ISSUE 13 July 27, 2006
PLANT DIAGNOSTIC LAB SUMMARY
Below is a summary of samples diagnosed from July 5, 2006 to July 19, 2006 (research samples and seed health testing results are not included):
Host |
Diagnosis |
Taxonomic name |
County |
Corn |
Drought Stress Damage |
Abiotic pathology |
Clay |
Spruce |
Spider Mite Injury |
Oligonychus ununguis |
Becker |
Soybean |
Symptoms mimicing growth regulator herbicide injury - likely due to environmental stress |
Abiotic pathology |
Marshall |
Grape |
Black Rot |
Guignardia bidwellii |
Cass |
Sunflower |
Poor Or Insufficient Sample |
Grand Forks |
|
Crabapple |
Mechanical Damage |
Abiotic pathology |
Cass |
Spruce |
Growth Regulator Effect |
Abiotic pathology |
Becker |
Sunflower |
Herbicide Injury |
Abiotic pathology |
Cass |
Spruce |
Water deficiency |
Abiotic pathology |
Cass |
Symptoms that mimic growth regulator injury on soybean may not be due to herbicide exposure. If you see growth regulator symptoms uniformly throughout a field, consider physiological stress as a possible cause. Researchers in Iowa, Illinois, and southern Minnesota have reported seeing this phenomenon (growth regulator type symptoms, in the absence of possible herbicide exposure), and they speculate heat stress and/or water stress may be the underlying cause(s). See links below for more information:
http://www.ent.iastate.edu/Ipm/Icm/2002/7-22-2002/pgr.html
http://swroc.coafes.umn.edu/SWMNPEST/01News/ipmstuff71201.PDF
Kasia Kinzer
NDSU Plant Diagnostic Lab
Website:
www.ag.ndsu.nodak.edu/diaglab
e-mail: diaglab@ndsuext.nodak.edu
Telephone: 701-231-7854
206 Waldron Hall, PO Box 5012
Fargo, North Dakota 58105