REDUCING CARBON DIOXIDE-RELATED POSTHARVEST DISORDERS

Internal and external postharvest disorders attributed to carbon dioxide sensitivity continue to contribute to annual losses. Symptoms of CO2 sensitivity are diverse but generally present on peel of less mature fruit and in flesh of more mature fruit of multiple existing cultivars. Symptoms can be eliminated using a combination of CO2 abatement and diphenylamine treatment of cultivars with average susceptibility. Eliminating CO2-related disorders can be more difficult where crop protectants are restricted or where fruit are highly sensitive. Also, newer cultivars present a challenge as damage can appear and sensitivity is unknown when they have never been screened. Evidence indicates that elevated CO2 exposure is linked with particular changes in peel and flesh chemistry that may reveal if fruit have been exposed to and/or compromised by elevated CO2 or if a particular injury resulted from CO2 exposure. We propose to develop a protocol for determining CO2 sensitivity of cultivars new to our growing region, determine best storage practices for those cultivars when produced under organic or crop protectant-restricted regimes, and determine means for assessing compromised asymptomatic and symptomatic fruit. Our goal is to reduce unexpected internal and external disorders in the organic apple cold-chain and improve diagnostic accuracy. Objectives: 1. Screen cultivars for CO2 sensitivity. 2. Determine best cold chain practices when CO2 sensitivity is indicated. 3. Indicate chemistry associated with CO2 sensitivity.