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Flower Bud Induction Overview and Advisory

NOTICE FOR CITRUS EXTENSION AGENTS & SPECIALISTS AND GROWER NEWSLETTERS
The following information has been developed as part of the Decision Information System for Citrus

L.  Gene Albrigo, Horticulturist Emeritus
Citrus Research & Education Center, Lake Alfred, FL

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11/06/2003

FLOWER BUD INDUCTION ADVISORY #1 for 2003-2004-11/6/03

NOTICE FOR CITRUS EXTENSION AGENTS & SPECIALISTS AND GROWER NEWSLETTERS 
The following information has been developed as part of the Decision Information System for Citrus. 
L. Gene Albrigo, Horticulturist 
Citrus Research & Education Center, Lake Alfred, FL 

Overview of flower bud induction in Florida –  It is time to start following citrus flower bud induction conditions for the coming year's bloom. Low temperatures first stop growth and then promote induction of flower buds as more hours of low temperatures accumulate. A period of 5-12 days of high temperatures in winter can then initiate bud differentiation which after sufficient days of warm springtime temperatures leads to bloom. The meteorologists predict that this winter in Florida will be slightly warmer than normal, an ENSO Neutral year. If this winter is only slightly warmer than normal, enough hours of low temperatures below 68 degrees F. should accumulate to induce adequate flower buds for a satisfactory crop. Sufficient flower bud induction under Florida conditions should be achieved when total uninterrupted, accumulated hours of low temperatures exceed 850 hours below 68 degrees F. if the current crop is heavy. If the crop load is light, sufficient flower bud induction can occur after 750 hours of accumulated low temperatures. A warm period of 7 to 12 days with max. temperatures > 70 to 75 degrees F. after some low temperatures have accumulated can trigger growth (bud swelling). Fewer days of higher temperatures (> 80 degrees F.) are required to stimulate growth. Current and previous seasons weather information is available on the Florida Automated Weather System fawn.ifas.ufl.edu for locations near you.. The 8 day forecast from the National Weather Service predicts Florida weather for several sites around the citrus belt and is linked to http://www.crec.ifas.ufl.edu/crechome/crecweather.shtml

Some flower buds will be induced in the range of 300 to 600 accumulated hrs < 68 degrees F. Warm events after these levels of induction are reached result in weak flowering intensity, and therefore many buds remain that can be induced by later cool periods. This scenario results in multiple blooms. When early winter bud break in Florida was not prevented by cool temperatures or drought stress (1963 to 2002 records), multiple blooms occurred in over half of the years. Historically, the time period in which a warm 7-12 day period can lead to some bud growth and then result in multiple blooms is roughly Thanksgiving to Christmas. Presently, the only management tool available to eliminate or reduce the chance of multiple blooms is to promote water stress by stopping irrigation before these predicted warm periods occur. If the warm periods(s) are of the typical 7 to 10 day duration, mild water stress will have little impact on current crop development or quality. Mild water stress may be interpreted as leaf wilt observed by 10 or 11 am, but leaves recovering by early the next morning. If no rains interrupt a mild stress condition of citrus trees, buds will not grow in response to high temperatures. If an extended warm period has passed, trees again can be watered to minimize current crop water stress. Although no weather prediction is guaranteed, rains in the winter usually come on the fronts of cool periods. Therefore, the chances of being able to use water stress to prevent an early flower bud differentiation event is reasonably good for most warm periods. A difficulty that occurred 2 years ago, which resulted in a very small crop, was that high temperatures were continuous through the fall until December 18 th . If trees were allowed be water stressed for this extended period, this could lead to low photosynthesis, little fruit growth or sugar accumulation and probably excessive fruit drop.

In the shallow soils of bedded groves, it is relatively easy to create sufficient water stress to suppress growth by withholding irrigation for a few days if no rains occur. In deeper sandy soils, 2 or more weeks without irrigation or rainfall may be required. To minimize the time required for soil to dry sufficiently to initiate water stress, the soil should be allowed to dry out by mid-November so that trees show wilt by mid-day. For bedded groves, minimum irrigation can then be applied at low rates as needed until a weather prediction indicates a warm period is expected. At this time, irrigation should be shut down. For deep sands, the soil needs to be dried out and kept nearly dry below 6 to 8 inches of depth until at least Christmas so that no growth can occur. Minimum irrigations that re-wet perhaps the top 6 inches of the root zone may minimize excessive drought, while allowing quick return to a water stress condition if a high temperature period is forecast. This may be risky for ‘Hamlin' or other early maturing cultivars not yet harvested that tend to drop fruit near harvest. Much of what has been stated above has now been incorporated into a ‘Flowering Expert System for Florida Citrus'. Future advisories (usually weekly) will update accumulating hours of related temperatures and other weather effects on flower bud induction plus methods for enhancing or reducing flowering intensity as conditions and cultivars dictate. Read the archived advisories from previous years for more background.

1999-2000_bloom (Figure 1, with added infrmation in color or bold lettering, is from the ‘Flowering Expert System for Florida Citrus'and represents the different aspects of apparent flower induction. The level of potential flowering would be greater (orange line) with a light crop or less (green line) with a heavy crop for the same amount of hours of induction. This system will be tested again this winter with several growers that helped us refin the system last year.)

Last year's results - Last year (2003-2003) by late December we had 850 hours of uninterrupted cool inductive temperatures with a low current crop on the trees. The following warm period initiated almost all the buds on all of the spring and summer flush to differentiate and bloom in early March. We had a fairly leafy bloom of very short duration (slightly more than 2 weeks ). A strong spring flush of leaves may have out competed and suppressed fruit set in navels and grapefruit. In spite of the high temperatures during and following bloom, a good fruit set occurred in other round oranges resulting in the highest crop forecast for Florida that FASS has ever predicted. A good rainfall pattern through the spring and summer allowed the fruit to size better than would be expected for such a large number of fruit. The early March bloom and subsequent warm, wet weather have advanced maturity to result in low juice content (early cultivars are drying out at stem end) with low solids and acidity. Poorer than average fruit quality will make this another difficult year to schedule harvests to get good fresh fruit quality and high yields of solids with moderate ratios for processing.

