How to Manage Pests

UC Pest Management Guidelines

DAMAGE
Heavy feeding by the soft brown scale reduces tree vigor, kills twigs, and reduces yields. Sooty mold grows on excreted honeydew and may affect fruit grade. The honeydew also attracts ants, which interfere with the biological control of a number of pests.

MANAGEMENT
Management of brown soft scale focuses on preserving its natural enemies and controlling ants. Avoid the repeated use of organophosphates and carbamates, especially formetanate hydrochloride (Carzol), for the control of other pests; instead use sabadilla (Veratran), abamectin, or spinosad to control citrus thrips and Bacillus thuringiensis or cryolite for orangeworms in spring. Individual treatment of this scale is rarely necessary. If natural enemies do not control the scales, a spot treatment with an oil spray is usually sufficient.

Biological Control
The most effective parasite of brown soft scale is Metaphycus luteolus, which destroys the scale in its early instars before it can reproduce or cause substantial injury. In addition, the lady beetles Rhyzobius (Lindorus) lophanthae, Chilocorus orbus, and C. cacti prey on brown soft scales. Ants will protect brown soft scale from parasitism and predation because they feed on the honeydew that soft scales produce. Maximizing parasitism by controlling and reducing ants is critical for brown soft scale control because pesticides are not very effective against this scale species.

Organically Acceptable Methods
Biological control and petroleum oil sprays are acceptable for use on organically certified citrus.

Monitoring and Treatment Decisions
Monitor brown soft scale from June through October when disruption of biological control may be a problem. Check the level of parasitism by looking for parasite exit holes and for developing parasites within the scale body.

Common name		Amount to Use	Minimum Days before Harvest+
(trade name)		(type of coverage)**
A.	NARROW RANGE OIL#	1.2–1.4 gal/100 gal (TC)	4 hours
	(415, 440)
	RANGE OF ACTIVITY: Broad (unprotected stages of insects and mites)
	PERSISTENCE: Short
	COMMENTS: To avoid phytoxicity problems, see timings for California red scale. Apply higher rate of narrow range oil in July or Aug. only. Narrow range 440 spray oil is preferable in the Central Valley during warmer months because of greater persistence, but risk of phytotoxicity increases. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
B.	CHLORPYRIFOS*
	(Lorsban) 4EC	0.5–0.75 pt/100 gal (TC)	See comments below
		...or...
		6–12 pt/acre (LV)
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Intermediate
	COMMENTS: For use on all varieties; however it may cause ridging on lemons. Apply thorough coverage spray in 1,200–1,600 gal/acre; do not apply during daylight hours of bloom period or exceed 12 pt/acre/application or 15 pt/acre/year of chlorpyrifos; no more than 2 applications/fruit year, and no closer than 30 days apart. Minimum period before harvest is 21 days for up to 7 pt/acre and 35 days above 7 pt/acre. Do not apply during Dec., Jan., or Feb. See label for additional restrictions. Rates greater than 8 pt/acre are allowed only in Fresno, Tulare, Kern, Kings, Stanislaus, and Madera Counties.
C.	CARBARYL*
	(Sevin) 80S	0.6 lb/100 gal (TC)	5
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Long
	COMMENTS: For use on all varieties. Do not exceed 25 lb/acre/application. May cause outbreaks of citrus red mite and citrus thrips.
D.	CARBARYL*
	(Sevin) 80S	0.4 lb/100 gal (TC)	5
	...PLUS...
	NARROW RANGE OIL	0.5–1.4 gal/100 gal
	(415, 440)
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Long
	COMMENTS: For use on all varieties. Reducing the rate of carbaryl increases survival of natural enemies. Reducing the rate of the oil reduces the risk of phytotoxicity, especially in warmer growing areas of the state. Do not apply during bloom or exceed 25 lb/acre/application. May increase citrus red mite populations. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval.
E.	METHIDATHION*
	(Supracide) 25WP	0.5–1 lb/100 gal (TC)	14
		...or...
		12–16 lb/acre (LV)	60
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Long
	COMMENTS: For use on all varieties. Do not apply during bloom or exceed 40 lb/acre/season or 2 applications/fruit year, 45 days apart for dilute (TC) sprays. Only 1 application allowed for LV treatments. Low-volume application is available under a Special Local Needs permit. Preferred timing is immediately postbloom before fruit becomes infested. May increase citrus red mite populations.
F.	METHIDATHION*
	(Supracide) 25WP	0.5 lb/100 gal (TC)	14
	...PLUS...
	NARROW RANGE OIL	0.5–1.4 gal/100 gal
	(415, 440)
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Long
	COMMENTS: For use on all varieties. Reducing the rate of methidathion increases survival of natural enemies. Reducing the rate of the oil reduces the risk of phytotoxicity, especially in warmer growing areas of the state. Do not apply during bloom or exceed 40 lb methidathion/acre/season or 2 applications/fruit year, 45 days apart. May increase citrus red mites. Caution: Serious hazards are associated with oil treatments to green lemons because of phytotoxicity after sweating; check label for preharvest interval. For lemons, do not exceed 10 pt/acre or apply more than once/season when tank mixed with oil.
G.	MALATHION 8 Spray	1–2 pt/100 gal (TC)	7
	RANGE OF ACTIVITY: Broad (insects and beneficial mites)
	PERSISTENCE: Intermediate
	COMMENTS: For use on all varieties.
**	TC - Thorough coverage uses 1,000–3,000 gal water or more/acre, depending on tree size.
	LV - Low-volume uses 20–100 gal water/acre.
+	Minimum days before harvest takes into account the California restricted entry interval and the federal preharvest interval and lists the longer interval. (See Table 1 Mandatory Intervals Between Application, Reentry and Harvest, and Hazards to Bees.)
*	Permit required from county agricultural commissioner for purchase or use.
#	Acceptable for use on organically grown produce.

PUBLICATION

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Insects, Mites, and Snails
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O’Connell, UC Cooperative Extension, Tulare Co.
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura Co.
C. E. Kallsen, UC Cooperative Extension, Kern Co.
D. R. Haviland, UC Cooperative Extension, Kern Co.
Acknowledgments for contributions to the insect, mite, and snail section:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
H. Griffiths, E. S. I., Corona, CA
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
T. Roberts, E. S. I., Corona, CA
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA

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