ASHS 2025 Conference

Several apple cultivars are susceptible to lenticel breakdown including but not limited to ‘Honeycrisp’, ‘Red Delicious’, ‘Gala’, and ‘SweeTango’. ‘Honeycrisp’ in particular has received considerable scrutiny by apple growers and packers due to its low percentage of packable fruit. ‘Honeycrisp’ in Michigan are put into storage with little to no disorders and, in 3-5 months, are pulled out of storage achieving less than 50% pack-outs of quality fruit in severe cases. These low pack-outs are a result of internal disorders, a physiological disorder ‘bitter pit’, lenticel breakdown, advanced decay, and some unknown light brown spotting that can be similar or smaller in size than lenticels. Investigations into the mechanisms behind these various ‘spots’ and discriminating between them is an essential first step in understanding the disorders and the discovery of solutions for growers and storage operators. In this study, three preliminary assessments were made to resolve the ambiguity behind lenticel breakdown and associated ‘spots’: 1) apple lenticels were imaged by light and scanning electron microscopy and characterized, 2) ‘Honeycrisp’ and ‘SweeTango’ apples were wrapped in paper and mesh bags on the tree as a field chemical spray exclusion assessment, and 3) a preliminary look at the microbiome of healthy and unhealthy lenticels. The latter effort revealed that ‘Alternaria’ species dominate the fungal community of unhealthy lenticels.