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CES Mimeo Series 71-2
CITRUS EXPERIMENT STATION
SLAKE 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
,ear. Weather conditions (temperature, rain, humidity) may affect populations directly,
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 APRIL THROUGH JUNE 1970
Citrus pest populations held at managable levels during the period. Some species
exhibited wide departures from normal.
Rust mite population was above normal throughout the period. It was at high
level April to mid-May and again in late June when economic infestations were present
in 44% of groves. Citrus red mite was low in April and moderate in May; then went above
normal and into the high range in June. Texas citrus mite remained subnormal and low.
A few scattered groves developed important infestations in June. Six spotted mite was
in normal abundance and only 3% of groves developed heavy infestations at the May peak.
Whitefly population was above normal throughout the period and in May and June
was the greatest in 18 years of record. In June, 88% of groves were infested and 10%
had heavy infestations. However little damage was evident. Mealybugs were very scarce
through mid-May then rapidly increased to the normal high level at the end-of-June peak.
In June, 22% of groves had heavy infestations. Aphids peaked in mid-April slightly be-
low the normal level.
Glover scale reached the high range at mid-May, but it and purple scale, yellow
scale and chaff scale were below normal and at low to moderate level at other times.
Black scale was very scarce in April due to the January cold and remained much be-
low normal despite a rapid increase in June.
Snow scale gradually increased during the period. Populations in April, May and
June were higher than in those months of prior years due mainly to occurrence of new in-
festations rather than to increase in groves already infested. 26% of groves are now
Although citrus trees generally were in vigorous condition, some groves became very
dry in the period from mid-April untillate May when little if any rainfall occurred.
GENERAL FORECAST JULY THROUGH SEPTEMBER 1970
Rust Mite: Population will continue to increase through July, remain high through
August and decrease in September. Moderate or heavy infestations will occur on fruit
in 40 to 50% of groves.
Citrus Red Mite: Population will decrease after mid-July, drop out of the high
range in August and be at low level in September.
Texas Citrus Mite: This mite will continue to be moderately abundant through
July; then decrease to low level in August and September.
Glover scale will remain in the high range through July then gradually decrease
Purple scale, chaff scale, and yellow scale will be moderate to low level in
July. Decrease is expected in August and September.
Black scale will continue below normal abundance in July despite an increase in
that month. A new brood of crawlers will hatch in August but most of these will not
live to reach the adult stage; hence the population will be low in September. Only
scattered infestations in East and South districts are expected to be important.
Snow scale will become more numerous and i: esT-mrifi'&pv".~
Whitefly population is expected to remain t 'd h i th ough July and
then diminish until late September. Adults and ggs will be abnormally m merous in
August and September. JU !_ ,1j F7,
Mealybug will attain the high level normal for July, then gradually decrease in
ugust and September.
S- AJy 2, 10 WAS r' r.-: Simant
0 July 22, 1970 WAS W.A Simanton