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How to Manage Pests
UC Pest Management Guidelines
Citrus
Selectivity of Insecticides and Miticides
(Reviewed 9/08,
updated 9/08)
In this Guideline:
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Some pesticides are less toxic than others to natural enemies such as green lacewings,
lady beetles,
parasitic wasps,
beneficial mites,
and predatory
bugs. When an insecticide is less toxic to the natural
enemy than the pest it feeds on, it is a selective insecticide. Insecticides
that are not selective, but may be even more toxic to the natural enemy than to
the pest or have an impact on a wide range of pests and natural enemies, are
called broad-spectrum. Examples of broad-spectrum pesticides include most
organophosphate (e.g., malathion, dimethoate), carbamate (e.g., carbaryl–Sevin,
methomyl–Lannate), pyrethroid (e.g., cyfluthrin–Baythroid,
fenpropathrin–Danitol), and foliar-applied neonicotinoid
(imidacloprid–Provado, acetamiprid–Assail) insecticides. If
broad-spectrum insecticides are used in a selective manner, such as in baits,
spot treatments, or applied systemically through irrigation water, some of the
detrimental effects on natural enemies can be avoided.
Within each of the major groups of pests in citrus, there are
selective and broad-spectrum pesticides that can be used to control them. For
instance, citrus
thrips can be controlled with the broad-spectrum
organophosphate dimethoate and the carbamate insecticide formetanate
hydrochloride (Carzol) or with selective insecticides such as sabadilla
(Veratran), abamectin (Agri-Mek, etc.), or spinetoram (Delegate). Lepidopterous
pests, such as fruittree
leafroller and citrus cutworm,
can be controlled with broad-spectrum organophosphate and carbamate
insecticides (chlorpyrifos–Lorsban and methomyl–Lannate) or with
selective Bacillus thuringiensis microbial insecticides (Javelin, Dipel, etc.) or the stomach poison cryolite
(Prokil Cryolite and Kryocide). Finally, armored scale can be controlled with broad-spectrum organophosphate and carbamate
insecticides (chlorpyrifos–Lorsban, methidathion–Supracide, and
carbaryl–Sevin), by selective narrow range oil treatments, or by releases
of Aphytis parasites.
Botanical, microbial, and oil insecticides are not disruptive to most natural
enemies. Oil can reduce natural enemies present at the time of treatment but is
fairly selective because of its limited persistence. In addition, some
broad-spectrum pesticides can be relatively selective when used infrequently
and at very low rates: for example, 0.5 pint per acre of chlorpyrifos (Lorsban)
for katydids,
compared to high rates (6 to 12 pints per acre) used for California red scale.
Some insecticides are selective or safe for one group of natural
enemies but not another. For example, lacewings are naturally tolerant of
pyrethroids, but parasitic wasps, and predatory mites, and beetles are very
susceptible to this group of pesticides. Insect growth regulators such as
pyriproxyfen (Esteem) and buprofezin (Applaud) are safe for parasitic wasps but
are very toxic to beetles such as the vedalia beetle needed for cottony cushion
scale control. The miticide dicofol (Kelthane) is safe for predatory and
parasitic insects but is quite toxic to predatory mites.
Both selective and broad-spectrum pesticides can be quite persistent
or residues may degrade quickly. For example, both sabadilla (Veratran D) and
pyriproxyfen (Esteem) are relatively selective, but sabadilla persists only for
a short period of time (several days), whereas residues of pyriproxyfen are
quite persistent (2 to 3 months or more with detrimental impacts on beetles).
If a persistent, broad-spectrum pesticide has been applied, residues on the
plant may be harmful to natural enemies for weeks or months. For example, if
adult Aphytis wasps are placed in a jar
with leaves that were sprayed in the field with the dilute rate needed to
control California red scale, chlorpyrifos (Lorsban) residues are toxic to
adult Aphytis for 3 to 6 weeks,
methidathion (Supracide) affects adults for 9 weeks, and carbaryl (Sevin)
affects adults for 5 months after the treatment. In the case of the predatory mite Euseius tularensis, some San Joaquin
Valley populations have developed resistance to chlorpyrifos (Lorsban) and
their populations are unaffected by this pesticide, but they are easily killed
for several months by the carbamate formetanate hydrochloride (Carzol).
Occasional, single treatments of broad-spectrum pesticides are much less
harmful to natural enemies than multiple selective treatments.
