Seeding
Treatments
Seeds can be treated with a fungicide to control downy mildew but
there are no registered treatments for seedling blight. For specific
seed treatment information, consult the current
Guide To Crop Protection.
Dates
Sunflower seeding should begin anytime after May 1 and ideally be finished
by June 1. Seedlings are relatively frost-tolerant up to the 4-leaf stage. Confection
varieties are longer maturing than oilseed types. If seeding is delayed into the first
week in June, switching to oilseed types is recommended as well as choosing earlier-maturing varieties.
Rates
Seeding rate for sunflowers depends on sunflower type. Oil-type
sunflower populations range from 20,000 - 22,000 plants per acre (0.6 plants
per ft2)
but confection-type sunflowers should not exceed 18,000 plants per acre
(0.4 plants
per ft2)
to ensure large seed size. Seeding rates for both oil and confection-type sunflowers
should be adjusted when germination is low and for the number of weed control harrowing
operations expected. Refer to Tables 1
and 2 below for
information on plant density as well as seed size and weight.
Table 1. Seed Density as a Function of Row
Spacing
Row Spacing
(inches) |
| |
16 |
18 |
22 |
30 |
36 |
| Plants per Acre |
Average Seed Spacing Within
Row
(inches) |
16,000
18,000
20,000 |
23
20
18 |
20
17
16 |
16
14
13 |
12
10
9 |
10
9
8 |
Table 2. Sunflower Seed Size and Associated Seed Weight
Oil-Type
Sunflowers |
Confection-Type
Sunflowers |
| Seed Size |
Seeds per Pound |
Seed Size |
Seeds per Pound |
| No. 2 |
5000-6000 |
Medium |
4000-5000 |
| No. 3 |
6000-7000 |
Large |
3000-4000 |
| No. 4 |
7000-9000 |
Extra Large |
2000-3000 |
Solid Seeding
Recommended row spacing for solid seeding is 10 to 12 inches
(25.4 to 30.5 centimetres) for both confection- and
oil-type sunflowers. Plant populations should remain the same as stated above regardless
of row spacing. The sunflower plant will compensate for differences in plant population
through changes in seed and head size. These changes are more noticeable in confections
and caution should be taken when calculating the seeding rates.
Seeding Depth
Sunflowers need to be placed in moisture but not deeper than
3 inches (7.6 centimetres). The ideal
seeding depth is 1.5 to 2 inches (3.8 to 5 centimetres) deep. Planting equipment should firm the
soil over the seed row to maintain a moist seedbed.
Fertilizer
Recommendations
General
Have your soil tested for specific recommendations on fertilizer rates. Phosphate and
potassium should be sidebanded to the sunflower row, along with some or all nitrogen.
Nitrogen is often banded between the rows after planting. If soil analysis is not
available, a general recommendation is as follows:
|
Nitrogen (N) |
Apply 0-30 lb/acre N following fallow or legume breaking, 30-55
lb/acre N following grass and grass-legume breaking and 55-90 lb/acre N following stubble.
The primary nitrogen deficiency symptoms are reduced growth (plant height) and general chlorosis, with the lower leaves showing a greater degree of chlorosis than the upper
leaves.
|
|
Phosphate (P2O5) |
Apply phosphate at 30-40 lb/acre P205. The
primary phosphate deficiency symptom is reduced growth and dark-grey necrosis of the lower
leaves of the plant.
|
|
Potassium (K2O) |
On sandy textured or organic soils, apply
potassium at rates of 15-30 lb/acre K20 in a sideband or 30-60 lb/acre
K20 broadcast. The primary
potassium-deficiency symptom is yellowing, with large necrotic patches on the oldest
leaves.
|
|
Sulphur (S) |
Apply sulphate sulphur at 20 lb/acre on well-drained soils. Sulphur deficiency may occur
in many soils and in any area of the province. A soil test is recommended to establish the
available sulphur status of fields. The primary sulphur deficiency symptom is a general
chlorosis of the plant, with the youngest leaves showing a greater degree of yellowing
than the older leaves. |
Sunflowers take up and remove modest levels of
nutrients compared to barley or canola. Table A indicates the range
of nutrients taken up and removed by a crop yielding 2000 lb/acre.
