response of peach and nectarine cultivars to girdling

Fig. 5. Development of a corky layer on the upper surface of
'Woodard' blueberries grown under 3 mil cellulose acetate filtered FS-40
Westinghouse sun lamps and 44 UV-B units irradiation.
Literature Cited
1. Balazs, E. and A. Toth. 1974. Jonathan spot induced by ultraviolet
light. Ada Phytopathologica Scientarum Hungaricae 9:179-184.
2. Biggs, R. H., W. B. Sisson and M. M. Caldwell. 1975 Response of
higher terrestrial plants to elevated UV-B irradiance. p. 34-50. In
Impacts of climatic change on the biosphere, Part I—Ultraviolet
Proc. Fla. State Hort. Soc. 91:175-177. 1978.
radiation effects, Monog. 5. D. S. Nachtwey, M. M. Caldwell and
R. H. Biggs, eds. Climatic Impact Assessment Program, U.S. Dept.
of Trans. Report No. DOT-TST-75-55, Nat. Tech. Info. Serv.
Springfield, VA.
3. , S. V. Kossuth and D. E. Brabham. 1978. Plastic films as
ultraviolet radiation attenuators and some possible uses. 14th In
ternational Agricultural Plastics Congress. Nov. 10-13. 9 pp.
4. Brandle, J. R., W. F. Campbell, W. B. Sisson and M. M. Caldwell.
1977. Net photosynthesis, electron transport capacity, and ultrastructure
of Pisum sativum L. exposed to ultraviolet-B radiation.
Plant Physiol. 60:165-169.
5. Campbell, R. N. 1962. Ultraviolet radiation as a probable cause of
brown blotch of honeydew melons. Phytopathology 52:360 (Abstr.).
6. Garrard, L. A. and J. R. Brandle. 1975. Effects of UV radiation on
component processes of photosynthesis. P. 20-22. In Impacts of
climatic change on the biosphere, Part I—Ultraviolet radiation ef
fects, Monog. 5. D. W. Nachtwey, M. M. Caldwell and R. H. Biggs,
eds. Climatic Impact Assessment Program, U.S. Dept. Trans. Report
No. DOT-TST-75-55, Nat. Tech. Info. Serv. Springfield, VA.
7. Green, A. E. S., T. Sawada, and E. R. Shettle. 1975. The middle
ultraviolet light reaching the ground, p. 2-29-2-38. In Impacts of
climatic change on the biosphere, Part I—Ultraviolet radiation
effects, Monog. 5. D. S. Nachtwey, M. M. Caldwell and R. H. Biggs,
eds. Climatic Impact Assessment Program, U.S. Dept. Trans. Report
No. DOT-TST-75-55, Nat. Tech. Info. Serv. Springfield, VA.
8. Lipton, W. J. 1977. Ultraviolet radiation as a factor in solar injury
and vein tract browning of cantaloupes. J. Amer. Soc. Hort. Sci.
102:32-36.
9. Merrill, T. A. 1936. Pollination of the highbush blueberry. Mich.
Agr. Exp. Sta. Bull. 151. 10 pp.
10. Moore, J. N. 1964. Duration of receptivity to pollination of flowers
of highbush blueberry and the cultivated strawberry. Proc. Amer.
Soc. Hort. Sci. 85:295-301.
RESPONSE OF PEACH AND NECTARINE CULTIVARS
TO GIRDLING
C. P. Andrews
IF AS, Agricultural Research Center,
Rt.3,Box213B,
Monticello, FL 32344
W. B. Sherman and R. H. Sharpe
IF AS, Fruit Crops Department,
University of Florida,
Gainesville, FL 32611
Additional index words. Prunus persica, fruit size, fruit
ripening.
Abstract. Studies were conducted on the effect of girdling
on 8 peach and 2 nectarine cultivars grown in central and
north Florida. Girdling resulted in earlier fruit ripening in
peach cultivars, 'Flordasun' and 'Early Amber', and in 'Sunred'
nectarine at Hawthorne, Florida. Time of ripening was en
hanced 3 to 5 days on all varieties at ARC, Monticello. Fruit
size was increased by girdling in all cultivars at both loca
tions. Percent soluble solids in fruit of 'Springcrest' variety
increased slightly from girdled trees while external color
development remained rather constant. No adverse effects on
tree vigor were observed on cultivars girdled in central
Florida. However, a difference in tree vigor was recorded
among varieties girdled at Monticello. Severe necrosis of
leaves was observed in the 'Springbrite' cultivar while gird
ling appeared to have no harmful effects on 'Springcresf
peach and 'ArmKing' nectarine.
peach and nectarine production in Florida
is dependent upon cultivars with a low chilling requirement
Proc. Fla. State Hort. Soc. 91: 1978.