The new season's situation - In spite of the heavy current crop, most groves had a surprising amount of vegetative flush, particularly spring flush. The strong flush is good for available buds to become flower buds next year. There have to be sufficient buds available to induce in order to have a good crop. Since we have a large current crop, we will need higher accumulations of low temperatures to induce those buds to produce flowers. So far this Fall, little cool weather has occurred to slow down or stop vegetative growth on mature trees, only about 100 to 120 hr < 68 degrees F. in all districts. Also, the National Weather Service (NOAA) predicts that there will be almost no temperatures below < 68 degrees F. during the next 8 days. To view FAWN data for a location near you in the citrus growing areas, use ( www.crec.ifas.ufl.edu ) and click on FAWN or for NOAA's 8 day forecast go to Weather in the homepage graphic locator and 8 day forecast.

The major concern for the next 60 days is the possibility of 1) continuous warm weather that will push vegetative buds to grow as occurred 2 years ago or 2) a warm period with a minimum of 10 to 12 days with max. temperatures > 75 to 80 degrees F following an inductive period of 300 to 500 hrs < 68 degrees F that will initiate differentiation of easily induced flower buds. The first condition will lead to low flowering and the second to multiple blooms. Therefore, keep irrigation amounts low to moderate (if fruit are still present) to minimize growth possibilities, even though a heavy crop should help minimize vegetative growth potential. Keep groves relatively dry and watch for the next advisory.

(Request for potential cooperators) - I believe that we may help our recent problems of low solids and acids for processed oranges and fresh grapefruit by delaying bloom dates each year. This might be accomplished by using water stress to prevent growth during warm winter periods until mid-January has passed. If you are interested in putting a block or a few rows of grapefruit, ‘Hamlin' or ‘Valencia' trees under this protocol, please let me know ( albrigo@crec.ifas.ufl.edu or phone 863-956-1151).



11/14/2003

FLOWER BUD INDUCTION ADVISORY #2 for 2003-2004-11/14/03

NOTICE FOR CITRUS EXTENSION AGENTS & SPECIALISTS AND GROWER NEWSLETTERS 
The following information has been developed as part of the Decision Information System for Citrus. 
L. Gene Albrigo, Horticulturist
Citrus Research & Education Center, Lake Alfred, FL

Other websites for information related to flower bud induction in Florida -The 8 day forecast from the National Weather Service predicts Florida weather for several sites around the citrus belt and is linked to http://www.crec.ifas.ufl.edu/crechome/crecweather.shtml . Use (www.crec.ifas.ufl.edu ) and click on FAWN to get up-to-date accumulated low temperatures for a site near you. Look at hrs<65 degrees F for a good idea of accumulated effective temperatures.

The current situation - Finally some cool climate with low temperatures in the flower bud induction range. FAWN records indicate that 100 to 200 hrs < 68 degrees F have accumulate from Ft. Pierce to northern districts, respectively. The 8 day forecast from NOAA indicates that another 80 hours will be accumulated this coming week, bringing our totals to about 200 to 300 hours depending on location. Temperatures are predicted to be lower by the end of next week. Some flower buds will be induced in the range of 300 to 600 accumulated hrs < 68 degrees F. Warm events at these levels of induction result in weak flowering intensity, and therefore many buds remain that can be induced by later cool periods. This scenario results in multiple blooms. Therefore, it will be important to follow the 8 day forecasts closely from this point forward in order to anticipate any warm weather events that could stimulate bud growth.

The only management tool available this early in the season to eliminate or reduce the chance of multiple blooms is to promote water stress by stopping irrigation before these predicted warm periods occur. Now that cool weather has started, mild water stress during warm periods of the typical 7 to 10 day duration will have little impact on current crop development or quality. Mild water stress may be interpreted as leaf wilt observed by 10 or 11 am, but leaves recovering by early the next morning. If no rains interrupt a mild stress condition of citrus trees, buds will not grow in response to high temperatures. If an extended warm period has passed, trees again can be watered to minimize current crop water stress. In the shallow soils of bedded groves, it is relatively easy to create sufficient water stress to suppress growth by withholding irrigation for a few days if no rains occur. In deeper sandy soils, 2 or more weeks without irrigation or rainfall may be required. To minimize the time required for soil to dry sufficiently to initiate water stress, the soil should be allowed to dry down now so that trees show wilt by mid-day. For bedded groves, minimum irrigation at low rates can then be applied more frequently until a weather prediction indicates a warm period is expected. At this time, irrigation should be shut down. For deep sands, the soil needs to be dried out and kept nearly dry below 6 to 8 inches of depth until at least Christmas so that no growth can occur. Minimum irrigations that re-wet perhaps the top 6-8 inches of the root zone may minimize excessive drought, while allowing quick return to a water stress condition if a high temperature period is forecast. In bedded groves, maintaining a fairly high water table (bottom of water furrow) may also be sufficient to minimize the severity of water stress from shutting down irrigation. Therefore, keep irrigation amounts low to moderate (if fruit are still present) to minimize growth possibilities, even though the current heavy crop should help minimize vegetative growth potential. This will allow you to quickly bring about sufficient water stress to stop any bud development should a warm spell be predicted.

Due to a trip next week, a new advisory may not be posted until the Monday, November 24th . Be sure to follow the 8 day forecasts until then.

(Request for potential cooperators) - To improve the situation that may have led to the recent problems of low solids and acids for processed oranges and fresh grapefruit, it may help to delay bloom dates each year. This might be accomplished by using water stress to prevent growth during warm winter periods until at least mid-January has passed. This will delay bloom and then it should delay maturation so that we do not get the rapid decline in acidity and juice content in the Fall. This delay may allow enough time for sugars to accumulate before ratios get too high. If you are interested in putting a block or a few rows of grapefruit or orange trees under this protocol, please let me know (albrigo@crec.ifas.ufl.edu or phone 863-956-1151). There have been two offers to participate in this study from South Florida growers. I am still looking for East Coast and Ridge growers interested in participating.


11/22/2003

FLOWER BUD INDUCTION ADVISORY #3 for 2003-2004-11/22/03

With last weeks weather, we now have 200 to 300 hours of accumulated hours below 68 degrees F. From southern to northern districts, respectively. The next week will be relatively cool according to the NOAA 8 day forecast. This should result in at least another 80 hours of temperatures in the induction range. This should bring all areas to near 300 hours or higher. From that point onward, a warm period is more likely to initiate some bud growth. Any warm periods in the 8 day forecast after this coming week will indicate that it is advisable to stop irrigation to order to induce some water stress. That concern and irrigation procedure should be continued at least until Christmas or New Years.

