Q.Lettuce leaf issues
I am a first time gardener. I live in Eastern Wa. Zone 6B-hot, dry summers, cold, snowy winters-and I planted Bonnie Buttercrunch Bibb Lettuce starts in a shady part of my west-facing garden, about 3 weeks ago. I thought the lettuce was doing fantastic, until I went to harvest for the first time this morning. The outer (first?) leaves are white tipped and have white spots dotted over them (they look more white in person) the inner leaves are very bumpy, with some parts that appear almost translucent. I water with a buried soaker hose, mornings, and also evenings, when it’s gotten over 80, and into the 90’s. What’s going on?
I think you have a case of White spot. It is a leafy vegetable disease caused by fungus Pseudocercosporella capsellae. The crop infected by the fungi usually has brown or gray spots on the leaves. The leaves later turn yellow and fall off within a few days.
http://ipm.uconn.edu/documents/raw2/Diseases%20of%20Lettuce%20in%20Connecticut/Diseases%20of%20Lettuce%20in%20Connecticut.php?aid=69
The fungus can survive on seeds, so you can prevent it by planting certified seed. You can also prevent the harmful microorganisms by avoiding cool and damp conditions in your garden.
The best way to control white spot is to eradicate the infected crop. The disease spreads fast, so you should remove the sick crop immediately after seeing the symptoms. The fungus can be killed by suitable fungicides and copper products, which means that you can these chemicals to treat your infected crops.
Make sure the plants have adequate sunlight and air circulation. Soil should began to dry slightly between waterings. Constant damp and soggy soil can help harbor and spread the fungus.
