Maturity?
Maturity of a variety is often described as
early, mid-season and late. Differences will occur between regions but the
general rule of thumb that I follow is early - 60 days, midseason - 90 days,
and late - 120 days measured from the time of planting until harvest. Potatoes
will emerge anywhere from 3-5 weeks after planting. It is important to have
frost-free days from the time of emergence until harvest.
Chitting?
Whole seed can be chitted (green sprouted)
prior to planting, this will ensure earlier emergence and may allow you to
delay planting. Potatoes are heavy feeders, if you have adequate moisture, add
4lbs of a 7-7-7 fertilizer per 25 feet of row. Planting shallow encourages
early emergence especially if the soil is cool. This also reduces the
occurrence of Rhizoctonia (Black Scurf).
When to Plant?
How warm should the soil at planting time be?
The soil temperature should be at least 5°C. Ideally the soil temp at the
depth that the seed piece will be placed should be 10°C. It is also very
important that the temperature of the seed piece is close to being the same as
the temperature of the soil at planting time.
Scab?
A number of people have asked about scab.
Bacteria that are present in most soils cause scab. The incidence of scab is
dependent on the following factors: variety, soil, and moisture. Some varieties
are more susceptible than others are. There are no varieties that are
completely resistant to scab. Russets seem to be less likely to get scab than
other varieties. The following varieties are considered susceptible:
Pontiac, Shepody and Yukon Gold The following are considered
moderately resistant: Kennebec, Red Norland, Russet Burbank and
Viking.
The higher the level of organic mater the more
risk of scab, regardless of variety. If you have added large quantities of
straw or manure to your garden site you have raised the percentage of organic
matter and raised the risk of scab. If your garden is on an old farm site and
happens to be on the site of an old straw pile or manure pile your risk of scab
is very high. Sandy soil, which is low in organic matter, has a low risk of
scab. Dry years tend to be worse than wet years for scab. Scab only affects the
appearance of the potato and does not affect the eating quality of the flesh of
the tuber. Yield is not generally affected by scab. In a dry year keeping the
soil moist with watering should reduce the amount of scab.
Spacing?
What is the best seed spacing when planting?
It depends on the variety. Early varieties can be planted close together
(4"-8"), as they tend to have a low number of tubers per hill; this helps to
keep the size of those nice new potatoes to a minimum. Midseason varieties can
be planted 8" to 12" apart. Late season varieties should be planted 12" or
more.
Stan
Mills
