A. P. Nyczepir Collaborators Bruce Wood, USDA-ARS Janete Brito, FL - - PowerPoint PPT Presentation

Nematode Management in Pecans

• A. P. Nyczepir

Collaborators

• Bruce Wood, USDA-ARS
• Janete Brito, FL Dept. Agric. Cons. Serv.
• Don Dickson, Univ. Florida

HISTORY

(Meloidogyne partityla on Pecan)

(Pecan Root-Knot Nematode)

• 1986 – 1st reported in South Africa.
• 1996 – 1st report in US (TX).
• 2001 – 2nd report in US (NM).
• 2002 – 3rd report in US (GA).
• 2005 – 4th report in US (FL)
• 2006 – 5th report in US (AZ & OK)

ABOVE-GROUND SYMPTOMS (M. partityla on Pecan)

• Dead branches in

upper canopy.

• Some trees severely

stunted.

BELOW-GROUND SYMPTOMS (M. partityla on Pecan)

Typical root galls Mature female

IDENTIFICATION (M. partityla on Pecan)

• Protein Analysis (USDA – Byron) (see below)
• DNA Analysis (NM State Univ.)

Distribution of M. partityla in Georgia

• In 2003-04, a survey was conducted in the major

pecan growing regions of Georgia.

• Root samples infested with root-knot nematode

were obtained from 13 different commercial pecan production sites.

• M. partityla was the predominant root-knot

nematode found; occurring in 72% of the

• rchards sampled.

Nyczepir, Reilly, & Wood, 2004

Influence of M. partityla (Mp) on severity of ME symptoms of pecan.

Uninoculated Mp-alone

Nyczepir et al., 2006

• M. partityla is a contributing factor to promoting “Nickel” deficiency in pecan.

CONTROL (M. partityla on Pecan)

• Chemical – no effective control (Temik).
• Cultural –

unknown to date.

• Rootstock – unknown to date.
• Biological – unknown to date.

OBJECTIVE (M. partityla on Pecan)

• Determine the susceptibility of 9 selected

pecan rootstocks to M. partityla.

• Determine the susceptibility of 5 selected

peach rootstocks to M. partityla.

METHODS (M. partityla on Pecan)

• Open pollinated seedling stocks evaluated:

– Apache - Pawnee - Moneymaker – Caddo

• Schley

– Curtis

• Stuart

– Elliott

• Wichita

METHODS (M. partityla on Pecan)

• Root-Knot Nematodes evaluated:

– M. partityla (Pecan root-knot). – M. incognita (Southern root-knot). – M. arenaria (Peanut root-knot).

• 1,400 eggs per pot

METHODS (M. partityla on Pecan)

• Data recorded after ~160 days:

– No. egg masses per root system. – No. root galls per root system. – No. eggs per root system.

RESULTS (M. partityla on Pecan)

• Regardless of

rootstock, there were more (P < 0.05) egg masses & galls per root system assoc. with M. partityla vs. Mi & Ma.

• Pecan is a better host

for Mp than either Mi

• r Ma.

RESULTS (M. partityla on Pecan)

• All pecan rootstocks

tested supported greater (P < 0.05) numbers of M. partityla than Mi or Ma

• M. partityla

reproduces better on pecan than either Mi

• r Ma.

Egg/g root Eggs/mass “Elliot”

METHODS

(M. partityla on Peach)

• Peach seedling stocks evaluated:
• Nemaguard
• Lovell
• Guardian
• Halford
• Flordaguard

METHODS (M. partityla on Peach)

• 1,500 eggs per pot
• Elliott pecan (Control)
• Data recorded after ~127 days:

– No. egg masses per root system. – No. root galls per root system. – No. eggs per root system.

RESULTS

(M. partityla on Peach)

• All peach rootstocks were rated as non-

hosts (highly resistant) to M. partityla infection.

• Number M. partityla eggs per plant
• All peach stocks (0 eggs/plant)
• Elliott (>17,000 eggs /plant)

Nyczepir and Wood, 2012

Field Microplot Study

OBJECTIVE: Conduct a long-term field evaluation study to determine if ‘Curtis’ or ‘Elliott’ tree growth is impaired due to M. partityla infection.

Influence of M. partityla on Tree Growth

Trunk Diameter (mm)

a b

Tree growth of both ‘Elliott’ & ‘Curtis’ rootstocks was suppressed in the presence

• f M. partityla 2 years after

inoculation.

CONCLUSIONS

• All open pollinated pecan seedlings tested were

good hosts to M. partityla.

• All peach rootstocks tested were non-hosts to M.

partityla.

• Interplanting pecan & peach trees in a

commercial orchard does not appear to intensify

• M. partityla populations between these 2 crops.
• Growth suppression was observed at the same

level in both ‘Curtis‘ & ‘Elliott’ stocks in the presence of M. partityla.

Biological Control

Pasteuria penetrans

• Is an endospore-forming bacterial parasite.
• Has been shown to have great potential as

a biocontrol agent of root-knot nematodes.

• Has never been evaluated against the

pecan root-knot nematode, M. partityla.

OBJECTIVE

Determine if Pasteuria penetrans can effectively suppress populations

• f M. partityla on pecan.

METHODS

• Evaluate three (3) different Pasteuria

isolates for parasitism against of M. partityla (GA-pecan isolate) in the laboratory.

• Bacteria endospores of the most

promising isolates will then be increased and re-evaluated under field microplot conditions at USDA-Byron.

RESULTS

• Laboratory results have identified specific
• P. penetrans isolates that have exhibited

attachment & efficacy against the juveniles

• f pecan root-knot nematode.
• M. partityla juvenile

A B C

A B

METHODS

1) Nematode-alone (Mp) (4,000 eggs/pot) 2) Both organisms (Mp + Bacteria (720,000 spores/pot) 3) Control

Tree Growth

Trunk Diam. (mm)

a ab b a ab b

Tree Death (2013)

• Control = 0%
• Mp+Pp = 8%
• Mp-alone = 42%

SUMMARY

The findings of this research indicate that the Pecan Root-Knot Nematode is:

• 1. A potentially economically important

pathogen to the pecan industry in the SE United States.

• 2. The search for an IPM management

strategy (i.e., rootstock, biological, chemical, etc.) for control of this nematode pest on pecan is warranted.