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STANDARD VIEW MARC VIEW
CES Mimeo Series 68-4
CITRUS EXPERIMENT STATION
LAKE ALFRED, FLORIDA
QUARTERLY CITRUS INSECT AND MITE OUTLOOK
CAUTIONARY NOTE: This Outlook is based on the assumption that weather beyond the
period of the current U.S. Weather Bureau 30-day Outlook will be normal. Therefore, the
forecasts given below cannot be viewed with the same degree of confidence as those in the
"Insect and Disease Summary" usually released twice each month by this Station.
Each pest has more or less regular periods of increase and decrease throughout the
year. Weather conditions (temperature, rain, humidity) may affect populations directly,
or indirectly through effects on predators, parasites and tree growth. Departures from
the average population level may be caused by conditions that occurred months before.
Other fluctuations may reflect recent weather changes. The latter influences can be
forecast only to the extent that weather forecasts are available.
RECENT SITUATION APRIL THROUGH JUNE 1967
Citrus pests were of much concern to growers, not only because some of the mites
were especially abundant; but because a prolonged period of drouth and low fruit prices
limited the availability of labor and funds for pest control.
Citrus rust mite continued to be the most important'species. It was above normal
abundance throughout the period and attained a record high level in April and May,
when 44 to 59% of groves showed economic infestations. Texas citrus mite also was at
the highest April, May and mid-June levels ever recorded in Florida. At the June 30
peak, 69% of groves harbored economic infestations. Citrus red mite population was above
normal in April but below it in May and June. Six-spotted mite was less abundant than
normal throughout the period and was of no concern.
Glover scale was the most abundant scale species. Population was above normal and
in the high range from April through mid-June after which a slight downward trend became
evident. Purple scale, chaff scale, yellow scale and Florida red scale all were near or
below average abundance and were of little importance. Black scale started the spring
increase later than usual. It was below normal and at low level in April and May but
by the end of June had reached the high level normal for that period and was still in-
creasing strongly. Citrus snow scale continued to spread within groves and to infest
more new groves than before. It is now present in 11% of survey groves and all of
these infestations are of concern to growers. Brown soft scale populations for May and
June were the lowest in 16 years of record.
Aphids increased sharply in early April, peaked above normal level in mid-April,
then quickly decreased to low level in May. Mealybug population increased rapidly
after mid-May and peaked in late June at the average high level for recent years.
Whitefly adults and eggs were less abundant than in prior years.
The weather was notable because of a drouth in the citrus areas that extended from
late February until mid-May. Weekly rainfall in that period averaged 0.14 inches.
June rainfall was heavy.
GENERAL FORECAST JULY THROUGH SEPTEMBER 1967
Rust mite population will increase in July and subside after.mid-August. It will be
in the high range during that period. Mites are expected to be above average abundance
through September. Heavy infestations will develop on fruit in about 20% of groves.
Texas citrus mite and citrus red mite will decrease rapidly after mid-July and be
at low level by September. Only scattered infestations will be important.
Black scale will remain at high level through July then gradually decrease to low
level by September. A new generation of crawlers will appear late in August but these
are not expected to be of much importance this year.
Glover scale will continue in the high range through July, decrease to low level in
August, then gradually increase in September. Citrus snow scale will follow a similar
trend in groves presently infested.
Purple scale, chaff scale, yellow scale and Florida red scale will continue at low
to moderate level during July, then decrease to low level until mid-September. None are
expected to be very troublesome.
Mealybug will decrease from the high range by the end of July and gradually decrease
to low level through September.
Whitefly will be moderately numerous but below normal abundance. A decrease is
expected through August followed by gradual increase in September.
700 July 21, 1967 WAS
W. A. Simanton