How to Manage Pests

UC Pest Management Guidelines

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)	Chemical class1	Mode of Action2	Selectivity3 (affected groups)	Predatory mites4	General predators5	Parasites5	Honey bees6	Duration of impact to natural enemies7
abamectin (Agri-Mek)	M	6	moderate (mites, leafminers)	H	L	M/H	II	long to predatory mites and affected insects
Bacillus thuringiensis ssp. aizawai	M	11.B1	narrow (caterpillars)	L	L	L	IV	short
Bacillus thuringiensis ssp. kurstaki	M	11.B2	narrow (caterpillars)	L	L	L	IV	short
bifenazate (Acramite)	CE	25	narrow (spider mites)	L	L	L	IV	short
bifenthrin (Capture)	P	3	broad (insects, mites)	H	H	H	I*	long
carbaryl (Sevin) bait	C	1A	narrow (cutworms, army-worms, grasshoppers, etc.)	L	L	L	IV	short
carbaryl (Sevin) 4F, 80	C	1A	broad (insects, mites)	L/H	H	H	I	long
carbaryl (Sevin) XLR Plus	C	1A	broad (insects, mites)	L	H	L	III	long
chlorpyrifos (Lorsban) seed trt.	OP	1B	narrow (soil insects)	L	L	L	IV	none
cryolite (Kryocide)	I	9A	narrow (foliage chewing insects)	L	L	L	IV	short to none
cyromazine (Trigard)	TZ	17	narrow (leafminers)	L	L	L	III	none
diazinon–foliar	OP	1B	broad (insects, mites)	L	H	H	I	moderate to long
diazinon–granular	OP	1B	narrow (soil insects)	L	L	L	IV	short
dicofol (Kelthane)	—	20	narrow (pest mites and mites)	H	M	M	IV	long to beneficial mites
dimethoate	OP	1B	broad (insects, mites)	H	H	H	I	long
endosulfan (Thionex, Thiodan)	OC	2A	broad (insects, mites)	L	M	M	II*	short
esfenvalerate (Asana)	P	3	broad (insects, mites)	H	M	H	I*	moderate
imidacloprid (Admire)	N	4A	narrow (sucking insects, beet armyworm, cutworms)	—	L	L	II	—
malathion	OP	1B	broad (insects, mites)	H	H	H	II	moderate
methomyl (Lannate)	C	1A	broad (insects, mites)	H	H	H	III	moderate
methoxyfenozide (Intrepid)	IGR	18	narrow (caterpillars)	L	L	L	IV	none
oxamyl (Vydate)	C	1A	broad (insects, mites)	H	H	H	III*	moderate
oxydemeton-methyl (Metasystox-R)	OP	1B	narrow (sucking insects, mites)	H	H	H	III	moderate
paraffinic oil (JMS Stylet Oil)	CON	—	broad (exposed insects, mites)	L	L	L	III	short to none
permethrin (Ambush bait)	P	3	narrow (cricket, cutworms, grasshoppers)	—	—	—	—	—
petroleum oil	CON	—	broad (exposed insects, mites)	L	L	L	III	short to none
pymetrozine (Fulfill)	PY	9B	narrow (aphids, whiteflies)	L	L	L	III	short
rosemary oil (Hexacide)	B	—	broad (exposed insects, mites)	L	L	L	IV	—
soaps	CON	—	broad (exposed insects, mites)	M	M	M	IV	short to none
spinosad (Entrust, Success)	M	5	narrow (caterpillars, thrips, whiteflies, aphids, leafminers)	L	M8	L/M	III	short to moderate
spiromesifen (Oberon)	—	23	narrow (whiteflies, mites)	—	—	—	—	—
sulfur	I	—	narrow (mites and citrus thrips)	L/H	M/L	H	IV	short
thiamethoxam (Platinum)	N	4A	narrow (sucking insects)	—9	—	M	I	moderate
H = high M = moderate L = low — = no information   1 Chemical class: B = botanical; C = carbamate; CE = carboxylic acid ester; CON = contact including smothering and barrier effect; I = inorganic; IGR = insect growth regulator; M = microbial; N = neonicotinoid; OC = organochlorine; OP = organophosphate; P = pyrethroid; PY = pymetrozine; TZ = triazine 2 Modes of action are important in preventing the development of resistance to pesticides. 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. 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 is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. 3 Selectivity: broad means it affects most groups of insects and mites; narrow means it affects only a few specific groups. 4 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. 5 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. 6 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. If marked with an asterisk (*), the rating is the next higher rating for lower label rates. For more information, see How to Reduce Bee Poisoning From Pesticides, Pacific Northwest Extension Publication PNW518. 7 Duration: short means hours to days; moderate means days to 2 weeks; and long means many weeks or months. 8 Toxic against some natural enemies (predatory thrips, syrphid fly larva) when sprayed and shortly after (8-24 hrs.). 9 May causes increase in spider mite populations.

PUBLICATION

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Relative Toxicities of Pesticides Used in Cucurbits to Natural Enemies and Honey Bees
Acknowledgments: This table was compiled based on research data and experience of University of California scientists working on a variety of crops.

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