Apricot

Agricultural pest management


Herbicide Treatment Table

(Reviewed 10/14, updated 10/14)

In this Guideline: More about weeds in apricot:

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

UPDATED: 10/14
Calculate impact of pesticide on air quality
The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
PREPLANT
 
Preemergence (before weeds germinate)
A. PENDIMETHALIN
  (Prowl 3.3EC) 2–3.9 lb a.i. 24 365
  (Prowl H2O) 2–3.8 lb a.i. 24 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to soil in 10 gal/acre or more before planting and incorporate mechanically 2.5 inches deep. Use untreated soil to fill in around tree roots.
 
B. TRIFLURALIN 0.5–1 lb a.i. 12 0
  (Treflan)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Broadcast preplant in 5 to 40 gallons of water per acre. Trifluralin must be incorporated immediately after application to avoid loss of activity. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Controls many annuals and is helpful in suppressing perennial weeds. Residual period: 2–12 months.
 
Postemergence (after weeds emerge)
A. CLOVE OIL      
(Matran II)# (BurnOut II Concentrate) 5–8% dilution 0 0
(BurnOut II Concentrate) 3:1–2:1 mixing ratio (Water:BurnOut) 0 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Apply to actively growing weeds. Thorough coverage is important. Use 50 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
B. D-LIMONENE#      
(Avenger) 8% a.i. broadcast 4 up to first fruit set
11% a.i. spot treatment 4 7
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Do not exceed 8.5 gal of Avenger/acre per application. Thorough coverage is important. Use a minimum of 60 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
C. GLYPHOSATE      
  (Roundup UltraMax) 1–4 lb a.i. 4 17
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Apply with a shielded controlled applicator or with low-pressure flat fan nozzles. For annual weed control, use 1 lb/acre in 3 to 10 gal water. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to significantly improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the high label rate for control. May be used on young weeds in the planting row followed by planting into the dead weeds. As a result of the no-till effect, new weeds usually do not establish for a month or more. Do not use more than 10.6 lb per year.
 
NEWLY PLANTED ORCHARDS (non-bearing trees)
 
Preemergence
A. FLUMIOXAZIN
  (Chateau SW) 0.188–0.376 lb a.i. 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Apply in 10 or more gal water/acre to soil under trees when completely dormant. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 21 days. Can be mixed with other pre- or postemergence herbicides. It will not provide adequate control of emerged weeds, unless mixed with a postemergence herbicide. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Residual period: 3–6 months.
 
B. INDAZIFLAM
  (Alion) 0.0652–0.0848 lb a.i. 12 14
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: For use in orchards established for at least 3 years. Apply in 20 to 40 gal water/acre to soil under trees when completely dormant. Best control is achieved when irrigation or rainfall occurs within 21 days. Controls a wide variety of annual broadleaves and annual grasses. Control may be reduced if weed seedlings have germinated and are about to emerge at time of treatment. Can be mixed with other pre- or postemergence herbicides. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Residual period: at least 5 months.
 
C. ISOXABEN 0.5–0.9975 lb a.i. 12 365
  (Trellis)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 21
  COMMENTS: For use in non-bearing orchards only. Wait until soil has settled around newly planted trees before applying. Controls broadleaf weeds only before they have germinated; will not control emerged weeds. If weeds are emerged, lightly cultivate or add a postemergence herbicide. Requires incorporation for activation, either by light cultivation (1–2 inches) or rainfall (minimum of 0.5 inches) within 21 days after application. Sprinkler or flood irrigation can also be used for incorporation. Apply in at least 10 gal/acre of water.
 
D. ORYZALIN 2–6 lb a.i. 24 0
  (Surflan, Oryzalin 4 A.S. etc.)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence selective herbicide for annual grasses. Apply to the soil surface in 20 to 40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5 to 2 inches of water. May be combined with a postemergence herbicide if weeds are present. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Most effect on annual grasses and numerous broadleaf annuals. Very safe for young or newly planted trees and on sandy or sandy loam soils. Used to maintain control in strips down the row. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 4–10 months.
 
