Statewide Citrus Research and Extension

December 5, 2025

Flowering Bud Induction Advisory #1

Season Forecast: This winter and spring (2026) are predicted to bring a weak La Niña, which means Florida will experience warmer-than-normal temperatures and lower-than-normal rainfall. Drought conditions are already evident in many citrus-growing areas and are likely to persist. This makes the season challenging: warm weather will encourage bud break, while drought stress will promote flower induction. Moreover, the intermittent cold spells we are seeing add further complexity by providing additional induction hours. Overall, the greater the fluctuations between warm and cold conditions, the more likely we are to see multiple waves of bloom.

We are in for warm and dry winter weather. Under these conditions, enough hours below 68° F 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 very prolonged bloom. On the positive side if dry weather prevails during the bloom period there could potentially be lower incidence of postbloom fruit drop.

Current Condition: Currently, citrus-producing regions have moderate flower bud induction. Below is an extensive table of estimated induction hours accumulated around each FAWN station in the region. The next 10 days are predicted to be on the cooler side in most of the regions, which will be good for flower bud induction and keeping buds dormant.

Cool weather stops growth and then promotes induction of flower buds as more cool weather accumulates. A warm spell, especially with rain, can then initiate differentiation, which, after sufficient days of warm temperatures, will lead to bloom. Trees will be very vulnerable to growth stimulation by a warm period after they accumulate 300-400 hours of cool temperatures if soil moisture is adequate. 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 you 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. Management of flower bud induction is limited at the low induction level.

We are currently working on updating the old DISC website, and we apologize for any inconvenience as it may be intermittently unavailable. In the meantime, a comprehensive list of all FAWN stations along with accumulated induction hours will be published every Monday until the website becomes fully accessible to everyone.

Contact Dr. Tripti Vashisth (tvashisth@ufl.edu) for any questions or concerns.

Flowering related management considerations for HLB-affected trees:

DO NOT drought stress HLB-affected trees even though drought stress promotes flower induction and suppress vegetative growth, you should not risk current crop due to additional drought stress. Drought stress can exacerbate fruit drop. Daily, lower volume irrigations to minimize fall drought stress is suggested, especially when the weather is warm,
Flowering enhancing fertilizer to increase the number of flowers are NOT suggested for severely HLB-affected trees as they are very less likely to benefit because of 2 reasons: (1) HLB-affected trees have more dead wood therefore, there are fewer buds available to become flower, interestingly a good branch of severe HLB trees has same flowering potential as mild HLB trees. So additional flowering promoting fertilizer is not needed. (2) High twig dieback and low fruitlet retention is the main concern with severe HLB trees in regards to fruit set. Only 2% of the total flowers turn into harvestable crop therefore, pushing tree to flower more is not advisable as that is likely to waste trees’ energy and resources in extra flowers.
Gibberellic acid sprays can be used to suppress early spring flowering but the timing of application is critical for GA to be effective. GA should be applied before warm temperatures (that is before differentiation begins). Previous research on HLB-affected trees in 2017-2018 (a La Niña winter) has shown that when GA applied in fall, early flowering was suppressed. Therefore, if you have a weak crop load and are forecasted to have warm spells, GA application can be considered to suppress off season flowering.

Given the current weather conditions and forecasts, applying GA sprays to suppress early flowering is advisable. Suppressing early bloom will help synchronize flowering and improve leaf production, resulting in a better source-to-sink ratio. A stronger canopy translates to better fruit production, especially on HLB-affected trees. GA sprays also provide the added benefit of reducing pre-harvest fruit drop. However, if the fruit is intended for the fresh market, peel color can be a concern; a 2–4 month interval between the last spray and harvest is recommended. Research has consistently shown that GA applications do not affect Brix in ‘Valencia’ when this harvest interval is maintained. Do not apply GA on early and mid varieties if the crop is still present.

Do not apply GA after January 1st for flowering management.

*Date: 03-Dec-2025*
*Location*	*Induction Hours*	*Level*
Alachua	769	Moderate to High
Apopka	615	Moderate to High
Arcadia	541	Low to Moderate
Avalon	641	Moderate to High
Bapson Park	520	Low to Moderate
Balm	608	Moderate to High
Belle Glade	397	Low to Moderate
Bristol	861	Moderate to High
Bronson	756	Moderate to High
Brooksville South	706	Moderate to High
Carrabelle	816	Moderate to High
Citra	747	Moderate to High
Clweiston	443	Low to Moderate
Dade City	635	Moderate to High
DeFuniak Springs	906	High
Dover	651	Moderate to High
Fort Lauderdale	207	Low
Fort Pierce	423	Low to Moderate
Hastings	720	Moderate to High
Homestead	303	Low to Moderate
Immokalee	465	Low to Moderate
Jay	878	Moderate to High
Joshua	586	Low to Moderate
Kenansville	546	Low to Moderate
Lake Alfred	599	Low to Moderate
Lecanto	774	Moderate to High
Live Oak	834	Moderate to High
Macclenny	799	Moderate to High
Marianna	845	Moderate to High
Mayo	833	Moderate to High
Monticello	908	High
North Port	560	Low to Moderate
Ocklawaha	689	Moderate to High
Okahumpka	652	Moderate to High
Okeechobee	556	Low to Moderate
Ona	604	Moderate to High
Palmdale	502	Low to Moderate
Panama City	858	Moderate to High
Pierson	745	Moderate to High
Poinciana	642	Moderate to High
Putnam Hall	794	Moderate to High
Quincy	876	Moderate to High
Sebring	429	Low to Moderate
St. Lucie West	504	Low to Moderate
Tiger Creek	611	Moderate to High
Umatilla	647	Moderate to High
Wellington	266	Low
Yeehaw Junction	581	Low to Moderate