Midwest Vegetable Guide - 2022 - 233

Potato - Horticulture
Potato - Horticulture
Major update by Ben Phillips, Liz Maynard - Oct 2020
Reviewed by Liz Maynard - Aug 2021
Crop Description
Potatoes (Solanum tuberosum) are a staple food grown from
small tubers of a mother plant that is grown by specialized
seed-potato producers. The Midwest produces potatoes
primarily for table stock and processing into potato chips.
Varieties used for chipping are usually brown skinned, whitefleshed,
and globe-shaped to facilitate slicing from any
direction. Table stock potatoes include 'starchy' (high dry
matter) baking varieties and 'waxy' (low dry matter) boiling
varieties in numerous skin and flesh color combinations with
widely variable sizes and shapes. Starchy varieties include
the Russets. Waxy varieties include Norland Reds. Some
varieties are intermediate between those two types, for
example Yukon Gold.
Scab is an important disease that affects the marketability of
table stock potatoes. One way to manage scab is to maintain a
soil pH of 5.0 to 5.2. However, low soil pH reduces
phosphorus availability, and most rotational crops will not
perform well at the low pH. In fields with a history of scab,
using scab-resistant varieties is the best option to avoid
having to adjust pH to the detriment of rotational crops.
Planting and Spacing
Tuber production: Rows 34 to 36 inches apart. Seed pieces
9 to 11 inches apart in row, depending on variety and
intended use. Seed 16 to 18 100-pound bags per acre. Seed
piece should be 1-1/2 to 2 ounces. Using B-size certified seed
will save cutting labor and reduce tuber-borne diseases.
Seed stock production: Select seed stock from high-yielding
hills that are smooth, well-shaped, and free of diseases and
insect injury. When possible, obtain certified G1 or G2
(generation) seed stock. Store seed stock in new crates to
avoid disease contamination. Seed potatoes should be at least
1-1/2 to 2 ounces in weight. If cutting larger seed potatoes,
warm to 45°F before cutting, then sort to remove blind, slab,
sliver, ripped, and undersized pieces after cutting. Cure cut
stock at 38°F to 40°F, with 85% to 95% humidity in piles less
than 6 feet deep, with good air circulation for 6 to 10 days.
To supply one acre of seed potatoes, you need roughly 14,000
to 26,000 seed pieces.
Fertilizing
pH: Maintain a soil pH of 5.5 to 6.5.
Before planting, do not fertilize with N or P, but apply 50 to
400 pounds K2O per acre based on soil test results and
recommendations from your state. The most efficient way to
spread the remaining fertilizer is with a banded application at
planting at least 2 inches below and 2 inches to both sides of
the tuber. As a banded starter fertilizer, apply 0 to 30 pounds
N per acre, 0 to 150 pounds P2O5 per acre, and 0 to 200
pounds K2O per acre. The rate of K2O should not exceed 200
pounds per acre when banded.
Manganese may be needed when the soil pH is above 6.5 on
mineral soils and above 5.8 on organic soils. Use a soil test to
determine the amount of manganese needed. Include the
required amount of manganese in the starter fertilizer, or
spray the foliage with 1 to 2 pounds of manganese per acre at
least twice during active growth. On sandy soils, broadcast 30
pounds or band 15 pounds sulfur per acre.
Sidedress once at emergence and once at hilling or tuber
initiation with 50-75 pounds N per acre each time. The
second application can be adjusted according to rainfall and a
petiole nitrate-N analysis. Use lower end of range for earlymaturing
varieties. Reduce the amount of fertilizer N applied
by the value of N credits from green manures, legume crops
grown in the previous year, compost and animal manures,
and soils with more than 3 percent organic matter. The total
amount of N from fertilizer and other credits should be 100 to
150 pounds per acre.
Harvesting
" New " potatoes can be dug by hand from the sides of hills for
continual harvest for fresh market sale, but they do not keep
as well as a mature tuber. New potatoes can also be once-over
harvested in sections at a time, but the chain conveyors can
blemish the soft skins of these immature tubers.
Storage potato market life can be lengthened by preventing
sprouting of potatoes in storage; use maleic hydrazide (Royal
MH-30) according to label directions one week after
blossoms fall. For varieties and conditions where flowering
does not occur, apply four to six weeks before potatoes are
mature and ready for harvest. Make only one application.
Apply when no rain is expected for 24 hours. Potatoes treated
with maleic hydrazide cannot be used for seed because
sprouting will be inhibited. Follow label directions.
Storage potatoes benefit from uniform maturation for
mechanical harvest. This can be accomplished by killing the
vines with a labeled herbicide. Once vines are down and
dried, mechanical harvest can begin with chain-conveyor
diggers. The labeled vine-killing herbicides are listed below,
along with instructions.
Midwest Veg Guide 2022
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Midwest Vegetable Guide - 2022

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