E. PENDIMETHALIN      
  (Prowl 3.3EC) 2–3.9 lb a.i. 24 365
  (Prowl H2O) 2–3.8 lb a.i. 24 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Prowl 3.3 EC is for use on dormant non-bearing trees only, while Prowl H20 can be used on dormant bearing or non-bearing plantings. Apply in 10 or more gal water/acre to soil under trees. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Where the 3.3 EC formulation is used, best control is achieved when irrigation or rainfall occurs within 7 days. Prowl H20 can remain on the soil surface for up to 21 days before rainfall is required to activate it. Will not control emerged weeds. Residual period: 4–10 months
 
F. RIMSULFURON 0.03 lb a.i. 4 14
  (Matrix SG)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 2
  COMMENTS: For use in orchards established at least 1 year. Apply in 20 to 40 gal water/acre to soil under trees. Controls a variety of annual broadleaves and grasses. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made, treating 50% or less of an orchard, a second application can be made. Will suppress emerged weeds, including nutsedge. Residual period: 4–10 months.
 
H. TRIFLURALIN 1–2 lb a.i. 12 0
  (Treflan)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence selective herbicide for annual grasses. Apply prebloom by ground as a directed spray and mechanically incorporate, taking care not to injure the trees with the incorporation. Must be incorporated immediately after application to avoid loss of activity. Used on new plantings or established orchards as a strip treatment. Suppresses bermudagrass, johnsongrass, and dallisgrass rhizomes. Only one application per year. Residual period: 2–12 months.
 
Postemergence
A. CARFENTRAZONE 0.008–0.031 lb a.i. 12 3
  (Shark EW)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: A postemergence, contact herbicide used for quick top kill of many broadleaf weed species. Can be applied anytime during the season, but if fruit are present, it should either be avoided or applied with extreme care to avoid drift. It can also be used for sucker control. Apply in a minimum of 20 gal water/acre to weeds less than 6 inches tall. Repeat treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.124 lb a.i./acre per season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or methylated seed oil (MSO) surfactant.
 
B. CLETHODIM
  (SelectMax) 0.095–0.125 lb a.i. 24 365
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use on non-bearing trees only. Apply to young perennial grasses. Repeat applications will be required for the control of perennial grasses. Apply in 5 to 40 gal water/acre. Add 0.25% volume per volume nonionic surfactant to the spray solution. Spray pressure should be between 30 and 60 psi, with higher pressures used when weed density is high. Do not apply a broadleaf herbicide within one day following application or reduced grass control may occur. Residual period: less than one month.
 
C. CLOVE OIL
  (Matran II)# 5–8 % dilution 0 0
(BurnOut II Concentrate) 3:1–2:1 mixing ratio (Water:BurnOut) 0 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Apply to actively growing weeds. Thorough coverage is important. Use a minimum of 60 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
D. D-LIMONENE#
  (Avenger) 8 % a.i. broadcast 4 up to first fruit set
11 % a.i. spot treatment 4 7
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Do not exceed 8.5 gal of Avenger /acre per application. Thorough coverage is important. Use a minimum of 60 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
E. PYRAFLUFEN ETHYL 0.0013–0.0053 lb a.i. 12 Prebloom
  (Venue)      
  WSSA MODE-OF-ACTION GROUP NUMBER: 14
  COMMENTS: Must be tank mixed with another foliar active broadleaf herbicide for complete control of most broadleaf weeds. For best results, use for control of annual or perennial herbaceous broadleaf weeds less than 4 inches in height or rosettes less than 3 inches in diameter. Use the higher rates and spray volumes for control of larger weeds; control may be reduced with weeds larger than 4 inches.
 
G. SETHOXYDIM 0.19–0.47 lb a.i. 12 25
  (Poast)      
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to young perennial grasses in non-bearing orchards only. Repeat applications will be required for the control of perennial grasses. Add 2 pt/acre of a nonphytotoxic crop oil concentrate to the spray solution. Residual period: less than one month.
 
ESTABLISHED ORCHARDS
 
Preemergence
A. FLUMIOXAZIN
  (Chateau SW) 0.188–0.376 lb a.i. 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Apply in 10 or more gal water/acre to soil under trees when completely dormant. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 21 days. Can be mixed with other pre- or postemergence herbicides. It will not provide adequate control of emerged weeds, unless mixed with a postemergence herbicide. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Residual period: 3–6 months.
 