(hours below 7.2°C) and adapted to mild winters. Cultivars
currently recommended for central Florida vary in chill re
quirements from 100 to 400 hours (2) while cultivars grown
in north Florida range from 450 to 750 hours (1). A major
factor influencing peach and nectarine production in Florida
is the earliness of fruit ripening. For maximum profits, cul
tivars should ripen before those grown in the large volume
areas of the north and west. However, due to the small fruit
size of many early ripening cultivars, consumer acceptance
has been limited.
Branch girdling has been reported to influence fruit size
and maturity in several deciduous fruit species. Girdling
caused an increase in fruit size in apples (6), apricots (3, 5),
grapes (4) and peaches (8) while time of ripening was
hastened in apples (7), apricots (3,5), cherries (7), grapes
(4, 7), peaches (7) and pears (7). Crane and Campbell (3)
found that girdling had deleterious effects on vegetative
growth and subsequent fruit production in apricots. This
study was conducted to determine the effect of girdling on
vegetative growth and fruit development of peach and
nectarine cultivars in Florida.
Materials and Methods
Mature trees of 'Sunred' nectarine and 'Early Amber',
'Flordasun', 'White Knight' and selection 5-58 peaches were
girdled on April 6, 1968 in a commercial orchard at Haw
thorne, Florida. Eight trees of each cultivar were selected for
uniform vigor and size of crop. Girdling cuts 3mm wide
were made with a California Grape Girdling Knife and a
narrow knife along with a wide knife cut of 6mm. Bark was
removed with each type of cut. Scoring was done by running
175

a knife once around a branch completely through the
cambium. Fruit size was measured with a vernier caliper on
April 20 and 26, 1968, on all cultivars. A third measurement
was taken on May 3 on 'Sunred' nectarine, 'Early Amber'
and 5-58 peaches to determine their increase in diameter.
Harvest dates averaged late April to early May for 'White
Knight', 'Flordasun' and 'Sunred' while 'Early Amber' and
5-58 were harvested in mid-May and early June respectively.
Trees were observed for callus formation, gumming, and
tree vigor throughout the growing season.
Four year old trees of 'ArmKing' nectarine and peach
cultivars 'Bicentennial' 'Camden', 'Springbrite' and 'Springcrest'
were girdled four weeks after full bloom at the Agri
cultural Research Center at Monticello, Florida. 'ArmKing'
was girdled on April 14, 'Bicentennial' on April 19 and
'Camden' on April 21 while 'Springbrite' and 'Springcrest'
were girdled on April 17. A narrow cut about 3mm wide was
made around the trunks of the trees and the ring of bark
removed. Fruit were thinned to 6 inches apart on all cul
tivars prior to girdling. 'Camden' was the first cultivar to
ripen in early May with harvest of the other cultivars in
mid May. Individual fruit diameter was measured at harvest
using a peach sizer or if the diameters were larger or smaller
than the sizer permitted, a caliper was used. Tree vigor rat
ings were recorded for control and girdled trees on October
3, 1978.
Results and Discussion
Girdling resulted in earlier fruit ripening of most cul
tivars at Hawthorne (Table 1). The number of fruit picked
Table 1. Effect of girdling on number of fruit picked at first and second
harvests at Hawthorne in 1968.
Cultivar
White Knight
Flordasun
Sunred
Early Amber
Selection 5-58
1st 2nd Control Girdled
Harvest Harvest
1st 2nd
1st 2nd
April 26
April 26
May 10
May 18
May 28
April 30
May 1
May 14
May 21
June 1
1002
75
139
316
18
713
711
475
647
3
1,152
219
340
489
50
175
838
415
615
34
at first harvest was greater on girdled trees than control trees
of 'Flordasun', 'Sunred' and 'Early Amber', thus indicating
an enhancement of maturity. Ripening dates were generally
3 to 5 days earlier on cultivars responding to treatment.
Girdling did not appear to affect the ripening date of
'White Knight' and selection 5-58. The treatment date for
'White Knight' was late in its season, only 20 days prior to
first harvest, and did not hasten fruit maturity. Only 2 har
vests very early in the normal maturation period were re
corded for 5-58 and data is incomplete. The time of fruit
ripening was 3 to 5 days earlier on all cultivars girdled at
Monticello (Table 2). 'Camden' was the first cultivar to
ripen with first harvest on treated trees on May 8 as com
pared to May 12 for control trees. Similar results were ob
Table 2. Effect of girdling on time of ripening of peach and nectarine
cultivars at Monticello in 1978.