Remember that with the heavy crop on most trees, it will take higher levels of induction this year to provide good flowering and initiation of differentiation should be delayed until the new year. Until then, keep your eyes on the weather for warm spells.

If you have any suggestions or questions, please contact me (albrigo@ufl.edu)


12/1/2003

FLOWER BUD INDUCTION ADVISORY #4 for 2003-2004-12/1/03

This is a service to our citrus growers posted on the CREC website. The indicated Expert System on intensity and time of bloom can be accessed at the designated Web Site: http://disc.ifas.ufl.edu/bloom

Current Status:  For those following the accumulated hours on the FAWN site, there are some discrepencies in the data, particularly for the Umitilla site. Rely on the Tavares site for now. Some daily data has negative signs also.

We now have 260 to 400 hours of accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next week also will be cool . This should result in at least another 84-96 hours of temperatures in the induction range. This should bring all areas to 350 to 500 hours of inductive temperatures. From that point onward, a warm period is more likely to initiate some bud growth.

Any warm periods in the 8 day forecast from now on will indicate that it is advisable to stop irrigation in order to induce some water stress. This procedure to create water stress if a warm spell is indicated in the forecast should be continued at least until Christmas or New Years. It is a good idea to look at the 8-day forecast at least every-other day.

If these cool temperatures continue for two more weeks, some areas may have reached 600 hours of inductive temperatures. That will be the first time to consider using urea or PO3 sprays at the beginning of a warm period to enhance flowering and trigger an early bloom and perhaps obtain earlier maturation. Check last years advisories (below) for general procedures for using flower enhancing sprays.

Remember that with the heavy crop on most trees, it will take higher levels of induction this year to provide good flowering and in general initiation of differentiation should be delayed until the new year or in the 800 or more hour range. Until then, keep your eyes on the weather for predicted warm periods.

If you have any questions, please contact me (albrigo@ufl.edu)


12/8/2003

FLOWER BUD INDUCTION ADVISORY #5 for 2003-2004-12/8/03

We now have 360 to 460 hours of accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next week also will be cool with most temperatures below 68 degrees F. This should result in at least another 100 - 140 hours of temperatures in the induction range, although the flowering program only projects an additional 85-83 hrs. This should bring all areas to 500 to 600 hours of inductive temperatures. From December 15 th onward, a warm period is most likely to initiate some bud growth if there is adequate soil moisture for growth.

Any warm periods in the 8 day forecast from now until after New Year's day will indicate that it is advisable to stop irrigation in order to induce some water stress. Irrigation should be minimal (see previous advisories) in order to maintain fruit condition or photosynthesis, but without irrigating the full rooting depth. This will allow rapid creation of water stress if a warm period is forecast and it hasn't rained recently. This procedure to create water stress if a warm period is indicated in the forecast should be continued at least until Christmas or New Years. It is a good idea to look at the 8-day forecast at least every-other day.

If these cool temperatures continue for two more weeks, some areas may have reached 700 to 800 hours of inductive temperatures. That will be the first time to consider using urea or PO 3 sprays at the beginning of a warm period to enhance flowering and trigger an early bloom and perhaps obtain earlier maturation. If you choose to use one of these sprays, urea should be applied at 25 to 28 lbs N per acre in 10-15 (aerial with good spray distributors), 25-30 (ultra low volume), or 50-125 (speed sprayer) gal/ac of water. Speed sprayers can be calibrated for as little as 50 or 60 gal/ac at 4-5 mph if large acreage needs to be covered. High speeds do increase risk of operator driving error. Phosphorous acid should be applied at the equivalent of 2.6 quarts of 26-28 % P product in similar gal/ac as recommended for urea sprays. If you plan to use any of these sprays, be sure you get the product on hand now. If you don't use it for the winter sprays, you can incorporate the products in either bloom or post-bloom sprays.

Remember that with the heavy crop on most trees, it will take higher levels of induction this year to provide good flowering and in general initiation of differentiation should be delayed if possible until the New Year or in the 800 or more hour range. Until then, keep your eyes on the weather for predicted warm periods.

If you have any questions, please contact me (albrigo@ufl.edu)


12/15/2003

FLOWER BUD INDUCTION ADVISORY #6 for 2003-2004-12/15/03

I have some good news, bad news, good news, bad news, and finally good news for all of you this morning. The first good news is that it rained Sunday to give us good soil moisture levels for maintenance of the current crop essentially everywhere in the citrus growing areas of Florida. The bad news is also that it rained everywhere and the citrus tree buds will start to grow if warm weather occurs in the near future, and we don't have adequate levels of flower bud induction yet considering the heavy current crop. The good news is that cool weather is still projected for the next 8 days. More bad-good news is that Wednesday may bring more rain, but cool weather will probably continue. Also good news, our citrus trees should have reasonable cold hardiness going into the high probability freeze period that lasts until mid-January.

We now have 475 to 680 hours of accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next week will be cool with almost all temperatures below 68 degrees F. This should result in at least another 130 - 160 hours of temperatures in the induction range, although the flowering program only projects an additional 120 hrs. This should bring all areas to at least 600 to 800 hours of inductive temperatures by December 22 nd . From December 22 nd to January 5 th , a warm period is most likely to initiate some bud growth as adequate soil moisture is available for growth, and it will probably take that long for the trees to use up the available soil moisture so that water stress can occur if a warm period occurs. If we get to January without a warm period and you wish to delay initiation of flowering after the first week of January, irrigation should be minimal, after the current soil moisture is used. This will allow rapid creation of water stress if a warm period is forecast in early to mid-January and it hasn't rained recently. This procedure to create water stress, if a warm period is indicated in the forecast, can be continued until late January. If this procedure can be applied successfully, it should result in a later bloom. Keep watching the 8-day forecasts for indication of a possible warm period and any freeze warnings.

If a warm period occurs before New Year's, all districts should have no more than 700 to 900 accumulated hours below 68 degrees F when buds are initiated to grow. Because of the heavy crop on most trees, it may be advisable to consider using urea or PO 3 sprays just before and at the beginning of such a warm period to enhance flowering. A fairly early bloom is likely to occur under this late December warm period senerio, but the trees will most likely start the flowering process whether you spray or not. It is not a good idea to spray these products during a cold period as forecast for the next 8 days. Very low uptake occurs during cold weather. If you choose to use one of these sprays when temperatures get warmer (daytime highs in the 70s), urea should be applied at 25 to 28 lbs N per acre in 10-15 (aerial with good spray distributors), 25-30 (ultra low volume), or 50-125 (speed sprayer) gal/ac of water. Speed sprayers can be calibrated for as little as 50 or 60 gal/ac at 4-5 mph if large acreage needs to be covered. High speeds do increase risk of operator driving error. Phosphorous acid should be applied at the equivalent of 2.6 quarts of 26-28 % P product in similar gal/ac as recommended for urea sprays. If you plan to use any of these sprays, be sure you have the product on hand. If you stock and don't use these materials for the winter sprays, you can incorporate the products in either bloom or post-bloom sprays.

