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CES Mimeo Series 67-28
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.
REVIEW JANUARY THROUGH MARCH 1967
The three major species of mites were abnormally abundant during the period but most.
other citrus pests were near or below normal levels.
Rust mite was of most concern. An unusual increase starting in January led to the
highest February and March populations on record. At the end of March, 58% of groves
harbored moderate to heavy infestations compared to an average of 34% for that date.
Texas citrus mite also departed from the usual trend and increased steadily in the
period. Population was at a record high level in March, with 36% of groves having
moderate to heavy infestations. Most infestations did not cause important damage because
of good tree vigor. Citrus red mite, although more abundant than in the past 6 years,
was of concern only in scattered groves mostly in the North and West districts. Six-
spotted mite was much below normal abundance and very scarce.
Glover scale was the most numerous scale insect, being in moderate to heavy abundance
in 20% of groves and above the normal March level. Snow scale infestations continued to
spread and statewide population was the highest on record. Although present in less than
7% of groves, this potentially serious pest was an important grower problem.
Purple scale, yellow scale, and black scale were widely distributed in near normal
numbers. Chaff scale, also widely distributed, was below normal abundance.
Whiteflies were slightly above the moderate levels normal for the season, with adult
emergence well underway in March. Aphids increased more rapidly than usual in March,
reflecting earlier flushes of growth. Mealybugs were under the low population levels
normal for the period.
GENERAL FORECAST APRIL THROUGH JUNE 1967
Rust mite: Abnormally high populations will continue, despite decreases in April
and May. Fruit will become infested earlier and heavier than usual. A strong June
increase is expected.
Texas citrus mite: Population will be above average. It will hold near current
moderate level through April then increase rapidly in May and June into the high range.
Citrus red mite: Scattered heavy infestations will occur in about 10% of groves
during April and May. A rapid increase in June is expected in a majority of groves.
Six-spotted mite: Increase is expected through April but population will be below
(average and very few infestations will be important.
Black scale: Population will decrease through April. Buildup of crawlers and
young stages will be rapid in May with adults becoming abnormally numerous through June.
Glover scale: Light to moderate infestations will occur in a majority of groves in
all districts. These will become moderate or heavy infestations during June in about 30%"
Yellow scale: Gradual increase will result -in a peak population at moderate level
in June. Less than 5% of infestations will be heavy and most of these will be in the
Chaff scale and purple scale will be less abundant than normal but may occur with
Glover scale in sufficient numbers to present a scale problem.
Mealybugs will increase in May and June. They are expected to be near normal :
abundance and less numerous than in the prior two years.
Whitefly population is expected to be slightly below normal.
700 April 12, 1967 WAS
W. A. Simanton