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F/-- 7, CES Mimeo Series 71-18
CITRUS EXPERIMENT STATION
LAKE ALFED, FLORIDA
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-...-QQARERLY-ICtRUS-1tSECT 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 OCTOBER THROUGH DECEMBER 1970
Rust mite continued to be the pest of greatest importance on citrus. In October
and November population was the largest for those months in 20 years of record and was
near the all time high for any month. In early November 77% of groves had economic
infestations. Population decreased in December but was still high and above normal at
The cloudy-winged whitefly and the citrus whitefly were much above normal level
except in December when population dropped into the low range for the first time since
September 1969. However, except for sooty mold, whitefly damage generally was not evident.
Citrus red mite was slightly above normal. Population remained in the low range
despite a gradual increase. Economic infestations occurred in 8 to 16% of groves during
the period. Texas citrus mite was slightly less abundant and of little importance.
Black scale was more plentiful than usual until late December. The low to moderate
population was widely dispersed and of little concern. Glover scale and purple scale
increased from low to moderate level. Infestations were numerous but light.
Snow scale was more abundant than in any prior year. It was present in 25% of
groves and moderate to heavy in 15%.
Chaff scale, mealybug and aphid populations held to low and near normal levels.
Of the other pests, yellow, brown soft, cottony cushion and pyriform scales were below
normal and low; green scale was above normal but in the very low range.
Rainfall was deficient in October, November and December. An unusually early cold
spell caused temperatures of 250 F. or below in some parts of the citrus belt on
GENERAL FORECAST JANUARY THROUGH MARCH 1971
Rust Mite: Population is expected to decrease until mid-February then increase
through March. It will remain in the high range and above normal much of the time.
Heavy infestations are predicted for 20 to 30% of groves.
Citrus Red Mite: Both species are expected to remain near the current low levels
Texas Citrus Mite: normal for January and February. Slight increase is expected
in March with 5 to 10% of groves developing heavy infestations.
Six-spotted Mite: Light infestations will occur in February and March in about 3%
Glover Scale: These 3 armored scales will be present in a majority of groves
Purple Scale: but mostly as light infestations. Little change from the normal
Chaff Scale: low to moderate level is expected until March.
Yellow scale will increase from low to moderate level January through March in
Snow scale will gradually spread and intensify. March population is expected to
be higher than in any prior month with infestations in 26% of groves.
Whiteflies: Larval and pupal stages will increase in February to the normal
moderate level. Adults will be more abundant than average in March.
Aphids will appear in February. They are expected to increase rapidly to above
normal level by the end of March, especially in cold damaged groves.
.600 January 15, 1971 WAS
W. A. Simanton