1st Harvest date
Cultivar Control Girdled
Camden
Springbrite
Springcrest
Bicentennial
ArmKing
May 12
May 16
May 17
May 18
May 19
May 8
May 12
May 12
May 15
May 15
tained with 'Springbrite', 'Springcrest' and 'Bicentennial'
peach and 'ArmKing' nectarine.
Table 3 summarizes the effect of girdling on fruit size of
cultivars at Hawthorne. Girdling treatments resulted in an
increase in fruit size in all cultivars. A marked increase was
noted for 'Flordasun' peach and 'Sunred' nectarine. An in
crease in fruit size was also obtained in 'Early Amber' and
selection 5-58 but final measurements were made 15 and 25
days respectively before first harvest. Increase in fruit size
was less in 'White Knight' than in the other cultivars, indi
cating the treatment was late.
Girdling also increased fruit size of all cultivars at
Monticello (Table 4). For example, girdling increased the
Table 4. Effect of girdling on fruit size of peach and nectarine cultivars
at Monticello in 1978.
Cultivar
ArmKing
Bicentennial
Camden
Springbrite
Springcrest
Table 3. Effect of girdling on fruit diameter of peach and nectarine cultivars at Hawthorne in 1968.
Variety
White Knight
Flordasun
Sunred
Early Amber
5-58
176
1
April 20
April 20
April 20
April 20
April 20
Treatment
Control
Girdled
Control
Girdled
Control
Girdled
Control
Girdled
Control
Girdled
Percent fruit size by diameter (inches)
1% 1%
2 2%
0
0
19
8
5
0
21
5
1
0
percentage of 2 inch diameter fruit by 8% in 'Springbrite',
12% in 'ArmKing' and 'Bicentennial', 16% in 'Camden' and
31% in 'Springcrest'. Weinberger and Cullinan (8) reported
increased fruit size up to 34% and 36% for 'Georgia Belle'
and 'Elberta' cultivars respectively. They stated the accumu
lation of food caused by ringing the bark increases the ef
ficiency of the individual leaf in sizing the fruit. Additional
observations on fruit quality were made on the 'Springcrest'
cultivar. Percent soluble solids in fruit increased slightly
from girdled trees while external color development re
mained rather constant.
No adverse effects on tree vigor were observed on cul
tivars girdled in central Florida regardless of the type of cut
Dates of measurement Date 1 Date 2
2
3
Girdled Non-girdled Girdled Non-girdled
April 26
April 26
April 26
April 26
April 26
—
May 3
May 3
May 3
42.0
43.5
31.9
30.7
32.7
40.9
42.5
30.0
30.0
30.5
51.4
52.3
34.9
33.2
34.4
50 9
50 9
31.8
31.4
33.4
9
0
37
32
44
11
36
30
38
11
23
18
35
38
38
51
35
49
34
27
Girdled
40 5
37.4
35.4
58
70
9
21
12
28
8
16
27
58
10
12
0
1
1
10
Non-girdled
37 fi '
35 0
33.0
Proc. Fla. State Hort. Soc. 91: 1978.
0
0
0
4

made. However, a varietal response was noted at Monticello
(Table 5). No deleterious effects on growth were recorded
for 'ArmKing', 'Camden' or 'Springcrest' while tree vigor was
reduced in 'Bicentennial* and 'Springbrite'. Severe necrosis
of leaves and gumming in the area of the cut were also ob
served in 'Springbrite'.
Table 5. Effect of girdling on tree vigor of peach and nectarine cultivars
at Monticello in 1978.
Cultivar Vigor rating1
ArmKing
Bicentennial
Camden
Springbrite
Springcrest
"Vigor rating: 1 = poor, 5 = excellent.
5.0
3.0
5.0
2.0
5.0
In summary, girdling of peach and nectarine cultivars in
Florida generally increased fruit size and enhanced time of
ripening. However, due to adverse effects on tree growth of
Proc. Fla. State Hort. Soc. 91:177-180. 1978.
some cultivars, girdling should be limited as a cultural prac
tice until more information is obtained on cultivar response.
Literature Cited
1. Andrews, C. P. and C. E. Arnold. 1978. Commercial peach and
nectarine variety recommendations. Monticello ARC Research Re
port 1978-4.
