Issue link: http://read.dmtmag.com/i/37334
30 ladder capacity - optional kit available for 36 ladder cap. Nate Reed MCP-ETHYLENE combination tested S cientists are exploring the idea of combining ethylene with SmartFresh (1-methylcyclo- propene) to modulate the effect on ripening. MCP has been used successfully on apples to delay ripening in storage and enhance their stora- bility. It is also being used on pears to extend the storage life, but Dr. Nate Reed, head of pome fruit research and development for AgroFresh, said pears are more sensitive to the material than apples are. There’s also the complication that pears need to soften up after treatment, whereas hardness in an apple is a positive trait. MCP inhibits ripening by binding to ethylene receptors in the fruit and excluding the ripening hormone ethylene. Reed said he’s doing tests with a combination of SmartFresh and ethylene with the idea that the ethylene will modulate the effect of the MCP on ripening and provide the option of having an intermediate effect, rather than long-term. In theory, this might be accomplished just by using a lower rate of MCP, but Dr. Jim Mattheis, postharvest physiologist with the U.S. Department of Agriculture in Wenatchee, Washington, said the recommended dose of MCP for pears, which is between 100 and 300 parts per billion, is so low that reducing the application rate further could lead to more inconsistent results. A rate of 30 ppb, for example, is getting close to the limit of detectability with research instruments. Using the recom- mended rate and counteracting it to some extent with ethylene makes it easier to manage. When the two are applied together, the ethylene competes with the MCP and prevents it from binding to the ethylene receptors as efficiently. In effect, it reduces the MCP concentration in the fruit. Mattheis has found the combination to be suc- cessful at the research level. It appears to increase the consistency of the MCP treatment, reduce the period of time during which the fruit won’t ripen, and still provide scald control on d’Anjou pears. He is researching the optimum ethylene rates and looking at potential problems with the combi- nation, such as the effect not lasting long enough. —G. Warner www.goodfruit.com GOOD FRUIT GROWER AUGUST 2011 15