Table A. Nutrient Uptake and Removal by Sunflower
| Sunflowers at 2000 lb/acre |
Nitrogen
(lb N/acre) |
Phosphorus
(lb P205/acre) |
Potassium
(lb k20/acre) |
Sulphur
(lb S/acre) |
| Uptake1 |
67-82 |
23-28 |
33-41 |
8-9 |
| Removal2 |
48-59 |
14-18 |
11-13 |
4-5 |
Uptake1
= total nutrients taken up by the crop
Removal2 = nutrients removed in the sunflower seed
Compiled by the Canadian Fertilizer Institute |
Soil Test Recommendations
Fertilizer recommendations based on soil testing were developed and used by Manitoba Agriculture, Food and Rural Initiatives.
Recommendations are based on a 0 to 6-inch (0 to
15.2 centimetre) sample for phosphorus and potassium, and on a 0 to
6-inch (0 to 15.2-centimetre) sand 6 to 24-inch (15.2 to 61-centimetre) sample for nitrate-nitrogen and sulphate-sulphur. The fertilizer
recommendations are listed in Tables B
and C.
Table B. Nitrogen Recommendations for Sunflowers (based on
spring band application)
Target Yield
(lb/acre) |
2,500 |
2,250 |
2,000 |
1,750 |
Fall Soil N03-N |
|
lb/acre
in 0-24 in. |
Rating |
Nitrogen
Recommendation
(lb/acre) |
| 20 |
VL |
200 |
150 |
100 |
50 |
| 30 |
L |
170 |
120 |
70 |
15 |
| 40 |
M |
140 |
90 |
40 |
0 |
| 50 |
M |
115 |
65 |
10 |
0 |
| 60 |
H |
85 |
35 |
0 |
0 |
| 70 |
H |
55 |
5 |
0 |
0 |
| 80 |
VH |
25 |
0 |
0 |
0 |
| 90 |
VH |
0 |
0 |
0 |
0 |
| 100 |
VH+ |
0 |
0 |
0 |
0 |
Germinating sunflower seeds are
sensitive to fertilizer placed with the seed. When sunflowers are seeded with row
equipment, all phosphate and potash should be side banded 2 inches (5 centimetres) beside and below the
seed at time of seeding. Some or all of the nitrogen may also be
side banded. The total
amount of fertilizer material side banded should not exceed 300
lb/acre. When sunflowers are solid-seeded in 12- to 24-inch
(30.5 to 61-centimetre) row spacing, up to 25 lb/acre P205
can be applied provided all fertilizer runs are left operating. If all phosphate must be
placed with seed, the amount of phosphate should not exceed 15 lb
per acre P205
for 12-inch (30.5-centimetre) row spacing, 10 lb per acre P205 for 18-inch
(45.7-centimetre) row spacing and
5 lb/acre P205 for 24-inch
(61-centimetre) row spacing. Nitrogen requirements not side-banded should be placed away from the seed as a band or broadcast application.
Table C. Phosphorus, Potassium and Sulphur Recommendations
for Sunflower Based on Soil Test Levels and Placement
Soil Phosphorus
(sodium bicarbonate P test) |
Fertilizer
(P205 lb/acre) |
Soil Potassium
(ammonium acetate
K test) |
Fertilizer
(K20 lb/acre) |
Soil Sulphate
(Sulphur in
0-24 in.) |
Fertilizer
S (lb/acre) |
| Ppm |
lb/acre |
Rating |
Sb1 |
ppm |
lb/ac |
Rating |
Sb1 |
PPI2 |
lb/ac |
rating |
N/A3 |
| 0 |
0 |
VL |
40 |
0 |
0 |
VL |
30 |
60 |
0 |
VL |
20 |
| |
5 |
VL |
40 |
25 |
50 |
VL |
30 |
60 |
5 |
VL |
20 |
| 5 |
10 |
L |
40 |
50 |
100 |
L |
15 |
30 |
10 |
VL |
20 |
| |
15 |
L |
35 |
75 |
150 |
L |
15 |
30 |
15 |
L |
20 |
| 10 |
20 |
M |
30 |
100 |
200 |
M |
0 |
0 |
20 |
L |
20 |
| |
25 |
M |
20 |
125 |
250 |
M |
0 |
0 |
25 |
M |
20 |
| 15 |
30 |
H |
15 |
150 |
300 |
H |
0 |
0 |
30 |
M |
20 |
| |
35 |
H |
10 |
175 |
350 |
H |
0 |
0 |
35 |
H |
0 |
| 20 |
40 |
VH |
10 |
200 |
400 |
VH |
0 |
0 |
40 |
VH |
0 |
| 20+ |
40+ |
VH+ |
10 |
200+ |
400+ |
VH+ |
0 |
0 |
40+ |
VH+ |
0 |
Sb1 = side banded
PPI2 = broadcast
and preplant incorporated
N/A3 = placement
does not influence effectiveness of sulphate forms of sulphur
fertilizer |
Plant Tissue Analysis
Plant tissue analysis is an important tool is assessing nutrient status of the growing
crop. Following are plant tissue analysis interpretive criteria used by the former
Manitoba Agriculture Provincial Testing laboratory. These levels should be used for the
top 1 to 3 most mature leaves collected at the bud stage. Consult with your soil and plant
tissue laboratory for guidelines when sampling at other stages of growth.
