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1.This document is HS 747, one of a series of the Horticultural Sciences Department, Florida C ooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date first printed: April 1999. Please visit the EDIS Web site at http://edis.ifas.ufl.edu .The Institute of Food and A g ricultural Sciences is an equal opportunit y /affirmative action emplo y er authorized to provide research, educational information and other services onl y to individuals and institutions that function without re g ard to race, color, sex, a g e, handicap, or national ori g in. For information on obtainin g other extension publications, contact y our count y Cooperative Extension Service office. Florida Cooperative Extension Service / Institute of Food and A g ricultural Sciences / Universit y of Florida / Christine Ta y lor Waddill, Dean2.J. J. Ferguson, professor, Horticultural Sciences Department; and G. D. Israel, professor, Program Development and Evaluation Center, Agricultural Education and Communication Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida Gainesville, 32611.HS 747Management Decisions Affecting Citrus Cold-Protection Practices: A 1996 Survey1 J. J. Fer g uson and G. D. Israel2Although a major freeze has not affected the Floridawere bedded (primarily poorly drained, shallow soils in citrus industry since 1989, growers on nonbedded orthe Indian River area and southwest Florida) and Ridge groves indicated in a 1992 survey that cold nonbedded (primarily the deeply drained, sandy soils of protection was their third most important information needthe Ridge). Data were also analyzed in terms of grove size: after pest management and cost-effective chemicals.1-25 acres, 26-49 acres, 50-99 acres, 100-499 acres, 500Growers on bedded groves ranked cold protection ninth999 acres, and greater than 1,000 acres. In add ition, coldout of 17 items. A moderate freeze in the 1995-96 seasonprotection practices were compared within pr oduction further emphasized the need to document currentsystems, production regions, management patterns, and management decisions affecting cold protection.grove size. In some cases, growers could choose more than A mail survey was therefore conducted in 1996,questions (i.e., factors in c hoosing cold-protection obtaining a sample population of 674 citrus growers frommet hods) requiring a yes or no answer (for each factor) the mailing lists of extension agents in 27 Florida countieswere combined into one graph, resulting in what appears where citrus was commercially grown. Of the mailedto be a greater than 100% response. "N" values indicate surveys, 451 useable responses were returned (66%the number of resp ondents answering a question. response rate) with an expected sampling error of 4% at the 95% level. Data were analyzed on five different levels: 1) statewide, 2) production system, 3) production region, 4) grove size, and 5) ownership and management pattern. Ownership and management patterns included growers who owned but did not manage their groves (owners only), those who owned and managed their own groves (owners/managers), caretakers who managed the groves of others (manages others), and those who both owned their own groves and managed the groves of others (manages both). Production regions included the central Florida Ridge, the Indian River area (east coast of Florida), southwest Florida, west Florida, and a multic ounty category that included respondents with groves in more than one county. Planting system referred to groves that one response; in other cases, data from a series ofIndustry CharacteristicsWhen the distribution of survey respondents was considered, the largest percentage of respondents were located on the Ridge (41%), followed by the Indian River area (26%), 10% in southwest Florida, and 19% in west Florida. Only 3% of respondents fell into the mu ltic ounty category. When asked about management patterns, the greatest percentage of growers (58%) indicated they were both owners and managers, with 18% and 16% saying they managed the groves of others and managed both their own groves and those of others, respectively. Only 8% said they were owners only. Fifty-eight percent indicated they produced citrus on bedded groves and 42% on
Mana g ement Decisions Affectin g Citrus Cold-Protection Practices: A 1996 Surve y Pa g e 2April 1999 Figure 1 Sources of weather information. Figure 2 Cold dama g e in different freezes.nonbedded groves. These data were similar to those reported for groves in bedded (504,291 acres or 58%) and nonbedded ( 350,620 acres or 42%) counties in the 1996 Commercial Citrus Inventory. On a statewide basis, 30% of surveyed growers indicated that their groves were less than 49 acres, with 25% each saying their groves were in the 99 to 499 and greater than 1,000 acre range. Thirteen percent had groves from 49 to 99 acres, and 7% had groves from 499 to 999 acres.Sources of Weather InformationGrowers were asked about their sources for weather information during the 1995-96 season and in the future. On a statewide basis, the National Weather Service (NWS) and commercial radio/TV were the primary sources of weather information in 1996 (48% of growers), but with the discontinuance of the Weather Service reports after 1996, more growers indicated they would rely on commercial radio/TV (72%), private meteorologists (20%), and the extension service (32%) than in previous years. Sixteen percent of respondents listed other sources, including the Almanac, Florida