This is the time of the season when tomato plants start showing signs of disease infections, usually as different shapes and colors of spots depending on which particular disease has infected the plant.
Earlier this week I took an informal survey of several varieties of tomatoes to see how each variety is holding up under early disease pressure. My MO was to look for leaf spots on the plants. Then I ranked them on a scale of zero to ten depending how bad the plants looked. Zero meaning no spots were visible, 10 meaning severe symptoms. No plants were bad enough to score what I imagined to be 10.
I didn’t count how many leaves were infected; or measure how many square centimeters were discolored; or brix levels of leaves; or levels of ethylene gas; or any other scientific criteria. Heck, I didn’t even alphabetize the list of varieties. I ignored any cultural differences such as mulch, staked or caged plants, planting history, etc. Over half were heirloom varieties, some of those looked quite good compared to the modern ones.
I surveyed about 15 gardens in two different locations about 20 miles apart. I made a point to look at them all the same day because twenty four or even twelve hours could mean the difference between no spots and spots. Here’s a chart of what I came up with:
|Tomato variety||Plant score|
|Pink Honey Drip||3|
|Large Red Cherry||6|
Pruden’s Purple, by far looked the best it had no spots and the leaves appeared to be growing vigorously. Chadwick Cherry came in a close second. There were a few different beefsteak-type tomatoes that were not specifically tagged by variety but all of them had more advanced disease progression.
Keep in mind this is only a snapshot of conditions for one day. That could all change later on as the plants begin to get stressed by fruit production.