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CES Mimeo Series 69-11
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 1968
Rust mite and black scale were the citrus pests of general concern in most of the
citrus belt. Rust mite continued to increase beyond the abnormally high level of June
and by mid-August 30% of leaves and 367 of fruit were infested. At that time 73% of
groves had economic infestations. Decrease to normal level occurred only for a brief
period near mid-September, after which the fall uptrend started. Texas citrus mite held
to the normal high population level through July when 54% of groves had economic infesta-
tions, then rapidly decreased in August to the lowest September level since 1955. Citrus
red mite increased only slightly over the moderate level of May and at the July peak only
33% of groves harbored economic numbers. Population remained subnormal and decreased to
the lowest September level in 18 years of record.
Black scale population continued at very high level through July, then gradually
decreased to low level by the end of September. Population was above normal June to
mid-September. Snow scale was above normal abundance and rather constant throughout the
period. Infestations occurred in 15% of groves. Glover scale decreased from a high
level in July to low level in September and was below normal abundance throughout the
period. Only 3% of groves had economic infestations in July compared to a 6 year average
of 12%. Green scale, although of little concern, was present in 18% of groves in July,
which is the highest population in 18 years of record. In contrast, chaff scale, purple
scale, Florida red scale and Florida wax scale were at record low levels within the period.
Mealybug population remained in the high range through July and then gradually de-
creased. It was above normal through the period.
Whiteflies continued to be slightly above the normal level through July but there-
after dropped below normal and into the low range by September.
GENERAL FORECAST OCTOBER THROUGH DECEMBER 1968
Rust Mite: This important mite will gradually increase until mid-December when a
gradual downward trend is expected. Population will be in the high range throughout most
of the period with about 50% of groves developing important infestations.
Texas Citrus Mite:
Citrus Red Mite: These two spider mites will gradually increase but are expected
to be less numerous than usual. Moderate to heavy infestations will occur in 10 to 15%
of groves at some time in the period and will be of greatest concern in young groves.
lover S e These scales are expected to be below normal abundance
--r Scae: and at unimportant level.
Snow scale activity will be less than last year but the orange colored crawlers will
be evident on the bark in most infested groves. These crawlers can be transported on
picking crews and equipment and thereby start new infestations.
Whiteflies are expected to remain at low to moderate level.
625 October 11, 1968 WAS W. A. Simanton
OCT 11 1968
I.F.A.S. Univ. of Florida