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Grower Fruit Drop Survey

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Grower Survey of 2012-13 Pre-harvest Fruit Drop Rates

With the increasing numbers of HLB infected trees and the high pre-harvest drop rates experienced by most growers, it is important to identify citrus blocks with very little drop and those with severe drop this year.  We want to identify grove conditions and/or production practice levels associated with either good or bad fruit retention.

In order to find possible relationships between fruit variety and environmental or management for pre-harvest drop rate, we need a minimum of 40 to 50 blocks each with high or low drop rates and probably an equal number in between.  More blocks greatly increase our chance of finding significant relationships. Low drop rates are probably 10 % or less and high rates are 25 % or more.  See guide below to help with estimating drop rates.

Below is a table with tree diameter, canopy volume and ground area covered by trees of the indicated size.  With information about how many fruit these size trees were carrying, you can get a good estimate of percentage fruit drop, particularly for the low, high categories asked for on the survey.  You can more accurately estimate total fruit per tree by counting fruit in ¼ canopy sections and on ¼ of the ground under a tree multiplied by 4. Do 4 trees of a given size.

Tree diameter (ft)                                           10                      15                    20
Tree canopy volume (ft3) estimates                 400                  1150                2800
Ground area covered/tree (ft2)                        80                    177                  314
Possible fruit/tree                                           200                   500                1000
% fruit drop if 1 fruit/ft2 on ground                  40                      35                    31 (high drop rate)
% drop if 1 fruit/2 ft2                                     20                      17                   16 (medium drop rate)
% drop if 1 fruit/4 ft2                                     10                       9                     8 (low drop rate)

Your assistance with this survey is greatly appreciated. To the best of your ability, please provide current information requested on the next pages for each block.  For early and late oranges, mandarins or grapefruit please use as many survey forms as you have good or bad examples with different conditions or practices.  Follow up with individual growers to collect additional data will be requested as warranted.  All locations will be coded and no identities will be associated with the data summaries. Please fill in all fields or indicate none if you didn’t do a given practice.

With your participation we hope to determine the important factors at the grove level making differences in pre-harvest fruit drop levels. Once factors are determined to reduce fruit drop, it is our hope these factors will be practiced by growers to reduce their fruit drop in the future.  Filling out a form for each block should require approximately 15 minutes. Have soil-water pH, ground fertilizer and foliar nutrition program data handy before filling out survey.

Please send completed forms by Thursday, May 30, 2013 to Dr. Gene Albrigo via email, albrigo@ufl.edu or via mail to University of Florida, IFAS, CREC, Attention: Gene Albrigo, 700 Experiment Station Rd., Lake Alfred, Florida 33850. If you wish, you may complete the survey online, it will be available until Thursday, May 30, 2013.

If you have any questions, please do not hesitate to contact me at 863-956-8707.

Thank you,

L. Gene Albrigo, Ph.D.
Emeritus Professor of Horticulture, University of Florida, IFAS, CREC

Survey options

PDF version (print out and mail in)

Word version (fill it out and email)

Online survey (survey will be available until Thursday, May 30, 2013)

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