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5 /7/.1 CES Mimeo Series 71-10
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 JULY THROUGH SEPTEMBER 1970
Rust mite was a general problem and kept spraying and dusting equipment busy.
Population of rust mite increased to very high level on both leaves and fruit by the end
of July. At that time 41% of groves had been sprayed and 40% of groves not recently
sprayed harbored heavy infestations. Rust mite remained high despite a slight decrease in
The cloudy-winged whitefly and also the citrus whitefly were more abundant in July
than in any prior July in 19 years of record. Heavy infestations were present in 16%
of groves. Although decrease occurred in August whitefly population was in the high
range and at record high level for August and September.
Mealybug was another pest that was in the high range in July through mid-August.
In July heavy infestations were present in 12% of groves. Population slowly decreased,
but remained above average through September.
Citrus red mite population was above normal and in the high range in July whereas
Texas citrus mite was below normal and at moderate level in July. Both of these spider
mites had decreased to low level by September.
Glover scale, yellow scale and black scale were at moderate to high levels briefly
in July, then decreased to unimportant levels in August. Snow scale reached a record
high level at mid-July, decreased slightly in August but was again at the highest level
on record by mid-September. At that time 28% of the survey groves had infestations
and 15% of groves had infestations in the moderate or heavy category. Green scale and
wax scale were above average abundance although both were at a very low population level.
Rainfall during the period was below normal but appeared to be adequate for tree
requirements due to rather uniform distribution. Foliage growth was above normal.
GENERAL FORECAST OCTOBER THROUGH DECEMBER 1970
Rust Mite: Population will continue in the high range until December. Increase
is expected until mid-November followed by gradual decrease. Heavy infestations will
occur in about 20% of groves.
Citrus red mite and Texas citrus mite will increase steadily until year end.
Statewide populations are not expected to exceed the normal low to moderate level.
Heavy infestations of either species may build up rapidly in young groves.
Whiteflies will increase in October, then decrease in November and December.
Population is expected to be above average and in the high range in most districts.
Glover scale, purple scale, yellow scale and black scale will gradually increase
through December but are not expected to become troublesome during the remainder of
Snow scale will attain a higher statewide level than in any prior month due to
intensification within groves and probable spread to previously uninfested groves by
picking crews and equipment.
Mealybug population will continue to decline to very low level.
600 October 14, 1970 WAS W. A. Simanton
OCT 2 9 1970
I.F.A.S. Univ. of Florida