Controlling Problem Weeds. John Roncoroni UCCE Weed Science Advisor Napa County

Controlling Problem Weeds John Roncoroni UCCE Weed Science Advisor Napa County

Problem Weeds Resistant Rigid Ryegrass Italian Ryegrass Junglerice Tolerant Cheeseweed Filaree Willowherb Horseweed Hairy Fleabane

Problem Weeds Resistant Ryegrass Junglerice Horseweed Hairy Fleabane

Rigid and Italian Ryegrass (Lolium rigidum and L. multiflorum) Often co-exist (swarm) Annual grass Obligate outcrossers Throughout CA but more common weed in northern Central Valley 2 to 15-fold resistance

Ryegrass

Glyphosate resistant species

Problem Weeds Resistant Ryegrass Junglerice Horseweed Hairy Fleabane

Junglerice (Echinochloa colona) Summer annual weed Very similar to BYG Resistant to Glyphosate May or may not have stripes Produces a lot of seeds

SJV junglerice Greenhouse dose response 0.75 lb ae/a use rate Up to 4x Photos taken 21 DAT Moretti and Hanson

Ryegrass and Junglerice Highly resistant to glyphosate May be resistant to Rely in Sonoma Resistant to almost all herbicides in Australia Alion, Chateau and Matrix PPO s Goal, Shark- no or weak Surflan, Prowl pre- Poast or Fusilade Post

Problem Weeds Resistant Ryegrass Junglerice Horseweed Hairy Fleabane

Horseweed (Conyza canadensis) AKA mare s tail Annual weed Prolific seed producer Wind-blown seed Early colonizer Doesn t tolerate disturbance 6-fold resistance (whole plant) 4-8 fold resistance (in vivo) Mechanism -translocation mutation

Horseweed Rosett e Young plant Adult Pictures taken Sept 19

Is this the root of the problem?

Problem Weeds Resistant Ryegrass Junglerice Horseweed Hairy Fleabane

Hairy Fleabane (Conyza bonariensis) AKA flaxleaf fleabane Annual weed Wind-blown seed Early colonizer Doesn t tolerate disturbance 3 to 10-fold resistance (whole plant screening) ~ 4-fold resistance in vivo Mechanism not known

Horseweed and Fleabane Germinates all year-except, mid-winter Glyphosate-NO, Rely-when small Alion, Chateau, Matrix*,Mission*,Goal*, Zeus*,Trellis* Now problem in all of California. Tolerant in Northern California-resistant in most of State

Tolerant Problem Weeds Chesseweed (Malva) Filaree Willowherb

Malva C155-11 C155-15

Problem Weeds Tolerant Chesseweed (Malva) Filaree C139-06 Willowherb C139-08

Malva and Filaree Germinates in early fall Physically remove large plants Glyphosate and Rely work on seedlings to small Early application Goal, Chateau, Alion, others work-early

Problem Weeds Tolerant Chesseweed (Malva) Filaree Willowherb

C162-02 Panicle Willowherb (Epilobium brachycarpum C. Presl) Erect summer annual to 2 meters tall Taproot simple or branched and weakly woody Reproduces by seeds that germinate in fall through late spring. Tolerant of glyphosate C162-06 C162-01

Willowherb Nov 28 March 1

February 28

Roundup on willowherb

Willowherb Germinates in Fall-October Glyphosate works when very small-not later Rely works well to pretty large size Most pre-emerge control- Alion, Matrix, Chateau, Mission, Goal, (+) Shark,(+) Venue- Surflan, Prowl, Trellis- spotty Remove leaves

Two More Weeds Sharp-point Fluvellin and Stinkwort

Sharppoint Fluvellin Kickxia elatine(l.)dumort. Most seeds germinate in spring- but many will germinate in fall if moisture is present. Reproduces by seed that can survive for up to 20 years! Growth form in fall or early spring may be upright Growth form in late spring changes from opposite to alternate leaves and is prostrate and can form a dense mat

There is a milk carton under this plant! Fall growth form of fluvellin Fluvellin competing with newly planted grapes

