Presentation on theme: "Weed Control in Carrot PNVA, Pasco"— Presentation transcript:
1 Weed Control in Carrot PNVA, Pasco Rick BoydstonUSDA-ARSProsser, WA
2 Carrot Weed ControlCarrots are very susceptible to competition from weeds (reduces carrot size, may cause malformed carrots, harvest losses)eg. volunteer potato reduced carrot yield by 22 to 91% depending on potato densities.Weeds can also act as hosts to insect pests, nematodes, and diseases of carrots.
3 Cultural and Mechanical Weed Control in Carrots Pre-sowing:Various types of tillage implements and bedformersWeeding implements for first flush of weedsAfter sowing – pre-germination of carrots:Flame or steam weederHarrow for blind weedingAfter germination of carrots:Various types of tine cultivatorsBrush weederSteerage hoe (cultivator)Hand hoe**Early weeding most critical on carrot yield (first 4-6 wks)**
4 Stale seedbed – a fresh start Till soil and form bedsAllow weeds to germinate (irrigate)Remove/control germinated weedsManual removal – shallow tillageIn dry months, withhold irrigationFlameHerbicidesPlant desirable species (minimal tillage)
5 Alternative StrategyPrepare seedbed just 5-7 days prior to planting carrots to promote weed emergence prior to carrots – followed by flaming before carrots emerge.
6 Flame weeding Propane fueled burners Idea is to just break cell membranes (dark green color after flaming)Controls primarily young, emerged annual broadleaf weeds that have exposed growing pointsGrass and perennial weed control often poor, with re-growth after treatmentGrass weeds: growing point often below-groundPerennial weeds: re-grow from root tissueEnergy costs are high
7 Prototype II in carrot: Band steamedPrototype II in carrot:80-90% weeding effectiveness against annual weeds at 800Ctendency for a higher marketable yieldfuel consumption < 400 l ha-1
8 Goosefoot tine cultivator Power rotary harrowReduction in numbers of carrot seedlings and weeds by three different weeding implements (Mildura 2002)Goosefoot tine cultivatorFinger-tine harrowPower rotary harrowCarrotsWeeds67%83%33%82%0%80%
10 Roundup, Gramoxone, Flaming Prior to crop emergence – stale seedbedNonselectiveAim 2EW – carrot stand loss and yield loss when applied at rates of 1 or 2 fl oz/a
11 Trifluralin (Treflan, others) Preplant incorporated treatment for control of annual grasses and broadleavesSoil TextureTreflan 4EC (pints)Coarse1Medium1.25 – 1.5Fine
12 Lorox 50DF Status: Primary carrot herbicide “Do not apply to sand or loamy sand. Do not use on soils with less than 1% organic matter”Use: PRE and POST control of most broadleaves and annual grasses; Max. 2 lb ai/a/yrConcerns: POST applications at temp >85F can burn carrots; some weeds have developed resistance to PS II inhibitorsPOST - Wait 2 wks or more after first applicationCarrots must have 2 lvs or more (~3 inches tall)
13 Sencor 75DF Triazine, PS II inhibitor Use: POST control of annual broadleaves when carrots have 5-6 leavesConcerns:May burn carrots at temp <55 or >85FSensitive varietiesDo not tank mixWeed resistance
14 Fusilade, Poast, SelectUse: POST grass control; volunteer small grainsAvoid tank mixes with Lorox or SencorAvoid applying to water stressed grassesAlways use adjuvants according to label
15 Prowl H2O (3.8 CS) Use: 2 pts/acre (max. 2 pts/season) - Postplant, preemergence w/in 2 days of planting- Layby as a directed spray before weed emergence.Chemigation – only prior to carrot emergence.Possible substitute for Treflan
17 Nortron (Ethofumesate) Labeled in OR and WABayer - sugarbeet, grass seed herbicide1.5 – 2 lb ai/a (48 – 64 fl oz/a)PRE 48 oz coarse soils64 oz med and fine soilsEarly POST (PRE to weeds) – 64 fl oz(2-4 leaf carrot)Max 128 fl oz (1 gal) per seasonRotation crop interval – 12 monthSome carrot leaf fusion at higher doses
21 Carrot Trial 2003Nortron applied PRE delayed potato emergence, stunted potato growth, and caused epinastic growth on potato.Nortron also applied POST at 2 leaf stage of carrot (potatoes had 6 leaves).May 15, 2003 – Delayed potato emergence
22 Reduced due to potato competition bPOST/POSTPOSTPRE/POST
23 SummaryNortron applied PRE delayed potato emergence and applied POST reduced potato growth in carrots.Sequential applications of Nortron 1.5/2 lb ai/a (PRE/POST) reduced number and weight of potato tubers and prevented carrot yield loss from volunteer potato.Sequential applications of Nortron and Caparol applied POST also provided good potato control without reducing carrot yields.
24 Caparol 4F – NOT Labeled Status: Possible label in 2008 PRE or POST control of broadleaves.Use as a substitute for Lorox (controls many similar weeds as Lorox)Volunteer potato - single or sequential POST applications of Caparol at 1 to 2 lb ai/a, were safe on carrot and suppressed volunteer potato.Mode of action similar to Lorox (PS II inhibitor); potential crop stunting
25 Dual Magnum – NOT labeled in WA Status: 24c label in Oregon; growers must Indemnify Syngenta before useUse: PRE control of nutsedge, annual grasses, pigweeds, and nightshades.Keep rates low to avoid crop damageConcerns: Stand thinning on sandy soilsFuture: Use with Lorox for nutsedge and crabgrass, and resistant pigweed control
26 Summary Organic systems: stale seedbed, flame, cultivation, hand-weed Prowl H2O – pre or post directed, 2 pts/agrass and small seeded broadleaf weedsNortron – pre (48-64 fl oz), post (64 fl oz)volunteer potato suppression, grasses, and selected broadleaf weedsFuture labels?? Caparol – pre and postDual – pre for nutsedge, grasses
27 Crossing paths on their respective journeys of destiny, Johnny Appleseed and Irving Ragweed nod “hello.”
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