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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Yellow nutsedge, Cyperus esculentus.

Carrot

Herbicide Treatment Table

(Reviewed 10/05, updated 10/05)

In this Guideline: More about weeds in carrot:
Herbicide
Amount/Acre
P.H.I.+
(trade name)   (days)
PREPLANT
A. METAM SODIUM 42% product
37.5­–75 gal
  
  COMMENTS: Soil should be free of large clods and irrigated about 2 weeks before application of the metam sodium. For flood applications, meter metam into water continuously throughout the entire irrigation. Sprinkler applications are much quicker; after running the sprinklers 5–10 minutes to moisten the soil surface and to be sure the system is working properly, inject the total amount of metam into the pump in about 20 minutes, then shut off the system. In any chemigation system, it is very important to have controls in place to prevent water flowing backward into the uncontaminated water source. Fumigants, such as metam sodium and 1,3-dichloropropene, are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available.
       
B. PARAQUAT*
0.49–1 lb a.i.
  
  (Gramoxone Max)
1.3–2.7 pt
  
  COMMENTS: A nonselective foliar herbicide that kills emerged weeds. Can be used before planting or after planting, but before the crop emerges. Any crop plants exposed to the spray will be killed, even germinating seed in the crook stage. No soil residual activity. Use the lower rate on small broadleaf weeds, the higher rate on larger weeds and grasses. Highly toxic if ingested, inhaled, or through dermal contact; wear protective clothing. More active on warm, sunny days.
       
C. GLYPHOSATE    
  (Roundup)
1–4 lb a.i. (1–4 qt)
  
  ...OR...    
  (Touchdown)
0.375–3.75 lb a.i. (0.5–5 qt)
  
  COMMENTS: A nonselective, foliar herbicide applied to premade beds before planting to kill emerged weeds. Allow 3 days after treatment before planting. Use the lower rate for annual grasses and weeds, the higher rate on perennial weeds. Consult the label for specific recommendations on particular weed species. Do not apply to weeds stressed for moisture. For perennial weeds, allow 7 days after application before cultivating.
       
D. TRIFLURALIN
0.5–1 lb a.i.
  
  (Treflan HFP)    
  COMMENTS: Controls annual grasses and broadleaf weeds. Incorporate mechanically into the top 2–3 inches of the final seedbed. The lower rates are recommended on sandy soil; however, crop tolerance is excellent.
       
POSTPLANT
Before the crop emerges
A. TRIFLURALIN
0.5–1 lb a.i.
  
  (Treflan HFP)
1–2 pt
  
  COMMENTS: Apply after sowing to prevent weed germination. Incorporate with irrigation water. See label for plantback restrictions.
       
B. LINURON
0.5–1 lb a.i.
14
  (Lorox) 50DF
1–2 lb
  
  COMMENTS: Apply after planting, incorporate with sprinklers. Will control many broadleaf weeds and annual grasses. A postemergent treatment is also allowed, but must not exceed a total of 3 lb linuron/acre/season.
       
After the crop emerges
A. LINURON
0.5–1 lb a.i.
  
  (Lorox) 50DF, etc.
1–2 lb
  
  COMMENTS: May be applied twice, first when the crop is 3 inches tall. Good control of emerged broadleaf weeds, small grasses, and suppression of yellow nutsedge. Total per season must not exceed 3 lb /acre (or 1.5 lb a.i./acre).
   
B. FLUAZIFOP-P-BUTYL
0.32–0.96 lb a.i.
45
  (Fusilade DX)
16–48 fl oz
  
  COMMENTS: A selective, foliar herbicide for control of grasses. A surfactant (crop oil concentrate or nonionic surfactant) is recommended. Safe to the crop. Not effective on drought-stressed grasses or on certain species (e.g., annual bluegrass, sprangletop). Do not apply more than 48 oz/acre/season.
       
C. SETHOXYDIM
0.09–0.47 lb a.i.
30
  (Poast)
0.5–2.5 pt
  
  COMMENTS: A selective, foliar herbicide for control of grasses. A surfactant (crop oil concentrate or nonionic surfactant) is recommended. Safe to the crop. Not effective on drought-stressed grasses or certain species (e.g., annual bluegrass, sprangletop).
       
D. CLETHODIM
0.095–0.125 lb a.i.
30
   
13–17 fl oz
  
  COMMENTS: Controls annual bluegrass in the 2- to 3-leaf stage as well as other annual and some perennial grasses. Do not apply through any type of irrigation system. Always apply with a crop oil concentrate. Use higher rate on perennial grasses.
       
+ Preharvest interval. Do not apply within this many days of harvest.
* Permit required from county agricultural commissioner for purchase or use.
       

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Carrot
UC ANR Publication 3438
Weeds
R. F. Smith, UC Cooperative Extension, Monterey Co.
J. Nunez, UC Cooperative Extension, Kern Co.
G. J. Poole, UC Cooperative Extension, Los Angeles Co.
Acknowledgment for contributions to the weeds section:
C. E. Bell, UC Cooperative Extension, Imperial Co.

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