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UC Pest Management Guidelines

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Cucurbits

Relative Toxicities of Pesticides Used in Cucurbits to Natural Enemies and Honey Bees

(Reviewed 12/09, updated 12/09)

In this Guideline:

Cucurbits depend on bees for successful pollination. In addition, beneficial insects and mites play a key role in maintaining populations of aphids, leafminers, and spider mites below economically damaging levels. They also are instrumental in controlling populations of whiteflies, armyworms, and loopers. Some insecticides and miticides used in cucurbits are toxic to these beneficials and must be used with extreme care to minimize destruction of natural enemy populations. To ensure survival of natural enemies, use Bacillus thuringiensis (Dipel, Javelin, Biobit, etc.) or soft contact chemicals such as soaps and oils in the early plant stages, if needed, rather than harsh disruptive materials (pyrethroids, organophosphates, and carbamates). To protect honey bees, do not use moderate-to-highly toxic materials when the crop is in bloom and bees are in the field. The following table outlines the general toxicity of cucurbit pesticides to beneficial organisms.

Common name (trade name) Mode of Action1 Selectivity2 (affected groups) Predatory Mites3 General Predators4 Parasites4 Honey bees5 Duration of impact to natural enemies6
abamectin (Agri-Mek EC) 6 moderate (mites, leafminers) M L M/H I7 moderate to predatory mites and affected insects
acetamiprid (Assail) 4A moderate (sucking insects, larvae) —8 — — III moderate
Bacillus thuringiensis ssp. aizawai 11.B1 narrow (caterpillars) L L L IV short
Bacillus thuringiensis ssp. kurstaki 11.B2 narrow (caterpillars) L L L IV short
bifenazate (Acramite) 25 narrow (spider mites) L L L III short
bifenthrin (Capture) 3 broad (insects, mites) H H H I-III9 long
buprofezin (Courier) 16 narrow (sucking insects, beetles) L H15 L IV long
carbaryl (Sevin) bait 1A narrow (cutworms, army-worms, grasshoppers, etc.) L L L IV short
carbaryl (Sevin) 4F 1A broad (insects, mites) M/H H H I10 long
carbaryl (Sevin XLR Plus) 1A broad (insects, mites) L H H I11 long
chlorantraniliprole (Coragen) 28 narrow (primarily caterpillars) L L L/M IV short
cryolite (Kryocide) 9A narrow (foliage chewing insects) L L L IV short
cyromazine (Trigard) 17 narrow (leafminers) L L L III short
diazinon (WP, EC) 1B broad (insects, mites) L H H I moderate to long
dicofol (Kelthane) UNC narrow (pest mites and mites) H M M IV long to beneficial mites
dimethoate 1B broad (insects, mites) H H H I long
dinotefuran (Venom) 4A narrow (sucking insects) L — L — short
endosulfan (Thionex) 2A broad (insects, mites) L M M II12 moderate
esfenvalerate (Asana) 3 broad (insects, mites) H M H I7 moderate
imidacloprid (Admire) 4A narrow (sucking insects, beet armyworm, cutworms) — L — I13 —
indoxacarb (Avaunt) 22 narrow (caterpillars) L L L III moderate
malathion (EC) 1B broad (insects, mites) M H H II moderate
methomyl (Lannate) 1A broad (insects, mites) H H H III moderate
methoxyfenozide (Intrepid) 18A narrow (caterpillars) L L L IV short
oxamyl (Vydate) 1A broad (insects, mites) H H H II12 moderate
oxydemeton-methyl (Metasystox-R) 1B narrow (sucking insects, mites) H H H III moderate
paraffinic oil (JMS Stylet Oil) — broad (exposed insects, mites) L L L III short
pyrethrin (PyGanic) 3 broad (insects) — M M III short
petroleum oil — broad (exposed insects, mites) L14 L L III short
pymetrozine (Fulfill) 9B narrow (aphids, whiteflies) L L L III short
pyriproxifen (Knack) 7C narrow (aphids, whiteflies) L H15 L IV short
rosemary oil (Hexacide) — broad (exposed insects, mites) L L L IV —
soaps — broad (exposed insects, mites) M M M IV short
spinetoram (Radiant) 5 narrow (caterpillars, thrips, whiteflies, aphids, leafminers) L/M M16 L/M III moderate17
spinosad (Entrust, Success) 5 narrow (caterpillars, thrips, whiteflies, aphids, leafminers) L/H M16 L/M III short to moderate
spiromesifen (Oberon SC) 23 narrow (whiteflies) — — — — —
sulfur — narrow (mites, thrips) L/H M/L H IV short  
thiamethoxam (Actara) 4A narrow (sucking insects) —18 — M I moderate
H = high M = moderate L = low — = no information
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
2 Selectivity: broad means it affects most groups of insects and mites; narrow means it affects only a few specific groups.
3 Generally, toxicities are to western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain/native strain.
4 Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific chemical depends on the species of predator or parasite, environmental conditions, and application rate.
5 Ratings are as follows: I-Do not apply to blooming plants; II-Apply only during late evening; III-Apply only during late evening, night, or early morning; and IV-Apply at any time with reasonable safety to bees. For more information, see How to Reduce Bee Poisoning From Pesticides (700 KB, PDF), Pacific Northwest Extension Publication PNW591.
6 Duration: short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
7 If rate is 0.025 lb a.i./acre, rating is II.
8 May cause flare-ups of spider mite populations.
9 If rate is less than 0.04 lb a.i./acre, rating is III; if 0.04 lb a.i./acre, rating is II; if 0.06 lb a.i./acre, rating is I.
10 If rate is 1 lb a.i./acre or less, rating is II.
11 If rate is 1.5 lb a.i. or less and dilution not greater than 1:19, rating is II.
12 If rate is 0.5 lb a.i./acre or less, rating is III.
13 If rate is 0.025 lb a.i./acre, rating is II.
14 Rating depends on rate used.
15 Kills lady beetles.
16 Toxic against some natural enemies (predatory thrips, syrphid fly and lacewing larvae, beetles) when sprayed and up to 5-7 days after, especially for syrphid fly larvae.
17 Residual is moderate if solution is between pH of 7 to 8.
18 May cause increase in spider mite populations.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
General Information
Acknowledgements: This table was compiled based on research data and experience of University of California scientists who work on a variety of crops and contribute to the Pest Management Guideline database, and from Flint, M. L. and S. H. Dreistadt. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386.

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