Until next week, keep your eyes on the weather for predicted warm periods and best wishes with all the Christmas shopping we haven't finished yet.

If you have any questions, please contact me (albrigo@ufl.edu).


12/22/2003

FLOWER BUD INDUCTION ADVISORY #7 for 2003-2004-12/22/03

This week's advisory has more questions than answers. This is a transition week with the potential for accumulated cool hours to go from moderate to high levels or for trees to start initiation of lower bud differentiation if mid-seventy degree daytime highs continue through the week. Southern areas are particularly in question as to what the trees will decide to do.

We now have 600 to 800 hours of accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next week again will be cool, but daytime highs will be lower 70 to mid 70 degrees F. This should result in at least another 70 to 80 hours of temperatures in the induction range, the flowering program projects an additional 75-85 hrs. This should bring all areas to at least 700 to 900 hours of inductive temperatures by December 29 th . Any time a warm period occurs now, initiation of differentiation (growth) of many of the available buds is likely as long as adequate soil moisture is available for growth. It will probably take at least another week or 10 days for the trees to use up the available soil moisture so that water stress can occur if a warm period occurs.

Are the next 4 or 5 days the beginning of a warm period that can trigger initiation of flower bud differentiation? Predicted highs of mid 70s for 3 or 4 days may not be enough to trigger growth considering the heavy crop load on most trees. I don't know yet if the warm period will extend long enough to start bud development, but it is possible and may be a reasonable time to boost flowering and probably initiate bud development by spraying urea or PO3. Most locations have too much soil moisture to prevent growth if the warm trend continues. This warming trend may be most critical in southern areas, as temperatures are usually a few degrees higher than the central and northern regions.

If a sufficient warm period does occur before New Year's, all districts should have no more than 750 to 830 accumulated hours below 68 degrees F when buds are initiated to grow. Because of the heavy crop on most trees, it may be advisable to consider using urea or PO 3 sprays just before and at the beginning of such a warm period to enhance flowering in those trees. A fairly early bloom is likely to occur under this late December warm period scenario, but the trees will most likely start the flowering process whether you spray or not if warm temperatures continue. It is not a good idea to spray these products during a cold period but the current forecast indicates that daytime highs will be in the 70s for the next few days. Very low uptake occurs during cold weather. If you choose to use one of these sprays now as temperatures get warmer (daytime highs in the 70s), I would wait until the possible rain front predicted for Tuesday night-Wednesday goes through. Then urea should be applied at 25 to 28 lbs N per acre in 10-15 (aerial with good spray distributors), 25-30 (ultra low volume), or 50-125 (speed sprayer) gal/ac of water. Speed sprayers can be calibrated for as little as 50 or 60 gal/ac at 4-5 mph if large acreage needs to be covered. High speeds do increase risk of operator driving error. Alternatively, phosphorous acid (PO3) should be applied at the equivalent of 2.6 quarts of 26-28 % P product in similar gal/ac as recommended for urea sprays. If you plan to use either of these sprays, you should have the product on hand by now. You can incorporate the products in either bloom or post-bloom sprays if you don't use it now.

We have now reached the stage where navel trees with a light crop, most navel trees this year, are likely to have excessive flowers induced. These flowers will be weak and face excessive competition from one another. One way to minimize this effect is to apply a gibberellin spray when a warm spell occurs (EDIS - Enhancing Cropping of Low-Yielding, Heavily Flowering Citrus by Reducing Floral Initiation Ed Stover and Gene Albrigo; EDIS publ. # HP 799). If this period of warm temperatures looks like it will continue through the week, allow 3 or 4 days of the warm spell to occur before spraying to moderate the effect. A spray of 20 oz. GA per acre is recommended in at least 100 to 125 gal / acre.

Alternative (IF) scenario : If this week's warm weather is not sufficient (stops by Christmas day), we can get into January without initiation of flower bud differentiation. If we don't have much rain on Tuesday-Wednesday, we can re-impose water stress for an early January warm period by withholding irrigation. This procedure to create water stress, if and when another warm period is indicated in the forecast, can be continued until late January. If this procedure can be applied successfully, it should result in a later bloom. Keep watching the 8-day forecasts for indication of a continuation of the predicted warm period, a possible downturn in temperatures and anything else you might wish to hope for on Christmas.


12/29/2003

FLOWER BUD INDUCTION ADVISORY #8 for 2003-2004-12/29/03

We now have 750 to 830 accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next week will have highs in the upper 70s to 80 degrees F. This should result in 85 hours of temperatures in the induction range, and should bring all areas to 830 to 1000 hours of inductive temperatures by January 4th. This induction level should be high enough to result in a reasonable level of flowering, particularly if urea or PO3 is sprayed during the current moderate warm period.

It appears to me that the continued highs of near 80, especially in the southern region, may be sufficient to initiate differentiation (growth) of many of the available buds if soil moisture has not been depleted to the point that afternoon wilt occurs. If soil moisture does appear to be in the wilt range, continuing without irrigation or deficit irrigation should delay initiation of flower development. This procedure to maintain water stress can be continued until mid January by applying minimal irrigation. Keep watching the 8-day forecasts for indication of the continuation of this moderate warm period or cooler weather that will allow moderate irrigation.

However, if no signs of water stress are evident or you have continued to irrigate, then bud development is likely to start within a week if these moderately warm temperatures continue. Because of the heavy crop on most trees, it is advisable to consider using urea or PO 3 sprays over the next 7 to 10 days. A fairly early bloom is likely to occur under this late December warm period, but the trees will most likely start the flowering process whether you spray or not if soil moisture is adequate for growth. Reasonable uptake of these spray products should occur based on the temperatures forecast for the next 8 days. If you choose to use one of these sprays, urea should be applied at 25 to 28 lbs N per acre in 10-15 (aerial with good spray distributors), 25-30 (ultra low volume), or 50-125 (speed sprayer) gal/ac of water. Speed sprayers can be calibrated for as little as 50 or 60 gal/ac at 4-5 mph if large acreage needs to be covered. High speeds do increase risk of operator driving error. Phosphorous acid should be applied at the equivalent of 2.6 quarts of 26-28 % P product in similar gal/ac as recommended for urea sprays.