B. INDAZIFLAM      
  (Alion) 0.0652–0.0848 lb a.i. 12 14
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: For use in orchards established for at least 3 years. Apply in 20 to 40 gal water/acre to soil under trees when completely dormant. Best control is achieved when irrigation or rainfall occurs within 21 days. Controls a wide variety of annual broadleaves and annual grasses. Control may be reduced if weed seedlings have germinated and are about to emerge at time of treatment. Can be mixed with other pre- or postemergence herbicides. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Residual period: at least 5 months.
 
C. NORFLURAZON 1.97–3.93 lb a.i. 12 60
  (Solicam DF)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 12
  COMMENTS: Similar to oryzalin but is effective on more annual broadleaf and grass species. It can suppress yellow nutsedge or bermudagrass when used year-after-year. Apply to soil as a directed spray from fall to early spring under trees established for at least 1.5 years. If no rainfall occurs within 4 weeks, incorporate with sprinkler or flood irrigation. Remove existing weeds with cultivation or a postemergence herbicide, because it has no postemergence activity. Avoid higher rates on sandy or gravelly soils to prevent injury to trees. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Do not use in the Coachella Valley. Apply in 20 to 100 gal water/acre. Residual period: 6–12 months.
 
D. ORYZALIN 2–6 lb a.i. 24 0
  (Surflan, Oryzalin 4A.S. etc.)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to the soil surface in 20 to 40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5 to 2 inches of water. Most effect on annual grasses and numerous broadleaf annuals. Very safe for sandy or sandy loam soils. Used to maintain control in strips down the row. May be combined with a postemergence herbicide if weeds are present. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 4–10 months.
 
E. OXYFLUORFEN 0.5–2.0 lb a.i. 24 0
  (Goal 2 XL, GoalTender, etc.)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant trees only. Apply following harvest up to February 15 (February 1 in the Coachella Valley). Apply by ground one time per season in 40 to 100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre- and postemergence herbicide. Effective on little mallow (cheeseweed). Useful combined with other postemergence herbicides, such as glyphosate, or in combination with preemergence herbicides, such as oryzalin or thiazopyr. Both formulations have similar effectiveness when used preemergence and at comparable rates. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Check label for use period. Residual period: 4–10 months.
 
F. PRONAMIDE* 1–4 lb a.i. 24 0
  (Kerb)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Do not apply to trees less than 1 year old. Selective herbicide for control of winter annual and perennial grasses. Apply in fall after fruit harvest. Apply in 40 to 50 gal water/acre to the soil at the base of the trees. Must be applied before weed emergence because it will not control emerged weeds. Rainfall or irrigation is essential after application for effective weed control. Residual period: 4–8 months.
 
G. RIMSULFURON 0.03 lb a.i. 4 14
  (Matrix SG)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 2
  COMMENTS: For use in orchards established at least 1 year. Apply in 20 to 40 gal water/acre to soil under trees. Controls a variety of annual broadleaves and grasses. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made, treating 50% or less of an orchard, a second application can be made. Will suppress emerged weeds, including nutsedge. Residual period: 4–10 months.
 
H. TRIFLURALIN 1–2 lb a.i. 12 0
  (Treflan, etc.)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence selective herbicide for annual grasses. Apply prebloom by ground as a directed spray and mechanically incorporate, taking care not to injure the tree. Must be incorporated immediately after application to avoid loss of activity. Frequently used as a strip treatment. Suppresses bermudagrass, johnsongrass, and dalligrass rhizomes. Only one application per year. Residual period: 2–12 months.
 
Postemergence
A. 2,4–D* 0.95–1.425 lb a.i. 48 40
  (Saber)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 4
  COMMENTS: For use on established trees one year or older. Effective on most broadleaf annual weeds. Provides partial control of field bindweed. Apply as a directed spray to weeds, using low-pressure, flooding nozzles between the tree rows. Best results are obtained when applied a few days after an irrigation. Do not allow drift onto the trees or injury may result. No more than two applications allowed during the growing season. Residual period: 4–6 weeks.
 
B. CARFENTRAZONE 0.008–0.031 lb a.i. 12 3
  (Shark EW)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: A postemergence, contact herbicide used for quick top kill of many broadleaf weed species. Can be applied anytime during the season, but if fruit are present, it should either be avoided or applied with extreme care to avoid drift. It can also be used for sucker control. Apply in a minimum of 20 gal water/acre to weeds less than 6 inches tall. Repeat treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.124 lb a.i./acre per season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or methylated seed oil (MSO surfactant).
 
