Managing Post-Petal Fall Nutrition
Almond bloom has wrapped up in most areas. There has been concern surrounding bee hours, leaf wetness, and bacterial blast in all parts of the state. According to local CIMIS data, the average high temperatures for the month of February ranged from 59.4° F in Shafter to 54.9° F in Williams, with average low temperatures coming in at 48.7°F and 46.4° F, respectively. The state saw between 0.9” of precipitation in the south and a whopping 7” fall in the north during the same period. Because honey bees reportedly don’t engage in much foraging activity below 54° F, the previously mentioned concerns appear justified. However, I urge all of you to take a moment to let your mind wander back to last year’s frost scare before throwing in the towel…
There was an unprecedented frost event last year throughout the almond-growing regions. Many areas experienced lows in the low- to mid-20’s for several days during full-bloom and lacked significant improvement in the days following. Damage was visible in just about every growing region immediately following the freeze, yet the most thoughtful responses to the event were, “it’s too early to tell” or “we’ll have a better picture in May”. In the end, some regions did experience significant damage on certain varieties and fields. Some who saw damage early recorded their best crops ever. It is important to remember that almond trees produce many more flowers than actually turn into nuts. The take away message is that the textbook rules are not always hard and fast in the field and we are dealing with a living system that can be full of surprises.
Almond bloom damage, California, February 2018
In the coming weeks, as we enter full leaf expansion, the demand for available nitrogen will increase dramatically. It is estimated that around 50% of the nitrogen for this year’s crop is taken up by the tree within 80 days after bloom. Additionally, mature almond trees require 25-30 lbs N/ac to support perennial growth. Applying readily available nitrate-nitrogen today will provide the fuel to support this new growth which can pay dividends in the tree’s ability to produce photosynthates needed to support this year’s crop and future bud development. Remember, it takes time for applied nutrients to make their way from the soil, into the roots, and through the vascular system to where they are needed in the canopy. Additionally, application of foliar nutrients during this time is an important component of a comprehensive nutrient management plan to help assure the top yield. Make strategic adjustments to your soil and foliar nutrient applications in the coming months as needed; in the meantime provide the nutrition necessary for a strong foundation now.
Crop Manager, Tree Nut
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