SUNIVER ITY OF Agricultural Research and Education Center
13138 Lewis Gallagher Road, Dover, FL 33527
SFLO I A Dover AREC Research Report DOV-1993-2
Institute of Food and Agricul ural Sciences
DEFOLI TION OF STRAWBERRY TRANSPLANTS FOR FRUIT ; .
PRODUCTION IN FLORIDA
E. E. A bregts, C. K. Chandler, and C. M. Howard1:' i ,ry i .:
Strawberry transplants for the Florida fruiting fields have various amounts
of the original folia e remaining on the plant at transplanting. Harvesting
of transplants may result in some of the leaves becoming partially or
totally removed, and some petioles of other leaves may be broken. These
leaves will be of lit le value to the freshly set transplant. The packing,
shipping, and transpla ting procedures can also reduce the amount of foliage
remaining on the tran lant. Some out-of-state nursery growers may remove
all of the foliage if lants have received chilling in the nursery. Locally
grown nursery transpl nts are rarely defoliated. Transplants grown in
cooler areas of the United States or in Canada with shorter daylengths in
the early fall general y will have flower buds in the crown and starch in
the roots. Until new leaves are in place, starch can serve as a temporary
food source for the de oliated transplants. The flower buds in the crown
result in earlier harve ting of fruit at a time when fruit prices generally
are high. Of course, i generally is more expensive to grow plants out-of-
state because of shippi g costs and/or lower transplant production in those
areas. Shipment of part ally or totally defoliated transplants would reduce
shipping costs compared to non-defoliated transplants, and would lower the
probability of diseases nd mites being introduced into the fruiting field.
This could reduce pestic de usage. With foliage removed, transplants would
require less irrigation for establishment, but fruit production might be
adversely affected by the use of partially or totally defoliated plants. If
fruiting were delayed or yield reduced, the use of defoliation may not be
economically acceptable o growers.
The purpose of this study was to determine the effect of various amounts of
defoliation on the plan growth and fruiting response of Florida and
Canadian-grown strawberry transplants.
MATERIALS AND METHODS
Studies were conducted at the Agricultural Research and Education Center
(AREC), Dover, during f ur winter (October through April) seasons,
'Professor (Soil Scientist) Assoc. Professor (Plant Breeder), and Professor
(Plant Pathologist), resp actively with the Univ. of Florida, IFAS,
Agricultural Research and education Center, 13138 Lewis Gallagher Road,
Dover, FL 33527.
1987-88 through 1990-91, using the annual hill cultural system.
Transplants of 'Dover' and breeding line FL-79-1126 were produced at
AREC-Dover, and 'Chandler' and 'Selva' transplants were produced in
southern Ontario.- Raised beds were fertilized with 224N-20P-184K
(kg.ha ), fumigated1 with a 98% methylbromide and 2% chloropicrin
mixture at 448 kg.ha of bed area and mulched with black polyethylene.
Transplants were set on 27 Oct. 1987, 20 Oct. 1988 and 1989, and 22 Oct.
1990, with two rows per bed and plants spaced 12 inches between and 11
inches within rows. Overhead sprinkler irrigation and labeled
pesticides were applied as needed. Defoliation treatments of
transplants consisted of removing a specific percentage of the foliage.
