Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Herbicide Treatment Table for Outside Greenhouses

Common name Amount per Acre REI‡ PHI‡
(Example trade name) (hours) (days)
Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the table SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTOL for information on specific weed control. Always read the label of the product being used.
 
PREEMERGENCE HERBICIDES
A. ISOXABEN
  (Gallery 75 DF) 0.9975 lb 12 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 21
  COMMENTS: Apply preemergence or combine with a postemergence herbicide if young weeds are established. May be combined with other preemergence herbicides to control additional broadleaf weeds.
 
B. ORYZALIN
  (Surflan AS) 2–4 qt 24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Combine with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control a broader spectrum of grasses and broadleaf weeds.
 
C. PENDIMETHALIN
  (Pendulum 3.3 EC) 2–3.96 lb a.i. 24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Apply preemergence. May be combined with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control grasses and certain broadleaf weeds.
 
D. PRODIAMINE
  (Barricade) 0.65–1.495 lb 12 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Apply preemergence. May be combined with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control grasses and certain broadleaf weeds.
 
POSTEMERGENCE HERBICIDES
A. DIQUAT
  (Reward) 1–2 pt plus 16–32 oz nonionic
surfactant/100 gal water
24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Apply 15–40 gal/acre or enough to wet young weeds. Apply when weeds are young for improved control.
 
B. GLUFOSINATE
  (Finale) Spot application: 1.5 fl oz/1 gal water 12 NA
    Broadcast application: 3 qt when weeds are less than 6 inches tall or 5 qt when weeds are 6 inches or taller.
  WSSA MODE-OF-ACTION GROUP NUMBER1: 10
  COMMENTS: Apply as directed spray under benches or on floors of the greenhouse or around the periphery of the greenhouse. Do not have air circulation fans running. Apply using large droplets and low pressure to avoid drift or contact with green leaves or stems. Do not use in greenhouses with edible crops.
 
C. GLYPHOSATE
  (Roundup Pro) Annuals: 2 qt–1 gal/100gal water
or 0.66–1.33 oz/gal water
4 NA
    Perennials: see comments
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Apply lower rates to young weeds. Apply to perennials when in flower stage and the soil moisture is sufficient to maintain active growth of the weeds.
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.
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.
NA Not applicable.
Text Updated: 07/20