Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Herbicide Treatment Table for Inside Greenhouses

Common name Amount to use 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. Indaziflam
  (Marengo) 7.5-15.5 fl oz/acre 12 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: Very long residual. For use under benches and greenhouse floors only. Do not exceed 18.5 fl oz in a 12 month period.
 
POSTEMERGENCE HERBICIDES
A. DIQUAT
  (Reward) Spot application: 1–2 qt plus 8–16 oz nonionic surfactant/100 gal water 24 NA
    Broadcast: 1–2 pt plus 16–32 oz nonionic surfactant/100 gal water
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Apply in 15–40 gal water/acre. Do not allow contact of spray or drift to desirable foliage.
 
B. GLUFOSINATE
  (Finale) Spot application: 1.5 fl oz/1 gal water 12 NA
    Broadcast application: 3 qt when weeds less than 6 inches tall or 4 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 of crop. Do not use in greenhouses with edible crops.
 
C. GLYPHOSATE
  (Roundup Pro) Spot application: 0.66–1.33 oz product/1 gal water 4 NA
    Broadcast application: (annuals) 2 qt–1 gal/100 gal water
(perennials) up to 2 gal/100 gal water
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Apply to young weeds under benches along walkways or along the edge of the greenhouses. Use low pressure and large droplets to reduce chance of drift of spray on to leaves of the crop. Do not apply to any runoff water. Turn off air circulation fans during application. Desirable vegetation should not be present during application.
 
D. PELARGONIC ACID
  (Scythe) See label 12 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 26
  COMMENTS: Apply to young weeds under benches, along walkways, or along the edge of greenhouses.
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