Citrus Greening Effects on Starch Content and Nutrient Balance of Citrus Leaves

Citrus Greening Effects on Starch Content and Nutrient Balance of Citrus Leaves

Tim Spann, Arnold Schumann, Ed Etxeberria, Ron Brlansky

CREC, Lake Alfred

Tim Spann, Arnold Schumann, Ed Etxeberria, Ron Brlansky

CREC, Lake Alfred

IntroductionIntroduction

• Blotchy mottle symptom of greening resembles nutrient deficiencies

• Zn, Mn, Fe and other deficiencies commonly appear on trees with greening symptoms

• Blotchy mottle symptom of greening resembles nutrient deficiencies

• Zn, Mn, Fe and other deficiencies commonly appear on trees with greening symptoms

ObjectivesObjectives• Determine the nutritional status of leaves

with different symptoms on greening symptomatic tree and compare these with control leaves from healthy trees

• Determine if there are changes in leaf nutrients that can be used as early indicators of greening infection

• Determine how foliar application of nutrients affects greening symptoms

• Determine the nutritional status of leaves with different symptoms on greening symptomatic tree and compare these with control leaves from healthy trees

• Determine if there are changes in leaf nutrients that can be used as early indicators of greening infection

• Determine how foliar application of nutrients affects greening symptoms

Experimental SiteExperimental Site• 9-year-old ‘Valencia’ on

carrizo• First greening find Dec.

2006– 109 trees, removed

immediately

• Jan. 2007, second find– 102 trees, 100 removed in

August 2007

• Jan. 2008, 74 trees with visible symptoms

• 9-year-old ‘Valencia’ on carrizo

• First greening find Dec. 2006– 109 trees, removed

immediately

• Jan. 2007, second find– 102 trees, 100 removed in

August 2007

• Jan. 2008, 74 trees with visible symptoms

MethodsMethods

• Branch study

• 22 trees with greening symptoms and 15 “healthy” trees were selected– All “healthy” trees were PCR –

– 19 of the 22 symptomatic trees returned a PCR value

• Treatments were applied on Feb. 29

• Branch study

• 22 trees with greening symptoms and 15 “healthy” trees were selected– All “healthy” trees were PCR –

– 19 of the 22 symptomatic trees returned a PCR value

• Treatments were applied on Feb. 29

TreatmentsTreatments• 9 treatments, 5 reps on greening and healthy

trees– Grower’s fertilizer 4B shot bag (0.06 Fe, 4.34 Mg, 1.0 Mn,

0.93 Zn) applied at recommended 2 gal / acre

– FeSO4, MgSO4, MnSO4, ZnSO4

– K-Phite 7LP (phosphorous acid)– KeyPlex (Mg, S, B, Fe, Mn, Mo, Zn)– SAver (2-0-10)– Water + adjuvant control

• All treatments applied with hand pump up sprayer to run off

• 9 treatments, 5 reps on greening and healthy trees– Grower’s fertilizer 4B shot bag (0.06 Fe, 4.34 Mg, 1.0 Mn,

0.93 Zn) applied at recommended 2 gal / acre

– FeSO4, MgSO4, MnSO4, ZnSO4

– K-Phite 7LP (phosphorous acid)– KeyPlex (Mg, S, B, Fe, Mn, Mo, Zn)– SAver (2-0-10)– Water + adjuvant control

• All treatments applied with hand pump up sprayer to run off

Data CollectedData Collected• Each limb was documented

photographically• Leaf samples

– pre-treatment, 2 WAT, and 6 WAT

– nutritional analysis (P, K, Mg, Ca, S, Zn, Mn, Fe, Cu), PCR, starch and ash content

– greening tree samples were taken for each symptom on that tree (yellow veins and blotchy mottle)

• Sampled leaves were also documented photographically

• Each limb was documented photographically

• Leaf samples – pre-treatment, 2 WAT, and 6 WAT

– nutritional analysis (P, K, Mg, Ca, S, Zn, Mn, Fe, Cu), PCR, starch and ash content

– greening tree samples were taken for each symptom on that tree (yellow veins and blotchy mottle)

• Sampled leaves were also documented photographically

Results NarrativeResults Narrative

• Starch was significantly higher (3-4x) in leaves of HLB infected trees compared to healthy trees

• P, Ca, S, Zn, Mn, Fe, and Cu were all significantly lower in HLB leaves

• K was significantly higher in HLB leaves• Mg was unaffected by HLB • N, B not analyzed

• Starch was significantly higher (3-4x) in leaves of HLB infected trees compared to healthy trees

• P, Ca, S, Zn, Mn, Fe, and Cu were all significantly lower in HLB leaves

• K was significantly higher in HLB leaves• Mg was unaffected by HLB • N, B not analyzed

Results NarrativeResults Narrative

• Mn was the only element affected by treatments– Both MnSO4 and shot bag significantly

increased Mn in control trees – HLB trees were unresponsive

• Visually, no change in symptoms were detected

• Mn was the only element affected by treatments– Both MnSO4 and shot bag significantly

increased Mn in control trees – HLB trees were unresponsive

• Visually, no change in symptoms were detected

ConclusionsConclusions• There are significant changes in quantities and

ratios of certain nutrients in greening trees as well as accumulation of large quantities of starch

• Changes may be detectable in parts of the tree where PCR cannot detect bacterium

• Changes may occur prior to the development of visual symptoms

• More data is needed to validate these results and determine if these changes are unique to greening

• There are significant changes in quantities and ratios of certain nutrients in greening trees as well as accumulation of large quantities of starch

• Changes may be detectable in parts of the tree where PCR cannot detect bacterium

• Changes may occur prior to the development of visual symptoms

• More data is needed to validate these results and determine if these changes are unique to greening

Next StepsNext Steps• More data is needed to validate these results

and determine if these changes are unique to greening

• Treatments need to be applied at other times of year when better uptake can be achieved

• Longer term studies need to be conducted• Higher, remedial rates of nutrients need to be

applied, not just label recommended maintenance rates

• More data is needed to validate these results and determine if these changes are unique to greening

• Treatments need to be applied at other times of year when better uptake can be achieved

• Longer term studies need to be conducted• Higher, remedial rates of nutrients need to be

applied, not just label recommended maintenance rates

Take Home MessageTake Home Message

• Better plant nutrition will Better plant nutrition will notnot cure cure greening, but it’s not going to hurt and greening, but it’s not going to hurt and it just may help slow the disease it just may help slow the disease progression in a treeprogression in a tree

• Better plant nutrition will Better plant nutrition will notnot cure cure greening, but it’s not going to hurt and greening, but it’s not going to hurt and it just may help slow the disease it just may help slow the disease progression in a treeprogression in a tree