seed
Selecting
and Buying Seed
The use of healthy seed is essential for good yields and quality. Be
absolutely certain that the seed you are using is relatively free of major
diseases and pests. As a general rule, use only certified seed. Certified
seed is inspected by professionals and considered to meet certain strict
standards. For example, certification almost invariably prohibits the known
presence of bacterial ring rot, rootknot nematodes and certain other diseases
which can lead to devastating crop losses. Strictly enforced tolerances
have been established for other lesser pests and diseases. The Oregon
Seed Certification Service provides a handy on-line listing of
Oregon certified crops and the standards/tolerances required for each.
Certification standards for seed potatoes are available either in printed
form or on-line at Oregon
Seed Potato Certification Standards. Contact information for other Canadian
and
U.S.
certification
agencies is available at North American Seed Cert. Agencies
Certification is not a guarantee of quality. Certification reports typically
emphasize what is seen during visual field inspections. Diseases present
at low levels during inspection may go unobserved, increase dramatically
before harvest, and lead to seed tuber infection levels far beyond tolerances.
To guard against this problem, most states require some type of winter
grow out test in which a small sample of each seed lot is planted and grown
out for further visual inspection. Winter testing requirements vary considerably
among states and among Generations within states using Limited Generation programs, as most do.
Factors other than field diseases can also affect the performance of
seed. Remember, seed certification is primarily field oriented with some
follow-up in winter grow out and laboratory tests. Seed handling during
harvest, storage, and shipping may have more influence on crop performance
than disease readings reported by certification inspectors. Seed should
be carefully examined for excessive mechanical injury, decay, sprouting
and shriveling before accepting delivery. Remember, when you accept delivery,
the seed is yours along with all of the associated problems. If you have
questions about quality, call in local experts for "third party" inspections.
Keep in mind that poor seed performance may lead to lawsuits.
Seed which has been stored too warm or produced under adverse field
conditions may look sound and vigorous but be physiologically "old". Old
seed typically emerges, tuberizes and matures early, produces many stems
and tubers, and may have lower yields than "young" seed, especially in
long season locations. Physiological age of seed can be partially compensated
for by changes in cultural management. On the other hand, physiological
age of seed can be tailored to local needs. For example, "old" seed may
be highly desirable in short season or seed production situations where
early maturity or small tuber size are preferred.
A close, long-term working relationship with a few dependable seed growers
is probably the best overall guarantee of consistently good seed quality
year after year. By comparison, dealing with new suppliers can be dangerous.
Most seed grower take care of their regular customers first and save whatever
is left for new and/or late contacts (you). When dealing with new seed
suppliers, on-farm visits during both the growing season and shortly before
shipping are highly desirable. Also, a conscientious effort to obtain certification
records and learn something about the grower's reputation is highly advisable.
Strong fences make good neighbors; so do written contracts. Make certain
transaction details are clearly spelled out by using a Seed
Sale Contract (under P.A.C.A. Regulation Sec 46.43). We apologize for the poor quality of the sample
document provided here; steps are being taken to obtain an improved base
copy from the original authors. It is somewhat usable (some imagination
required) in its current printed form because of the pdf format.
U.S. seed certification agencies typically recommend use of some version of
the North
American Seed Health Certificate which can be extremely useful
in quantifying seed quality. Most good seed growers will also enthusiastically
welcome the use of such forms. You will need to obtain a printed copy (using
the preceding link), fill in the grower name, variety and seed lot along
with your mailing address and send the form to your local state certification
agency for completion. Because of the extreme importance of winter testing
for viruses, be certain to obtain final certification readings which are
typically available in early to mid winter. All U.S. certification agencies
provide such readings but some do not reject seedlots based on winter tests.
This means, of course, that "certified" seed lots can contain a much higher
level of viruses than some certification standards imply at first glance.
Time invested in finding and purchasing good seed is obviously time
well spent whether dealing with familiar or new trading partners. Seed
prices may range from $8 - $20/cwt and growers may plant up to a ton per
acre at common spacings (Table 1). The temptation to shave corners and
take chances can obviously be troublesome. In such situations, bear in
mind that "Good seed doesn't cost, it pays" in terms of yield,
quality and profits.
