As fresh strawberries continue to sweeten tables across Maryland, a new disease has become a major threat to the entire industry. Neopestalotiopsis, a water-dispersed fungal pathogen that causes fruit rot, leaf spots, and plant decline, has been making its way into strawberry nurseries and fields across the U.S., sparking urgent interest among plant pathologists and growers facing sudden crop losses.
The problem became clear in 2021 when nursery plants began arriving infected. Large outbreaks of Neopestalotiopsis were recorded in Florida, causing significant strawberry crop losses. The disease’s symptoms on nursery transplants (i.e. plug plants) often appear near or after delivery to fruit growers, making it difficult for both sides to assess plant health and make informed decisions in time.
Strawberries are a valuable early-season cash crop in Maryland, particularly for “you-pick” farms. According to University of Maryland Associate Professor Mengjun Hu, a single acre can hold around 15,000 plants. With each plant yielding about 1.2 pounds of fruit and strawberries selling for $5 per container or more, the potential payoff is high, but so is the risk. Hu and his graduate student Samantha Hasselhoff, are working to better understand the pathogen and help Maryland growers minimize both crop and economic impacts.
“In fewer cases, growers get transplants that look perfectly fine, but the disease may have already occurred inside without showing any symptoms,” Hu said. “Crop loss is costly, so it causes issues between nurseries and growers.”
Nurseries may lack the capacity for thorough pathogen screening, leaving growers to take significant risks on plant health.
“The issue is that growers have very few nursery options for their preferred cultivars and delivery dates,” Hasselhoff said. “And they often accept weak appearing plants because returning them is costly and even more risky for their season.”
Field Trials and Fungus Tracking
To investigate how the pathogen spreads and survives, Hasselhoff is conducting field research at the Maryland Agricultural Experiment Station’s Wye Research and Education Center. Her work focuses on disease progression across different strawberry cultivars, the timing of chemical application, and how environmental conditions, such as weather patterns, affect outbreaks.
Based on studies conducted in Florida and published in the American Phytopathological Society journal, cooler weather could prove beneficial in combating the disease, as early data suggest that Neopestalotiopsis struggles to sporulate at temperatures below 50–55 degrees Fahrenheit.
“Winter might be our friend in the Northeast,” Hasselhoff said.
She emphasized that more efforts and data are needed in production areas outside Florida with diverse weather conditions before drawing firm conclusions.
Another key goal of the research is identifying which strawberry cultivars commonly grown in this area are more resistant or more susceptible to the Neopest. Hasselhoff and Hu’s first year of trials included cultivars like Chandler, Galleta, Keep Sake, and Malwina. But in the future, they hope to include varieties like Camino Real and Ruby June, which are known for being vulnerable to infection but are a notable consumer favorite.
“We are not aiming to make blanket recommendations yet,” Hasselhoff said. “But, understanding how these cultivars respond under real field conditions in our area is essential.”
Impact on Growers
“Growers put everything into these plants — money, time, labor,” Hasselhoff said. “When you lose 30-40 percent of your crop because of a pathogen you could not see coming, that is not only frustrating — it can be the difference between a profit and a loss.”
Neopestalotiopsis may be microscopic, but the challenge it presents is massive. However, Hasselhoff and Hu are striving to find solutions and help the future of the Maryland small fruit industry.
“It is all about helping growers,” Hasselhoff said. “The more we know, the more precisely we can act. Whether it is spray timing and fungicide choice, or selecting the right cultivar for their microclimate, we want growers to succeed.”