Citrus Flower Bud Advisory Starts for the Season

LAKE ALFRED, Fla. — The University of Florida will resume providing growers regular flower bud advisories as the critical time for citrus grove management begins this winter.

UF Institute of Food and Agricultural Sciences associate professor Tripti Vashisth restarted the advisories Nov. 21 and will continue providing them every other week through the early spring.

The advisories provide critical information about the intensity and time of citrus blooms. Growers use this information to determine when to spray for Asian citrus psyllid control as well as when to stop pesticide spraying so that pollinating bees may be moved into or placed near citrus blocks.

The flower bud advisories may be found at the UF/IFAS Citrus Research and Education Center websites at Flower Bud Induction – University of Florida, Institute of Food and Agricultural Sciences (ufl.edu) or crec.ifas.ufl.edu/flower-bud-induction.

“This is going to be a La Niña winter, which means Florida will experience temperatures warmer than normal.  Rainfall pattern, though, is not very clear but it is expected to be below average for at least until the end of the year. It is going to warmer and drier for the next few weeks. The precipitation pattern for February-March is still unclear,” said Vashisth who manages the flower bud advisory information. “Under these conditions, enough hours below 68 degrees Fahrenheit are likely to accumulate to induce an economic level of flower buds but intermediate warm periods during the winter can lead to multiple flower cohorts and a prolonged bloom.”

Flower bud advisories are driven by the Citrus Flowering Monitor which predicts date(s) when citrus trees will bloom based on observed and predicted weather patterns and other parameters (cultivar, expected yield, tree age and soil type). Growers can enter parameters specific to their grove to get a prediction. Knowing the bloom date is important for managing bloom and other related events. The Citrus Flowering Monitor also gives specific recommendations on how to manage bloom. The Citrus Flowering Monitor can be accessed from the advisory page or directly at: http://disc.ifas.ufl.edu/bloom

This year flowering can be unpredictable not only because of the upcoming weather conditions but also because of hurricanes Ian and Nicole. Trees lost a significant number of leaves and fruit and endured high speed wind and rain, thus, increasing the stress level on trees. Fruit presence on the tree interrupts flower bud induction, therefore, with fruit loss one can expect to see early flowering. However, the significant leaf loss that has happened in last month also plays a major role in upcoming flowering. Due to significant leaf loss most of the trees are flushing, therefore utilizing the carbohydrate resources thus reduction in carbohydrate level may reduce overall flowering. Under these circumstances and the current weather condition, Vashisth does not expect to see a significant early flowering to happen though she expects to see two to three cohorts of flowering. The situation will become clearer in the next couple of weeks as cooler temperatures are expected.

Keep track of induction hours in your area and watch for projected warm periods from the weather services. Normal healthy trees could have their induction boosted by applying some drought stress. Unfortunately, with vulnerable root systems associated with HLB, growers shouldn’t risk heavier preharvest fruit drop of the current crop by using water stress to prevent unwanted early vegetative growth and enhance induction of flowers. Based on weather predictions, if you are concerned about early flowering in your region, a gibberellic acid (GA) application can prevent some early flowering. There are many things to consider when using GA.  Please see the flower bud website for additional information before using GA Flower Bud Induction – University of Florida, Institute of Food and Agricultural Sciences (ufl.edu) or crec.ifas.ufl.edu/flower-bud-induction.

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The mission of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) is to develop knowledge relevant to agricultural, human and natural resources and to make that knowledge available to sustain and enhance the quality of human life. With more than a dozen research facilities, 67 county Extension offices, and award-winning students and faculty in the U.F. College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions to the state’s agricultural and natural resources industries, and all Florida residents.

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