Tools available to maintain productivity - PowerPoint Presentation

Slide1

Tools

available to maintain productivity of HLB-infected mature citrus groves.

Gene Albrigo, Megan Dewdney, Reza Ehsani, Jim Graham, Evan Johnson, Michael Rogers, Arnold Schumann, Ariel Singerman, Lukasz Stelinski and Tripti VashisthSlide2

Considerations for Maintaining Productivity

Psyllid ManagementTree HealthRetaining fruit on treesSlide3

Bad News First!

Psyllid ManagementTree HealthRetaining fruit on treesNeed to be aware of the problems with trying to control fruit drop

Give consideration to how much money spent on these efforts based on results from past studiesSlide4

Retaining fruit on trees?

HLB Induced Preharvest Fruit DropSlide5

Recent History of Preharvest Fruit Drop

USDA-NASS Records% Fruit Drop

Fruit type 2009-20122012-132013-142014-15Early-mids9-11182331Late oranges

9-11

22

31

25

Grapefruit

18

27

26

Over 10 % increase last 3 yearsSlide6

2014-15 harvest season

Fruit drop – PGR testsCan Plant Growth Regulators reduce fruit drop?

Which ones, if any, have an effect?AlbrigoSlide7

Summary of PGR Trials

Overall about 25 % of trials had a significant reduction in fruit drop due to a PGR applicationMore of the differences occurred in Hamlin trials than Valencia, but Hamlin also had higher % drop ratesNo block characteristics

were identified as a reason for a PGR working or not workingAlbrigoSlide8

Summary

Over all Hamlin tests (pooled), GA plus 2, 4-D appeared to significantly reduce fruit drop about 5 %This was about $100 of fruit value for 400 boxes/ acre yieldStill questionable if this is economically viable practice

AlbrigoSlide9

Why was PFD so difficult to control?

Many trees in groves in various stages of declineTrees affected by HLB often had multiple bloomsWhich bloom should be targeted for fungicide application?The one that will give the most fruit in the blockRain events more than once a week during bloomHeavy rainfall reduces residual effects of fungicides

Difficulty of applying fungicides every 10 daysMany demands for sprayers and large acreagesDewdneySlide10

Fungicide efficacy

No longer have long residual period fungicidesBenlate or Topsin-MIn bad PFD years, failures occurred even with these fungicidesStrobilurin

fungicides not as efficacious or as long residual effectBetter with Ferbam but there is a very limited supplyConducted trial with available fungicides including newer strobilurin mixturesStill collecting fruit data DewdneySlide11

Canker-Related Fruit Drop

In areas with high canker incidence, use of copper sprays to manage canker can minimize canker-related fruit drop

Keep trees healthySlide12

Things you can do now to help sustain productivity

Psyllid Management

Tree HealthSlide13

Psyllid Management

Keeping psyllids at low levels remains important

An aggressive psyllid control program is required!Slide14

Management varies widely

Organic

Intermittent Management

Abandoned (>57,000 ha in FL)

Conventional Management

6-12 sprays

2-3 sprays

No treatment

StelinskiSlide15

More

psyllids

found where management is intermittent

Stelinski

Insufficient Control!!!Slide16

How far can

psyllids

move on their own?

Psyllids

are capable of 3 hours of continuous flight.

This translates to approximately four miles of continuous flight.

StelinskiSlide17

Coordinated sprays through the CHMA program provide the greatest reduction in ACP populations!

There is an economic benefit to participating in a CHMA – Presentation by Ariel

Singerman

later this morning!!!Slide18

Jan

Feb

MarAprMay

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Pyrethroid

Organophosphate

Pyrethroid

Organophosphate

Pyrethroid

Organophosphate

Blue shading = Coordinated sprays; Using pyrethroid or OP

Green shading = Non-coordinated sprays; not using a pyrethroid or OP

Example Coordinated Spray Plan

Keys to success:

Scheduled, fast and cheap!!!Slide19

Overall Tree Health

There are a number of approaches that can be used now to improve or maintain health of HLB-infected treesSlide20

Root HealthSlide21

Soil pH and well water quality affect root health and HLB disease expression

Common condition: pH > 6.5 in wetted zone is associated with well water high in bicarbonate (>100 ppm) and > HLB expression (i.e. fruit drop)

Bicarbonate reduces root uptake of Ca, Mg, K, Fe (e.g. high Ca in soil/moderate levels in leaves)Groves with bicarbonate stress are experiencing > deterioration in fibrous root density, lifespan and function in root uptakeRootstock sensitivity: Swingle > Carrizo > Sour orange > Cleopatra GrahamSlide22

Acidification of the soil and/or water reduces root zone pH and promotes release of Ca and Mg for root uptake

Water

conditioningLower soil bicarbonate, faster not working during rainy season Inject N-furic acid or sulfuric acid (40%) to reduce irrigation water to 100 ppm bicarbonates Soil conditioning