Citrus Mutual, the Internet, water-management districts, and neighbors (Fig. 1). During the 1995-96 season, bedded growers used the NWS (56%), commercial radio/TV (42%), private meteorologists (12%), and the extension service (18%), whereas nonbedded growers used NWS (37%), commercial radio/TV (55%), private meteorologists (4%), and the extension service (17%). After 1996 the use of commercial radio/TV increased dramatically for both bedded (68%) and nonbedded (78%) growers. Bedded growers used private meteorologists (26%) and the extension service (33%) more so than did nonbedded growers, 11% of whom used private meteorologists and 28% of whom used the extension service. Use of the NWS and the extension service for weatherincurred by freezes on a statewide basis, a higher information during the 1995-96 season generally increasedpercentage of growers reported damage in all categories in with grove size, and the use of commercial radio/TV1989 than in other freezes. Fruit loss, w ood damage, and decreased with grove size. After 1996 a high percentage oftree loss were more widely reported in 1983, 85, and 89 growers with groves of all sizes (54 to 85%) said theythan in 1995, but a higher percentage of growers would use commercial radio/TV. The use of privateconsistently indicated leaf drop in all 4 freezes (Fig. 2). meteorologists and the extension service also increasedComparing production systems, bedded growers suffered with grove size. more fruit loss, leaf drop, and w ood damage than During the 1995-96 season, the highest percentage ofgrowers had greater tree losses in each year. Bedded growers who used the NWS, the extension service, andgrowers appeared to have sustained more damage, except private meteorologists were those that managed othersfor tree loss, compared to nonbedded growers. However, groves and managed both their own groves and those ofthese results may have understated the losses of nonbedded others. Those who were owners only and owners/managers relied more heavily on commercial radio/TV. After 1996, commercial radio/TV was the most commonly used source of information, with the extension service second. A higher percentage of those that managed others groves and managed both their own groves and those of others used private meteorologists than growers in other categories.Cold DamageWhen respondents were asked to estimate the damage nonbedded growers in all years cited, but nonbedded
Mana g ement Decisions Affectin g Citrus Cold-Protection Practices: A 1996 Surve y Pa g e 3April 1999 Figure 3 Factors in choosin g cold protection methods.growers because the sample was based on those still inof growers with groves greater than 1, 000 acres adopting business after the freezes of the 1980s rather than before.consultants recommendations and 28 to 37% of growers A sample based on those in business prior to the freezewith smaller groves adopting those recommendations. might have indicated different losses for bedded and nonbedded growers. Those who were owners only were more likely to Comparing production regions, Ridge growersadopt the recommendations of consultants, while those suffered greater losses in all categories in each year thanwho were owners and managers were more likely to growers in other production regions. Comparingconsider a range of factors. Those who managed the management patterns, those who managed both their owngroves of others and who managed both their own groves groves and those of others generally reported the greatestand the groves of others were more likely to adopt UF freeze damage in all categories in all years.recommendations and to assess the risks based on the When deciding if and when to use irrigation for coldChoosing Cold-Pro tection MethodsWhen deciding which methods to use for cold protection, a similar percentage of growers on a statewide basis said they adopted University of Florida recommendations (35%) and assessed risks based on grove history (37%), with a lower percentage indicating they adopted consultants/suppliers recommendations (30%) and assessed the costs and benefits of particular cold-protection methods (32%) (Fig. 3). Other factors mentioned included growers developing their own methods, equipment limitations, personal experience, recommendations by other growers, and water restrictions. When factors were considered within production systems, the highest percentage of bedded growers indicated that adopting UF recommendations (36%) and assessing risks based on grove history were equallyWhen growers were asked about the effectiveness of important (41%), while nonbedded growers rated thetheir cold-protection practices at minimum temperatures of following factors equally: adopting UF recommendations28, 20 and 15 ( F for at least 4 hours, their confidence (33%), adopting recommendations of consultants andabout the effectiveness of their cold-protection practices suppliers (33%), assessing costs and benefits (36%), anddecreased as temperatures decreased (Fig. 4). Seventyassessing risks based on grove history (33%). Whenthree percent thought their practices were very effective at factors were considered within production regions, the28 ( F, with 22% considering their practices somewhat highest percentage of Ridge growers said UF recommendations (40%), assessing costs and benefits (38%), and assessing risks (39%), were the most important. Assessing risks based on grove history was the most important factor for growers in the Indian River area and southwest Florida. For west Florida growers, assessing