Leaf Drop and Head Lettuce (2001) - 3 pages
Leaf drop of lettuce is a common problem in Saskatchewan - particularly at sites with a long history of vegetable crop production. The fungus which causes leaf drop (Sclerotinia sclerotiorum and S. minor) attacks a wide range of vegetable crops including beans, carrots, cole crops and tomatoes. Repeated cropping of a site to sensitive hosts results in high population of this fungus in the soil. The fungus gains entry into the lettuce crop by attacking any older senescent leaves which come into contact with the soil. As the infection develops the plants show a characteristic tendency to wilt even when adequately watered - leading to the “leaf drop” name. Eventually, the infected tissues produce resting bodies or sclerotia which resemble rodent droppings. These resting bodies are capable of persisting for several years in the soil. The wide host range and persistent resting bodies limits the potential to control
“Leaf Drop” or related diseases via crop rotation. This study evaluated the potential to use fungicides to reduces losses to Leaf Drop in a direct-seeded lettuce crop.
The trial was conducted as a component of a larger lettuce variety trial conducted in Outlook and Saskatoon in 2001. Both the production sites have a long history of continuous cropping to vegetables - with the associated problems with Sclerotinia. A number of varieties of head lettuce were direct seeded at each site in early May.
