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STANDARD VIEW MARC VIEW
E CES Mimeo Series 70-27
7)-Z 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 JANUARY THROUGH MARCH 1970
Citrus pests were not unusually troublesome during the period although some were
above normal levels.
Rust mite population decreased in January and February from the levels of the prior
7 months but was continuously in the high range and much above normal. Moderate or heavy
infestations were present in at least 40% of groves. Citrus red mite was slightly above
normal abundance but only scattered infestations were important.
Texas citrus mite and six-spotted mite were at very low level.
Although Glover scale and yellow scale were the most numerous scales and near their
normal levels, populations were in the low or moderate range and only scattered infestations
were important. Black scale decreased to the lowest March level since 1963 and this was
attributed to mortality due to low temperatures in January. Citrus snow scale occurred
in more groves (25%) and at higher density than in the first quarter of any prior year;
yet it was not highly active until late in March.
Whiteflies were present as larval and pupal forms in above normal numbers. Popula-
tion was at high level and was the highest for March in 19 years of record. 61% of groves
were infested and 35% harbored moderate or heavy infestations. The whitefly larvae, al-
though numerous, were mostly inactive due to cool weather and did not cause noteworthy damage
Aphids increased rapidly in early March but were less active at month end. Although
26% of groves were infested, less than 1% had heavy infestations.
The period was characterized by 4 nights with temperatures 22 to 270 F January 8, 9,
10 and 11, and above normal rainfall. Growth and bloom started 2 weeks later than average,
peaked above normal level and developed quickly.
GENERAL FORECAST APRIL THROUGH JUNE 1970
Rust Mite: Population is expected to remain in the high range in April, decline
briefly in late May and again increase to high level in June. Heavy infestations may be
expected in 30 to 40% of groves.
Citrus Red Mite: Gradual increase will resume at mid-April and continue until the
end of June. Population will reach the normal high level in June and about 15% of groves
will harbor heavy infestations.
Texas Citrus Mite: This mite will remain at low to moderate level despite a gradual
increase through June. A few groves in scattered locations may be expected to develop
Six-spotted mite will occur in about 8% of groves before mid-June then quickly de-
crease. Less than 1% of groves will have important infestations.
Black scale will start to increase in May but population is expected to remain
below average and at moderate level.
Glover scale: Gradual increase will occur April through June. Very few heavy infesta-
Purple scale: tions are likely to develop in this period. Glover scale is expected
Yellow scale: to approach or enter the high range, purple scale and yellow to attain
Chaff scale: a moderate level and chaff scale to remain in the low range.
Snow scale infestations are expected to occur in more groves and to intensify and
spread in groves already infested.
Whitefly adults will be unusually numerous in April, then decrease. Larval forms
are expected to increase rapidly in May and reach an abnormally high level in June.
Mealybug population will show a sudden increase in May and enter the high range about
Aphids will decrease in April and remain at abnormally low level.
600 April 8, 1970 WAS
W. A. Simanton