nutrient release.  

 This year will also be an important year to collect in-season plant tissue analyses at multiple times to confirm your nutrient management practices are working and there aren’t deficiencies in early fruit development. This may be something you’ve not considered or done before, but with the cost of delivering sub-par quality crops to the packer or processor and input costs at all time high levels, how can you afford not to be more precise, in your horticultural practices? Talk with your Certified Crop Advisor for more information on how to incorporate any or all of these practices into your program this year. If you don’t get the kind of help or information you are looking for contact me. I’ve helped many growers increase productivity, and in many cases, lower input costs too. This is a year to take advantage of the gifts Nature has given, in the form of deep soil moisture and full reservoirs in California, and high fruit bud counts in Washington. But, it will require proper nutrient management in the soil and the plant, in order to produce a good quality crop. 

Here’s to your crops’ success!