Potato variety demographics appear to be changing yearly with new varieties introduced to the industry on a consistent basis. Some of you may be growing a new variety for the first or second time and may be curious on how a variety may compare to the standard Russet Burbank or others such as Ranger Russet or Umatilla Russet. Even if you are not growing one of these varieties this year, you may have the opportunity in the future. Some of these newer varieties include Premier Russet, Clearwater Russet, Alpine Russet and Classic Russet. With the exception of Classic Russet, all can be used as high-quality process potatoes. It is highly desirable to have low glucose concentrations for process potatoes since glucose (a reducing sugar) reacts with amino acids in the presence of heat (frying) to form a darkened color of fried products. Table 1 shows the impact of storage temperature and variety response on glucose levels of these newer varieties compared to varieties currently being grown. Alpine Russet and Clearwater Russet have low glucose levels in comparison to the standards in the industry. Premier Russet has exceptionally low glucose levels compared to all varieties and indicates this variety has a vastly different carbohydrate metabolism than the others listed. Classic Russet is considered well-suited for the fresh-pack market. This variety has an added benefit of typically having lower glucose concentrations compared to Russet Norkotah, therefore making off-grade more desirable for use in premium dehydrated products.
Russet Burbank is known for long-term storage, and one reason for this greater storability is the inherent long dormancy of the variety. Interestingly, very few varieties evaluated at the University of Idaho Potato Storage Research Facility have a longer dormancy than Russet Burbank except Alpine Russet (~10 days) making this variety suitable for long-term storage. Premier Russet and Clearwater Russet have a shorter dormancy than Russet Burbank and Umatilla Russet but not as short as Ranger Russet (Table 2). Although these varieties respond well to chlorpropham (CIPC) applications to limit sprout development, there is a tendency for enhanced storability with longer dormancy varieties.
Below are a few characteristics about each variety based upon our experience with Idaho grown and stored potatoes that may provide some hindsight on storing your crop.
Premier Russet: This variety has extremely low reducing sugar (eg. glucose) levels even at low storage temperatures. The fry color of this variety is extremely light with very few to no fry color quality issues such as mottling or sugar ends. This variety can be successfully stored for mid- to long-term storage but additional care is needed to avoid wet rot, especially pink rot, in the field. An aggressive pink rot management program should be established and a post-harvest application of phosphorous acid going into storage may be necessary to minimize pink rot spread in storage. This variety is also susceptible to dry rot and additional care in handling may be necessary. Unfortunately, Premier Russet tends to have a high weight loss (about 2 times higher than Russet Burbank) in storage and this may limit the ability to store long-term.
Alpine Russet: This long-dormant variety is ideal for long-term storage. It also has exceptional fry color quality and low glucose concentrations desirable for process grade potatoes. Alpine Russet has similar weight loss in storage as Russet Burbank but is moderately to highly susceptible to dry rot. Additional management to minimize wounding at harvest would be recommended to mitigate greater dry rot potential.
Clearwater Russet: This variety has outstanding process fry color quality and low glucose levels even at lower storage temperatures. It is similar to Premier Russet in terms of greater dry rot susceptibility and shorter dormancy length although Clearwater Russet does not have as low of glucose levels nor does it have as high of weight loss as Premier Russet.
Classic Russet: This variety is being deemed the potential "Russet Norkotah" replacement due to high-quality fresh-pack attributes. It has similar dry rot susceptibility as Russet Burbank, although it has moderate to high weight loss in storage. This additional predisposition to shrinkage may impede long-term storage although management strategies to lessen shrinkage can be used.
Additional information regarding seed sources, recommended production practices and storage management for these varieties can be found at www.pvmi.org, www.ag.uidaho.edu/potato, www.kimberly.uidaho.edu/potatoes.
Table 1. Percent glucose (% fwt) at three storage temperatures at about 160 days after harvest.
| Variety | 42°F | 45°F | 48°F |
|---|
| Russet Burbank |
0.12 |
0.07 |
0.06 |
| Classic |
0.21 |
0.07 |
0.04 |
| Ranger |
0.18 |
0.08 |
0.06 |
| Highland |
0.17 |
0.07 |
0.07 |
| Blazer |
0.10 |
0.06 |
0.04 |
| Alpine |
0.09 |
0.03 |
0.02 |
| Clearwater |
0.05 |
0.02 |
0.02 |
| Owyhee |
0.05 |
0.02 |
0.02 |
| Premier |
0.012 |
0.006 |
0.002 |
Table 2. Approximate dormancy length at three storage temperatures in days after harvest.
| Variety | 42°F | 45°F | 48°F |
|---|
| Russet Burbank |
175 |
155 |
130 |
| Alpine |
185 |
165 |
140 |
| Classic |
155 |
130 |
100 |
| Umatilla |
145 |
130 |
100 |
| Owyhee |
140 |
120 |
100 |
| Premier |
120 |
100 |
85 |
| Clearwater |
110 |
90 |
85 |
| Highland |
110 |
85 |
80 |
| Ranger |
100 |
85 |
80 |
Editor's Note: Olsen is a potato specialist and Brandt is a support scientist for the University of Idaho.