It is almost with relief that tomato season has finally ended in northeast Ohio. It was rough.
Although many gardeners still managed a decent harvest, I wish I had a dollar for each time I heard the phrase, ''late blight got my tomatoes.'' I wouldn't be rich, but I'd probably have enough cash for a night out at the movies.
So what is late blight and why was it such a problem this year? Did all of those gardeners really have it or were they simply victims of a wilt disease and blaming it on late blight was the trendy thing to do?
First, let's talk a bit about plants and how they can be related.
Plants, like us, have families. At the top of the genealogical plant tree is the family name and in the case of tomatoes that name is Solanaceae. If you picture what emerges from the trunk of the Solanaceae tree, you will find individual branches for potatoes, eggplant, peppers, tomatillos, petunias, the weeds we call common and deadly nightshade and tobacco. These plants are botanically related.
What determines how plants are related is always subject for debate, but botanists look at a number of common characteristics among plants, including the fruit and the flowers, a plant's reproductive parts and the numbers of petals and stamens.
Plant diseases are usually specific to plant families. Just like a dog doesn't contract the human cold virus, a green bean plant from the Fabaceae family, won't get the same diseases that attack the Solanaceae family. That's not to say beans don't get their own version of a blight disease. (The term ''blight'' can be either a fungal or bacterial infection that is highly contagious and can easily wipe out an entire genus of plants).
If you want to get technical about it, and I am assuming you do, late blight of nightshade plants is caused by a fungus-like pathogen called Phytophthora infestans. According to Cornell University's department of plant pathology, the disease can infect all parts of the plants, including leaves, stems, fruit and in the case of potatoes, the tubers.
It was late blight that appeared in Ireland in 1845 that caused the famine that wiped out much of the country's food supply. Had the farmers in Ireland practiced plant diversification, a famine might not have occurred, but that's a topic for another column.
The reason for the rapid infestation in Ireland was blamed on everything from static electricity caused by the installation of the ''modern'' railroad system to divine punishment for the sins of the people, but in reality, it was nothing more than the weather. The disease grows and spreads rapidly during conditions of high moisture content coupled with moderate to cool temperatures.
With nearly record-breaking rainfall in June and July this season, as well as cooler than normal night temperatures that rarely rose over 55 degrees until mid-August, conditions were excellent for late blight in northeast Ohio.
Symptoms of late blight include dark, greasy-looking lesions on stems and leaves and in the case of potatoes, the disease can spread to underground tubers by way of the reproductive spores falling to the ground and seeping into the soil where the tubers are actively growing below. Lesions most often show up after periods of wet weather. If humidity is high, the spores grow quickly and are easily dispersed by the wind to host plants as far as several miles away. It's easy to see how the disease can spread from one garden to the next.
Unfortunately, the disease can overwinter on potatoes because tubers are still alive even after they are dug from the ground and pulled away from the plants' roots. According to Cornell University, the tubers are safe to eat (humans can't get plant diseases), although they might not be very attractive or taste quite as good as healthy potatoes. Some gardeners simply cut away the affected portion of the potato and eat the rest. If your potatoes were infected, don't save tubers for starting new plants next year. Instead, purchase new, healthy seed potatoes and plant them in a different location in the garden, just in case you missed a few tubers when you dug this season's harvest.
Fortunately, late blight must have a living plant as a host, so you won't have to worry about it much on the tomatoes you've harvested and preserved for winter, as long as the fruit you picked wasn't affected. If you save seeds from your heirloom tomato plants for next year, Cornell's botanists advise these seeds will be safe to use. Rotate your tomato plants in next year's garden as well, which you should be doing anyway to keep soil-borne diseases from attacking year after year.
To combat late blight, should it occur again, there are a couple things you can do. Fungicides can be regularly applied to the plants on a regular basis if the weather conditions are right for an infestation. Or if you prefer not to use chemicals on your garden, keep a watchful eye on your plants and immediately remove any leaves, stems or fruit that show signs of the disease.
We may have had a difficult summer with our nightshade plants this season, but the great thing is, there's always next year.