Potato Production Stages: Scheduling Key Practices
Characterization of potato growth and development is important for the scheduling of production practices, yield prediction and hail loss insurance. Most past descriptions emphasize vine growth above-ground and neglect the below-ground tubers (Anonymous, 1976; Sparks, 1972; Sparks and Woodbury, 1959). Recently, growth stages have been described integrating both vine and tuber growth and relating some agronomic practices to them (Bishop et al., 1986; Bissonnette et al., 1993; Rowe, 1993). This section (based on Pavlista, 1995) describes stages of potato production and indicates key practices at each stage. Norgold Russet, an early season potato, grown in Scottsbluff, Nebraska, was used as a model to depict planting on May 10 and subsequent plant development occurring chronologically in a desired production situation (see "Model Systems"). For each stage or time period, key production practices and potato development events are described in the order shown in Table 1. For pest descriptions, fertilizer suggestions, and variety requirements, see appropriate panels in this web-site.
Most Critical Actions = seed handling and preparation, fertilization.
Key Biological Activities = seed ageing and dormancy.
Starter fertilizer may be applied prior to planting. A dry N-P-K (nitrogen-phosphorous-potassium) fertilizer mixture (18-46-0 is commonly used in Nebraska) may be broadcast and disced into the soil before planting. If used in home gardening, application at planting is recommended. Gardeners can break the ground up with a hoe or shovel just prior to planting or have the area be garden plowed. Pre-irrigation may be used to eliminate soil clods for ease of planting. A soil moisture of 70 to 80% field capacity (3,10) is considered ideal for most soils.
During this period the main concern is to prepare the seed pieces for planting and avoid seed decay by diseases. In the USA, potatoes are not produced from true seeds but from tubers harvested from the previous crop. Nearly all production is from "seed pieces" cut from larger "seed-certified" tubers; some production is from "single drops" which are small whole tubers. Gardeners might want to use single drop seed if available and avoid some of the seed preparations otherwise recommended. All seed pieces should be about 2 ounces in weight (6 to 10 even-sized seed pieces per pound of whole potato tubers). Those less than 1½ ounces should be discarded. Since seed tubers are stored at 36-40 degrees F, they need to be warmed before planting. When a 40-degree F seed piece is planted in 50 degrees F and wet soil, moisture will condense on the surface of the piece, creating an environment highly favorable for disease development. Cut seed pieces need to be warmed slowly and kept ventilated to allow for wound healing, which is the formation of a protective layer, called the suberin layer, over the cut surface.
At the time of cutting, seed pieces should be treated with a fungicide dust. This aids in drying the cut surface and gives the seed pieces some protection against decay by micro-organisms. Commercial growers using mechanical cutters need to disinfect the cutting blades between each lot of seed-tuber to protect against carryover of disease organisms from one lot to another. Homeowners who hand-cut seed, can dip a knife into a 10% clorox solution between cutting washed tubers. Note that dirt can inactivate the bleach so the solution should be changed often (Rowe, 1993).
During storage, seed tubers harvested the previous season were dormant. Toward the end of the storage period, dormancy usually ends and, to varying degrees, sprouting may begin. The tuber is the sole source of water and nutrition for the sprouts and the life activities within the tuber. Performance of seed pieces is greatly influenced by the tuber's physiological age which is affected by time, handling and storage conditions. Bruised seed tubers are physiologically older than non-bruised ones. Plants grown from seed pieces cut from physiologically older tubers tend to emerge faster, have more stems, grow smaller vines, have more tubers per plant, bulk tubers quicker, die faster, and yield less. Seed that is not aged excessively is preferred.
- Anonymous. 1976. Potato loss instructions. National Crop Insurance Assoc. Bull. #6453.
- Bishop, G.W., G.D. Kleinschmidt, K.W. Knutson, A.R. Mosley, R.E. Thornton, and R.E. Voss (Technical Coordinators). 1986. Integrated pest management for potatoes in the western United States. Univ. California Agric. Nat. Resources Bull. #3316.
- Pavlista, A.D. 1995. Potato Production Stages: Scheduling Key Practices. Univ. Nebraska Coop. Extension Circ. #95-1249.
- Rowe, R.C. (Editor). 1993. Potato Health Management. Publ. The American Phytopathological Society Press, St. Paul, MN.
- Sparks, W.C. 1972. An aid for determining stage of potato plant growth. Univ. Idaho Current Information Ser. #186.
- Sparks, W.C. and G.W. Woodbury. 1959. Stages of potato plant growth. Univ. Idaho Agric. Exp. Sta. Bull. #309.