|COX, ROBERT - Texas Tech University|
|KOSBERG, LANCE - Us Forest Service (FS)|
|SHAW, NANCY - Us Forest Service (FS)|
Submitted to: Native Plants Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2011
Publication Date: 12/16/2011
Citation: Cox, R.D., Kosberg, L.H., Shaw, N.L., Hardegree, S.P. 2011. Effect of fungicide on Wyoming big sagebrush seed germination. Native Plant Journal. 12:262-267.
Interpretive Summary: The majority of seed germination studies and evaluations utilize some form of fungicide to control fungal growth and to make it easier to visualize germinating seeds. Some wildland species are particularly sensitive to fungicide, however, and seed evaluation can be significantly affected by fungicide type and application rate. We evaluated a number of common fungicide applications and determined that Wyoming big sagebrush should be evaluated without fungicide treatment to obtain an unbiased evaluation of seed performance. This species dominates millions of acres of rangeland in the intermountain western United States, but is increasingly being disturbed by wildfire and invasion of introduced annual weeds. Seed germination and emergence is a critical establishment phase for this species and evaluation of germination response will play a key role in designing restoration strategies for this species. Our results ensure that future studies of the germination response of this species will not be biased by what is otherwise a common experimental procedure in such experiments.
Technical Abstract: Because fungal infection may complicate both the logistics and the interpretation of germination tests, seeds are sometimes treated with chemical fungicides. Fungicides may reduce the germination rate and/or germination percentage, and should be avoided unless fungal contamination is severe enough to interfere with accurate observation of germination. We tested the effect of seed-applied fungicides on germination of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) at 2 different water potentials (-0.033 and -0.7 MPa) and found that treating test seedlots with fungicide reduced the germination percentage by up to half in some treatments. This effect was greatest at lower water potentials. We found that the fungicides were successful at delaying infection of the seeds or test media with fungi, but that the costs of reduced germination related to fungicide application make this practice undesirable. We recommend instead that those conducting germination trials with Wyoming big sagebrush either test untreated seed and accept some level of fungal contamination, or explore other methods of seed coat sterilization that may have less impact on total germination. Any treatment for reducing fungal infection, however, should first be evaluated for potential effects on germination percentage.