Penn State Extension released a disease update for commercial fruit growers on April 21, outlining the current risks and management recommendations for orchard diseases across Pennsylvania.
The update is important as it helps growers manage the impact of shifting weather conditions on apple, peach, and cherry crops during a critical stage in the growing season. Effective disease control can protect yields and ensure crop quality.
According to Penn State Extension, apple scab infections are likely between April 24 and April 25 due to forecasted weather conditions. The southern half of Pennsylvania is nearing the end of peak ascospore availability from overwintering leaves. Cedar apple rust and quince galls continue to produce spores during rain events, while Marssonina blotch infection risk is increasing as petal fall approaches. Fire blight remains a concern after two significant infection events occurred between April 14-18, with Epiphytic Infection Potential (EIP) levels exceeding thresholds that indicate high risk if wetting occurs. The update recommends using prohexadione calcium products like Kudos or Apogee to prevent shoot blight in apples.
The report also highlights an increased risk of powdery mildew due to recent dry conditions affecting both apples and stone fruits. Cherry leaf spot is another concern for tart cherry trees as optimal temperatures later in the week may favor its spread. Many fungicides labeled for apple scab are also effective against cherry leaf spot.
Growers are advised to monitor local weather and tree growth closely when making management decisions, use online resources such as the NEWA website for real-time data, comply with regulations before applying chemical products, and consult product labels from sources like CDMS, Agrian or Greenbook.
Penn State Extension supports community well-being by addressing problems and fostering innovation for individuals and businesses according to the official website. The organization delivers science-based education promoting agriculture, food safety, and responsible resource management according to the official website. Its services reach every county in Pennsylvania through local offices and digital tools according to the official website. Penn State Extension collaborates with government agencies, industry partners, and nongovernment organizations to provide educational programs according to the official website, offering workshops, online courses, consultations on farming topics including pest control according to the official website, with programming focused on agriculture, nutrition and environmental stewardship according to the official website.
As unpredictable spring weather continues across Pennsylvania orchards this year, Penn State Extension’s regular updates will help guide fruit growers through ongoing challenges.
