Day 226: The War on Tomato Blight

July 23, 2012

purple Jasper

I’m a little more than tomato crazy. It’s kind of an addiction. I attempt cultivation of over 15 heirloom varieties from unusual seeds collected around the world. I grow white, cream, orange, pink, purple, neon green, yellow, black, and even a few red tomatoes of varying sizes and shapes. A hobby gone wild is a bit of an understatement.

16oz Sweetheart

I’m always looking for better methods to grow heirloom tomatoes. In my geographical location, the beautiful and rainy Pacific Northwest, growing tomatoes can be somewhat of a challenge. Apart from our not-so-sunny skies, overwatering, under-watering, and tomato blight pose problems.

blight on stem

My first crop of tomatoes was obliterated by a powdery black mildew that started on a few leaves and spread in a matter of days. Grass-green tomatoes were left to decompose on rotting vines. I ate a ton of fried green tomatoes and canned tubs of green tomato relish that year.

After my first tomato-flop, I researched blight causes and remedies. I learned the fungus responsible for tomato blight exists in the soil. It is recommended that infected soil, like the dump-truck full of very expensive organic stuff I purchased from a well-respected dealer and carted by the wheelbarrow full down a huge hill and into my garden beds, be replaced yearly. For me, that’s not an economical or labor-friendly solution. It took me weeks to move a truck-load of soil down a steep hill. No to mention, I spent $500 for the stuff. Starting my garden organically was important to me. Unfortunately, organic did not mean sterile. And there is nothing inorganic about naturally occurring fungus flourishing in our wet conditions.

blighted vines

Several natural gardening sites recommended adding soil amendments, like copper. But in the end, most concede there isn’t much to be done to repair infected soil.  I added copper the second year and blight held off a bit longer, but by mid-August, I noticed a few black mildew spots. A week later my crop was gone and the fried green tomato eating commenced.

blight spots

After hours of research, it seems the most economical way to battle blight is through careful watering. Overwatered and under-watered tomatoes are susceptible to diseases, pest infestations, and blights. The interesting thing about tomato blight is that it doesn’t seem to grow or spread on dry leaves and it cannot infect the leaves unless the fungus-infested soil splashes on the plant during watering.

So the trick is to water the tomato without getting it wet and to keep the infected soil from touching the plant. Sounds almost impossible, but I’ve figured out a way. My first impulse was to purchase several commercial containers with automatic watering systems to keep my plants dry. But the investment of $30 per tomato planter was too great. I needed a do-it-yourself option.

I made almost-free self-watering planters using buckets. The construction of each planter requires two 5-gallon buckets, a pint container with plenty of punched holes, and a 4ft length of 1” PVC pipe.  I scavenged and purchased 100 bucket, and I already had dozens of square, plastic flower pots leftover from purchasing flowers and seedlings. Large yogurt containers with holes punched along the walls also work great.

The idea is to stack the buckets and use the space created between the stack to hold a reservoir of water. The inner bucket holds the soil plant, while the outer bucket acts as the water reservoir. I drilled a few holes in the inner bucket and cut out a square space to insert the pint-sized flower pot. The flower pot extends into the reservoir and allows the soil and roots to act as a wick and move the water up through the plant. I also cut a 1” hole with a hole-saw bit. The length of PVC pipe stuffed through the hole serves not only as a way to deliver water into the reservoir, but also works great as a plant stake to provide support to the growing plant.

potted tomatoes

Once the buckets were constructed and filled with dirt, I transplanted tomato seedlings and packed cedar shavings around each seedling. The cedar created a barrier between blight-infected soil and my precious heirlooms. The shavings also prevent cut worms and other nasty pests from breeding in the soil.

So far, I see no signs of the powdery, black mildew. It’s only mid-July and a little too early to tell if my battle with the blight will be victorious.  The individual plants consume the perfect amount of water every day. There is no risk of overwatering. Reservoirs need replenished every 3 days. The task saves time and is as easy as sticking the garden hose down into the PVC pipe and allowing the space between the buckets to fill.

The greenhouse is packed with 50 healthy plants, most of them towering over me. The plants are loaded with yellow blossoms and what seems like zillions of green tomatoes. A lack of warm weather and sunshine set my garden back a couple of weeks, so I’m not counting on fresh tomatoes for another week or two. Although delayed, the crop looks promising. I’ll eat fresh tomatoes throughout the summer until the first frost in November forces a clean pick of remaining fruit. If all goes well, there will be lots of sauce making to keep me busy and to get me through until next spring, when I start the whole process over again.