Special Considerations
Sunflowers have deep tap roots that can obtain water and nutrients
5 to 6 feet
(1.5 to 1.8 metres) deep in the soil. These reserves of water and nutrients are unavailable to most other
annual crops, making sunflower a good rotational crop.
Sunflowers are very susceptible to seed-placed fertilizer injury. To avoid seedling
injury from fertilizer, best results are obtained by placing starter fertilizer in a band
2 inches (5 centimetres) below and beside the seed. The remainder of the fertility should be applied in
one of the following ways:
-
Broadcast incorporated prior to seeding
-
Side dressing in crop (nitrogen)
-
Fall or spring banding
Table D. Sunflower Tissue Analysis Interpretation
|
Nutrient |
Content
Rating |
| Low |
Marginal |
Sufficient |
High |
Excess |
|
Nitrogen % (N) |
1.4 |
1.5-1.9 |
2.0-3.4 |
3.5-3.9 |
4.0 |
| Phosphorus % (P) |
0.14 |
0.15-0.24 |
0.25-0.49 |
0.5-0.79 |
0.8 |
|
Potassium % (K) |
0.9 |
1.0-1.4 |
1.5-2.9 |
3.0-4.9 |
5.0 |
| Sulphur % (S) |
0.14 |
0.15-0.19 |
0.2-0.39 |
0.4-0.99 |
1.0 |
|
Calcium % (Ca) |
0.19 |
0.2-0.29 |
0.3-1.9 |
2.0-2.4 |
2.5 |
| Magnesium % (Mg) |
0.09 |
0.1-0.19 |
0.2-1.4 |
1.5-1.9 |
2.0 |
|
Zinc ppm (Zn) |
11 |
12-14 |
15-69 |
70-149 |
150 |
| Copper ppm (Cu) |
2 |
3-5 |
6-24 |
25-74 |
75 |
|
Iron ppm (Fe) |
14 |
15-19 |
20-249 |
250-499 |
500 |
| Manganese ppm (Mn) |
9 |
10-14 |
15-99 |
100-249 |
250 |
|
Boron |
No provincial guidelines
developed. Consult analytical companies. |
Field Scouting
Check for Potential Problems Regularly
Field scouting involves walking into the field and
assessing the overall health of the crop. While field
scouting, look for plants showing symptoms of insects or diseases,
and watch for insects or diseases that may be evident in the field.
If a particular insect or disease appears to be of concern in the
field, then it is necessary to do a more thorough examination of that
specific insect or disease to determine the extent of the problem
and whether control measures are possible and economical.
Information in the following sections on insects and diseases will
provide the details on how to do a more thorough examination for
each of the major insect and disease problems in sunflowers, and
provide advice on if and when controls are economical.
Check for Beneficial Organisms
In addition to looking for pests and problems when
field scouting, also watch for beneficial organisms, such as
pollinators, predators and parasites of potential pests.
Pollinators can increase yield by enhancing pollination of
sunflowers, and natural controls can keep some potential pests below
damaging levels.
Pollination
Sunflower yields benefit from honeybee pollination.
Sunflowers produce a large supply of nectar for honeybees, and
therefore colonies located near the field will actively forage and
pollinate the crop. Try to Minimize Harm to Beneficial Organisms if
Pests Need to be Controlled
If some pest levels are above economic threshold,
and a pesticide application would be economical, consider applying
the pesticide at a time and in a method that minimizes harm to the
beneficial insects in the field. For example, if applying an
insecticide to a sunflower field that is flowering, apply the
insecticide in the evening or early morning when the bees are not
foraging. If you are aware of any beehives nearby, contacting
the beekeeper in advance (i.e. 48 hours) of insecticide application
will allow the beekeeper to move or protect bee colonies from
insecticide damage.
