Shrub & Garden Fundus
I have a persistent fungus each year that affects my dogwood, peonies, rhododendron and tomato plants. With the exception of the tomatoes I have been using Infuse every three weeks, which seems to slow the progress during the summer, but eventually the fungus overtakes the leaves by late summer. This appears as brown spots on the dogwood and rhododendron; tomato plants shrivel starting at the base and works its way up the plants.
In general the above plants can be susceptible to various fungal diseases. In many cases, the problem may be cultural or environmental and a fungicide may not be needed. Fungicides in general, can help to protect new or uninfected foliage, they are not curatives. It would be helpful to identify the problem and know what you are dealing with and spraying for.
Next season monitor your plants and send us digital photos of the plants as soon as you notice symptoms. Below are publications on dogwood and rhododendron with information on possible diseases.
Peonies can be susceptible to several fungal diseases. Avoid overhead irrigation. Maintain low humidity. Remove infected plant parts. Clean up debris at season end.
Tomatoes - From your description you may be dealing with early blight, a common fungal disease. See our website for information, prevention, and control
Following the suggestions given to my original question, I've been using Copper Fungicide on my tomato plants and zucchini, with limited success. See attached photos. Any further suggestions?
Thanks for the photos. Your plants are suffering from environmental stress, primarily caused by their proximity to the white, brick wall adjacent to them. The reflected heat from that wall is scorching and dehydrating the plants.
If the fungicide was sprayed on the plants on a hot, sunny day, they suffered additional phytotoxic damage.
You hit the nail on the head regarding heat stress due to proximity to the white brick wall. As soon as I covered the bricks, the plants began to thrive. Now there is a disease process that is killing leaves from the ground up. See attached photos. What is the suggested remedy? Thank you.
This is a normal occurrence in tomatoes as the plants get older. The older leaves turn yellow and fall off. There may be some septoria also in these older leaves. Pull off affected leaves. http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG56%20IPM%20Tomatoe... vw