Fluvellin Control Treatment 7/9/12 8/7/12 Treated 12/8/11 Rate Rating 7/10 Overall FLU Overall FLU UTC 6.75 8.88 4.75 7.25 Rely 280 2 qt 4.50 5.75 RT 6.75 7.5 Roundup WM 2 qt 4.25 4.75 RT 7.0 9.88 Trellis 1 lb 8.25 9.25 7 8.75 Chateau 12 oz 8.50 8.50 6.25 7.0 Goal 2XL 3 qt 5.63 5.88 3.75 4.75 Shark 2 oz 5.0 5.0 RT 8.25 9.5 Venue 4 oz 5.0 5.75 RT 7.75 9.5 Zeus 12 oz 5.0 5.25 3.5 3.75 Matrix 2 oz 4.50 4.75 2.75 2.75 Alion 5 oz 7.38 7.50 6.50 6.75 All treatments except Rely 280 are mixed with 2 qt/ac Roundup WeatherMax

Fluvellin Germinates year round except mid-winter Does not germinate well under competition Not actively growing in cold-reduced herbicide activity Outlasts pre herbicides-treat early Glyphosate-good, Rely-only on small Use long-lasting herbicide- Alion,Trellis,Chateau(+-) Goal, Matrix-may not last long enough-

Stinkwort

Stinkwort (Dittrichia graveolens) Native to Mediterranean region Erect, fall flowering, aromatic annual about 2 feet tall. Also invasive in Australia First reposted in Alameda County in 1995 Unpalatable to livestock Resembles Russian thistle, but is more similar to tarweeds

Stinkwort March 6

Stinkwort Strong smelling-problem? Causes dermatitis Only see it growing under vine where pre not used Germinate February-? Flowers in November Control-glyphosate-early? And Preemerge-? In American Canyon, Carneros-spreading north

Controlling Problem Weeds What do all of these weeds have in common?

Problem Weeds Resistant Rigid Ryegrass Italian Ryegrass Horseweed Tolerant Cheeseweed Filaree Willowherb Hairy Fleabane Junglerice They all have germination periods in either mid or late summer/early fall

November 3

October 15

Controlling Problem Weeds What do all of these weeds have in common? What herbicide are all these weeds either resistant to, tolerant of, or avoiding?

Controlling Problem Weeds What do all of these weeds have in common? What herbicide are all these weeds either resistant to, tolerant of, or avoiding? Glyphosate-especially late applications

Controlling Problem Weeds What do all of these weeds have in common? What herbicide are all these weeds either resistant to, tolerant of, or avoiding? What are we doing that makes these weeds such problems?

Controlling Problem Weeds Is a Post + Pre tankmix enough?

Controlling Problem Weeds Is a Post + Pre tankmix enough? Depends

Controlling Problem Weeds Is a Post + Pre tankmix enough? Are the weeds that have been growing for 3-4 months resistant or tolerant to the postemergence herbicide you are using?

Controlling Problem Weeds Is a Post + Pre tankmix enough? Are the weeds that have been growing for 3-4 months resistant or tolerant to the postemergence herbicide you are using? Does the preemergence herbicide you are using have any postemergence activity?

Controlling Problem Weeds Not all herbicides have the same activity.

Controlling Problem Weeds Not all herbicides have the same activity. Example: You have been using Chateau + Roundup WM in late January.

Controlling Problem Weeds Not all herbicides have the same activity. Example: You have been using Chateau + Roundup WM in late January. Now you want to switch to Alion + Roundup WM-

Controlling Problem Weeds Not all herbicides have the same activity. Example: You have been using Chateau + Roundup WM in late January. Now you want to switch to Alion + Roundup WM-W What do you need to think about?

No Treatment Round Up Rely

Chateau 12oz +RU Mission 2.14oz +RU Matrix 4oz +RU

GoalTender 2qt +RU Trellis SC 23oz + Rely 11 Trellis 23oz + Goal 2XL 5 pts+

t Alion 2.5 oz+ Zeus 12 oz + RU Alion 5oz + Matrix 2oz + RU Alion 3.5oz + Chateau 4oz + RU

19 21 20 Trellis 23oz+ Prowl 6 qt + Rely Trellis 23oz+ Alion 2.5oz + Rely Trellis 23oz+ Chateau 6oz

23 22

Controlling Problem Weeds Make applications as successful as possible.