Navel trees with a light crop, most navel trees, are now likely to have excessive flowers induced. These flowers will be weak and face excessive competition from one another. One way to minimize this effect is to apply a gibberellin spray once the next warm spell occurs ( EDIS - Enhancing Cropping of Low-Yielding, Heavily Flowering Citrus by Reducing Floral Initiation Ed Stover and Gene Albrigo; EDIS publ. # HP 799). Allow 3 or 4 more days of this warm period to occur before spraying to moderate the effect. A spray of 20 oz. GA per acre is recommended in 125 to 150 gal / acre.

If I receive an update on soil moisture situation in South Florida, I will post an advisory update tomorrow or the next day as to whether trees are more likely or less likely to initiate flower bud growth in the next week. Watch the weather! I hope you had a Merry Christmas and best of luck with a Happy New Year.

If you have any questions, please contact me (albrigo@ufl.edu)


1/12/2004

FLOWER BUD INDUCTION ADVISORY #10 for 2003-2004-1/12/04

We now have 980 to 1200 accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the weather next week will provide 70 to 120 more hours of inductive temperatures with warm days (mid 70s) starting Thursday to Saturday from southern to northern districts, respectively. This should result in all areas being over 1000 hours of inductive temperatures by January 18th.

The flowering model indicates that trees in all areas have started differentiation of flower buds for the first wave of flowers this coming Spring. Initiation dates for flower bud differentiation were December 22-23 for most districts and December 29 th for the Indian River District. These initiations of growth started after 780 to 880 hours of inductive temperatures. Bloom dates for this wave of flowers are now predicted to be March 3 to 6, with Ft. Pierce being the later date. We have now checked buds on some well watered navel and Valencia trees at Ft. Pierce and a few first and second leaf axis buds are swelling or even have a leaf tip showing, but fewer than reported last week at Lake Alfred.

Since induction hours were in the 800 range, this should be a major bloom with any secondary bloom of smaller magnitude, but due to the heavy current crop the next bloom wave could still contain a fairly large number of flowers. With the projected additional hours below 68 degrees F. this week, about 320 to 440 hours will be added to induction for the second bloom wave. This should put most trees into an acceptable induction range for total flowers, even though they may come in two waves. According to the flowering model, some districts already have a second initiation of differentiation with a predicted bloom date of March 13. If correct, this flowering wave should be small and appear as part of the first wave since they are only 10 days apart.

If soil moisture was maintained in the deficit range during the late December warm period, trees may have only one flowering event triggered during the next warm period, if soil moisture is adequate at that time. A later date of initiation may be obtained if soil moisture was low during the late December warm period, and a low to deficit soil moisture condition is maintained until late January. The only FAWN station in the citrus area reporting any significant rain this past week was Lake Alfred with 0.34 inches (January 9-10). Trees in this area may use sufficient soil moisture to return soils to a deficit condition before another prolonged warm period occurs. Unfortunately, many of us put a shallow irrigation on early last week so that after the rain more of the root zone is wet in the Central Florida area than desirable for deficit irrigation management.

If some blocks have a very heavy crop and you were not able to get to a soil moisture deficit condition (no wilt by noon during last warm period), a flower enhancing spray of urea or PO 3 may be beneficial at the end of the current cool period to boost the second wave of flower initiation. Look with a hand lens at the first two buds at the terminal ends of 10 to 15 spring and summer shoots to see if some of them are swollen. If some are swollen, you did not stop initiation with any attempt at deficit irrigation. If you choose to use one of these sprays, urea should be applied at 25 to 28 lbs N per acre in 10-15 (aerial with good spray distributors), 25-30 (ultra low volume), or 50-125 (speed sprayer) gal/ac of water. Speed sprayers can be calibrated for as little as 50 or 60 gal/ac at 4-5 mph if large acreage needs to be covered. High speeds do increase risk of operator driving error. Phosphorous acid should be applied at the equivalent of 2.6 quarts of 26-28 % P product in similar gal/ac as recommended for urea sprays. Remember that temperatures should be in the low 70s or higher on days you spray to get good uptake.

Navel trees with a light crop, most navel trees this year, are now likely to have excessive flowers induced and 2 waves of flowers in the Spring. These flowers will be weak and face excessive competition from one another, plus an increased potential for post-bloom fruit drop due to multiple blooms, if Spring rains occur. One way to minimize this effect is to apply a gibberellin (GA) spray towards the end of this warm period ( EDIS - Enhancing Cropping of Low-Yielding, Heavily Flowering Citrus by Reducing Floral Initiation Ed Stover and Gene Albrigo; EDIS publ. # HP 799). A spray of 20 oz. GA per acre in 125 to 150 gal / acre can be applied for decreasing flowering of navels, other seedless cultivars and poorly setting Rhode Red strains. If you did not spray a block already, some benefit will likely come from spraying when temperatures reach the mid 70s later this week. This should block any new induction that has occurred and perhaps still diminish the number of flowers in the first wave of flower induction now projected to reach full bloom in early March.

If you have any questions, please contact me (albrigo@ufl.edu)


1/19/2004

FLOWER BUD INDUCTION ADVISORY #11 for 2003-2004-1/19/04

We now have 1100 to 1330 accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the weather next week will provide 130 more hours of inductive temperatures with daytime highs of 63 to 70 starting tomorrow, Tuesday, and continuing until Saturday. The warmer temperatures will be in southern areas but still only slightly higher than the 68 degree F. threshold for flower bud induction. This should result in all areas being over 1220 hours of inductive temperatures by January 24 th , when a warm period may occur since daytime highs are predicted to be 72 to 76 degrees F. for all areas on the weekend. If that warm trend this weekend continues for another 3 or 4 days next week, all potential flower buds will probably initiate growth if they have not already done so.

