I am looking for leaf-off imagery for Oklahoma, Kansas and Texas. 1m leaf-off imagery would be ideal, although any substitute would be helpful. I need fairly high resolution imagery to distinguish conifer from deciduous trees--Landsat would likely be too coarse. How can I obtain leaf-off imagery for KS, OK, TX?
Nationally, you could check the list of programs at http://www.ndop.gov/maintenance.html or http://pubs.usgs.gov/fs/2009/3055/pdf/FS2009-3055.pdf. At least 2 programs that fly leaf-off are listed.
You will probably find more current and higher-resolution options if you check with each state's natural resources, forestry, or emergency management agencies, and maybe state universities. They may fly their own leaf-off imagery or collect and consolidate imagery from other agencies or county governments. I started to find promising hits by googling things like 'texas leaf off imagery'...
The National States Geographic Information Council (NSGIC) maintains a list of GIS representatives for each State. These rep's are often the GIS coordinator for their respective State, and as such they have alot of information about data availability. You could contact the rep's from those three States to ask if high-res leaf-off imagery is available, and how to obtain it.
Since the date of your question, Nearmap (go.nearmap.com) has been regularly flying US metro areas and they typically will capture both spring and fall leaf-off aerial imagery.
And yes, I work for them as well.