Twenty years ago a one-size-fits-all harvest management program could be used when most of the potatoes grown in Idaho were Russet Burbank, but now a one-size-fits-all management program may not work. Two of the new fresh market or dual purpose varieties released within the last few years are Classic Russet and Premier Russet, and each comes with its own set of harvest considerations.
Classic Russet is susceptible to shatter bruise, but is rated moderately resistant to Fusarium dry rot, similar in susceptibility as Russet Burbank. Even so, care should be taken to minimize shatter bruise potential. Tubers that are more hydrated (crisp) tend to shatter more easily than those with a lower tuber hydration level.
Consequently, during the last couple weeks prior to killing vines, gradually reduce the amount of water applied so as to lower tuber hydration to an intermediate level as the skins mature. Also, avoid late-season nitrogen applications to facilitate skin maturation. Classic Russet is less susceptible to black spot bruise than Russet Burbank.
Premier Russet is susceptible to black spot bruise. Therefore, killing vines before natural vine death and harvesting tubers to coincide with the minimum time period needed for skin set may help reduce black spot bruise potential. Also, maintain available soil moisture above 60 percent during tuber maturation to maintain tuber hydration, as dehydrated tubers tend to black spot bruise more easily.
Premier Russet is more susceptible to Fusarium dry rot than Russet Burbank. Remember, Fusarium can only infect a tuber with a cracked or broken skin, so manage the crop to minimize shatter bruise and skinning. Premier Russet is also susceptible to pink rot. Tests have shown that phosphorous acid is very effective in minimizing pink rot infection for this variety, and should be applied to tubers (read and follow all label directions) going into storage that are harvested from fields that may have a problem with pink rot.
Regardless of the variety you are harvesting, there are several general harvest management practices that need to be followed to minimize tuber damage. Of utmost importance is tuber temperature.
Regardless of the type of bruise damage, the colder the tuber pulp temperature, the more potential there is to bruise tubers-cold tubers bruise more easily. Ideally, tuber pulp temperature should be 50 to 60 degrees F. Check tuber pulp temperature frequently during harvest, preferably every load. It would be wise to schedule harvest of bruise-susceptible varieties like Classic early in the harvest schedule when pulp temperatures are more likely to be in the optimum range.
Harvester conveyors should be filled with tubers because tubers landing on other tubers will bruise less. Harvester conveyor speeds may need to be adjusted if tubers are landing in a single layer on the chain links. Remember, too, tubers can be damaged on any piece of equipment, not just the harvester, so keep all drops to a minimum and run all conveyors at maximum capacity.
Additional information about these and other varieties can be found online at www.ag.uidaho.edu/potato/VarietyInfo.htm. Here you will find information about planting, fertilization, irrigation and more.