Table 1. Approximate
Cwt. of Seed Required to Plant an Acre Using 34 inch Rows1
|
Seed |
Seed Piece Weight, Oz. |
|
Spacing, In. |
1 |
1.5 |
1.75 |
2 |
|
6 |
19.2 |
28.8 |
33.6 |
38.4 |
|
8 |
14.4 |
21.6 |
25.2 |
28.8 |
|
10 |
11.4 |
17.4 |
20.4 |
22.8 |
|
12 |
9.6 |
14.4 |
16.8 |
19.2 |
|
15 |
7.8 |
11.4 |
13.8 |
15.6 |
1For 36 inch rows, multiply by 0.93
A Seed Buyer’s Checklist (for a printable pdf, see A
Seed Buyer’s Checklist)
-
Use certified seed, preferably early generation stocks.
-
Establish cordial, long-term relationships with 2-3 good seed suppliers.
-
Consider planting seed lots of each variety from more than one supplier.
If R. Burbank from one supplier does poorly, for example,
another lot from another
grower is available for comparison.
-
Carefully check the reputation(s) of new suppliers.
-
Visit prospective seed lots in the field and in storage.
When visiting farms, look for sound, healthy seed/crops
and a neat, clean overall physical operation.
Quiz the grower about cultural practices, kill down
dates, yields and so on. Killing vines late
to maximize seed yield is not necessarily beneficial
to you.
-
Be aware of unusual production problems (excess PVY, late blight, severe
freezes etc.) in
production areas you are looking to for seed.
-
Obtain all certification records, including results of winter grow outs.
-
Develop and use a written Seed Contract
specifying grade, quality, delivery & payment schedules, price, etc.
The NPC developed a “Universal Seed Contract” several
years
ago which is still widely used.
-
Ask suppliers to provide North American Seed
Health Certificates, or equivalent, for questionable lots.
These “certificates” are prepared by seed certification
agencies and are, therefore, unbiased. They contain
detailed information on certification readings, history,
and more. You will need to send a copy of the form along with
grower, variety and lot identification to your local
seed certification office.
-
Ask for a federal/state or other good "third party" shipping point inspection
of each load or seed lot.
Most U.S. states require such inspections; be certain
of the situation for your seed.
-
Never forget that seed physical condition at planting can be critical!!
Mechanical injury and associated decay organisms (Fusarium,
Erwinia, etc.), sprouting and shriveling
can be more detrimental to crop performance than all
certification disease readings combined!
-
Inspect seed carefully before accepting delivery.
After you accept delivery, you've not only bought
the seed but also all its problems! Never sign off until
you've thoroughly checked the load for mechanical
injury, decay (Fusarium dry rot, soft rots, other), shriveling,
sprouting, grade, size distribution, cleanliness and
other factors affecting performance. If problems seem to be
present, notify your supplier. Depending on his response,
immediately call in your local commodity inspection
service (in Oregon, contact the ODA Commodity Inspection
Division – ph. 503- 986-4620) for a second inspection
and a ruling on compliance. If inspectors agree with
your assessment, or even if they don’t and you remain concerned,
call in other local experts for unbiased third party
opinions. Document everything!!
-
If seed problems are evident and verified, provide the grower an opportunity
to make amends before proceeding further.
-
Maximize seed performance by storing, cutting and planting carefully.
At least half of all seed performance problems are
caused by events occurring after delivery. Never store seed in
a cellar recently treated with sprout inhibitors!
Don't suffocate, dry out, or overheat seed before or after cutting.
Cut, treat and plant shortly afterward in warm (>45F),
moist soil when possible. Don't irrigate before emergence in normal situations!
-
Maintain seed lot identity throughout the season.
Keep good records of all cutting and planting sequences
and field locations for each lot.
-
Sanitize cutters and other handling equipment between lots.
Cutting and planting sequence and sanitation records
can be crucial in lawsuits spawned by bacterial ring rot.
-
If seed disputes arise either before or after planting and emergence, call
in local experts for "third party" input.
As noted above, allow your grower/supplier first opportunity
to rectify the situation. Use the legal system only as a last resort.
