I<6 L?/L7 HUME LIBRARY
APR ? 1971
AGRICULTURAL RESEARCH CENTER, MONTI LLO
Mimeo Report BBL 71 4 F Fbr4 8af ida
PHONY PEACH DISEASE IN FLORIDA '
W. J. French1
The phony disease of peach and nectarine is a virus disease of long stand-
ing in the Southeast. It was recognized in Georgia as early as 1885 by Samuel
Rumph, the discoverer and developer of the Elberta peach variety. The dwarfed
trees were called "pony trees" by Rumph and grown as a curiosity. From the
time the disease was recognized until 1929 over one million trees were ruined
in Central Georgia alone. A federal quarantine of nursery stock was established
in 1929 to restrict movement of susceptible nursery stock within and from the
affected areas. Later state and federal agencies conducted surveys throughout
orchards in the Southeast and eradicated diseased trees from all states where it
was found. Over one and a half million trees were eradicated. Although the
disease is one of the most important in the Southeast it is of little importance
outside this area because of effective state and federal eradication programs.
Surveys are conducted by the Plant Protection Division of the U. S. Department
of Agriculture or EPA through the cooperation of state and federal agencies.
Seven southern states are enrolled in this survey and eradication program. It
is noteworthy that Florida is not among the seven state cooperators. In 1969,
4.2 million trees were surveyed in a 7 state area, revealing 10,753 infected
peach trees. The disease incidence rose from 0.13 percent to 0.25 percent
from 1968 to 1969. A breakdown of the 1969 survey results should be interest-
ing to Florida peach growers.
State Examined Infected
Missouri 30,200 0
Arkansas 191,675 .006
Texas 178,513 .01
South Carolina 1,364,250 .016
Louisiana 92,377 .23
Georgia 2,284,860 .41
Mississippi 41,850 2.29
It is significant that in spite of annual surveys and eradication, the
disease incidence has risen by approximately 5,000 new infections in one year.
What is the situation in Florida where there has not been a continuous organ-
ized eradication program nor a phony peach survey since 1963? To answer this
question a survey was conducted in North Florida in 1970 by personnel of the
Agricultural Research Center, Monticello, The survey revealed that 5.72% of
the 10,000 trees examined had phony peach virus. This is considerably higher
than the 7 state average and higher than Mississippi's 2.29% infection.
Phony peach is now found in all parts of Florida where peaches are
grown. Many growers remove trees that are obviously diseased and leave the
less obvious ones. The leafhopper vectors of the virus then spread the virus
to adjacent trees. Only technically trained inspectors are capable of identi-
fying infected trees in the early stages of disease development. The longer
the diseased trees remain in the orchard the greater the chances of spread by
Asst. Plant Pathologist)
insect vectors. The disease does not kill the trees but causes a dwarfing of
new growth and significantly reduces the size and yield of fruit. Unless
diseased trees are identified and promptly removed, an infected orchard would
rapidly become unprofitable. The major expense of the phony peach program is
the removal of diseased trees, the cost of which is borne by the grower.
Through this phony peach detect. a program the Plant Protection Division and
state cooperators in seven states are providing a service to the growers that
they cannot provide for themselves.
Florida peach growers should recognize the seriousness of phony peach
and should consider some type of state-wide eradication program. Working
through local and state peach associations growers can request assistance from
the University of Florida Extension Service. This agency can provide informa-
tion on disease identification and assist the growers in formulating a phony
peach eradication program.
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