What is Septoria Leaf Spot?
Dear Small Scale Life:
My husband really dove 100% into the gardening world last spring and worked tirelessly doing research, going to seminars, watching YouTube channels, talking with Master Gardeners. He tried the grow-bag system and at the height of summer had about 25 bags with wonderful goodness growing wonderfully…he watched his garden like a mama duck. He redirected our in-ground sprinklers away from the garden so they would just sit in 1″ of water in small kiddie pools and the bags would drink as needed through quite a few inches of mulch.
Towards the end of the summer, nearly everything had blight (all the soil was new). He even made 4 bags for his mother, who had the bags on a 2nd floor deck where she hand watered as needed…she too developed blight. When I handed him the seed catalog that arrived in the mail, he is completely discouraged and doesn’t feel he should do another garden & it was all a wasted effort. What can I do to encourage him to try again….?
Kelly in Wisconsin
There is nothing worse than losing an entire crop due to pests and blight. It is so frustrating and heartbreaking, especially when you have such high hopes at the start of the year. Believe it or not, blight and pests hit all of us. Whether it is aphids attacking your plants or blight, we all deal with issues at one time or another. This will be a two post answer to her question. The first post will cover Rain Gutter Grow Systems and the tomato blight septoria leaf spot, and the second post will be an answer about trying gardening again after a big set-back.
Rain Gutter Grow Systems
Kelly mentioned that two separate gardens with new soil that got hit with blight in 2015. Why did they get blight? Fortunately, I am familiar with both gardens and have pictures of them from 2015. First, let’t talk about the type of garden system used in these two cases.
Both gardens were built using Larry Hall’s Grow Bag Garden Systems, more commonly known as the Rain Gutter Grow Systems. In talking with Larry, he developed this system while researching ways to grow tobacco to hedge on costs on cigarettes in Minnesota. Over time and by experimentation, the system evolved from using net cups, five gallon buckets and rain gutters to putting a root pouch/Walmart bag into a readily available kiddie pool. Both systems allow water to wick up into the soil via netcups or grow bags. Plants take as much water as they want and a are watered automatically. The system is essentially a aquaponic system without the air stones, water circulation and fish.
It is an intriguing concept, and even I created a Hybrid Rain Gutter Grow System in 2014. In my experience with the system pictured above, I have gotten excellent results in 2014 and 2015. I have not tried tomatoes in this system yet, but I am tempted to try it this year as an experiment.
Kelly’s Tomato Plants
Kelly’s system was the Kiddie Pool System. I have posted a picture of her system above when they had just planted the bags and before the blight had taken over. In her post, Kelly stated the following:
“He redirected our in-ground sprinklers away from the garden so they would just sit in 1″ of water in small kiddie pools.”
Unfortunately, I know her husband did not redirect the sprinklers immediately, and this particular location got hit by not one but two sprinkler zones. That means that two different sprinklers were watering the tops of the tomatoes each sprinkler cycle (i.e., one sprinkler would stop and the other would begin). From memory, the blight attacked the lower part of the tomatoes first and worked its way to the top. Even though her husband tried to prune the plants and spray them, the blight was too advanced and killed the plants.
Mary’s Tomato Plants
Unfortunately for Mary, this was the second year that her tomato plants had gotten this blight. She thought that putting the Kiddie Pool System on the second story deck would protect her from it, but unfortunately, the blight followed her plants there. At the time of the pictures in early September 2015, you can see the blight developing on the upper leaves of the tomato. Why did the blight attack these systems? In this case, I believe infected soil from 2014 was used to create these grow bags.
Tomato Blight Septoria
I believe the tomato plants in both systems had septoria leaf spot, which is a fairly common fungal disease here in the Upper Midwest. One of the characteristics of septoria leaf spot is that it attacks the lower leaves of the tomato plant first and moves up the plant. According to the University of Minnesota Extension, spores are move up the plant with splashing water (especially when watered from above by a sprinkler) and by secondary infections.
Severely infected tomatoes plants have leaves that turn yellow and eventually fall off. While it does not affect the fruit, losing the leaves will kill the plant and could cause other fungal infections and sunscald.
Preventing Septoria Leaf Spot
- Check your garden at least once a week (I do it almost every day because….well….just because)
- Keep tomato leaves as dry as possible; use drip irrigation or soaker hose. I water with my hose, but I keep the water very low to the ground (no sprinklers)
- Remove low hanging branches and suckers so water cannot splash onto them (according to the University of Minnesota Extension, septoria leaf spot spores can be splashed six feet on rain or irrigation!)
- Give tomatoes enough space between plants to allow air flow between plants (note the picture above)
- Stake, cage or trellis your tomatoes to allow air flow between plants
- Plant tomatoes in a raised bed
- Remove tomatoes at the end of the season (spores can surivive in winter)
- Destroy affected plants; you can compost them IF your compost pile gets hot enough to kill spores
- Rotate your tomato crops
Treating Septoria Leaf Spot
I am not an expert in treating this fungus, so you will want to check with your local gardeners and nurseries. I was looking at other blogs like the University of Minnesota Extension, the Missouri Botanical Gardens and Tomato Dirt Blog, and each indicated that fungicide applications may be necessary. According to the University of Minnesota Extension, fungicides currently labeled for use are:
- Bordeaux Mixture
- Chlorothalonil (Daconil 2787)
- Liquid Copper
Again, I am not an expert with this, and you will want to check with local experts before treatment.
Whew! This was a long post, and you have the floor to provide feedback. Have you dealt with this particular blight in the past? How did it work out for you? What worked? What didn’t? How did you change your growing patterns?
In the next post, I will address the second part of the Kelly’s question: how do you rebound after a major gardening set-back?