It is important to carefully consider
the selectivity of a pesticide when making a treatment decision. This includes
the effect the pesticide has on nontarget species, its persistence in the
environment, and whether or not resistance to the pesticide has developed.
These factors are listed in the table below and under each recommendation in
the guideline. Range of Activity is
listed first and denotes the degree of selectivity each pesticide
recommendation has, along with the group of organisms primarily affected by the
treatment. For example, the range of activity for dimethoate is listed as
"Broad (insects)." This means dimethoate affects most groups of
insects. It also has an impact on beneficial mites as noted in the next column.
On the other hand, Bacillus thuringiensis is listed as
"Narrow (caterpillars)" because it only affects caterpillars. Persistence, or the length of time a pesticide remains
effective or toxic, is listed next and is categorized as short (days),
intermediate (up to 6 weeks), or long (months). And finally, in instances where
resistance has been observed in
either the pest or natural enemy, this information is included.
Factors
Affecting the Selectivity of Treatment Materials for Citrus Pest Management
|
Treatment material |
Range of Activity |
Resistance |
|
Pests targeted |
Persistence against pest |
Natural enemies affected |
Persistence against natural enemies |
| abamectin (Agri-Mek, etc.) |
intermediate (citrus thrips, mites, leafminers) |
intermediate |
predatory mites & thrips |
intermediate |
no |
| abamectin (Clinch) |
narrow (fire ants) |
intermediate |
other ants |
intermediate |
no |
| acequinocyl (Kanemite) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no |
| acetamiprid (Assail) |
broad (many insects) |
intermediate |
most natural enemies |
long |
no |
| Aphytis melinus |
narrow (armored scales) |
long, unless broad-spectrum pesticide used |
none |
none |
no |
| azadirachtin (Neemix) |
narrow (whiteflies, aphids, leafminers, caterpillars) |
short |
few |
short |
no |
| azinphosmethyl (Guthion) |
broad (many insects) |
intermediate |
most natural enemies |
long |
no |
| Bacillus thuringiensis |
narrow (caterpillars) |
short |
none |
none |
no |
| bifenazate (Acramite) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no |
| buprofezin (Applaud) |
narrow (scales, whiteflies) |
intermediate |
predatory beetles |
intermediate |
no |
| carbaryl bait |
narrow (earwigs, grasshoppers, cutworms) |
intermediate |
none |
none |
no |
carbaryl (Sevin 80S,
Sevin XLR Plus) |
broad (many insects) |
long |
most natural enemies |
long |
aggravates mites; resistance in some armored scale
populations; resistance in some Euseius tularensis populations |
| chlorpyrifos (Lorsban) |
broad (many insects) |
low rates-short
high rates-intermediate |
most natural enemies |
low rates-short
high rates-intermediate |
resistance in some armored scale and citricola scale populations;
resistance in some Euseius tularensis populations
and Aphytis melinus populations |
| copper bands |
narrow (brown garden snail only) |
long |
none |
none |
no |
| copper sulfate |
narrow (snails) |
long, unless washed off |
few, if any |
none to short |
no |
cryolite (Kryocide,
Prokil Cryolite) |
intermediate (foliage feeders such as worms, katydids, and Fuller rose beetle) |
long, unless washed off by rain |
few, if any |
none to short |
no |
| Cryptolaemus montrouzieri |
narrow (mealybugs) |
intermediate, does not survive winters well |
none |
none |
no |
| cyfluthrin (Baythroid) |
broad (many insects) |
intermediate |
most natural enemies |
low rates-intermediate
high rates-long |
resistance in some San Joaquin Valley citrus thrips populations |
| dicofol (Kelthane) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
resistance in some citrus red mite and twospotted spider mite populations |
| diflubenzuron (Micromite) |
intermediate (katydids, peelminer, leafminer, grasshoppers) |
intermediate |
predatory beetles |
intermediate |
no |
| dimethoate (Dimethoate) |
broad (many insects) |
intermediate |
most natural enemies |
long |
resistance in some citrus thrips populations |
| disodium tetraborate |
narrow (sugar-feeding ants) |
as long as the bait station is filled |
none |
none |
no |
| etoxazole (Zeal) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no |
| fenbutatin oxide (Vendex) |
narrow (mites) |
short |
predatory mites |
short |
no |
| fenpropathrin (Danitol) |
broad (many insects and mites) |
intermediate |