Remove leaves and debris Unraked plot Raked plots Plots raked and treated with 10 oz Chateau +24 oz Roundup

60% Leaf Cover Raked pre-treatment Raked post treatment Unraked pre-treatment Unraked post treatment

March 1 (75 DAT) June 12 (180 DAT) % Leaf Cover % Fillaree Cover % Willowherb control Raked Not Raked Not 60 5 50 100 70 50 7 30 100 50 50 15 40 90 40 40 3 20 90 50 40 5 10 100 70 33 1 15 90 70 25 5 20 100 70 Ave 8.30% 28% 96% 60%

Willowherb

Herbicides

Herbicide Modes of Action (MOA) Fruits, Nuts, Vineyards 1 ACCase inhibitor clethodim (Prism, Select) 2 ALS inhibitor rimsulfuron (Matrix) 3 Mitosis inhibitor (DNA) pendimethalin (Prowl H20, 3.3) 4 Synthetic auxin 2,4-D amine 5 Photosystem II inhibitor simazine (Princep Caliber 90) 7 Photosystem II inhibitor (diff site) diuron (Karmex DF) 9 ESPS inhibitor glyphosate (Roundup) 10 Glutamine synthase inhibitor glufosinate ammonium (Rely) 12 Carotenoid synthesis inhibitor (PDS) norflurazon (Solicam) 14 PPO inhibitor flumioxazin (Chateau) 15 Seedling growth inhibitor (site?) Napropamide (Devrinol) 20 Cell wall synthesis inhibitor (A) dichlobenil (Casoron) 21 Cell wall synthesis (B) isoxaben (Trellis) 22 Photosystem I paraquat (Gramoxone Max) 28 Cellulose inhibitor indaziflam (Alion)

Know your herbicides Alion Chateau Goal-GoalTender Matrix Mission Prowl Surflan Trellis Zeus Rely, Reckon, Cheetah Shark Venue

Alion and Chateau Alion and Chateau are base herbicides Longer spray to rain period? Both have wide spectrum control Both long-lasting Chateau 6 mon. Alion 6-9-? Chateau-Post; Alion-No Different MOA- PPO vs CBI Chateau-3 years; Alion 5 years Concerns for both

Goal and GoalTender Different control- Goal better post GT better pre PPO-weak on grasses Short-lasting pre Good Filaree and Malva control Spray after pruning- before bud break (Feb 15)

Matrix and Mission Same Family-similar herbicides A lot of experience with Matrix-not much Mission Need incorporation soon <1 Month Control 4-6 months Very good Horseweed control Pretty good burndown

Prowl and Surflan Grass and summer annual control Pigweed, spurge, sowthistle Not so good on Horseweed, Willowherb Mixing partners when grass may be problem

Others Zeus PPO not a lot of data yet Rumored good burndown Good on nutsedge Trellis Long-lasting preemergent broadleave herbicide has not been strong on willowherb or horseweed

Rely Good fit for early post harvest burndown Excellent on willowherb, good on Horseweed Not good on large fluvelin mid-season May be some resistance issues?

Shark and Venue Both postemergence broadleaf only Limited use on own-very small weeds May help heatup glyphosate Be careful when mixing more than 1 PPO

Others Zeus PPO not a lot of data yet Rumored good burndown Good on nutsedge Trellis Long-lasting preemergent broadleave herbicide has not been strong on willowherb or horseweed

Other Herbicides Glyphosate Paraquat Simazine 2,4-D

Summary Prioritize Weed Problems Know herbicide characteristics Apply Preemergence to clean beds Apply Postemergence early Clean leaves from vinerow

UC Pest Management Guidelines: Grape Integrated Weed Management In this Guideline: Monitoring Weed management before planting Weed management in new vineyards Weed management in established vineyards Publication Glossary More about weeds in grape: Special weed problems Weed management in organic vineyards Susceptibility to herbicides Herbicide treatment table Weed photo gallery

2014 Herbicide Trial Results

2014 Herbicide Trial Results Plots treated Feb 5, 2014 All plots treated with glyphosate and carfentrazone {Shark} December All plots swept and then back through with rakes before treatment to remove leaves No weeds were present at time of treatment All treatments except UTC contain 1 qt Roundup weather Max and 0.25% v/v AMSPro Treatments made at 30GPA

2014 Herbicide Trial Results Plots treated Feb 5, 2014 Rain amounts after treatment 5-Feb 0.21 inches 6-Feb 0.57 inches 7-Feb 1.33 inches 8-Feb 2.13 inches 9-Feb 1.16 inches Total rain after treatment 8.85 inches Ratings are average for control of major weeds: Horseweed, Willowherb, Sowthistle and grasses.

Thank you Questions?