During the 1987-88 season, clones FL-79-1126 and 'Chandler' were
evaluated; treatments were 0% and 87% defoliation, which occurred just
before transplanting. The Florida clones used.,during. the .subsequent
seasons were 'Dover' and FL-79-1126, from which,0%, 35%, 60%, or 87% of
foliage was removed just before transplanting. The Canadian-produced
'Chandler' transplants had 0% and 87% of foliage removed the-:first two
seasons. During the last two seasons, both 'Chandler' ,and 'Selva&l were
subjected to 0%, 60%, or 87% defoliation. Foliage wass removed just
before transplanting, except for one of the; two 87%,.defoliation
treatments in 1989-90, when foliage was removed from' Canadian
transplants 2 weeks before plant harvest. i. \
Fruit harvest began in early December with the Canadian-growrnclones_ and
in late December and January with the Florida-grown clones and continued
to mid-April for both. All fruit were harvested twice weekly, ;graded,
counted, and weighed. Marketable fruit were those free of rrot -not
misshapen, and weighing at least 10 gram each. Plants were rated
visually for size three or four times each season. For each -evaluation
date, relative plant size was rated from 1 (smallest) to 10;l,(argest)Lr
Defoliation of transplants affected marketable fruit yields -through
January (early fruit yield) (Table 1), except for 'Chandler'.-during the
first season. Early fruit yields generally were reduced more with
increasing defoliation. Canadian-grown, transplants defoliated- in :the
nursery 2 weeks before plant harvest in the 1989-90 seasonalso produced
lower early yields than those not defoliated, but the .same, yield 'as
transplants defoliated 87% just before transplanting. .; : i -v
Total marketable yields of Canadian-grown transplants for the 1;989-90M
season for three treatments were similar (Table 2). For all other
seasons, total marketable fruit yields of Canadian-grown plants
increased with decreasing defoliation. A significant interaction
between the Florida-grown clones and the defoliation treatments occurred
in the 1989-90 season for total marketable yields. Only 'Dover'
responded significantly to defoliation (Table 2; data for 79-1126 not
shown). Average fruit weight varied with defoliation during all seasons
with Florida-grown clones, and during 1989-90 and 1990-91 with
Canadian-grown clones (Table 3). The greatest difference in fruit
weight occurred between 87% and 0% defoliation. Except for one
evaluation date-fo 'each plant source, plant size was smaller throughout
the season with in reased defoliation (Table 4).
With Florida-grown clones, the percentage of the fruit rated cui"
because of small size (less than 10 g) generally increaSed with,
increasing defoliat on (Table 5). Clones grown in Canada in 1987-88 and
1989-90 responded similarly. Thus, not only could marketable fruit be
smaller because of efoliation (Table 3), but a greater percentage of
the culls may not b marketable because of small size.
Defoliati'on'of Flori a-grown transplants consistently reduced early 'nd
total yietds.si Defod 1ati on- of :Canadian-grown plants gave inconsistent
yield reductions. he-' starch in :the roots o"f Canadian-grown plants
would enable' 'faster growth of these plants than those grown in Florida,.
which are devoid of tarch at the normal transplanting date because of
the high'vambient ai 'temperature at plant harvest. Because of small
plant size,'at trans planting (see Table 4), Florida-grown clones that
were part aly- defoT ated may not have had sufficient photosynthetic
capacity>,to ffully -su ort high early fruit yields as well as seasonal
fruit yields and yet allow normal growth of the plant.
StudiesniD Californi showed: higher yields with defoliated plants.
However these' p1,nts' were set'in October and did not fruit until the
following Februarygi ing the plants considerable time to grow before
fruiting~.- The reducti n in early fruit yield of strawberry, hs economic,.
implications. ,The pri e of fruit generally is highest during-the period
of early.harvest in F orida; thus, a reduction in early'yield due to~
defoliatilon" lould resu t in a loss of income for growers.
Defoliation treatments ere usually detrimental to early and total,fruit
production hnd" reduced fruit and plant size. All of these responses ;
were, more"'evere o'n, Fl rida-grown than on Canadian-grown transplants."
The; differencb-in resp nse because of transplant source may be related
to.;the chilillHng:and sh rter daylengths received by' the Canadian-grgwn
plantsbein. theKi Ursery. This usually results in starch, reserves being
deposited i n'!plant root and flower buds forming in the crown. This
allows in faster growth of defoliated Canadian-grown tran plants 'and
earlier fruit production than that of similarly treated Florida-grown
traispftants. : -
Early marketable fruit yields of.strawberry
four seasons as affected by foliage removal
and plant source.
removed Early marketable fruit yield (Flats/A)
Plant source (%) 1987-88 1988-89 1989-90 1990-91
Floriday 87 119 b 349 145 -247
60 689 425 349
35 790 S 476 485
0 544 a 927 434 655
Treatment ** *** ** ***
Linear *** *** **
Quadratic *** NS
Canaday 87 391 553 b 391 b 451
60 391 b 536
0 391 876 a 527 a 7714
Treatment NS** ***
~i L. -
Y1987-88 data are only for
1988-89 data are only for
averages of two clones.
xNS, ** ***
respectively, using ANOVA
Florida-grown FL-79-11 26, anid -1987-88 and";
Canadian-grown 'Chandler'. A1liother data'are
or significant at P =-0.05, 0,01, drO.aOQ~i, -
F test (treatment) and regressions.
"Defoliated 87% 2 weeks before plant harvest.
Table 2. Total ma ketable fruit yields during four seasons as affected by
foliage removal nd.:plant "source..