2. Arnold, C. E. and T. E. Crocker. 1977. Peaches and nectarines in
Florida. Fla. Coop. Ext. Serv. Circ. 299-B.
3. Crane, J. C. and R. C. Campbell. 1957. The comparative effective
ness of girdling and 2, 4, 5-Trichlorophenoxyacetic acid for increas
ing size and hastening maturity of apricots. Proc. Amer. Soc. Hort.
Sci. 69:165-169.
4. Jacob, H. E. 1928. Some responses of the seedless varieties of Vitis
vinifera to girdling. Proc. Amer. Soc. Hort. Sci. 25:223-229.
5. Lilleland, O. and J. G. Brown. 1936. Growth study of the apricot
fruit. III. The effect of girdling. Proc. Amer. Soc. Hort. Sci. 34:264-
271.
6. Murneek, A. E. 1938. Further results on the influence of branch
ringing on fruit set and size. Proc. Amer. Soc. Hort. Sci. 36:398-400.
7. . 1939. Fruit production as affected by branch ringing.
Proc. Amer. Soc. Hort. Sci. 37:97-100.
8. Weinberger, J. H. and F. P. Cullinan. 1932. Further studies on the
relation between leaf area and size of fruit, chemical composition,
and fruit bud formation in 'Elberta' peaches. Proc. Amer. Soc. Hort.
Sci. 29:23-27.
WORLD TRADE DIRECTIONS IN MAJOR FRUITS
Cecil N. Smith
Food and Resource Economics Department,
University of Florida,
Gainesville, FL 32611
Additional index words. World trade in fruits, fruits-export
trends.
Abstract. World exports of fruits and related products
increased to a marked extent in the 1970-74 period. The
proportionate increase in exports of fruits and vegetables
from the United States, in current dollars, was 78%. This
compared with rises of 535% from South Africa, 208% from
Turkey, and 70% from Israel. Over the same period imports
into the United States rose 57%, but those into many other
countries, mostly in western Europe, increased by 100% or
more. In addition to general tendencies in the fruit trade,
world developments in trade in 3 major types of fruitsoranges,
apples, and bananas—are also examined.
The purpose of this paper is to delineate recent trends
and developments in world trade in fruits, with primary in
terest in fresh ones. Although comparatively a small entity
in the overall volume of world trade, the extent of imports
and exports of fresh and processed fruits is nevertheless very
important.
Although many factors, including prices, exchange rates,
the nature of demand in importing countries, the ability of
exporters to supply the varieties, qualities, packaging, and
other required characteristics of the product desired when
required, prior patterns of trade, the opinions of dealers in
importing countries, the extent of competition, and a host
of others, affect the level and direction of the international
fruit trade, it will not be possible to treat them in this paper
due to limitations of space.
Many types of fruits are involved in world trade. In
cluded are bananas, the tropical product which exceeds all
. Fla. State Hort. Soc. 91: 1978.
other individual fruit items in the volume traded in inter
national commerce; oranges, a citrus fruit produced com
mercially in tropical and subtropical areas; and the whole
plethora of temperate zone fruits. The data for these
products pertain to the years 1970 to 1975, the latest 6 years
for which statistics are available (3).
Directions in the overall pattern of exports and imports
of all fruits and vegetables1 are also considered in this paper.
The data primarily utilized are those for the most recent 6
year (1969 to 1974) period for which information released
by the Food and Agriculture Organization in its Trade Year
book are available (3). Unfortunately, summary data on
fruits alone are not published; it is most likely that the vast
majority of the trade in fruits and vegetables consists of the
former. Much trade in fresh products such as tomatoes,
cucumbers, peppers, and melons takes place between ex
porting nations with tropical climates or off-season produc
tion capabilities, some of which are in greenhouse facilities,
and consuming or importing nations. Other vegetable com
modities frequently marketed internationally are potatoes
and onions. Many of these items are also traded in processed
form.
The writer has had a long term interest in the subject. It
was renewed when he recently spent 8 months in South
America working on an export development project in
which he studied the competitive situation for temperate
zone fresh and processed fruits.
Directions in Fruit and Vegetable World Trade
World trade in fruits and vegetables consists of the sur
plus production of tropical, subtropical, and temperate zone
fruits exchanged for other goods and services with deficit
iData relating only to total world trade in all fresh fruits are not
known to the author. The only data located pertained to trade in all
fruit and vegetable products, including processed, and were released in
terms of current U.S. dollars.
177