risks based on grove history and adopting the recommendations of consultants were the most important factors. Fifty percent of growers with groves greater than 1,000 acres were more likely to adopt UF recommendations than growers with smaller groves (26 to 36% of growers with groves from 1 to 25, 26 to 49, 50 to 99, 100 to 499, and 500 to 999 acres). The reverse was true for adopting consultants recommendations, with 22% freeze history of the grove. protection, a similar percentage of respondents on a statewide basis based their decision on predicted low temperatures (67%) and actual grove temperatures (62%), with 24% considering the history of grove cold damage. Other factors considered by 5% or less of the respondents included the cost of irrigation, available water, cloud cover, dew point, duration of low temperatures, experience, power source, and wind. Within each production system, predicted and actual temperatures were also the most important factors. When considering these factors according to grove size and management pattern, predicted and actual temperatures were again the most important factors.Effectiveness of Cold-Protection Methods
Mana g ement Decisions Affectin g Citrus Cold-Protection Practices: A 1996 Surve y Pa g e 4April 1999 Figure 4 Effectiveness of cold-protection practices. Figure 5. Reasons for not improvin g cold-protection practices.effective at this temperature. At 20 ( F, only 12% said their practices were very effective, and at 15 ( F, only 3% indicated so. At 15 ( F, 51% did not know if their coldprotection practices were effective or not. Within production systems, 69% of bedded growers and 80% of nonbedded growers considered measures very effective at 28 ( F. When grove size and management pattern were considered, the highest percentage of growers with groves of all sizes said cold-protection measures were very effective at 28 ( F. An equal percentage of bedded and nonbedded growers considered measures somewhat effective at 20 ( F, with 17% of bedded growers and 10% of nonbedded growers considering these measures not effective. When grove size and management pattern were considered, the highest percentage of growers indicated that measures were somewhat effective. Within production systems an equal percentage of bedded and nonbedded growers (47 to 52%) said they did not know if coldprotection measures were effective at 15 ( F. When grove size and management pattern were considered, the highest percentage of growers with groves of all sizes and management patterns said they did not know if coldprotection measures were effective at 15 ( F.Reasons for Not Improving Cold-Pro tection MethodsWhen respondents were asked why they thought their cold-protection practices were or were not effective, 46% indicated the cost of alternative practices prevented them from changing to other (presumably more effective) practices, 12% specified inaccurate weather information, and 13% stated lack of information about cold protection (Fig. 5). Reasons for not improving cold-protection practices within production systems were also considered, with the most commonly cited reason being that alternative practices were costly. Considering production regions, a higher percentage of Ridge growers cited all of the above categories than growers in other regions. Costly alternative practices were the most commonly cited reason within production regions and among growers with groves of all sizes and all management patterns.Grove MicroclimateForty-one percent of respondents indicated they had analyzed their groves for microclimates in order to improve the usefulness of weather information, with 59% indicating they had not done so (Fig. 6). An equal percentage of bedded and nonbedded growers (41%) said they had considered microclimates. Within production regions, the highest percentage of growers who had considered microclimates were multic ounty growers (85%), compared to Ridge growers (47%) and southwest Florida growers (49%). As grove size increased, growers were more likely to analyze their groves, with 22% of growers with groves from 1 to 25 acres doing so, and 60% of growers with groves greater than 1,000 acres doing so. Those who managed both their own grove and the groves of others were also more likely to analyze microclimates (64%), with those who managed others (48%), owner/managers (33%), and owners only (29%) following in decreasing order.Conclusion After the National Weather Service discontinued agricultural weather forecasts in 1996, commercial radio/TV was the most commonly used source of weather information, with the use of private meteorologists and the extension service increasing with grove size. When deciding which cold-protection methods to use, a similar percentage of growers depended on University of Florida
Mana g ement Decisions Affectin g Citrus Cold-Protection Practices: A 1996 Surve y Pa g e 5April 1999 Figure 6 Grower anal y sis of g rove microclimates.recommendations and assessed risks based on grove history. Predicted and observed low temperatures were also used by a similar percentage of growers to decide to use irrigation for cold protection. Grower confidence about the effectiveness of cold-protection methods decreased as temperature decreased from 28 to 15 ( F. When asked why they did not improve their cold-protection methods, the most commonly cited reason was that alternative practices were costly. However, only 41% of growers said they had actually examined their groves for differences in microclimate.