Nutsedge Control in Onions - Monterey County

Nutsedge Control in OnionsRichard Smith & Oleg DaugovishFarm Advisor, Monterey & VenturaCounties

Background NutsedgeRhizomesGrow 8-14” deepTuber (nuutlet)

Nutlet forming atend of rhizomenutlet

• Once the plant hasdeveloped more than 5leaves it begins toform nutlets

3. MéthodologieDes outils pédagogiques adaptés au niveau d’instruction des femmes ont été utilisés pourmieux faciliter l’assimilation des présentations faites par les consultantes et faciliter lesdiscussions.Il s’agit :- de l’utilisation du Wolof comme langue de communication ;- des outils visuels (dessins) comme supports de cours ;- des outils traditionnels connus dans la tradition sénégalaise pour transmettre desmessages (cauris, etc.) ;- De l’utilisation du dialogue interactif.Une des animatrices utilise des cauris pour mieux communiquer5

Background• Both Outlook and Duual Magnum arechloroacetamides (mmitosis inhibitors)• It needs to be applied prior to theemergence of nutseddge as it has nopostemergence activvity• It can delay tuber sprouting and kill shootsof yellow nutsedge• It can cause tuber mortality

Timing of Nutssedge Control• In 2006, 2 nd true leafapplications ofOutlook and Dual Maagnum were effectivein Monterey County• However, in both 20007 and 2008, nutsedgeemerged prior to the2 nd true leaf stagewhich h did not allow Outlook to be appliedprior to nutsedge emmergence• Both of these materials need to be appliedprior to the emergennce of nutsedge to beeffective

2007 Nutseedge Trials• In 2007 Outlook (Dimmethenamid-p) wasregistered in Californnia for use on dry bulbonions

2007 Nutseedge Trials• Yellow nutsedge wasemerged by the 2 ndtrue leaf stage in 20007• We needed to find away to make Outlookwork• Three strategies testted:– 1) 1 st true leaf applicaations– 2) Burn back nutsedgge with acid fertilizer thenapply Outlook– 3) Basagran evaluatioons

April 18, 2007Test plotGrower Acid FertilizerApplication

• At the 2 nd true leafstage nutsedgewas well developed

Heavily Infeested SiteTreatmentMateriaal/AApplication7-7-0-7Fb Outlook 6.0Fb Outlook 6.07-7-0-7Fb Outlook 6.07-7-0-7Fb Outlook 6.0Fb Outlook 6.07-7-0-7Fb Outlook 6.0Untreated ----35 gallons7.0 oz70oz7.0 35 gallons14.0 oz35 gallons7.0 oz7.0 oz35 gallons14.0 ozPost 1 t. leaf14 days laterPost 1 t. leafPost 2 t. leaf14 days laterPost 2 t. leaf----

Post Acid Fertilizer Application

7-7-0-7Outlook 7.0 + 7.0st true leaf1 stMay 8, 2007

Untreated Outlook 14.0 oz1 st true leafafter 7-7-0-7

Weed RatingOutlook AfterAcid FertilizerApril 23; May 4; June 1; and August 97.0+7.0 oz 14.0 oz 7.0+ +7.0 oz 14.0 oz1st true 1st true 2ndtrue 2nd true

Nutsedge nutlets in the soil of the Outlook plots

Nutsedge Tubers Per 1000 cm 3 of Soil7.0+7.0 oz 14.0 oz 7.0+7.0 oz 14.0 oz1st true 1st true 2ndtrue 2nd true

Yield Evalaluations

Onion Trial Heaavy InfestationWith 7-7-0-7Yield –Tons/A*7.0+7.0 oz 14.0 oz 7.0+ +7.0 oz 14.0 oz1st true 1st true 2ndtrue 2nd true

Comparison ofYield – MeanLight vs HeavyHead Wt (lbs)7.0+7.0 oz 14.0 oz 7.0+7.0 oz 14.0 oz1st true 1st true 2nd true 2nd true

2008 Nutsedgee Control TrialDehydratoor Onions

Untreated 7-7-0-7+OutlookGoal Tender1 st true leaf

7-7-0-7 7 7 + Outlook 7+771 st true leaf7-7-0-7 7 7 + Outlook 7+772 nd true leaf

Untreated 7-7-0-7 + Outlook 7+71 st true leaf

Nutsedge Weed Control Rating

Yield ofOnionsT//A

Ventura Trials

Nutsedge emergged 5/21 to 6/26AAAAABA

Nutsedge emerged after final DualMagnum and Outtlook applicationABA7/11 (1 week)8/7 (4 weeks)AA

Dual Magnum:nutsedge controlUntreated check

Summmary• The Ventura trials shhowed good efficacyof Dual Magnum for controlling gyyellownutsedge in onions• It is unclear why therre is a difference inactivity of Dual Magnnum and Outlook inVentura County• No difference betweeen the two herbicideswas observed in Monnterey County

Summmary• Burning back nutseddge with acid fertilizerprovides an opportunity to make Outlookwork if nutsedge is emerged by the 2 ndtrue leaf stage• There may be a yieldreduction from thecaustic action of thefertilizer but it ismuch less than lettinng the nutsedge gouncontrolled

Summmary• Both Outlook and Duual Magnum will beable to help to safeguard the yield ofonions at sites with significant yellownutsedge pressure

Acknowledgements• Bob Martin, Rio Farmms• James Guidici, Chrisstensen & Giannini• Don Burgeson, ConAAgra Foods• Miriam i Silva Ruiz, Reesearch hA Assistantt