ISSUE 1   May 10, 2007

SUBMITTING SAMPLES TO THE NDSU PLANT DIAGNOSTIC LAB

County extension agents have been learning to use a new database to submit sample information and images for samples submitted to the NDSU Plant Diagnostic Lab. Using this database, samples from anywhere in the state can be checked into the NDSU Plant Diagnostic Lab right from the county offices. Information and images can be uploaded directly into the database, ultimately saving time and hopefully leading to faster turnaround times for diagnoses. County agents are encouraged to use this system, although it is not required.

The NDSU Plant Diagnostic Lab generally examines samples on a ‘first-come-first-serve’ basis, but certain samples (such as suspected high risk pests/pathogens and samples where a timely diagnosis is required for appropriate treatment) must take priority.

For more information on how to submit samples to the NDSU Plant Diagnostic Lab, please see the following website, http://www.ag.ndsu.nodak.edu/diaglab/, where you can obtain a lab form and tips on submitting good quality samples.

Before submitting a sample to the NDSU Plant Diagnostic Lab, please first consider using your local county extension agent or other local expertise. A nominal fee of $15 for North Dakota residents ($25 for non-residents) helps offset the cost of lab supplies and for technical support.

 

UPDATE FROM THE NDSU PLANT DIAGNOSTIC LAB

From January 1 to May 3, 2007, the NDSU Plant Diagnostic Lab has received at least the following samples:

Sample Category

Number

Seed Health/Phytosanitary

299

Woody ornamental (evergreen)

7

Field Crop

5

Woody ornamental (deciduous)

4

Turf

3

Soil – SCN extraction

1

Plant/Mushroom ID

1

Insect ID

1

Miscellaneous – drain tile

1

Total

322

Among the woody ornamental evergreens, winter injury or other environmental stress was the most common diagnosis, followed by possible root injury (mechanical or chemical). Root injury or soil-applied herbicide injury was suspected in at least two spruce situations. Spider mite injury was observed on at least 2 samples, but the spruce spider mite was only observed on one sample. Such mite injury probably occurred in prior years, and it was secondary to the primary problems faced by those particular samples.

No needle cast disease has been diagnosed yet this season. It has been a drier and warmer April, which does not favor disease development. So, hopefully needle cast will not be a problem in 2007.

Cytospora canker has been diagnosed on at least two spruce samples this year, based on symptoms alone (dead limbs, excessive sap production, no obvious mechanical wounds). A diagnosis for Cytospora canker is much more reliable if the fungal fruiting bodies are detected, but this usually requires submission of the entire limb (all the way back to the trunk of the tree), and for obvious reasons, this is often deemed impractical by the homeowner.

 

A BUR OAK PEST PREVIOUSLY UNKNOWN TO NORTH DAKOTA

A borer beetle has been detected on at least two bur oak samples that have come to the lab. Several other samples have been submitted to Michael Kangas (Forest Health Specialist, North Dakota Forest Service) and others. The identity of this borer beetle has not yet been confirmed. NDSU entomologists are currently processing the samples. Per Kangas, this pest has been observed "on young bur oak trees in several locations of eastern North Dakota as of 4/16/07." Species identification depends on observing the adult beetles. The species is suspected to be the living beech borer (Goes pulverulentus), but emphasis must be made that this is a tentative identification and it cannot be confirmed until the adults emerge.

According to Kangas, the damage (see photograph) has only been observed on Bur Oak in North Dakota, and not yet found on additional hosts (elms, cherry).

Kangas further encourages homeowners to continue to consider using Bur Oak, since it is "a long-lived, drought-tolerant, cold-hardy species that is well adapted for the northern plains," and it is unknown if this new pest is an outbreak or part of a normal periodic event.

Chemical controls are not recommended at this time, since efficacy is not known. Rather, pruning out affected limbs may be helpful. Severely infested trees should be removed. Older trees reportedly are not severely affected by this suspected pest. Natural predators of this pest include birds (woodpeckers) and carpenter ants. Maintaining tree vigor is always advised, since stressed trees are more attractive to these types of beetles.

bur oak infested twig
A twig of Bur Oak infested with pupae of an
unidentified borer beetle; the shredded bark results
from woodpeckers seeking the tasty but damaging
insect pests.

Kasia Kinzer
NDSU Plant Diagnostic Lab
e-mail: diaglab@ndsuext.nodak.edu
Telephone: 701-231-7854


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