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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Black nightshade fruit.

Potato

Herbicide Treatment Table

(Reviewed 8/07, updated 5/08)

In this Guideline: More about weeds in potato:
Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
When choosing an herbicide, consider information relating to the impact on environmental quality.
 
PREPLANT AND POSTPLANT
A. DIMETHENAMID
  (Outlook) 0.56–0.98 lb a.i. 12 40
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply preemergence following planting or after drag off. Broadcast uniformly followed by rainfall, irrigation or shallow mechanical incorporation. On muck and high organic matter soils use the 0.98 lb a.i. per acre rate.
 
B. EPTC
  (Eptam) 7EC 3 lb a.i. 12 45
  WSSA MODE OF ACTION GROUP NUMBER1: 8
  COMMENTS: For Irish potatoes. Apply and immediately incorporate just before planting; or apply after planting potatoes and incorporate using rolling cultivators (Lilliston types). Retreat, if necessary, after potato plants have emerged from the soil. Meter into the sprinklers before weeds emerge (about 30 days after the previous application). Do not exceed 14 pt Eptam 7EC/acre/crop. In Lassen, Modoc, Shasta and Siskiyou counties, up to 6 lb a.i./acre/application may be used.
 
C. GLYPHOSATE
  (Roundup) 0.5–4 lb a.i. 4 14
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: For Irish potatoes. Apply low rates with nonionic surfactant before potato emergence. Avoid contact of spray with the foliage or green stems of potatoes. Do not irrigate for 6 hours after application. For perennial weeds, apply appropriate rate for each weed, usually without a surfactant. Treatments in late summer and fall are best when weeds have been irrigated and are growing well.
 
D. PARAQUAT*
  (Gramoxone Inteon) 0.26–0.48 lb a.i 12 0
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Apply before potato emergence with a nonionic surfactant. Do not use on muck or peat soils to avoid injury to subsequent crops. For use on emerged annual weeds.
 
E. PENDIMETHALIN
  (Prowl) 3.3EC 0.5–0.75 lb a.i. 24 0
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not use on muck or peat soils. Works best preemergence on weeds, but somewhat less safe for crop. For annual weeds, apply and soil incorporate into planted beds before potato emergence, or apply preemergence at slightly lower than label rates and sprinkle within 7 days for annual weeds. Do not apply after potatoes are 6 inches tall.
 
F. SETHOXYDIM
  (Poast) 1.5EC 0.28 lb a.i. 12 30
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Do not cultivate within 5 days before applying or within 7 days following application. Use a nonphytotoxic oil concentrate in the spray tank. For annual or perennial grasses.
 
G. RIMSULFURON
  (Matrix) 0.25–0.375 oz a.i. 4 60
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: For activation, supply moisture by rainfall or sprinkler (0.25–0.75 inch) no later than 1 week, but no sooner than 4 hours after application. If weeds are present then use a nonionic surfactant with at least 80% active ingredient at 0.125–0.25% v/v. Temporary chlorosis may occur if crop is under stress. Check label for plant back restrictions.
 
HARVEST
A. PARAQUAT*
  (Gramoxone Inteon) 0.26–0.48 lb a.i. 24 1
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Do not use to desiccate potato vines when potatoes are to be stored or used for seed. Do not exceed 3 pt/acre/season. Use with a nonionic surfactant.
 
ADDITIONAL OPTIONS FOR TULE LAKE AND OTHER REGIONS
A. METOLACHLOR
  (Dual II Magnum) 1–2.3875 lb a.i. 24 60
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply preemergence and sprinkle or incorporate shallowly after hilling. Use lower rate on relatively coarse-textured soil or soil low in organic matter. Use the higher rate on fine-textured soils or soils high in organic matter. Not labelled in Kern County. Do not use on muck or peat soils. Do not harvest within 60 days after the at-planting to drag-off application.
 
B. EPTC
  (Eptam)7EC 3 lb a.i. 12 45
  WSSA MODE OF ACTION GROUP NUMBER1: 8
  COMMENTS: For Irish potatoes. Apply postplant as a direct spray to the soil and incorporate before crop emerges. Will provide some suppression of hairy nightshade but will not control it on soils exceeding 10% organic matter. May be applied again at layby. Do not exceed 14 pt Eptam 7EC/acre/crop.
 
C. METRIBUZIN
  (Sencor 75DF) 0.25–0.495 lb a.i. 24 60
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Do not use on Centennials, Shepody or other sensitive varieties. Crop injury may occur if postemergent applications are followed by cool, cloudy weather. For use in Modoc and Siskiyou counties only.
 
+ 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.
* Permit required from county agricultural commissioner for purchase or use.
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.plantprotection.org/HRAC/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Potato
UC ANR Publication 3463
Weeds
J. Nuñez, UC Cooperative Extension, Kern Co.
H. Carlson, UC Cooperative Extension, Siskiyou Co.
Acknowledgment for contributions to the weeds section:
W. E. Bendixen, UC Cooperative Extension, Santa Barbara Co.

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