-
Think long-term, beyond the current season, when dealing with seed suppliers.
-
Always strive to be a good trading partner.
Oregon
Seed Production
Information on available Oregon seed stocks by variety
and supplier can be found in the current Oregon
Seed Growers Directory (scroll down about 13 pages). Grower
addresses, phone numbers and e-mail addresses are available elsewhere in the
pamphlet.
Further information about Oregon seed, including the
latest Oregon
Field Readings, is available through the Oregon
Seed Certification Service. Selected seed suppliers for other
states and regions are linked under Seed
on the PAA Website (Industry Outreach) . You may also find it useful to sell or find seed
via the Potato
Country Magazine seed exchange
page. If you have questions about individual
seed
growers
or seed lots for any state
or Canadian
province,
access Seed
Certification Agencies for details.
Growers --
As of 2010, Oregon relies on the labs of Lorie Ewings (University of Idaho, Moscow, ID) for certified pre-nuclear seed potatoes (see: Idaho
Foundation Potato Seed Program). This material, as well as certified material from other sources is supplied to Oregon
Seed Growers in various high elevation, isolated regions of
the state for increase as Limited
Generation stocks according to strict Certification
Standards. Oregon
Seed Growers provide high quality seed of a number of chipping,
fresh market and processing varieties at competitive
prices. More information about Oregon seed is available from the Oregon
Seed Potato Growers Association and The
Oregon Seed Certification Service.
Producing Regions --
Klamath Basin--The Klamath Basin
is one of several excellent high elevation, short season, isolated seed
production areas. The Klamath area leads the state in total seed production.
Seed is grown in several isolated valleys at an average elevation of 4,100
feet primarily in three areas: Lower Klamath Lake, Upper Klamath Lake,
and Dairy-Bonanza. Klamath County has produced a large volume of seed for
over 60 years. Nearly all major western varieties are grown, but Russet
Burbank and Russet Norkotah dominate production. Jackson County is included
in this production area.
Central Oregon--Production is centered
primarily in Crook, Deschutes, and Jefferson counties with some seed in
Lake County. Elevation averages 3,000 feet. Fields are located near Culver,
Sisters, Redmond and Powell Butte. The area has a seed potato tradition
dating back nearly 70 years. Local growers are well acquainted with the
importance of high quality seed. The principal varieties are Russet Burbank,
Ranger Russet, and Russet Norkotah.
Northeastern Oregon--Seed growers
are located in Baker, Union, and Wallowa counties. Elevation ranges from
2,000 to 4,300 feet. Nearly all of the seed is grown at the higher elevation.
Wallowa County growers have established a seed control area which prohibits
production of any potatoes without an inspection for diseases. Wallowa
County has produced seed for 27 years. Russet Burbank is the principal
variety.
Eastern Oregon--Some seed is produced
in northwest Malheur, Grant, and Harney counties, well isolated from major
commercial production areas. These areas average 4,000 feet and are relatively
new to seed potatoes.
Seed
Production Methods
Procedures and standards for producing certified Oregon
seed potatoes, including Certification
Standards, are available from The
Oregon Seed Certification Service. Similar information for
other areas can be obtained from state and provincial certification
agencies throughout
North America (see Seed-Related Websites
for WWW listings of Certification agencies and other seed related topics).
Roguing is an essential practice in the production of healthy seed
potatoes in all producing regions. It is the process of identifying and
disposing of abnormal plants, including tubers and seed pieces. The affected
plants may be diseased, another variety, or simply different.
The following links provide useful information on seed production and
storage.
Roguing Seed Potatoes (OR)
Seed
Certification and Selection (ID) -- a general discussion of
certification methods and selecting healthy lots
Seed
Myths? (ID)
Seed Storage,
Physiology (Kimberly, Idaho) -- seed info and research
Additional
Seed Related Links
(PAA)
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Handling,
Cutting and Sanitation
See Also
- Disinfecting
Storages and Equipment (Maine)
- Seed Myths?
(ID)
- Seed
Certification and Selection (ID) -- a general discussion of methods
- Seed Storage,
Physiology (Kimberly, Idaho) -- seed info and research
- Seed
piece Size & Age, Effects of (ID)
- Selecting,
Cutting and Handling Seed (U. of Me. Ext.)