,._____. .. ': ,. '-----------
fruit yield (Flats/A)
1216 1360 1029
1760 2134 1275
2006 2389 1454
2236 2066 1777
*** ** ***NS
NS *** NS
YAll data-6avre-rTeage- two clones, except data are only from
Florida-grown .F-79-1 26 in.1987-88 and 'Dover' lin1989-90 and
Canadian-grown 'Chandlir' in-1987-88 and 1988-89.'
xNS,**,**Nonsignific nt or significant at P = 0.05, 0.01, or 0.001.
respective, ,using AN VA F test-(treatment) and regressions. '
"Defoliated 87% 2 weeks before plant harvest.
Table 3. Average fruit weight as affected by foliage removal and plant
source dur-ing four seasons.
removed Avg fruit wt- (gram/fruit) -,
Plant source (%) 1987-88 1988-89 1989-90 .990 91
Floriday 87 14.6 b 14.0 14.2 i3i 6
60 5..8 1 5.3 13 8
35 15.4 15.-7-;- 14 2
0 15.6 a 15.7 15.4 14 4
Treatment *** **
Linear :- ** ** .. ***
Quadratic ** *'- S
Canaday '- 87 16.5 16.0 14.6 b 14.3
S60 15.1 ab 1' 4.8
x 16.5 15.2 T5.7a' 14.8
Treatment NS NS ** *
Linear .. NS
data are only for
data are .only for
averages of two clones.
r e' v Nonsignificant
respectively,; using ANOVA
or significant at P = 0.
F test (treatment) and r
, and 1987-88 anti -
'. All other data are
05, 0.01, or 0.001,
Table 4. Relative plant size as affected by defoliation treatments and plant source
during four seasons. i
<. 'J A .
Foliage Rellative plant s-ize' : 't t ,:
removed 1987-88 198 -89 1989-90 199 Q-91
Plant source (%) 12 Dec. 9 Mar.-30 Nov,. P Feb. 30 Nov. 29 Jan. 14 Nov. 25 Feb.
Floriday 87 3.0 b 10.0. 2.9 .0 4.1 c 9.0 1.6 7.6
60 7.7;- .3 8. .9.3 2.8 8.6
35 -8.6 .4 9..' 9. 6 '5 7. 9 .1
0 10.0 a 9.4 ; L10.0 1 Q. 0 10. -: 10'.0 -.100) i1 .
Significancex r c a *
Treatment ** NS ..*** '** ** **
Linear ** ** *** ***
Linea ***r jNS *** NS ** S
Canaday 87 8.3 b 8.9 be 7.4 -bl 7t.5 b 'e 8.6 b.e 9'a. ;4 a0 ;-, w r 1
0 10.0 a 10.0 a. 10.0 oa-, 1 .0 a 10.0 a 10.0 10.0 10o .0
ox f Ca n ,
Treatment ** NS
Linear *** NS
Quadratic I NS NS
ZFor each evaluation date, relative. plant sizd in each plot was visually rated 1
(smallest) to 10 (largest).
Y1987-88 data are only for Florida-grown; FL-79-1126, and-19-87-88 and 1988-89 data, are"
only for Canadian-grown 'Chandler':. All other' data are averages of two clones.;
xNS* ** ***' Nonsignificant or significant :'at R. = 0.05, 0.01, or 0.001, respectivelyl,
using ANOVA F test (treatment) and-Pegression's. : C -
WDefoliated 87% 2 weeks before plant ha eest.| ': ... F ii :
~ j C)
Table 5., Percentage of small' fruit in cul during four sas affected
by foliage removal and plant source during four season.
'removed Small fruit in culls (%)
Plant source (%) 1987-88 1988-89 1989-90 1990-91"
Floriday 87 86 88 75 83
60- 82 63 79
35 78 61 79
0 75 77 61 74
Treatment ** *
CanadaY' 87 71 a 64 47 a 73
60 44 abw 74
0 63 b 66 37 b 75
Treatment NS NS
ZSmall cull fruit weighed
Y1987'-88 data ..are .only for
1988-89 data are only fdr
averages of two clones.
10 g. .'
Florida-grown FL-79-1126, and 1987-88 and
Cahadian-grown 'Chahdler'. All other datd are
xNS,* i ;. ,,j ,, '
x Nonsignificant di significant at P = O.5, respectively, using ANOVA
F test (treatment:) and:regressiohs.
WDefoliated 87% 2 weeks before plant Harvest.
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