With its refreshingly light taste, lettuce (Lactuca) can become bitter-tasting if it is exposed to certain growing conditions. You are right to avoid wetting leaves if possible. First appears as small white spots on the tops of the leaves, but then progresses a fine, pale gray-white powder, all over. What Is White Mold? Keep reading to find out the causes of white spots on lettuce plants. Spinach White Rust Disease – Treating Spinach Plants With White Rust, Radish Plant Has Yellow Leaves: Why Do Radish Leaves Turn Yellow, Prickly Kale Leaves – Does Kale Have Thorns, Corn Husk Wreath Ideas: How To Make A Corn Husk Wreath, DIY Air Plant Wreaths: Wreath Making With Air Plants, What Is Osmin Basil – Learn About Basil ‘Osmin’ Purple Plant Care, Wallis’s Wonder Plum Info – How To Grow A Wallis’s Wonder Plum Tree, Messina Peach Care: Growing Messina Peaches, Cinnamon Basil Info – How To Care For Cinnamon Basil Plants, Thanksgiving Tradition: Turning Homegrown Pumpkins Into Pie, Growing Thanksgiving Dinner – Must Have Turkey Side Dishes, Interesting Uses For Pecans: What To Do With Pecans, The Bountiful Garden: Bringing The Garden To Thanksgiving. Lettuce is a cool-weather crop. When they first develop, white molds are very hard to detect since the spores are so tiny that they can only be seen under a microscope. Yes? Leaf tissue around the spots turns yellow; Fuzzy white growth can be seen on the underside of the leaves; Bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. It could be ash if there are forest fires nearby or dust from a nearby quarry. Actually, do better than look – see if you can wipe the spots off. 1 of 5. The Causes of Bitter Lettuce Sap. Also, keep the garden free from plant debris that harbors the fungi. Lettuce and Endive > Leaves > Spots or blotches on leaves. Bacterial canker also creates whitish spots on leaves, but they will be slightly raised off the surface of the leaf. Next time around, plant varieties of lettuce that are resistant to this disease such as Arctic King, Big Boston, Salad Bowl and Imperial. The disease was first reported in California in 1964. The leaves will be surrounded by a brown or black ring. Fungal lettuce diseases, such as damping off or sclerotinia drop (white mold), are caused by soil borne fungi that thrive in cool, damp soil and are primarily lettuce seedling diseases. This fact sheet details the causal pathogen, favorable environmental factors and recommendations for control for greenhouse producers. Downy mildew is my number one culprit simply because it seems to attack all types of vegetation. The adult insect is a grey or white fly while the larva or maggot is a greenish yellow caterpillar with a pair of black mouth hooks. Sign up for our newsletter. Treating these lettuce diseases is achieved by spacing the plants apart to provide airflow and by reducing the amount of irrigation the seedlings receive. If that is the case, it is likely something in the air that has drifted down onto the leaves. Septoria leaf spot is a fungal disease that may cause white or grayish spots on leaves. Plants Affected: Lettuce, Mizuna, Chinese Cabbage, Radish, and Mustard Leaves, "Mizuna: White rust" by Scot Nelson is licensed under CC BY 2.0, "White rust of Chinese cabbage caused by Albugo candida" by Scot Nelson is licensed under CC BY 2.0, If you require information in an alternative format, please contact us, Copyright 2020 by College of Tropical Agriculture and Human Resources, White Rust of Cruciferous Vegetables in Hawai‘i by Erik Patnude and Scot Nelson, White rust of Chinese cabbage caused by Albugo candida, White spots or "pustules" on underside of leaves, Reduce leaf wetness, such as by using drip irrigation. Downy mildew thrives in infected crop residue. Once colonies form, however, white molds appear as spots on a surface. The leaves will be surrounded by a brown or black ring. Growth slows, leaves turn yellow and the plant dies. Powdery mildew is a common fungal disease encountered in greenhouse production of lettuce. Bacterial canker also creates whitish spots on leaves, but they will be slightly raised off the surface of the leaf. For best production, keep your lettuce in the coolest spot in your home – you’ll have trouble finding a spot so cool it isn’t happy! White molds can either remain white or change to green, black, grey, or practically any other colour over time. First of all, take a good look at the white spots. Mold symptoms appear on blossoms, stems, leaves, and pods that have water-soaked spots. Find more gardening information on Gardening Know How: Keep up to date with all that's happening in and around the garden. It thrives in temperatures from 55-70 degrees. The fungus that creates angular leaf spot forms white spots … Lettuce with white spots might mean a few different things, usually a fungal disease but not always. It has since been reported from the major lettuce growing regions worldwide probably due to contamination of seed. Another possibility is called white rust or Albugo candida.Another fungal disease, white rust may commonly affect not only lettuce but mizuna, Chinese cabbage, radish and mustard leaves.Initial symptoms are white spots or pustules on the underside of the leaves. Septoria leaf spot is a fungal disease that may cause white or grayish spots on leaves. Sure, AgSil16H is a good source of potassium silicate you can use (which I refer to in my post about silicate in general), however there are many other sources so I didn’t want to go straight to an AgSil16H reference. This post is filed under Defect Identification.. You can follow any responses to this entry through the RSS 2.0 feed.. You can leave a response, or trackback from your own site.. 2 Comments on “Romaine- Rib Discoloration” Jeff Provost Says: June 20th, 2012 at 10:25 am I was inspecting Romaine just yesterday, and came across yellow spots on the leaves (discoloration). 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