Citrus Weed Management Efficacy, Longevity &...

Citrus Weed Management- Efficacy, Longevity &

Crop-safety

Horticultural Sciences

Ramdas KanisserySouthwest Florida Res. & Education CenterImmokalee

Brent Sellers & Steve Futch

Citrus Weed Management

Managing difficult to control weeds

Research updates – steaming for weed mgmt. in citrus

Impacts of herbicides on citrus yield & productivity

PRE-emergent herbicide trials for long-term weed control

Efficacy

Longevity

Crop-safety





Efficacy

Longevity


Crop-safety

Weed management in citrus groves

Weed managed citrus rows

- ‘Weed free’ rows or under trees

Weed management in citrus groves

Weeds come up quickly in the citrus rows

- Constant supply of moisture from tree irrigation

- Major challenge is ‘longer-term’ suppression of weeds

Important strategy to prevent weed outbreak in your grove

“NEVER LET ‘EM SET SEED”

Heavy infestation of tropical whiteweed in citrus tree rows

Heavy infestation of “tropical whiteweed” in citrus tree rows

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Clustered pellitoryinfestation

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Clustered pellitoryinfestation

Seed bank formed in the soil

Managed by broad-spectrum POST-emergent sprays- glyphosate- paraquat

Goat weed

- Slow response to glyphosate & paraquat application

- Tiny seeds released from the ‘seed pods’

- Each plant can potentially add hundreds of thousands of seeds to soil

- Monoculture of goatweed

Heavy seed setters

Amaranth / Pigweed

Black Nightshade

Parthenium

- Each plant can potentially add hundreds of thousands of seeds to soil

• Active ingredient – Brand name(s)

POSTFoliar applied

•PR

E-EMER

GEN

TH

ERBIC

IDES

Selective herbicides

• Saflufenacil – Treevix

Consult Florida Citrus Production Guide 2018-19 for a complete list

• Carfentrazone – Aim EC

• Glyphosate + 2,4-D - Landmaster

• Paraquat - Gramoxone


POSTFoliar applied


Non-selective herbicides

• Carfentrazone – Aim EC

• Glyphosate + 2,4-D - Landmaster

• Paraquat - Gramoxone


POSTFoliar applied


Non-selective herbicides

• Glufosinate ammonium - Rely 280

Heavy seed setters

Amaranth / Pigweed

Black Nightshade

Parthenium

Glufosinate is an effective management option for parthenium

POSTFoliar applied

•PR

E-EMER

GEN

TH

ERBIC

IDES

Spray coverage on foliage – key factor

Higher spray volumes 20 to 30 gallons per acre

- Dense weed infestations- Large weeds / advanced growth

stage

POSTFoliar applied

•PR

E-EMER

GEN

TH

ERBIC

IDES

Spray coverage on foliage – key factor

Higher spray volumes 20 to 30 gallons per acre

- Dense weed infestations- Large weeds / advanced growth

stage

Surfactant addition





Efficacy

Longevity


Crop-safety

Applied to bare soil or minimum ‘existent weed coverage’ to ensure max soil incorporation

Pre-emergent OR Residual

herbicides Prevent seed germination

Active Ingredient(s) Products

Flumioxazin Chateau

Indaziflam Alion

Pre-emergent OR Residual

herbicides


Active Ingredient(s) Products Product Rate

(per acre)

Flumioxazin Chateau 6 oz.


Indaziflam Alion 3 oz.


Flumioxazin +Indaziflam

Chateau +Alion 6 oz. + 3 oz.



Control -- --

Study location: Immokalee


(per acre)









Control -- --




(per acre)









Control -- --

2 MonthsWeed control efficacy (%)

- Replication (n) = 5- Mean comparison: Tukey’s hsd (a 0.05)- All treatments including control received

glyphosate at ~2.0 lbs. A.E/acre

75%



(per acre)









Control -- --

Weed control efficacy (%)

5+ Months

75%

- Replication (n) = 5- Mean comparison: Tukey’s hsd (a 0.05)- All treatments including control received

glyphosate at ~2.0 lbs. A.E/acre


2 Months 2 Months

5 months after applicationIndaziflam + Flumioxazin



(per acre)









Control -- -- Study location: Zolfo springs


(per acre)









Control -- --

2 MonthsWeed control efficacy (%)

75%

- Replication (n) = 5

Study location: Zolfo springs


(per acre)









Control -- --

∼5 MonthsWeed control efficacy (%)

