How to Manage Pests
UC Pest Management Guidelines
Scientific name: Bemisia tabaci, Biotype B (=B. argentifolii)
In this Guideline:
adults are tiny (0.06
inch, 1.5 mm long), yellowish insects with white wings. Their wings are held
somewhat vertically tilted, or rooflike, over the body and generally do not
meet over the back but have a small space separating them.
Whiteflies are found mostly on the undersides of leaves. They fly readily when plants are
disturbed. The tiny, oval eggs hatch into a first larval stage that has legs
and antennae and is mobile. Both legs and antennae are lost after the first
molt and subsequent stages remain fixed to the leaf surface. The last nymphal
stage, often called the pupa or the red-eye nymph, is the stage that is easiest
to identify. Silverleaf whitefly pupae are oval, whitish, and soft. The edge of
the pupa tapers down to the leaf surface and has few to no long waxy filaments
around the edge.
Damage by silverleaf whitefly is mostly a problem in annual
plantings of artichoke in warm climates. Feeding by whiteflies produces sticky
honeydew on the leaves. Sooty mold may grow on the excreted honeydew. Artichoke
seedlings and transplants may be stunted by silverleaf whitefly feeding.
Fields planted down wind from other silverleaf whitefly hosts
may experience problems with this pest. Monitoring field margins and applying
spot treatments can effectively control this pest.
Plant your earliest artichokes at least one-half mile upwind from cotton
or melon fields. Destroy crop residues from these crops because they may harbor
whiteflies after harvest. Remove weeds that host the whitefly and the virus.
Present research indicates sprinklers may reduce whitefly populations and virus
wasps, including species in the Encarsia and Eretmocerus genera, parasitize whiteflies. Whitefly nymphs are
also preyed upon by bigeyed bugs, lacewing larvae, and lady beetles. Indigenous
parasites and predators and introduced parasites attack silverleaf whitefly, but
do not keep it below damaging numbers.
Organically Acceptable Methods
and biological controls, azadirachtin, or neem oil are acceptable for use on
organically certified crops.
Monitoring and Management Decisions
check field margins for whiteflies; these areas are usually infested first. Be
especially alert for rapid population buildup when nearby host crops are in
decline. During these critical periods, check artichoke fields twice weekly.
Sticky traps may be useful in detecting initial whitefly migrations into
fields. Allow beneficials an opportunity to control light whitefly
infestations. If higher populations are present at the field margins than the
field centers, then treat only the field margins. This approach will reduce
treatment costs and help preserve beneficials in the field. Thresholds are not
available for silverleaf whitefly in artichoke.
Whitefly control with insecticides is maximized by thorough
spray coverage. Ground application may give more complete coverage than air.
|When choosing a pesticide, consider
information relating to impact on natural enemies and
honey bees and to the environment.
||(Brigade) 2 EC
||6.4 fl oz
||MODE OF ACTION GROUP NUMBER1: 3
||COMMENTS: Do not exceed 0.5 lb a.i./acre/season.
||MODE OF ACTION GROUP NUMBER1: 18B
||MODE OF ACTION: Unknown. A botanical insecticide.
||COMMENTS: Thorough coverage is important; apply in a minimum of 75 gal water/acre.
UC IPM Pest Management Guidelines: Artichoke
UC ANR Publication 3434
M. A. Bari, Artichoke Research Foundation, Salinas
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgment for contributions to Arthropods:
W. E. Chaney, UC Cooperative Extension, Monterey County
W. L. Schrader, UC Cooperative Extension, San Diego County
L. Handel and T. K. Shannon, Kleen Globe, Inc., Castroville, CA
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