Tomato disease showing up
Thank goodness for the rain! As I prepared to write this column on Tuesday morning, after we had received a 10th of an inch of rain, I was still moaning and moving sprinklers. One 10th was NOT enough!
I got tied up with other things during the day and didn’t get to write. I am glad that happened! Early Wednesday morning we got over an inch of rain. Unfortunately, during that storm, we got hit by lightning (again) and our router, modem and a few televisions were blown, ugh.
Thursday morning, we got a little more, so I won’t be moving sprinklers for a few days. However, please pay attention to the soil. The recent rains may not have been sufficient to really bring the soil moisture back to a level to support plant growth.
The soil moisture level is great for pulling weeds. I have lots of them. I was pulling weeds Wednesday night and noticed that the soil is not all that wet, despite the rains. Check your soils.
The take-home message is this: Just because it rained doesn’t mean you have to stop watering. Pay attention to your plants and the soil.
Recent rains also provided perfect conditions for disease to flare up. I expect we will begin to see Septoria (leaf spot) and Alternaria (leaf blight) on tomatoes and other diseases in the garden. Some of you are already seeing the symptoms of these now.
Both of these diseases are quite common and chances are if you grow tomatoes you are familiar with them.
Septoria starts on the lower leaves with circular lesions that have dark borders and grayish centers. Outside the lesion, foliage begins to turn yellow as the disease progresses. Septoria progresses rapidly in rainy weather as the spores are splashed by rain.
Alternaria blight shows up as leaf spots on the lower leaves as well, but these spots are different. The lesions are brownishblack and as they enlarge, concentric rings begin to develop.
Leaves eventually dry up and drop and the disease progresses up the plant with both diseases. Severe infestations can result in total defoliation.
Unfortunately, both of these diseases are a challenge for the homeowner to control. Cultural practices such as crop rotation, removing dropped leaves and other infected plant debris in the fall, avoiding overhead irrigation and providing good air space between plants in order to dry out foliage are all recommended.
However, because of our recent weather patterns, cultural practices may not work when there is heavy disease pressure.
There are fungicide sprays containing chlorothalonil or mancozeb that work, but you need to apply them every seven to 14 days during wet weather. If you catch it early enough in the season, you may be able to prevent further spread.
The fruit affected with these diseases can be eaten, but the problem is, the fruit doesn’t develop as it should because of fewer leaves to support growth.
The recent rains were very welcome but unfortunately, along with them comes the potential for disease.
Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at bennett.27@osu.edu.