The following story took place last summer.
These are some red iceberg lettuces I was growing for seed. Everything looked great.
The rows in the front have had their outer leaves removed to increase ventilation. The rows in the back still have their outer leaves.
Do you see the holes in the lettuce patch? Over the next couple weeks, as the lettuces started to bolt, the red icebergs also started to rot. Whole heads would go from perfect salad material to slimy to gone in a couple of days.
For a brief period it was a real slimy jungle.
By the end of July, only a handful of plants survived and then they too succumbed to slime. A less than glorious seed crop.
What went wrong?
The simple answer is that this variety is not very disease tolerant. Here are some other thoughts.
Iceberg and other tight headed lettuces can be a challenge in humid climates like ours. The tightly wrapped leaves of these lettuce types hold moisture and create an ideal habitat for bacterial and fungal diseases.
I had thought last year would be ideal for lettuce seeds as it had one of the driest summers in a long time. Still in our climate, even the driest summers have a lot of humidity in the air.
Another option is poor crop rotation. In 2009, there had been chicories and lettuces right beside where the 2010 red iceberg plot would be. Though the 2009 lettuce crop had been a success there had been some traces of disease. Any lettuce pathogens would have built up over the 2009 season and been present in higher numbers for the 2010 season.
The combination of high disease pressure and tight iceberg heads might have been the losing combination.
How is this year’s lettuce seed crop? Well, for on thing I’m not growing any red iceberg lettuce for seed. I prefer seed crops that yield seed.
I’ll post some pictures of this year’s bolting lettuce soon.
How do your lettuce seed crops fare in your climate?