The flowering model indicates that trees in all areas have started differentiation of flower buds for two waves of flowers this coming Spring. Initiation dates for the first wave of flower bud differentiation were December 22-23 for most districts and December 29 th for the Indian River District. This growth started after 760 to 840 hours of inductive temperatures. Bloom dates for this wave of flowers are now predicted to be March 1 to 5, with Ft. Pierce being the latest date. As stated last week, the first wave of initiation has been confirmed by detecting swollen buds. A second wave of flower bud initiation also started in all districts January 2 to 9 th for northern to southern districts, respectively. These events occurred when accumulated inductive hours were 1000 to 915 hours from north to south and the projected bloom dates are March 12 th to 18 th from north to south.

Since induction hours were in the 900 plus range by the second initiation, a majority of potential flower buds should now be induced and growing. With the additional hours below 68 degrees F. expected be 320 to 470 hours by this coming weekend, a third initiation should account for all potential flower buds. This should put all trees into an acceptable induction range for total flowers, even though they may come in a prolonged bloom.

Some growers may have successfully managed to maintain soil moisture at a low level until this weekend and will see one heavy and concise bloom from one major initiation of differentiation after this current cool period. All areas report 0.7 to 1.8 inches of rain on Sunday, January 18 th , and more rain is expected today. With the projected warm period starting next Saturday, all remaining buds that can be initiated to develop as flower buds should be. I guess the bloom date for this wave will be about March 24 th . The Citrus Flowering Monitor System should predict a more accurate date of bloom later next week if the warm period continues until mid-week.

If no urea or PO3 spray was applied earlier, it is very doubtful that any benefit will come from its application now that accumulated low temperature induction levels are so high. It would be better to save any left over material for a bloom or post bloom spray.

Navel trees will have excessive flowers induced and at least 2 waves of flowers in the Spring if low soil moisture levels were not obtained during earlier warm periods. These flowers will be weak and face excessive competition from one another, plus an increased potential for post-bloom fruit drop due to multiple blooms, if Spring rains occur. If you have not done so yet, one way to minimize this effect is to apply a gibberellin (GA) spray towards the end of this coming warm period ( EDIS - Enhancing Cropping of Low-Yielding, Heavily Flowering Citrus by Reducing Floral Initiation Ed Stover and Gene Albrigo; EDIS publ. # HP 799). A spray of 20 oz. GA per acre in 125 to 150 gal / acre can be applied for decreasing flowering of navels, other seedless cultivars and poorly setting Rhode Red strains. Spray later next week if temperatures continue to be in the low to mid 70s or higher. This should block any new induction that has occurred since the last warm period earlier in January and perhaps still diminish the number of flowers in the second wave of flower induction now projected to reach full bloom in mid-March.

Watch the weather and the flower buds as they both develop.

If you have any questions, please contact me (albrigo@ufl.edu)


1/26/2004

FLOWER BUD INDUCTION ADVISORY #12 for 2003-2004-1/26/04

We now have over 1250-1450 accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the weather this week will provide 100 more hours of inductive temperatures with daytime highs of 80 to 73 today and tomorrow followed by 2 to 3 cool days and then back in the mid-70s for the rest of the week. This should put all areas above 1300 hours as the last potential wave of flower buds is initiated to differentiate, if any potential flower buds still remain uninitiated.

The flowering model indicates that trees in all areas have started differentiation of flower buds for two waves of flowers this coming Spring. For the Immokalee area, three initiation dates are indicated with bloom dates of March 2, 13 and 22 for the three waves. In other areas from coastal southern to northern, bloom dates for the first wave of flowers are now predicted to be March 5 to 1. The second initiation wave of flower bud differentiation has projected bloom dates of March 18 th to 12 th from south to north.

Since induction hours are now in excess of 1250 hours and warm temperatures are happening and expected to continue most of this week, we can expect that all potential flower buds are probably going to initiate growth this week. If all 3 waves occur, then we will have a prolonged bloom period through most of March. If you successfully created water stress from late December to mid-January, then you should get a peak bloom date of 22 to 25 March according to the model. We can expect a fair bloom on trees that produced a reasonable amount of new Spring and Summer flush last year. We will assess the impact of the heavy current crop on flowering and fruit set in a later advisory.

If no urea or PO3 spray was applied earlier, it is very doubtful that any benefit will come from its application now that accumulated low temperature induction levels are so high. It would be better to save any left over material for a bloom or post bloom spray. We will test this timing to see if it is correct that little benefit will come from an application this late in the flower bud induction-initiation of differentiation process.

Navel trees will have excessive flowers induced and at least 2 waves of flowers in the Spring if low soil moisture levels were not obtained during earlier warm periods. These flowers will be weak and face excessive competition from one another, plus an increased potential for post-bloom fruit drop due to multiple blooms, if Spring rains occur. If you have not done so yet, one way to minimize this effect is to apply a gibberellin (GA) spray this week while temperatures are warm enough to get good uptake (low to mid 70s or higher so avoid Tuesday or Wednesday this week) ( EDIS - Enhancing Cropping of Low-Yielding, Heavily Flowering Citrus by Reducing Floral Initiation Ed Stover and Gene Albrigo; EDIS publ. # HP 799). A spray of 20 oz. GA per acre in 125 to 150 gal / acre can be applied for decreasing flowering of navels, other seedless cultivars and poorly setting Rhode Red strains. This should block any new induction that has occurred since the last warm period earlier in January and perhaps still diminish the number of flowers in the second wave of flower induction now projected to reach full bloom in mid-March.

If you have any questions, please contact me (albrigo@ufl.edu)


2/2/2004

FLOWER BUD INDUCTION ADVISORY #13 for 2003-2004-2/2/04

We now have 1250 to 1600 accumulated hours below 68 degrees F. from southern-coastal to northern districts, respectively. According to the NOAA 8 day forecast, the next 5 days will be at least in the mid to high 70s and probably the low 80s in southern areas. Next weekend may be in the high 60s, but final initiation should have begun before then. All inducible buds have been induced, and all initiation of flower bud differentiation should have occurred by next weekend if there is available soil moisture.

The flowering model indicates that trees in all areas will now have 3 waves of initiation after this warm spell, if flower buds were still available. Predicted bloom dates have moved back a little because of cool weather with full bloom dates now of March 2-5, 13-18 and 21-27 for the 3 waves of initiation. Central and northern areas may have some bloom about April 1 st from the 3rd wave of initiation.

Since induction hours were in the 900 plus range by the second initiation, a majority of potential flower buds should now be induced and growing. With the additional hours below 68 degrees F. since then in the 400 to 500 hour range, the third initiation should account for all potential flower buds. This should put all trees into an acceptable induction range for total flowers, even though they may come in a prolonged bloom through most of March for well-watered trees.

