Late blight returns to Maryland

Many Baltimore gardeners have only just planted their tomatoes and yet we have our first late blight warning of the 2010 gardening season. This past weekend, the University of Maryland’s Extension service reported that late blight was spotted in St. Mary’s County on May 7. The disease was found in an unnamed grower’s greenhouse and they are taking measures to control the problem. Officials do not yet know if this is the same strain from last year or a different one.

Late blight first appears on plants as black or brown patches and can affect potatoes as well as tomatoes. Various sources predict that potatoes will be the main problem in 2010. Before planting, clear your soil of any old potatoes. Also, potatoes thrown in your compost may later sprout in your garden if you use compost that has not matured. Remove any potato plants that you did not plant this spring and use only clean new seed potatoes.

To prevent late blight this spring:

Buy local plants. Try to purchase your tomato plants from a small local grower. There are many small farm stands along the roadsides in the counties of Maryland. In Baltimore city, try the local farmer’s markets, such as the one in Waverly each Saturday.

Keep your garden clean. Late blight can winter over on dead plants. If you have not cleaned the debris from your garden yet, do so before planting new tomatoes. Dead tomato or potato plants should be bagged up and put in the regular trash, not added to compost.

Look  for signs on new plants. Late blight appears as dark brown or blackish spots. These spots will enlarge until the whole plant turns dark and dies. Sometimes there is a bit of white fuzz. Remove these plants as soon as possible and throw them into the trash, not the compost pile. For more tips, read the Examiner article, "Watch for late blight on your tomato plants".

To learn more about the recent outbreak, see the University of Maryland’s Extension service article “Will late blight be a problem in 2010??”