Wednesday, August 20, 2014

Early Blight on Tomatoes - Some strategies that have worked for me

In July of 2006 my wife and I returned from a week long vacation and discovered that all of our
tomato plants were suffering from some disease.  Needless to say, we were devastated.  Mother
Nature can be such a bitch.  As I always do, I got over it and went looking for some answers.
The following is a summary of my blight control program.
Early blight on San Marzano Plum Tomatoes

In the Fall I spray every bed in which I grew tomatoes with copper sulfide fungicide as well as next
year's tomato beds.  
In the early Spring I spray the same beds once again.
Two weeks after the plants go into the ground I begin spraying once a week, alternating between
copper sulfide and Oxidate (an oxidizing fungicide).

When the plants go into the ground I immediately prune off any branches or leaves touching the
ground and continue this practice throughout the growing season.  In addition, I pinch out any
and all suckers on determinate tomato plants.
Regarding indeterminate tomatoes, I employ a little different strategy.  First of all, I prune and train
the plants to be more two dimensional.  It's so much easier to do a thorough spraying.  As with the
determinate tomatoes I prune anything that touches the ground.  In addition, I only allow the main
leader and two suckers to grow (one on each side of the main leader).  I use a trellis system consisting
of heavy duty steel fence posts driven into the ground.  I attach horizontal bars made up of fir or cedar
1 x 4's attached to the fence posts with nuts and bolts or bolts with cotter pins (my favorite).
I attach stainless steel screws to the 1 x 4's every 6 inches.  They are driven in part way.

I then zigzag tomato twine (available for Johnny's Selected Seeds) top to bottom.  I can then attach
the tomato plants to the twine using tomato clips.  I love this system because it allows me to easily
keep track of each plant's growth and to find and eliminate suckers as they emerge.  A neater, more
well groomed tomato plant is much easier to cope with if it should get the blight.  I will cut off the
diseased branches before spraying.   See my earlier post "Tomatoes, the First Pruning".

Plant Selection:
I have observed that some of my tomato plants seem to be more resistant to Early Blight than
others.  This year I tried growing "Nebraska Wedding" tomatoes for the first time.  They are
remarkably blight resistant.  In addition, BHN-624, a hybrid cherry tomato has shown above
average blight tolerance.

One final thought:
My mindset is one of managing the problem.  I expect to get Early Blight so I'm ready when
it occurs.

All the best,

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