If your blocks did not receive rainfall this past week, irrigation should be started this week to promote initiation during this warm spell to promote end of March bloom or development of already induced flower buds. Irrigation rates should be dictated by the weather but amounts applied don't need to be particularly high until new flush is pushing, when tree water use will increase greatly. If you followed the low irrigation protocol successfully, this warm week should result in a major bloom at the end of March if you irrigate now or had sufficient rainfall this past week.

Next week we should have a more exact 3 rd wave predicted bloom date for northern areas, an update on changes in predicted bloom dates for all areas after a week of warm weather, and a guess about the interaction of flowering intensity with last years crop load to determine potential for our next crop.

Time to fertilize, if you haven't yet, and watch those flower buds develop.

If you have any questions, please contact me (albrigo@ufl.edu)


2/9/2004

FLOWER BUD INDUCTION ADVISORY #14 for 2003-2004-2/9/04

We now have over 1600 accumulated hours below 68 degrees F. for all districts, but final initiation of flower bud differentiation started at about 1000 to 1200 hours from northern to southern districts, respectively. According to the flowering model,. central and northern areas have only 2 flowering waves initiated, while southern areas have 3. With the heavy current crop that most trees bore this year, there may have been buds left for a third wave in some blocks in the central and northern areas. We will have to see if that happens and adjust the flowering model if it does.

Bloom dates for Valencias are March 1-3, March 12-16 and March 21-24 (southern areas only). If a third wave occurs in central and northern area, it appears that the full bloom date would be about April 1 st . Hamlins may be a little behind these dates and grapefruit also. The first flowering will be in navels and Ambersweet (Feb. 22-26 and March 5-7), probably without a third wave. Mandarins will be last and the model predicts bloom dates of March 8-11, March 19-22 and March 28-30. Try to have bees placed by late February and if possible move the hives to mandarin blocks after the first week of March. In any case, place the hives so the bees will have to go through the mandarins to reach other cultivars.

If you successfully water stressed your trees during the first and second winter warm periods, you should observe only one or two of the later flowering dates. Please email me bloom date observations and describe attempts to impose water stress albrigo@crec.ifas.ufl.edu.

Where do we stand on crop potential for the coming year? We have reasonable levels of flower bud induction, but not quite as good as last year for the first wave. The second wave will be in response to a higher level of total induction than last year, since last year essentially all the flowers came in the first wave. The current heavy crop, whether harvested or not, will suppress flowering levels and there are fewer spring and summer shoots to have flowers for the new crop. Historically, yield swings that appear to be from alternate bearing effects have been about .4 to .7 boxes per mature tree equivalent, with Hamlins having less response. Previously, the crop load interaction with level of flower induction was never evaluated. We could imagine that this should be a fairly strong alternate bearing year, but it is coupled with a good year for flower bud induction and the vegetative flush in most groves was better than expected for the strong bloom and set. Well if you can weight all of those factors correctly, you have a good idea of what are crop potential is going into the bloom at the end of this month.

I will be gone for two weeks, so you will not be able to find out what I think the balance is. I will answer emails about flowering dates and induction levels for water stressed blocks. The next advisory will be in two weeks (mid-week, maybe February 25)

If you have any questions, please contact me (albrigo@ufl.edu)


2/23/2004

FLOWER BUD INDUCTION ADVISORY #15 for 2003-2004-2/23/04

I just returned from the 10th International Society of Citriculture Congress in Agadir, Morocco. I only have had time to look at flower development in our teaching block at Lake Alfred. Flower development looks like it is nearly on track with the flowering model. Navels in this area should be in full bloom tomorrow. Our trees look like they will make that within a day or two at worst (see pictures at the end of this advisory). Other oranges and grapefruit are projected for the first of March (again see picture taken today). Mandarins may meet the March 7 projection.

For our trees, it looks like most of the navel bloom will come in the first wave, while other orange cultivars appear to have a 50-50 split between the first and second wave. Today, the second wave flowers in Valencia or Hamlin trees are small pinheads to medium pinheads. In general, these trees have a good bloom coming with one or two flowers per inflorescence with several leaves. This bodes well for a good set if spring weather is reasonably good.

I have not had time to visit any blocks were winter irrigation was reduced to delay bloom. By next Monday, I hope to have some information from our test blocks and cooperator blocks. I expect that if bloom was delayed until late March, the new buds will be in early bud-break now.

Please email your observations of full bloom dates for different waves and your evaluation of proportion of flowers in each wave. For well watered trees, I don't think there will be many buds available for a third wave, unless some of the smallest pinheads take until late March to develop.

If you have any questions, please contact me (albrigo@ufl.edu)


3/1/2004

FLOWER BUD INDUCTION ADVISORY #16 for 2003-2004-3/1/04

Flower development appears to be about 1 week later than the flowering model predicted in Lake Alfred. Navels in this area should have been in full bloom on Feb. 24 th according to the model, but bloom appears to be closer to March 2 nd , while Valencias were targeted for this past weekend, but they are a few days off in a couple of blocks examined near Lake Alfred. Southern areas were projected for Feb. 20-22 for navel bloom and Feb. 26 to 27 for Valencia bloom. Northern areas were supposed to have the first wave of navel flowers bloom on Feb. 26 to 28 and Valencias on March 2-5. Second wave flowers should be open about 10 days later. Please report your observations of full bloom dates in your district ( albrigo@crec.ifas.ufl.edu ).

The delay in bloom may be partially due to cooler weather this past week stopping or slowing flower development, but the model accuracy is plus or minus 5 days. Corrections in the model are needed if the model consistently under or over predicts bloom date. Even with a one week delay from the model, bloom again this year is early and most flowers should be past petal fall before 15 March.

It is easy to see two waves of flowers developing on the trees, but inflorescences are at various stages so that there will be flowers open over an extended period, at least in this area. For well watered trees, I don't think there will be many buds available for a third wave, unless some of the smallest pinheads take until late March to develop. A third wave was projected for the southern citrus areas. In this part of Central Florida, it is not easy to see evidence of a third wave that would be flowering in late March. We did clearly delay flowering in one block of Hamlin and Flame trees by reducing winter irrigation. I don't know yet how much later full bloom dates will be for these two cultivars in this winter droughted block.

