On lettuce, the symptoms of rot caused by fungi are the most common. One of the most dangerous lettuce diseases isgray moldBotrytis cinerea. This fungus causes brown or gray spots on the leaves. In conditions of high air humidity on the infected tissues, a gray coating appears on the stems with spores.
Very often, gray mold is accompanied byblack rot at the base of the lettuce heads , caused by the fungus Thanotophorus cucumeris. This pathogen is also responsible for seedling dieback and lettuce seedlings. Sometimes significant losses are caused byScleroderma rotSclerotinia sclerotiorium.
The first symptoms of this disease are most often visible on the root collar. They have the form of wet spots covered with white mycelium, which increase their surface area. Leaves wilt and rot. As time passes, black lumps, the so-called lumps, appear in the mycelium. sclerotia, which are fungus spores. The source of infection are spores hibernating in the soil and poorly cleaned seed. The disease is prevented by sowing treated seeds and spraying young plants with plant protection products. Do not wet the leaves during watering and carefully collect and destroy plant residues.
Another common lettuce disease isdowny mildew of lettuceBremia lactucae.Olive-yellow spots appear on the upper side of the leaves, darkening with time. On the underside, during high air humidity, a gray-white coating of the spore-stems is visible. Infected plants stun and turn yellow. Leaves die in sections. Under favorable conditions, whole plants rot as a result of infection by other pathogens. The disease is favored by: temperature around 17ºC, high air humidity and lack of sun.
