Success StoryResearch to Farm: Improving Lettuce Crops by Understanding Disease Dynamics



Research to Farm: Improving Lettuce Crops by Understanding Disease Dynamics

Author: Nicole Gauthier

Planning Unit: Plant Pathology

Major Program: Horticulture, Commercial

Outcome: Initial Outcome

Lettuce is a common cool season crop that provides early- and late-season profits for specialty crop farmers across the commonwealth.   It is also a reliable source for healthy vegetables for home gardeners during spring and fall.  Diseases such as lettuce drop can often cause losses that affect growers for many years.  The causal fungus Sclerotinia sclerotiorum can affect a wide range of host crops and can survive for 8 to 10 years in soils.  Management is difficult, even with modern fungicides.  A recent grower survey indicated that commercial farmers who have a history of lettuce drop experience losses as high as 60%.  In 2022 and 2023, the UK IPM Vegetable Working Group developed a high tunnel-based research project to examine a range of cultural practices that can slow or suppress disease in contaminated soils.   Considerations such as soil moisture, planting date, and lettuce cultivar were examined for their potential benefits.  The study determined that the most common time for planting lettuce, mid-March, was the time that the fungus was most active and caused the highest levels of disease.  Earlier and later planting dates resulted in fewer disease losses.  Further, results showed that some cultivars that were reported as disease resistant were extremely susceptible, while other cultivars that were thought to be susceptible to lettuce drop were resistant.  These findings give growers options to continue to produce lettuce in contaminated fields and high tunnels.  According to the 2017 Ag Census, there are almost 300 commercial growers who produce lettuce in Kentucky.  This new information has the potential to save lettuce growers approximately $6,000 per acre.