- Seed
Potato Selection, Handling and Planting (NDSU)
-
Additional
Seed Related Links
Handle seed gently at all times up to and during planting. Impacts
should be minimal and changes in temperature should be gradual. Seed should
be protected from drying out and overheating in truck beds by tarping and
minimizing time in the field, especially in warm weather. If seed must
be stored more than a few days between cutting and planting, measures should
be taken to provide aeration and cooling as needed. Typically, cut seed
held more than a few days should be kept at 50-55F and high humidity with
good air movement (see "Storage" at this site) to promote suberizing and
healing.
Seed should be warmed to about 50oF a few days before cutting.
Warm seed not only cuts better with less tissue tearing, but is also more
physiologically active and heals faster than cold seed. Seed pieces should
average 1.5 to 2 oz. and have a minimum of cut surface; that is, blocky
seed pieces are preferred over slivers and slabs. Each seed piece should
have one to several eyes depending on the variety. Some varieties may have
few eyes near the tuber stem ends and produce a high percentage of "blind"
(eyeless or budless) seed pieces unless special care is taken. Such varieties
may call for larger seed pieces. (Ever wonder why tuber buds are called
"eyes"? Because they have "eyebrows" which are actually rudimentary leaf
scars.)
Before and during cutting, inspect seed for common diseases and pests such as
bacterial soft rot, bacterial ring rot, Fusarium decay, powdery scab and rootknot
nematodes. Excellent descriptions and control recommendations for common potato
pests and diseases are available through the following sites and many others
listed under Pests
and Diseases:
Seed pieces should be treated with a recommended, currently labeled
(see CDMS for current labels),
fungicide such as Maneb, Mancozeb, Thiabendazole or Thiophanate-methyl
immediately after cutting. When possible, seed should be planted soon after
cutting into warm (above 45F), moist but not wet soil. For rapid growth
and emergence, sprouts should be "peeping" (slightly enlarged) at planting
and physiologically active in preparation for rapid growth and emergence.
Extreme care should be taken to maintain seedlot identity throughout
the cutting and planting operation. Sanitize cutters and other equipment
between plantings to prevent the spread of bacterial diseases, especially
bacterial ring rot. Good planting sequence records, sanitation, and isolation
of lots is essential in proving the source of ring rot seed in the event
of lawsuits.
Bacterial ring rot (Clavibacter michigansis subsp. sepedonicus) is
the scourge of the potato industry. It is always introduced to seed farms
via seed, soil, or equipment contaminated with the organism. It survives
for extended periods (years) only in living potato tissues. In the unlikely
event that bacterial ring rot (BRR) is present in seed lots, precautions
should always be taken to minimize spread in order to contain the epidemic
and identify the contaminated seed lot for possible compensation. The following
steps will help reduce BRR infection.
-
Use only certified seed potatoes at all times.
-
Plant whole, single drop seed when possible and avoid using picker planters
because picks spread the disease.
- Disinfect cutting knives at least three times a day when cutting a single
lot of potato seed. Always disinfect before cutting a new seed lot.
-
Disinfect storage bins, tools, trucks and other equipment frequently during
cutting and planting operations. Always clean extensively before beginning
seed handling operations at the start of the season.
The following disinfectants or fumigants are effective against BRR.
In general, disinfect by wetting the surface with the product for at least
10 to 45 min and then thoroughly removing residues with water (see also
Tables 2 and 3 below).
-
Quaternary ammonium compounds at 1.6 cups of a 10% solution/10 gal water
-
Trimethylammonium chloride at 1 oz of a 10% solution/2 gal water (400 ppm)
-
Calcium or sodium hypochlorite in a 1,000 to 2,000 ppm chlorine solution;
for example, 1 gal of 5.25% calcium or sodium hypochlorite (household bleach)
/10 gal water
-
Chloropicrin at 1 to 1.5 lb/1,000 cu ft of space. For storage fumigation,
surfaces must be moist for effective control. Use a professional applicator
for safety.