High soil bicarbonate, slower, working all season long

300

lbs

/treated acre of Tiger 90 sulfur

lowered soil pH in 9 months

Valencia/

Swingle

- 10

yr

old ____________________________

Sulfur

pH

Root density

(mg/cm

3

)

No 6.4 1.1

Yes 5.9* 1.4*

____________________________

* Significant difference P < 0.05

GrahamSlide23

Valencia/Carrizo trees after 2.5 years of soil acidification in a grove with high bicarbonates – Hardee Co. 2015

Fruit crop 6/12/15

GrahamSlide24

HLB root loss

What we know30-50% root loss before leaf symptoms

70-80% loss as canopy thinsRoot growth is stimulated in HLB-affected treesRoot loss from shortened lifespanManagement considerationsIncreasing root growth is not likely to helpRoot growth already stimulated by HLBNeed to encourage root longevityEncourage optimal environment for roots

Minimize

stress

on

roots from pests

Management depends on rootstock and site

JohnsonSlide25

HLB reduces effectiveness of Phytophthora

control – timing is essential

JohnsonSlide26

Target applications of fungicides to onset of root flushes

JohnsonSlide27

Phytophthora, nematodes, weevils should be managed more aggressively to sustain root health – details in FCPMG

www.crec.ifas.ufl.edu/extension/pest/Phytophthora count >10-20 propagules/cm3 recommend

rotation of fungicides:Aliette/phosphite after spring shoot flush Mefenoxam after spring-early summer rains begin Aliette/phosphite after midsummer shoot flushMefenoxam after fall shoot flushes

Remember root flushes

follow

shoot flushes

Manage root pest and pathogens

after

correcting water/soil stresses

JohnsonSlide28

Balancing root : shoot ratios

HLB symptom expression on mature citrus tree canopies is preceded by considerable root decline

The unequal timing and severity of HLB symptom expression in the roots and canopies contributes to a major imbalance of root : shoot ratiosRoots sustain the canopies and the canopies sustain the roots, thus any major imbalance weakens the trees and may contribute to HLB symptoms like leaf and fruit dropIn response to HLB-induced root decline, a more favorable root : shoot ratio can be achieved by hedging and topping of mature tree canopiesHedging and topping results in vigorous leaf flushes which must be protected from psyllid and leaf miner insectsSchumannSlide29

8 feet

No ToppingSlide30

6 feet

8 feetSlide31

6 feet

8 feetSlide32

Severely Pruned

6 feetSlide33

Proper

use of macro- and micro-nutrients

Nutrition is a practical, feasible tool to improve tree vigor and slow the decline of mature citrus trees affected by HLBProper nutrient use in the HLB era includes:1) correction of critical HLB-induced deficiencies with foliar sprays to bypass the inadequate nutrient uptake capacity of HLB-impacted roots (N, K, Mg, Mn, Zn, B, Mo) – e.g. Rouse #7 spray2) Provide a constant balanced nutrient supply DIRECTLY to the roots (frequent fertigation, controlled release fertilizers)

3) Maintain a soil chemical composition in the root zone that is most conducive for efficient constant uptake of nutrients (e.g. Ca availability is enhanced by neutralizing bicarbonates).

Note that Ca, which is critically deficient in HLB-affected trees is not practically applied by foliar sprays and should be soil-applied

SchumannSlide34

Citrus Health Workshop(dates and times still tentative)

August 12, 2015 @ CRECHalf-day seminars on nutrition, root health, etc…Discussion of knowledge gapsEnlist assistance of growers in large-scale demonstration trials

…stay tuned for more details!Slide35

TENTING

Ehsani

SUPPLEMENTARY HEAT1

2

Using:

Solar heat

Target

:

Heat tree until it reaches

130

°

F but not exceed 140

°

F

Thermal Therapy

Using:

Dry heat

Steam

MethodsSlide36

Supplementary Heat

Ehsani

SUPPLEMENTARY HEAT

Systems using

steam

, recommended treatment at air temperature

130-136

°

F

for

15 seconds to 2 minutes

On the right is a system using a surplus military truck as the system’s platform

Below is a system using a ‘goat’ truck as the system’s platform

A boiler, a water tank, and a generator are mounted onto the platformSlide37

Summary

Considerations for managing current fruit-bearing trees:Unclear whether PGR’s and fungicides will reduce fruit drop due to HLB or PFD Preventing canker fruit drop where a problem will helpStay on an aggressive ACP control program (CHMAs)Take care of the root system of tree

Manage soil/water pHProper timing of phytophthora controlBalance root : shoot ratiosProvide trees with proper nutritionThermal therapy may be used to prolong life of infected treesSlide38

Acknowledgements

Citrus Research & Development Foundation

More Information?

Gene

Albrigo

, Megan Dewdney, Reza

Ehsani

, Jim Graham, Evan Johnson, Michael Rogers, Arnold Schumann, Ariel

Singerman

, Lukasz

Stelinski

and

Tripti

Vashisth