Pear

Agricultural pest management


Johnsongrass, Sorghum halepense.

Herbicide Treatment Table

(Reviewed 11/12 , updated 11/12 )

In this Guideline: More about weeds in pear:

Common name   R.E.I.+ P.H.I.+
(trade name) Amount/Acre (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
 
PREPLANT
Postemergence (after weeds emerge)
A. GLYPHOSATE 0.38–3.7 lb a.e. 4 1
  (Roundup WeatherMax, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: Apply with a controlled applicator or with low-pressure flat fan nozzles. For annual weed control, use 1 lb/acre in 3–10 gal water. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lb 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 3.7 lb a.e./acre rate of glyphosate for control. May be used to kill young weeds in the planting row before planting. 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. Resistance to glyphosate has been documented in certain weed species. Residual period: none.
 
POSTPLANT
Preemergence
A. DICHLOBENIL 4–6 lb a.i. 12 0
  (Casoron 4G)
  WSSA MODE OF ACTION GROUP NUMBER1: 20
  COMMENTS: Apply to soil under trees. Do not apply on young trees until 1 month after planting. Do not apply within 1 month of harvest. For best results, incorporate and follow with 1/2 to 1 inch of water or an immediate shallow cultivation. Dichlobenil can be very effective in controlling perennial weeds around sprinkler heads. Residual period: 4–6 months.
 
B. DIURON 1.6–3.2 lb a.i. 12 0
  (Karmex, Direx, Diuron)
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: Apply to the soil under trees at least 3 years of age. A single application may be made in winter or split applications between fall and spring. Diuron is sometimes combined with other preemergence herbicides to broaden the spectrum of weeds controlled. These combination treatments frequently use lower rates of diuron. Adjust rates according to soil texture. Do not use on soils with less than 1% organic matter. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8–12 months.
 
C. FLUMIOXAZIN 0.188–0.376 lb a.i. 12 60
  (Chateau SW)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant nonbearing and bearing trees established for one year or more. 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. Use is allowed under a supplemental label. Avoid creating dust that can move flumioxazin up into the tree canopy. Flumioxazin should not be applied within 300 yards of actively growing (non-dormant) pears. Residual period: 3–6 months.
 
D. ISOXABEN 0.5–1.0 lb a.i. 12 365
  (Gallery T&V)
  WSSA MODE OF ACTION GROUP NUMBER1: 21
  COMMENTS: For use on non-bearing trees only. Wait until soil has settled around newly planted trees before applying. Controls broadleaf weeds only with a preemergence application and 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 to 2 inches) or rainfall (minimum of 0.5 inch) within 21 days after application. Sprinkler or flood irrigation can also be used for incorporation. Apply in at least 10 gal/acre of water. Residual period: 4–6 months.
 
E. NORFLURAZON 2.0–3.9 lb a.i. 12 60
  (Solicam DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 12
  COMMENTS: Effective on annual broadleaf and grass species. 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 2 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. Apply in 20–100 gal water/acre. Residual period: 6–12 months.
 
F. 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 primarily for annual grass control. Apply to the soil surface in 20–40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5–2 inches of water. May be combined with a postemergence herbicide if weeds are present. 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. If Surflan was used previously in the field with regularity, stunting of newly planted trees has been observed. Residual period: 4–10 months.
 
G. OXYFLUORFEN 0.5–2 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Apply in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Often combined with oryzalin. Check label for use period. Do not use after February 15 to avoid phytotoxicity to foliage and fruit. Residual period: 2–6 months.
 
H. PENDIMETHALIN 1.9–3.8 lb a.i. 24 60
  (Prowl H20, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: 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. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Residual period: 4–10 months.
 
I. 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 40–50 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.
 
J. RIMSULFURON
  (Matrix FNV) 0.03 lb a.i. 4 7
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: Apply in 10 or more gal water/acre to soil under trees. Apply only to trees that have been established for one full growing season. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made and 50% or less of an orchard is treated, a second application can be made. Will not control emerged weeds. Residual period: 4–10 months.
 