Scouting Calendar for Sunflowers
| Stage of Sunflowers |
Insects to Look for When Monitoring |
Diseases to Look for When Monitoring |
|
Seedling |
Cutworms, wireworms,
sunflower beetles |
Assess incidence of downy
mildew |
| Vegetative States |
Sunflower beetles, thistle caterpillars,
stem weevils |
Look for first appearance of rust |
|
Flowering Stages |
Seed weevils, banded
sunflower moth, lygus bugs, honey bees |
Watch for factors
conducive to head blight infection (Sclerotinia) ex: areas
of saturated soil |
Weeds
In sunflowers, weeds can be controlled by using
pre-emergent herbicides, harrowing before crop emergence, inter-row
cultivation when the crop is in the 5 to 6 leaf stage and
post-emergent herbicides. Weeds should be removed within the first 4 weeks of crop growth to minimize yield losses.
Links:
Insects
Many insects can reduce sunflower yields, however only
some insects build up high enough
number to cause economic damage in sunflowers.
Links: |
Sunflower Beetle |
Diseases
For information on varietal differences to disease susceptibility consult
Seed Manitoba.
Links:
|
Sclerotinia |
 Harvesting
Timing
Sunflowers are usually the last crop to be
harvested in fall, since fall frosts are necessary for drying
down the crop (unless a desiccant is used). The period between
maturity and harvest should be kept as short as possible to minimize losses from bird
damage and head-rot diseases.
Desiccation
Chemical desiccation is used to hasten
dry-down of the sunflower heads. Desiccation is effective before a killing frost in
enhancing head dry-down but should not be applied before the back of the sunflower head
turns a deep, dark yellow and the bracts are brown and dry. At this stage the plant is said to be
physiologically mature and seed moisture will be 20 to 50%. Refer to the current
Guide to Field Crop Protection for details on desiccation products.
Combining
Sunflowers can be safely combined when the seed moisture reaches about 20%. However, allowing sunflowers to dry-down in the field to a
moisture content of 9.5 -12% reduces the need for drying toe crop
on-farm. Sunflowers can easily shatter if heads are very dry, and therefore combine speed must be
slowed accordingly. Cylinder speeds range from 300-500 rpm, with concave settings quite
open (1 inch in front and 3/4 inch in rear) to minimize seed breakage and dehulling.
Using the slowest seed cylinder speeds with the largest openings will result in the least seed
damage.
|
Harvesting Attachments
Combines that are suitable
for harvesting small grain will be adequate to harvest sunflowers. A proper header
attachment is necessary to reduce shattering losses and harvest efficiently.
There are two types of attachments:
-
The pan header, which is mounted on traditional
straight cut header and is suitable for both row crop and
solid seeding
-
The all crop header, which is only suitable for row crop
planting
or
less.o 12% moisture content seed can be stored in bins with aeration. Any
moisture content over 12% will require drying to avoid
spoilage. Oil-type sunflowers can be dried
with temperatures of 71º to 104º C (160ºF
to 220ºF) but confection-type
sunflower seed may scorch or wrinkle with these temperatures.
Sunflower seed should be cooled before storage, since even
sunflowers at 8.5% moisture can spoil if stored when warm.
Links:
Production Economics
Quality
The same grade standards, established by the
Canadian Grain Commission,
apply to both confection and oil type sunflowers. However,
confection contract standards are considerably higher than those
established for oil type sunflowers. Confection sunflower contracts
usually require 10% moisture, less than 1% sclerotia,
less than 1% dark roast, 155g/0.5 L (approximately 25 lb/bu) test weight and the seeds must be larger than 22/64-inch
round-hole sieve.
Since many sunflowers are commonly sold into the United States, the table below
outlines the grade standards for the United States which is a large market for sunflower
seeds.
Sunflower Grades from the United States
(Confection-Type)
|
Grade |
Minimum Test Weight per Bushel
(pounds) |
Maximum Limits of Damaged Sunflower Seed |
|
Heat Damaged
(percent) |
Dehulled Seed
(percent) |
Total
(percent) |
| U.S. No. 1 |
25.0 |
0.5 |
5.0 |
5.0 |
| U.S. No. 2 |
25.0 |
1.0 |
5.0 |
10.0 |
| U.S. Sample Grade |
-
Does not meet the requirements for the grades U.S. No. 1 or 2
-
Contains 8 or more stones which have an aggregate weight in excess of 0.20 percent of the
sample weight, 2 or more pieces of glass, 3 or more crotalaria seeds, 2 or more castor
beans, 4 or more particles of unknown foreign substance(s), or a commonly recognized
harmful or toxic substance(s), 10 or more rodent pellets, bird
droppings or equivalent quantity of other animal filth per
600 grams of sunflower seed
-
Has a musty, sour, or commercially
objectionable foreign odour
-
Is heating or otherwise of distinctly low
quality
|
|
