How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

The two species Empoasca fabaeand E. solana constitute over 90% of the Empoasca species found in sugarbeet. They are nearly identical morphologically and can only be distinguished by experts. The damage they cause is also nearly identical as are the treatment guidelines.

Empoasca leafhoppers are small (0.125 inch long), bright green, wedge-shaped insects. They may be distinguished from the green form of beet leafhopper by the lack of dark markings on the body. The small, wingless nymphs (immatures) are also wedge shaped and green and move rapidly forward, backward, and from side to side. Both adults and immatures are found primarily on the underside of leaves.

DAMAGE

Empoasca leafhoppers cause a symptom known as hopperburn in which the leaf margins turn yellow, particularly at the leaf tip, and these areas soon become necrotic. The entire leaf may become yellowed and the symptoms often resemble virus symptoms. The presence of adult and immature leafhoppers on the undersurface of the leaf serve to distinguish leafhopper injury from virus symptoms or mineral deficiencies. Empoasca leafhoppers do not spread beet curly top virus.

MANAGEMENT

Sample for Empoasca leafhoppers by counting the number of adults and nymphs per leaf. Examine a minimum of 10 leaves from 10 plants in at least four areas of the field. Pick fully expanded leaves, avoiding older leaves or leaves in contact with the ground. Also, select leaves that are shaded by other leaves because leafhoppers try to avoid the sun. Leafhoppers are found on the under surface of the leaf, so turn the leaf over and QUICKLY count the number of leafhoppers; both adults and immatures can run very fast so you must be quick. Before starting your actual count, look at and count three to four leaves so that you will know what the leafhoppers look like, particularly the small ones, and how they behave. Then begin your sampling and actual counts.

Apply treatments when leafhoppers (both nymphs and adults) reach 10 to 15 per leaf. Use the lower number for fields 2 to 3 months up to several months from harvest. Use the higher number for fields within 1 to 2 months of harvest. Do not treat if fields are within 2 to 3 weeks of harvest.

Common name		Amount/Acre	P.H.I.+
(trade name)			(days)
When choosing a pesticide, consider information relating to water quality and impact on natural enemies and bees.
A.	PHORATE*
	(Thimet) 20G	4.5 oz/1000 ft. row	30
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Do not feed tops to livestock. Do not place Thimet granules in contact with seed.
B.	OXYDEMETON-METHYL*
	(Metasystox-R) SC	1.5-3 pt	30-tops and roots
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: No more than 2 applications/year.
C.	NALED*
	(Dibrom 8)	1 pt	2
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
D.	ESFENVALERATE*
	(Asana XL)	5.8-9.6 fl oz	21
	MODE OF ACTION: A pyrethroid (Group 3)1 insecticide.
+	Preharvest interval. Do not apply within this many days of harvest.
*	Permit required from county agricultural commissioner for purchase or use.
1	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/.

PUBLICATION

UC IPM Pest Management Guidelines: Sugarbeet
UC ANR Publication 3469
Insects and Mites
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, Kern Co.
L. D. Godfrey, Entomology, UC Davis

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