Grape Research
By Dr. J.A. Mortensen


 Ever since early settlers came to
Florida and saw the abundant wild
grapevines in the woods, many at-
tempts have been made to grow Vi-
tis vinifera L. bunch grape cultivars
from Europe and, more recently,
from California. All plantings have
been short-lived due to strong dis-
ease pressure caused by fungi and
bacteria native to our humid, sub-
tropical climate.
 Florida growers planted V. la-
brusca L. bunch grape cultivars in
the Orlando area in the 1890's,
which also failed because the vari-
eties grown were entirely unsuited
to Florida conditions.
 A grape breeder in Texas, T.V.
Munson, crossed wild bunch grapes
from north and central Texas with
high-quality cultivars between 1880
and 1905. Through breeding, he in-
corporated native disease resistance
and Southern adaptability into usa-
ble cultivars of bunch grapes such as
'Extra', 'R. W. Munson', 'Carman',
'Armalaga', and 'Muench'. These
cultivars were brought into Florida
about 1920 and thousands of vines
were propagated and planted. By
1926 there were between 4,000 and
5,000 acres of Munson's bunch
grapes growing in central Florida,
and 500 or more acres in west Flor-
ida (Proc. Fla. State Hort. Soc.
29:71-73 and 215-220. 1926). Un-
fortunately, the bunch grape vine-
yards of Munson's varieties declined
in productivity due to several causes:
a disease known then as "vine de-
generation", the Mediterranean fruit
fly eradication program, depression


years prices after 1929, and post-
harvest shelling and drying prob-
lems with iced grapes shipped by rail
to Northern cities. A bunch grape
variety trial at the University of
Florida in Gainesville was planted
in 1924, and only 11 out of 63 va-
rieties still had living plants after 10
growing seasons.
 The Florida Grape Growers As-
sociation (FGGA), organized in
1923, sent three men to Tallahassee
in 1933 to seek funds for grape re-
search. The first $3500 was appro-
priated in 1934 for use on grape
disease research at the Leesburg Field
Laboratory (now ARC, Leesburg).
During the 1930's the Leesburg
Laboratory conducted pest control
experiments which established proper
timing of spray applications to pre-
vent fruit rots and other fungus
diseases, but vineyards were
disappearing.
 The cause of "vine degeneration"
was investigated in the 1930's and
1940's by controlled experiments on
soil fumigation, spraying, grafting
on resistant rootstocks, and minor
element fertilization, but none were
effective against the disease. How-
ever, newer organic fungicides tested
in the late 1940's and 1950's gave
excellent control of fruit rot and
other fungus diseases. Moreover, re-
search in the 1950's revealed that
the major cause of "vine degenera-
tion" was Pierce's disease (PD)
transmitted by leafhopper species
abundant in Florida. Recent work
at the Agricultural Research Cen-
ter, Leesburg, implicated a rickett-


sia-like bacterium as the causal agent
of PD. Cultivar resistance to PD
was found essential to contin-
ued productivity of grapevines in
Florida.
 Munson's success in using native
Texas species as breeding parents
stimulated private viticulturists in
Florida to begin breeding with na-
tive Florida bunch grape species as
parents. In 1927, Dr. Charles Demko
(Altoona, Florida), began hybridiz-
ing American cultivars with Florida
native species such as V. simpsoni
Muns. He developed 3 self-fertile
cultivars: 'Dunstan', 'Taylor', and
'Florida Concord', but none have
survived as commercial cultivars. In
1936, Joseph Fennell (Princeton,
Florida) began breeding with V. ru-
fotomentosa S., V. gigas Fenn., V.
tiliafolia H. & B., V. shuttleworthi
House, and V. smalliana Bailey as
Florida wild bunch grape parents.
He developed nine cultivars of bunch
grapes, including 'Tamiami'. 'Tam-
iami' was grown commercially in
Florida to some extent during the
late 1950's, but eventually suc-
cumbed to PD. The other eight cul-
tivars either were lost or are of no
importance commercially.
 Outstanding wild grapes were
collected in the early 1940's at ARC,
Leesburg, for possible use as sources
of longevity and resistance in breed-
ing. Initial F, seedlings were small-
fruited and of poor quality, but a
cross by L. H. Stover in 1945 gave
rise to 'Lake Emerald', released in
1954, which is resistant to PD and
good for wine and home gardens.