If you have any questions, please contact me (albrigo@ufl.edu)


3/8/2004

FLOWER BUD INDUCTION ADVISORY #17 for 2003-2004-3/8/04

Flower development: Flower development still appears to be about 1 week later than the flowering model predicted in Lake Alfred. Hamlin and Valencia trees are near full bloom for the first wave of flower buds. For second wave flowers, tree to tree and grove to grove variation is evident, with some trees having a significant amount of second bloom and some with almost none. On Valencia trees, second wave flower buds with pinhead flowers are more likely to be on branches near large clusters of fruit. Photos 1 and 2 show the delay of flowering on a Hamlin tree that has not been harvested compared to one that was harvest 1 month ago. Yesterday, I observed several blocks in the Ft. Pierce area in full bloom.

Please report your observations of full bloom dates in your district ( albrigo@crec.ifas.ufl.edu ).

The delay in bloom may be partially due to cooler weather 2 weeks ago slowing flower development. The model accuracy is plus or minus 5 days and we may be experiencing one of the larger variations, but last year full bloom was initially predicted for 6 to 7 March and then the model shifted to predicted bloom date to 1 March for this area. The actual date ended up about 7 March. Therefore, I can't say if the bloom model prediction was late or not last year, but its mid-course change was not correct. The model's response last year and this year to temperature (underestimating bloom date) does suggest that the model may be advancing flower development too rapidly. We may need to adjust the model's response to temperature to estimate a later bloom date. Next year, we will run an adjustment based on the last two years and compare it to the current equation to see if a new equation fits the observed bloom dates better.

In most cases that I have observed, the second wave of flowers is smaller than the first wave and represents perhaps not more than 10 to 20 % of the total flowers. If flowers are at different stages in the same inflorescence, they are still all from the same wave of flowering. If all of the flowers in an inflorescence are still at some stage of pinhead or small but only a little white showing, that is a different wave of flower buds from those that currently have flowers at full bloom to popcorn in the inflorescences (photo 3, left side vs right side).

We did delay flowering in one block of Flame trees by reducing winter irrigation, but bloom on Hamlin trees in this same block appear only slightly delayed from two nearby irrigated blocks. I don't know yet how much later full bloom dates will be for these two cultivars in this winter drought stressed block compared to well irrigated trees, but it does not appear that the delay will be more than 7 to 10 days.

Please email your observations of full bloom dates for different waves, and your evaluation of proportion of the total flowers in each wave. How far off from your observations were the predicted bloom dates for your area (see advisory 16)?

If you have any questions, please contact me (albrigo@ufl.edu)


3/15/2004

FLOWER BUD INDUCTION ADVISORY #18 for 2003-2004-3/15/04

Flower development: Full bloom is on the downside in Lake Alfred for Hamlin and Valencia trees, but more flowers are open today than last Monday. All you have to do is smell the air to know that. For second wave flowers, tree to tree and grove to grove variation is evident, with individual flowers ranging from pea size down to 1/8 th inch diameter. I saw only one later bloom wave inflorescence on 10 trees. Grapefruit with current crop not harvested are a little behind Valencias with crop. Mandarins have some open flowers, maybe 5 %, with Murcotts the least developed.

The general effect of climate and genetics in this area is to have produced a prolonged bloom that will probably last another 7 to10 days before the majority of flowers are past petal fall. Many of the inflorescences are generative with nothing but old leaves on last year's shoots. Tree to tree and within tree variability has occurred. On our trees, spring flush looks light.

The delayed bloom in one block of Flame trees with reduced winter irrigation is not to full bloom. Very few flowers are open. On the other hand, the same treatment in the Hamlin trees has delayed bloom no more than 3 or 4 days when compared to 2 nearby irrigated blocks. The delay in the grapefruit still appears to be at least 7 to 10 days.

I expect that 2 more advisories will be posted this year to wrap up the bloom period and have a perspective of temperatures during the first period of fruit set. I would like to report some grower observations of bloom in your areas, but I have to have reports to do that. All information will be kept anonymous. Please report your observations of full bloom dates in your district ( albrigo@crec.ifas.ufl.edu ). How far off from your observations were the predicted bloom dates for your area (see advisory 16)?

If you have any questions, please contact me (albrigo@ufl.edu)


4/5/2004

FLOWER BUD INDUCTION ADVISORY #19 for 2003-2004-4/5/04

Final advisory of 2003-04 flowering season

Flower development: Full bloom dates were about 5 to 7 days later than predicted by the flowering monitor in many groves around the state. However, some growers indicated that the predicted dates did reflect what they observed, and they clearly saw at least 2 waves of flowers as predicted.

Flowering intensity reports and observations were from light to heavy. Most growers reported good bloom and a few thought there were more flowers than last year. Some blocks did have light flowering. We expected fewer flowers than a year ago because of the current heavy crop and the slightly lower induction level than a year ago. In general, I would say that flowering was better than expected considering the heavy crop on most trees. The spring flush was also good considering the crop and the level of flowering. This should help to reduce the May-June drop.

The flowering period was extended considerably, partially due to 2 waves of flowering that significantly overlapped, but perhaps equally because of cool temperatures that have lasted until today. Few days exceeded the low 80s.

Fruit set perspective: The cool weather during the first drop period (bloom + 3 weeks) minimized any heat or water stress related drop. We will probably have an apparent heavy May-June drop because of this. This will not necessarily indicate a poor fruit set year. May-June is usually hot and dry, and we still get large crops in spite of this (consider last year).

An important factor in the final set of Valencias is the heavy current crop that will likely stay on more trees than usual through much of the May-June drop period while waiting for processing. This will increase the May-June drop and be a larger contributing factor to the level of alternate bearing in Valencia than will the return flowering level.

Fruit size: The new crop is starting growth under lower temperatures than the previous 2 or 3 years. This should result in a slow start on fruit growth and translate into smaller fruit than in the previous two years as far as growth temperatures are concerned. Above average rainfall in the spring and autumn can help offset the lower than normal early spring temperature effect on fruit growth.

Summary: Above you have my assessment, with some help from grower cooperators, of flowering, fruit set and fruit size for this coming crop,. Put it all together and you too can speculate on an early estimate of what the new crop will be. My first estimate for the year is in the vault at Price-Waterhouse. Good luck and good prices would be nice. See you next year. ( albrigo@crec.ifas.ufl.edu ).

This will be the last advisory for this year. If you have any questions, please contact me (albrigo@ufl.edu)