75%


Study location: Zolfo springs





Efficacy

Longevity


Crop-safety

-Glyphosate application

Impacts of herbicides on citrus health and yield

- most popular post-emergent herbicide in citrus

- glyphosate reliant weed mgmt. programs (3-4 applications / yr)


Spray contact


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Credits: Steve Futch

Citrus drop from glyphosate spray contact with fruit


Persistence in soil Citrus uptake

Glyphosate residues

Degradation products


Spray contact


- To investigate glyphosate linked fruit drop in citrus

Treatment Rate(a.e / A) Product

Control – water spray -- --

Low 0.75 22 oz/A

Medium 1.50 44 oz/A

High 3.75 110 oz/A

glyphosate rates



- Application was made during Nov – Feb

- Valencia


Fruit Detachment Force (FDF) – indicator of fruit holding capacity


FDF = higher possibility of fruit drop

- Application was made during Nov – Feb

- Valencia


FDF response to glyphosate rates

Kanissery, Batuman & Alferez (2018)

3

5

7

9

0 1 2 3 4 5 6 7 8

Frui

t det

achm

ent f

orce

(FD

F)

Weeks after glyphosate application

Control Low Medium High

2017 study



FDF response to glyphosate rates

Kanissery, Batuman & Alferez (2018)

3

5

7

9

0 1 2 3 4 5 6 7

Frui

t det

achm

ent f

orce

(FD

F)

Weeks after glyphosate application


2018 study


16.53% 15.94%

13.36%15.42%

0

5

10

15

20


FRU

IT D

ROP

(% O

F IN

ITIA

L FR

UIT

SET

)

HERBICIDE TEST RATES

2018 study

Citrus fruit drop v/s glyphosate application

% of fruit dropped - No statistical difference b/w treatments observed in this study

Yield was low in the control- Competition from

weeds



Persistence in soil Citrus uptake

Glyphosate residues



-Glyphosate in citrus production

Persistence in soil (?) Citrus uptake

Glyphosate residues



Fruit drop / Yield

Root growth (?)

CollaboratorsDr. Batuman(PATH)Dr. Kadyampakeni(SWS)Dr. Dittmar(HOS)Dr. Alferez(HOS)


Research update – steaming for weed mgmt. in citrus



Efficacy

Longevity


Crop-safety

Steaming – in citrus weed management

- Non-chemical weed management

- Sustainable

Mobile boom connected to steamer

Steam generator

Collaborator(s)Dr. Ampatzidis (ABE)Dr. Abdulridha


Steamer pulled by tractor

- Non-chemical weed management

- Sustainable


- For weed management in the citrus rows

Steam application for citrus row weed control




∼ 6 hrs. after steam application

Steam application for citrus row weed control



Untreated Control

Steam applied

Goat weed control in citrus

- Steam was applied followed by a contact herbicide

Steaming in combination with herbicide application

No steam

With Steam

Paraquat rate (pt. / acre)




No steam

With Steam


0

1

3

No steam

With Steam


0 0c 50c

1 46b 89a

3 93a 96a

CV 17.37

P-value 0.0013

1 Day after treatmentGoat weed control in citrus


- Contact herbicide found effective even at lower application rate when combined with steam application

- Replication (n) = 5- Mean comparison: Tukey’s hsd (α 0.05)

% weed control


No steam

With Steam


0 0c 54b

1 51b 92a

3 95a 96a

CV 19.64

P-value 0.0021

8 Days after treatment

% weed control



- Contact herbicide found effective even at lower application rate when combined with steam application

- Replication (n) = 5- Mean comparison: Tukey’s hsd (α 0.05)



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Summary

Difficult to control weeds- POST sprays before flowering/seeding- Coverage - Spray volume ; surfactants

Summary: Citrus weed management

PRE-herbicide combinations- Longer term weed control- Dealing with large data sets

Effects of glyphosate on fruit drop / yield- Could potentially lower the FDF- No significant %fruit drop observed

Steaming for weed management- Steaming + herbicide- Efficacy at low rates of chemicals

SWFREC weed science team

From left: Shea Teems, Biwek Gairhe, Robert Riefer, Ramdas KanisseryIn set: Cami McAvoy, Maria Martinez, Budji Toussaint

Thank you…

Contact

Ramdas Kanissery

UF/IFAS SWFREC2685 State Road NImmokalee, FL

Phone: (239) [email protected]

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