I would rather deal with drought than the weather we have had for the last two weeks! I can’t take the cloudy, rainy, cool, overcast weather anymore and hopefully this front moves away soon! I want summer.
This weather is also wreaking havoc on my tomatoes. The recent weather pattern has been absolutely perfect for diseases to thrive. My tomatoes have early blight and I am not happy.
At least with drought, I can drag hoses and water. With diseases on tomatoes that are encouraged by damp weather, I have very little control.
Early blight of tomatoes is a disease that loves prolonged periods of wetness. It can lead to loss of infected fruit and decreased vigor of the plant that also leads to decreased vigor.
My misfortune is a great opportunity to share a very important fundamental element of diseases, the disease triangle.
The three parts of the disease triangle are the host plant, the pathogen, and the environment.
The host plant in this case is a susceptible tomato. I have several varieties that are affected with Roma appearing to be very susceptible.
The pathogen for early blight is Alternaria solani and is present in the environment, just hanging around waiting for the right environment.
The environmental conditions that leads to this pathogen infecting tomatoes is abundant moisture and temperatures between 60 and 85F. As I mentioned, we have had the perfect conditions for this disease to thrive.
With the right environment, the spores of the pathogen germinate and grow into the leaf cells, causing damage. In the very early stages of infection, you don’t see the symptoms of the disease.
With early blight, the symptoms on the leaves are leaf blight with brown circular lesions. The lesions start to show up on the lower older leaves and progress upward. The infected leaves wither, die, and fall off.
As long as this weather pattern continues, further infection of upper leaves continues. You can spray with a fungicide to prevent further infections.
However — and this is another very important element when it comes to controlling disease — timing is critical. The fungicide has to be on the leaf surface before the pathogen infects the leaf.
The problem right now is that if I spray, rains just wash it off. So at this point, I am in the process of picking off the infected leaves to hopefully decrease the amount of pathogen present for further infections.
The bottom line is that environment plays a huge role in disease development and we are in a weather pattern that is perfect.
Sanitation (removing infected leaves) and attempting to keep a preventive fungicide on the plants may help reduce disease.