C. CLOVE OIL
  (Matran II)# 5–8% dilution 0 0
(BurnOut II Concentrate) 3:1–2:1 mixing ratio (Water:BurnOut) 0 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Apply to actively growing weeds. Thorough coverage is important. Use 50 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
D. D-LIMONENE#
  (Avenger) 8%a.i. broadcast 4 up to first fruit set
11% a.i. spot treatment 4 7
  WSSA MODE-OF-ACTION GROUP NUMBER1: Unknown. Botanical herbicide.
  COMMENTS: Do not exceed 8.5 gal of Avenger/acre per application. Thorough coverage is important. Use a minimum of 60 gal/acre spray volume. The addition of an organically approved adjuvant improves coverage and weed control.
 
E. FLUAZIFOP-P-BUTYL 0.125–0.188 lb a.i. 12 14
  (Fusilade DX)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For control of annual and perennial grass weeds. A crop oil concentrate at 0.5 to 1% volume per volume or a nonionic surfactant at 0.25 to 0.5% volume per volume must be added to the spray solution. In areas with hard water, it may be necessary to acidify the water before adding the herbicide and surfactant. Avoid contact of spray with foliage of trees. Apply in 5 to 40 gal water, with spray pressures of 30 to 60 psi. Best results are obtained when applied within 7 days after irrigation. Do not apply to grass that is stressed or poor control may result. Apply to johnsongrass when it is between 8 to 18 inches in height. Repeat applications may be required for johnsongrass and bermudagrass. Residual period: less than 1 month.
 
F. GLYPHOSATE
  (Roundup UltraMax) 1–4 lb a.i. 4 17
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Apply with a shielded controlled droplet application or with low-pressure, flat-fan nozzles. For annual weed control, use 1 lb a.i./acre in 3 to 10 gal water. Ammonium sulfate should be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. For chemical mowing, consult label for exact timing and rates, depending on weed size and species. Apply to young annuals or vigorously growing perennials. Some perennials require the high label rate for control. A good herbicide for perennial weeds, but doesn't eradicate field bindweed or nutsedge. Not effective on some broadleaf weeds at older stages of growth (little mallow and filaree). Avoid drift onto green bark or foliage of tree or injury will result. It is important to monitor treated areas for escaped weeds, as glyphosate resistant weeds have been observed in orchards where glyphosate has been used repeatedly for several years.
 
G. OXYFLUORFEN
  (Goal 2 XL GoalTender, etc.) 0.5–2.0 lb a.i. 24 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Dormant application to young (4-leaf-stage) weeds. GoalTender 4F has less activity than Goal 2XL when used as a postemergence treatment, so higher rates may need to be used with this formulation. It is effective on little mallow (cheeseweed) and filaree. Useful when combined with glyphosate or oryzalin. May be combined with other postemergence herbicides for specific weeds. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i. Apply following harvest up to February 15 (February 1 in the Coachella Valley). Apply by ground one time per season in 40 to 100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre-and postemergence herbicide. Residual period: 4–10 months.
 
H. PARAQUAT*
  (Gramoxone Inteon) 0.625–1.0 lb a.i. 24 28
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Nonselective postemergence, contact herbicide used for quick top kill of most weed species. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass and field bindweed). Most effective when used in late winter or early spring on small annual grass species in combination with preemergence herbicides. Apply in 10 to 60 gal water/acre to young weeds. Use 0.25% volume per volume nonionic surfactant or 1.0% volume per volume of a crop oil concentrate. Repeat treatment as new growth occurs. Do not exceed three applications per season.
 
I. PYRAFLUFEN ETHYL
  (Venue) 0.0013–0.0053 lb a.i. 12 Prebloom
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Must be tank mixed with another foliar active broadleaf herbicide for complete control of most broadleaf weeds. For best results, use for control of annual or perennial herbaceous broadleaf weeds less than 4 inches in height or rosettes less than 3 inches in diameter. Use the higher rates and spray volumes for control of larger weeds; control may be reduced with weeds larger than 4 inches.
* Permit required from county agricultural commissioner for purchase or use.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
1 Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode of action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433

Weeds

K. J. Hembree, UC Cooperative Extension, Fresno County

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2016 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/r5700411.html revised: April 15, 2016. Contact webmaster.