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STANDARD VIEW MARC VIEW
s 72-3 AGRICULTURAL RESEARCH AND EDUCATION CENTER
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 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 flucutations may reflect recent weather changes. The latter influen r
forecast only to the extent that weather forecasts are avail blkU. E LIBRAR
RECENT SITUATION APRIL THROUGH JUNE 1971
Populations of citrus pests were at tolerable levels during the period. Rust mile
was the pest of most concern. Several species exhibited wide departures from normal.
Rust mite continued above normal and in the high range thrfuBhlutt b/y. .pFIidP e
fruit rapidly became infested in May and June. At the end ofL. hunme aa- .ay ifer !ins
were present on fruit in 32% of groves. Citrus red mite population was near the normal
low level in April, but by June 30 was above normal and in the high range. At that
time 28% of groves harbored heavy infestations. Texas citrus mite population followed
a similar pattern and attained an even higher level, close to the record high established
in 1965. At end of June 49% of groves were heavily infested. Six-spotted mite occurred
in scattered groves but less than 2% of groves developed heavy infestations during the
Glover scale was the most numerous scale species. Population was below normal in
April, but in May and June advanced to the high level normal for those months. In
June,4% of groves were heavily infested. Purple scale held constantly below normal and
in the moderate range. Yellow scale and chaff scale populations remained below normal
and in the low range despite slight increases in May and June. Snow scale remained
quite constant during the period with about 25% of groves infested and 18% with moderate
or hepvy infestat-ins. May nno nulntin was higher than in any prior month. Black scale
activity did not accelerate until June, about l.month later than normal. Population
was very low through May, then increased rapidly. It entered the high range by the
end of June but was still much below normal.
Mealybug activity followed the same pattern as black scale. By the end of June
this insect was present in moderate numbers and population was much below normal.
Aphids were less numerous than average at their late April peak but were above normal
in May and June despite a decline. Whitefly population was below normal in April and
slightly above normal when it advanced to high level in June.
Weather for the period was characterized by deficient rainfall from early April to
mid-May. Melanose lesions on new leaves were less numerous than normal when examined
in May; however, lesions on new fruits were in average abundance in June.
GENERAL FORECAST JULY THROUGH SEPTEMBER 1971
Rust Mite: Increase will continue through July, hold at high level through August and
decrease in September. Heavy infestations can be expected in 30% of groves.
Citrus red mite and Texas citrus mite will recede from their abnormally high levels
during July and August and be at low level by September.
Glover scale will continue high through July, gradually decrease in August and be at low
to moderate level by September.
Purple scale, chaff scale and yellow scale populations will remain below normal and at
Black scale population is expected to increase during July, continue briefly in the
high range during August and drop to moderate level by September. Only scattered groves
will have important infestations.
Snow scale is expected to spread and intensify during July and September. Although
infestations will be spotty, statewide population is expected to be greater than in any
Mealybug population is expected to enter the high range briefly in July, then gradually
decrease. Population at the summer peak will be below normal.
Whitefly population is predicted to be near normal and mostly at moderate level.
Decrease is expected in August followed by an upward trend in late September.
50 July 9, 1971 WAS
W. A. Simanton