Plant disease - Ask Extension
I have been growing tomatoes, cucumbers and honeydews in a raised bed garden with drip irrigation for the past 2 years. Each year all 3 plants (beginn...
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Plant disease #306105
Asked March 10, 2016, 10:45 AM EST
I have been growing tomatoes, cucumbers and honeydews in a raised bed garden with drip irrigation for the past 2 years. Each year all 3 plants (beginning with the tomatoes) have developed a disease that begins with leaf spots on the lower leaves and progresses to almost complete defoliation by mid August.Last season I sprayed weekly with chlorothalonil but the disease returned, ending the fruit bearing season prematurely. The drip irrigation prevents any foliar wetting. I have enclosed pictures of the leaves. I have been growing resistant varieties such as Better boy, Jersey Hybrid and Sungold tomatoes. I check and adjust the soil pH annually and have used compost purchased at Chesapeake Compost Works. I have used the recommended amount of an osmotic slow release fertilizer.
Any ideas?
Baltimore County Maryland
Expert Response
This sounds like Early Blight, an extremely common and vexing tomato problem. The spores of this fungus overwinter in the soil and get splashed up onto the lower leaves early in the season and further rain splashes it up the plant.
Cover the soil around your plants with 3-4 layers of newspapers. (You can put straw or mulch over the papers to hold it down and it looks better.) Put the newspapers tight up to the tomato plant stems to keep spores from getting through. You still may see a fungal spot on a lower leaf. Pull it off immediately and spray with chlorothalonil. Keep after it. Here is our Grow It Eat It section's article on Early Blight: http://extension.umd.edu/growit/early-blight-vegetables
There are other fungal disease that act similarly. Same procedures for them.
Check out Grow It Eat It for more tomato culture and problemsolving. The IPM Series: Tomatoes is a publication that includes a good diagnostic chart.
ECN .
Cover the soil around your plants with 3-4 layers of newspapers. (You can put straw or mulch over the papers to hold it down and it looks better.) Put the newspapers tight up to the tomato plant stems to keep spores from getting through. You still may see a fungal spot on a lower leaf. Pull it off immediately and spray with chlorothalonil. Keep after it. Here is our Grow It Eat It section's article on Early Blight: http://extension.umd.edu/growit/early-blight-vegetables
There are other fungal disease that act similarly. Same procedures for them.
Check out Grow It Eat It for more tomato culture and problemsolving. The IPM Series: Tomatoes is a publication that includes a good diagnostic chart.
ECN .
