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How to Manage Pests
UC Pest Management Guidelines
Cucurbits
Beet Armyworm
Scientific Name: Spodoptera exigua
(Reviewed 12/09,
updated 12/09)
In this Guideline:
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Larvae are usually dull green and have wavy,
light-colored stripes running lengthwise down the back and broader stripes on
each side. Eggs are laid in a mass covered with hairlike
scales.
Primarily a foliage feeder, the beet armyworm will also attack
fruit, creating single or closely grouped circular or irregular holes. In many
cases, feeding is superficial and little loss would result if not for decay
organisms that enter wounds and rot fruit. The caterpillars occasionally
develop inside the fruit.
While populations of this pest tend to build up in alfalfa and weedy areas
around the field, beet armyworm only needs to be controlled if it is feeding on
the crop. Keep crop residue and weeds in field and surrounding areas to a
minimum to lessen the attraction of the field.
Biological Control
The parasitic wasp, Hyposoter exiguae, is important in controlling
populations of this pest. Beet armyworm larvae can be easily checked for the
presence of this wasp by pulling the larva apart and looking for the parasite larva.
Organically Acceptable Methods
Sanitation in the field and surrounding areas along with biological
control and sprays of Bacillus thuringiensis or the Entrust formulation
of spinosad are acceptable to use in an organically certified crop.
Monitoring and Treatment Decisions
Beet armyworm may be present in and around the field feeding on bindweed and little mallow (malva). Monitor foliage
for small larvae and treat before fruit damage occurs. Treat only if armyworm
feeding is observed on fruit.
| Common name |
Amount/Acre |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
|
| The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, pesticide registrations, information related to natural enemies and honey bees, and environmental impact. Not all
registered pesticides are listed. Always read label of product being used. |
| |
| A. |
SPINETORAM |
| |
(Radiant) SC |
5–10 fl oz |
4 |
see comments |
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MODE OF ACTION GROUP NUMBER1: 5 |
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COMMENTS: PHI for cucumbers is 1 day and for other cucurbits 3 days. |
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| B. |
SPINOSAD |
| |
(Entrust)# |
1.25–2.5 oz |
4 |
see comments |
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(Success) |
4–8 fl oz |
4 |
see comments |
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MODE OF ACTION GROUP NUMBER1: 5 |
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COMMENTS: Time spray to target eggs at hatch or small larvae.
Do not apply more than 9 oz Entrust or 29 fl oz of Success/acre/season. PHI for cucumbers is 1 day and for other cucurbits 3 days. |
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| C. |
CHLORANTRANILIPROLE |
| |
(Coragen) |
3.5–5 fl oz |
4 |
1 |
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MODE OF ACTION GROUP NUMBER1: 28 |
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| D. |
METHOXYFENOZIDE |
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(Intrepid) 2F |
4–10 fl oz |
4 |
3 |
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MODE OF ACTION GROUP NUMBER1: 18A |
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COMMENTS: Time spray to target eggs and small larvae. Use allowed under a supplemental label. |
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| E. |
BACILLUS THURINGIENSIS ssp. AIZAWAI# |
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MODE OF ACTION GROUP NUMBER1: 11.B1 |
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(various products) |
Label rates |
4 |
0 |
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COMMENTS: Use to control small armyworms only (first and
second instar) when populations are light and full coverage sprays are
applied. Repeat treatment as necessary. If mature larvae or heavy populations are present, use another material. |
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| F. |
INDOXACARB |
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(Avaunt) |
3.5 oz |
12 |
3 |
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MODE OF ACTION GROUP NUMBER1: 22 |
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| G. |
METHOMYL* |
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(Lannate) 90SP |
0.5–1 lb |
48 |
see comments |
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(Lannate) LV |
1.5–3 pt |
48 |
see comments |
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MODE OF ACTION GROUP NUMBER1: 1A |
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COMMENTS: For use on cucumbers, melons and summer squash only.
PHI is 1 day when 0.5 lb or less for 90SP or 1.5 pt or less for LV formulations is used; when more than 0.5 lb (90SP) or 1.5 pt (LV) is used, PHI is 3 days. |
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UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
C. S. Stoddard, UC Cooperative Extension, Merced & Madera counties
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
L. D. Godfrey, Entomology, UC Davis
C. B. Fouche, UC Cooperative Extension, San Joaquin County
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties
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