R d ® UltRemedy® Ultra f Cit Stfor Citrus Stump S t C t lSprout Control

Steve Futch, Ph.D.Extension Agent, Multi-County

U i it f Fl idUniversity of FloridaCitrus Research & Education Center

Lake Alfred, Floridashf@ufl.edu

The Issue of Sprouts and the LabelThe Issue of Sprouts and the Label

• Sprouts can be a significant threat to the Florida p gcitrus industry as sources of HLB (greening)*

• Limited recommendations for sprout control in Florida citrusFlorida citrus – Glyphosate, Pest Management Guide, 2002- present– Remedy® Ultra approved as Section 24(c),

EPA SLN NO FL080004 A t 2008• EPA SLN NO. FL080004, August 2008

• * Citrus Industry Magazine: – Sprout Control for Clipped Trees, December 2008, pgs 16-17

D t ti f G i i S t f Cit T St M h 2009 28 30– Detection of Greening in Sprouts from Citrus Tree Stumps, March 2009, pgs 28-30• HortTechnology

– Citrus Tree Removal Method Does Not Affect Performance of Reset Trees. 18:559-562 (2008)• Florida State Horticultural Society

– Influences of Methyl Bromide Soil Fumigation on Citrus Root Sucker Development and Growth y g pof Replant Trees. 107:76-78 (1994)

The ProblemThe Problem

The SolutionThe Solution

Sprout Control StudyObj iObjectives

1) To determine the effectiveness of1) To determine the effectiveness of Remedy® Ultra at various rates on the control of citrus sproutscontrol of citrus sprouts

2) Provide data to support label modifications and Florida SLN labelmodifications and Florida SLN label

Study SiteStudy Site• Trial was established in April 2008 in a DeSoto p

County citrus grove• Prior to tree removal, trees were diagnosed

i i f HLB b d i l ipositive for HLB based upon visual symptoms in various parts of the tree canopy

• Tests were not conducted to prove HLB• Tests were not conducted to prove HLB diagnosis

• Although symptomatic, trees were otherwise t oug sy pto at c, t ees e e ot e sehealthy

• Trees ranged from 7 to 15 years old

Plot Design & TreatmentsPlot Design & Treatments• Randomized complete block design was used in the

t dstudy• Trees randomly selected received one of four treatments

– Untreated control (no herbicides)25% Remedy Ultra + 75% diesel– 25% Remedy Ultra + 75% diesel

– 50% Remedy Ultra + 50% diesel– 75% Remedy Ultra + 25% diesel

• Treatments were applied using a 1-gallon compression pp g g psprayer

• Solution was applied to the outer cambium area of the cut stump in a volume to minimize runoff

• Each stump received 1 to 2 oz of spray solution within 5 minutes of clipping the tree

• Trees were removedTrees were removed with a standard tree shear

Study PeriodStudy Period• Stumps were rated every p y

30 days to determine regrowth

• As soon as anyAs soon as any vegetative growth was observed, trees were enclosed within a screenenclosed within a screen enclosure to prohibit psyllid feeding on stump regrowthregrowth

• Screen material is approved for green house structuresstructures

Sprout Formation at Each 30 Day R i I lRating Intervals

55 5

3 54

4.55

3 3

2.53

3.5Control25% Remedy

111.5

2 50% Remedy75% Remedy

* Balance of spray

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 000.5

30 DAT 58 DAT 88 DAT 117 DAT 146 DAT

p ysolution was mixed with diesel fuel

12 of 15 (80%) of the untreated stumps sprouted, as compared to zero of the 45 treated stumps

Percentage of Stumps Sprouting F h U d C lFrom the Untreated Control

90

123

70

80

ng 9

12

31

40

50

60

Stum

ps S

prou

tin 89

5

20

30

40

Perc

ent o

f

0

10

4/14/08 5/13/08 6/9/08 7/8/08 8/5/08 9/2/08Rating Date

15 stumps were untreated in this study

Number of Sprouts per StumpNumber of Sprouts per Stump30 1

226 25252345m

p

15

20 5678ts

per

Stu

8 8

12

79

710

891011

# S

prou

02 3

7

3

0

4

0

75

111213140 0 00

Individual Stumps1415

Average - 7.6 sprouts per stump

Sprouts Positive for GreeningSprouts Positive for Greening

• 80% of the stumps that were tested had80% of the stumps that were tested had one or more sprouts that tested positive for HLB using PCR testing methodsfor HLB using PCR testing methods.

• Of the sprouts tested, 30 of the 43 sprouts (70%) tested positive for HLB(70%) tested positive for HLB

ConclusionsConclusions• Remedy Ultra is very effective in controlling y y g

sprouts at a rate of 25% Remedy when mixed with diesel fuel

• Sprouts from stumps of trees removed due toSprouts from stumps of trees removed due to HLB can serve as a source of the HLB bacteriumSt t hi hl tt ti f llid• Stump sprouts are highly attractive for psyllids

• The control of sprouts is essential in combating HLB

• Be sure to have a SLN label at time of application and read and follow labeled directionsdirections

AcknowledgementsAcknowledgements

• Orange Co for supplying test site withOrange Co for supplying test site with special thanks to:

Jerry Newlin Shawron Weingarten Buddy– Jerry Newlin, Shawron Weingarten, Buddy Strickland

• Dr Ron Brlansky for PCR testing of• Dr. Ron Brlansky for PCR testing of sprouts