most natural enemies |
long |
resistance in some San Joaquin Valley citrus thrips populations |
| fenproximate (Fujimite) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no |
| formetanate hydrochloride (Carzol) |
broad (many insects) |
intermediate |
most natural enemies |
long, unless washed off |
resistance in some citrus thrips populations |
| hexythiazox (Onager) |
narrow (mites) |
intermediate |
predatory mites |
short to intermediate |
no |
| hydrated lime |
narrow (leafhoppers) |
long |
interferes with searching ability of many natural enemies |
long |
no |
| Treatment material |
Range of Activity |
Resistance |
| Pests targeted |
Persistence against pest |
Natural enemies affected |
Persistence against natural enemies |
imidacloprid, foliar
(Provado) |
narrow (citricola scale, aphids) |
intermediate |
most natural enemies |
intermediate |
no |
| imidacloprid, systemic (Admire, Nuprid) |
narrow (aphids, glassy-winged sharpshooters) |
long |
predatory beetles and parasites |
intermediate |
no |
| imidacloprid (Vitis Liquid Ant Bait) |
narrow (sugar-feeding ants) |
as long as the bait station is filled |
none |
none |
no |
| iron phosphate (Sluggo) |
narrow (snails) |
intermediate |
beneficial snails |
intermediate |
no |
| malathion |
broad (many insects) |
intermediate |
most natural enemies |
intermediate |
no |
| metaldehyde (Deadline) |
narrow (snails) |
short |
beneficial snails |
short |
no |
| Metaphycus helvolus |
narrow (soft scales) |
long, unless broad-spectrum pesticides used |
none |
none |
no |
| methidathion (Supracide) |
broad (many insects) |
long |
most natural enemies |
long |
resistance in some armored scale and vedalia beetle populations |
| methomyl (Lannate) |
broad (many insects) |
short |
most natural enemies |
intermediate |
no |
| methoxyfenozide (Intrepid) |
narrow (caterpillars) |
intermediate |
few |
intermediate |
no |
| micronized sulfur |
broad (mites, citrus thrips) |
intermediate |
most natural enemies |
intermediate |
no |
| naled (Dibrom) |
broad (many insects) |
short |
most natural enemies |
intermediate |
no |
| oil (dilute application) |
broad (unprotected stages of insects/mites) |
short |
most natural enemies |
short |
no |
| oil (low-volume) |
narrow (citrus red mite) |
short |
predatory mites |
short |
no |
| phosmet (Imidan) |
broad (many insects, mites) |
intermediate |
most natural enemies |
short |
no |
| propargite (Omite) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
resistance in some twospotted mite populations |
| pyrethrin/piperonyl butoxide (Pyrenone Crop Spray, etc.) |
broad (many insects) |
very short |
most natural enemies |
very short |
no |
pyrethrin/rotenone
(Pyrellin E.C.) |
broad (many insects) |
short |
most natural enemies |
short |
no |
| pyriproxyfen (Esteem) |
narrow (armored scale insects) |
long |
predatory beetles |
long |
no |
|
pyriproxyfen
(Esteem Ant Bait) |
narrow (fire ants) |
as long as the bait station is filled |
none |
none |
no |
| pyridaben (Nexter) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no, but stimulates citrus thrips |
| Rumina decollata |
narrow (brown garden snail) |
long, unless snail bait used |
none |
none |
no |
| sabadilla (Veratran-D) |
narrow (citrus thrips) |
very short |
predatory thrips |
very short |
no |
| s–methoprene (Tango) |
narrow (sugar-feeding ants) |
as long as the bait station is filled |
none |
none |
no |
| spinetoram (Delegate) |
narrow (thrips, katydids) |
intermediate |
predatory thrips |
intermediate |
no |
| spinosad (Success, Entrust) |
narrow (thrips, orangeworms, katydids) |
intermediate |
predatory thrips |
intermediate |
no |
| spirodiclofen (Envidor) |
narrow (mites) |
intermediate |
predatory mites |
intermediate |
no |
| spirotetramat (Movento) |
broad (mites, thrips, leafminer, aphids, armored scales) |
long |
predatory mites |
short |
no |
| sticky materials |
narrow (trunk climbers) |
long |
few, if any |
long |
no |
| vedalia beetle |
narrow (cottony cushion scale) |
long |
none |
none |
no |
| wettable sulfur |
narrow (mites and citrus thrips) |
intermediate |
most natural enemies |
intermediate |
no |
UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
General Pesticide Information
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O‘Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
C. E. Kallsen, UC Cooperative Extension, Kern County
D. R. Haviland, UC Cooperative Extension, Kern County
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