-
Copper 8--Quinolinolate (Mitrol PQ 57). Use a 5% solution in a 1:99 dilution
Recommended planting dates for Oregon range from early March in
the Columbia Basin through early June in Christmas Valley. High elevation
areas tend to be planted late because of cold soils and the danger of late
frosts. By comparison, some Willamette Valley plantings on heavy soils
can be delayed into June because of prolonged spring rains.
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Table 2. 1998 Ohio Potato Production Guideline (Bulletin
672) Disinfectant Ratings for Control of BRR
| Effectiveness
of Disinfectants for Control of Ring Rot Bacteria1 |
| Disinfectant |
Metal |
Wood |
Burlap |
| Betadine* |
g |
g |
g |
| Chlorine Bleach (10%) |
s |
s |
g |
| Coal Tar |
g |
g |
g |
| DeBac** |
g |
g |
g |
| Ethyl alcohol (95%) |
s |
g |
g |
| Formaldehyde (1%) |
s |
g |
s |
| Formaldehyde (2%) |
g |
g |
g |
| Formaldehyde (4%) |
g |
g |
g |
| Vesphene* |
u |
u |
s |
| Zephiran** |
g |
g |
g |
| Lysol concentrate |
u |
u |
s |
| Lysol spray |
s |
g |
s |
| Phenol (5%) |
s |
s |
s |
| Water |
u |
u |
u |
| Soapy water |
u |
u |
u |
1Materials may not be
labeled for use in all production areas; read labels carefully before using.
*Hospital disinfectant
**Quaternary ammonium compound
g = good control after 15-20 minutes
s = very slight survival of bacteria after 15-20 minutes
u = unacceptable control
Table 3. Materials shown in the following table are commonly
used for disinfecting potato
handling equipment and storage facilities for both seed and commercial
potato operations1
| |
Effectiveness |
Inactivation |
|
|
|
|
|
|
Material |
Wet Bact, Slime |
Dry Bact,
Slime |
Org. Matt. |
Hard
Water |
Corrosive ness |
Safety |
Conc. |
Exp.
Time |
Shelf
Life |
Quaternary
Ammon. Cpds. |
Ex. |
Ex. |
Slight |
No |
Slight |
Caution |
See
Label |
10 min |
1-2yr |
| Hypochlorites, 5.25% bleach |
Ex |
Ex. |
Yes |
No, ex. Iron |
Yes |
Irritant,
caustic |
1:50, 0.1% |
10 min |
3-4 mo.
undiluted |
| Iodine Cpds. |
Ex. |
Ex. |
Slight |
No, ex.
iron |
Yes |
Caution |
See
Label |
10 min |
1-2 yr. |
| Phenolics |
Ex. |
Ex |
Slight |
No |
No |
Oral
Poison |
See
Label |
10 min |
1-2 yr. |
| Formaldehyde |
Gd. |
Poor |
No |
Yes |
No |
Unsafe
Vapors |
0.37-1.0% |
30 min |
1-2 yr. |
| Copper Sulfate |
Gd. |
Gd. |
No |
Yes |
Yes |
Caution |
10lb/100
gal |
30-60 min |
>10 yr. as
solid |
1Materials may not be labeled
for all producing areas; read labels carefully before using.
Adapted from: Disease Control Guidelines for Seed Potato
Selection, Handling, and Planting, Extension Publication PP-877, North
Dakota State
University. Registrations may vary. Check with local
authorities.
Comments:
Quaternary Ammonium Compounds--Diluted
solutions are relatively safe but concentrated form is poisonous. Slightly
corrosive, use stainless.
Hypochlorites, 5.25% bleach--Quick
acting, inexpensive; caustic to skin and clothing. Use at 1:50 when mixing
with water only. For maximum effectiveness, use 1 part 5.25% bleach: 200
parts water; 0.6 parts white vinegar. Very corrosive.
Iodine Compounds--Not for internal
use. Becomes ineffective as yellow-brown color is lost. Tamed iodophor
compounds work best.
Phenolic Compounds--Provide residual
action. These compounds show "phenol" in the list of of ingredients.
Formaldehyde--Use may be canceled.
Produces irritating, choking fumes. Not generally recommended.
Copper Sulfate--Not widely used;
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Additional
Seed Related Links
|