University of Maryland. Cooperative Extension. Home and Garden Information Center.
Have a plant or pest question? Questions from Maryland and the District of Columbia are answered by Home and Garden Information Center’s Certified Professional Horticulturists. If you are located outside of these areas, you will be asked to enter your state and county. Your question will be forwarded to the appropriate extension expert.
Cornell University. College of Agriculture and Life Sciences.
California Oak Mortality Task Force.