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STANDARD VIEW MARC VIEW
S AGRICULTURAL RESEARCH AND EDUCATION CENTER
SLAKE ALFRED, FLORIDA Series 71-25
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 Center.
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 JANUARY THROUGH MARCH 1971
Citrus pests did not cause unusual problems during the period, although some were
above normal abundance. Rust mite and snow scale were of greatest concern.
Rust mite was in the high range and above normal on leaves and fruit despite a de-
crease in February. Heavy infestations were present in 31 to 40% of groves. Citrus red
mite was above normal abundance but at low to moderate level. Heavy infestations occurred
in 3 to 7% of groves. Texas citrus mite remained near normal and low with heavy in-
festations in 2 to 6% of groves. Six-spotted mite and aphids were at the very low level
normal for the period. Aphid population began to increase strongly in March.
Glover scale was the most numerous of the scale insects. It occurred at the normal
moderate level. Only 6 to 11% of groves had moderate infestations; less than 1% were
heavy. Snow scale increased early in January, then remained constant through March.
From 28 to 30% of groves harbored this insect and moderate infestations occurred in 13
to 16% of groves; 3% were heavy. Population was greater than in any prior year.
Purple, yellow, chaff and black scales, and mealybug were below normal abundance
throughout the period and were at low to very low level.
Population of whitefly larvae decreased from moderate to low level in February and
March and was below normal in those months. Adults began to appear early in March.
Of the very minor pests only Brevipalpus mites were above normal throughout the period;
they were of no importance.
Weather during the period included a dry January and early February which was fol-
lowed by a 3 to 4.5 inch rain on February 7 and 8. Temperatures approximating 250 F
occurred on January 20 and 21 and caused light to severe damage to trees. Lesser periods
of subfreezing weather occurred January 28, February 10, February 14 and 15, and March 5.
Growth and bloom occurred about 7 days later than average.
GENERAL FORECAST APRIL THROUGH JUNE
Rust mite is expected to decrease in April, then increase to high level in May and June,
as mites build up on new leaves and fruit. About 50% of groves will develop important
Texas Citrus Mite and Citrus Red Mite: Gradual increase will occur in April and accel-
erate until June. Moderate to heavy infestations are expected in 30% of groves.
Six-spotted mite infestations are expected to occur in about 9% of groves during May and
early June, then disappear. Less than 1% of infestations will be important.
Black scale will remain low and below normal despite a sharp increase in June. Infesta-
tions will be spotty and are expected to be highest in the east and west coast areas.
Glover Scale: Gradual increase is expected April through June. Nearly all groves will
harbor this scale and about 12% will develop important infestations.
Purple scale and chaff scale also will be present in a majority of groves as light to
Yellow scale will be less numerous than in recent years and of little importance.
Snow scale will be more abundant than in prior years as infestations spread and intensify.
Infestations will be present in 30 to 35% of groves.
Whitefly adults will be very numerous in April in a majority of groves. Larval forms will
increase through June but are expected to be less abundant than last June.
Aphids will infest about 45% of groves at the mid-April peak, then subside.
Mealybug will increase rapidly rirMay ve la a-hig population by mid-June.
600 April 9, 1971 WAS
W. A. Simanton