K. SIMAZINE 1–2 lb a.i. 12 0
  (Princep Caliber 90)
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Apply to the soil under trees older than 3 years. Make only one application per year. Use the high rate for heavy soils. Simazine is frequently used in combination with other preemergence herbicides. On light soils, simazine is often used at rates of 0.5–1 lb a.i./acre. Do not use on gravel, sand, or loamy sand soils. If irrigating immediately after application, limit water to 0.5 inch. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8–12 months.
 
Postemergence
A. 2,4–D* 0.95–1.4 lb a.e. 48 14
  (Orchard Master, etc.)
  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 or crop injury may result. No more than two applications allowed during the growing season. Residual period: none.
 
B. CARFENTRAZONE 0.008–0.03 lb a.i. 12 3
  (Shark)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Postemergence contact herbicide used for quick top kill of many broadleaf weed species. Apply anytime during the season, but if fruit is present, avoid use or apply with extreme care to avoid drift. Also 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 at least 14 days apart. Do not use more than 2 oz a.i./acre per season. Use 0.25% nonionic surfactant, 1.0% of a crop oil concentrate, or a silicone or MSO surfactant. Residual period: none.
 
C. CLETHODIM 0.07–0.12 lb a.i. 24 365
  (SelectMax)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Use on nonbearing trees only. Apply to young perennial grasses. Repeat applications will be required for control of perennial grasses. Apply in 10 to 40 gal water/acre. Add 0.25% nonionic surfactant to the spray solution. Spray pressure should be between 30 and 60 PSI, with higher pressures used when weed density is high and directed at the grasses (avoid applying over the tops of young trees). Do not apply a broadleaf herbicide within one day following application or reduced grass control may occur. Residual period: none.
 
D. FLUAZIFOP-P-BUTYL 0.25–0.375 lb a.i. 12 365
  (Fusilade DX)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Use on nonbearing trees only. Apply in 20 to 40 gal water/acre and add 0.5% nonionic surfactant. Do not apply to water-stressed grasses or poor control may result. Repeat applications may be required for johnsongrass and bermudagrass. Residual period: none.
 
E. GLYPHOSATE 0.82–3.3 lb a.e. 4 1
  (Roundup WeatherMax, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: Apply with controlled droplet application or with low-pressure, flat-fan nozzles. For annual weed control, use 1 lb a.i./acre in 3–10 gal water. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lb 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 4 lb a.i./acre rate of glyphosate 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 the herbicide has been used repeatedly for several years. Residual period: none.
 
F. OXYFLUORFEN 0.5–2 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Apply in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Often combined with oryzalin. Check label for use period. Do not use after February 15 to avoid phytotoxicity to foliage and fruit. Residual period: 2–6 months.
 
G. PARAQUAT* 0.625–1.0 lb a.i. 12 0
  (Gramoxone Inteon)
  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 10–60 gal water/acre to young weeds. Use 0.25% nonionic surfactant or 1.0% volume per volume of a crop oil concentrate. Repeat treatment as new growth occurs. Do not exceed 3 applications per season. Residual period: none.
 
H. SETHOXYDIM 0.19–0.47 lb a.i. 12 14
  (Poast)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to young perennial grasses. 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: none.
 
** Herbicide rates are expressed in lb a.i./acre. Always verify the concentration of the formulated herbicide product to ensure accurate and effective rates are used.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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 www.hracglobal.com.
* Permit required from county agricultural commissioner for purchase or use.
NA Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455

Weeds

R. B. Elkins, UC Cooperative Extension, Lake County
J. A. Roncoroni, UC Cooperative Extension, Napa County
C. A. Ingels, UC Cooperative Extension, Sacramento County
B. Hanson, Weed Science, UC Davis
Acknowledgment for contributions to Weeds:
W. T. Lanini, Weed Science/Plant Sciences, UC Davis

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