A. Seedbed Preparation:
Many different tillage systems can be used effectively for sunflower production. Conventional systems of seedbed preparation consist of moldboard plowing or chisel plowing to invert residue and several secondary field operations. Conventional systems have been shown to increase the availability and improve the distribution of potassium and nitrogen and to increase the seed zone temperatures. However, the risk of erosion and expense of the several tillage operations has led to greater interest in minimum or ridge tillage systems.
Both germination percentage and lodging have been shown to increase in ridge-till systems vs. level plantings. Several tillage systems have been used with some success in specific environments. Major considerations are: 1) firm placement of seed near moist soil, 2) absence of green vegetation during emergence, 3) maintaining an option to cultivate and 4) reduce the risk of soil erosion.
B. Seeding Date:
Sunflower can be planted at a wide range of dates, as most cultivars are earlier in maturity than the length of growing season in most areas. In areas of the world with no winters, sunflower has been planted at any month of the year to obtain satisfactory yields. In northern regions, highest yields and oil percentages are obtained by planting early - as soon after the spring-sown small grain crops as possible. In the northern midwest and Canada this is often May 1 through 20 and mid-March through early April in the southern USA. Resistance to frost damage decreases as the seedlings develop into the 6leaf stage, so too-early sowings in the northern USA or Canada can be risky.
A later planting date tends to increase the proportion of linoleic acid in sunflower, especially at southern locations. Damage of sunflower heads by insect larvae may be increased by early planting. Test weight tends to decrease with late plantings. A planting date of early to mid May is recommended in Minnesota and Wisconsin.
C. Method and Rate of Seeding:
A planting depth of 1 to 3.5 in. allows sunflower seeds to reach available moisture and gives satisfactory stands. Deeper plantings have resulted in reduced stands and yields. If crusting or packing of the soil is expected, with silt loam or clay soils, a shallower planting depth is recommended.
Sunflower row spacing is most often determined by machinery available, which might be 30 or 36 in. for corn, soybean or sorghum growers, or narrower rows for sugarbeet growers. In Minnesota trials, sunflower yield, oil percentage, seed weight, test weight, height, and flowering date did not differ at narrow vs. wide rows over five plant populations. Hence, row spacings can be chosen to fit available equipment. Row spacings of 30 in. are most common. There is evidence that earlier, semidwarf varieties may perform better in narrower rows at high populations.
Sunflower stands have the capacity to produce the same yield over a wide range of plant densities (Table 2). The plants adjust head diameter, seed number per plant, seed size, to lower or higher populations, so that yield is relatively constant over a wide range of plant populations. Trials in eastern North Dakota show increases in yields with densities up to 29,000 plants/acre, but most studies have shown less effect of seeding rate. Higher densities are often recommended for irrigated or high rainfall areas.
D. Fertility and Lime Requirements:
Research has shown that sunflower responds to N, P and K. Nitrogen is usually the most common limiting factor for yield. Nitrogen fertilizer tends to reduce oil percentage of the seed, change the amino acid balance, and increase leaf area of the plant. Yield increases from N fertilizer rates up to 175 lb/acre have been observed, but rates considerably lower than this are usually recommended. Nitrogen recommendations in dryer regions can be made from estimates of nitrate nitrogen in the soil, but in wetter regions, this is not feasible. In the wetter regions of eastern and southern Minnesota and Wisconsin, recommendations are based upon soil organic matter and previous crop history. Recommendations of approximately 18 lb N/acre after fallow or legume sod, 60 lb N/acre after small grain or soybean and 80 to 100 lb N/acre after corn or sugarbeet are common. On higher organic matter soils, amounts should be lowered. Nitrogen can be supplied from mineral or non-mineral sources (manures, legumes, compost). Row placement of P and K may be important in sunflower for maximizing efficiency of fertilizer use, as it is with many species.
More yield increases are reported as a result of applications of P than from K in Europe and North America. Recommendations for applications of P and K should be made from soil tests and the yield goal for each field. Recommendations range from 40 to 70 lbs P2O5 and -60 to 140 lbs K2O /acre for soils testing very low in P or K, depending on soil yield potential. These recommendations decrease as soil test P and/or K increase. Response to P is not expected if soil P exceeds 30 lb/acre nor to K if the K test is greater than 300 lb/acre.
Sunflower is not highly sensitive to soil pH. The crop is grown commercially on soils ranging in pH from 5.7 to over 8. The optimum depends upon other properties of the soil; no pH is considered optimum for all soil conditions. The 6.0 to 7.2 range may be optimal for many soils.
E. Variety Selection:
The development of a cytoplasmic male-sterile and restorer system for sunflower has enabled seed companies to produce high-quality hybrid seed. Most of these outyield open-pollinated varieties and are higher in percent oil. Performance of varieties tested over several environments is the best basis for selecting sunflower hybrids. The choice should consider yield, oil percentage, maturity, seed size (for non-oilseed markets), and lodging and disease resistance. Performance results from the Upper Midwest are usually available annually from North Dakota State University, University of Minnesota, and South Dakota State University.
F. Weed Control:
As a crop, sunflower yields are reduced, but rarely eliminated by weeds which compete with sunflower for moisture and nutrients and occasionally for light. Sunflower is a strong competitor with weeds, especially for light, but does not cover the ground early enough to prevent weed establishment. Therefore, early season weed control is essential for good yields. Annual weeds have been the primary focus of weed control research. Perennial weeds can also present problems but are usually not specific to sunflower.
Successful weed control should include a combination of cultural and chemical methods. Almost all North American sunflower plantings are cultivated and/or harrowed for weed control, and over 2/3 are treated with herbicides. Postemergence cultivation with a coilspring harrow, spike tooth harrow or rotary hoe is possible with as little as 5 to 7% stand loss when sunflowers are at the four to six leaf stage (beyond cotyledon), preferably in dry afternoons when the plants are less turgid. One or two between row cultivations are common after the plants are at least 6 in. tall.
Several herbicides are currently approved for weed control in sunflowers. Information on chemical weed control in sunflowers is available at most county extension offices.
G. Diseases:
The most serious diseases of sunflower are caused by fungi. The major diseases include rust, downy mildew, verticillium wilt, sclerotinia stalk and head rot, phoma black stem and leaf spot. The symptoms of these diseases are given in Table 3. The severity of these disease effects on total crop yield might be ranked: 1) sclerotinia, 2) verticillium, 3) rust (recently more severe), 4) phoma, and 5) downy mildew. Resistance to rust, downy mildew, and verticillium wilt has been incorporated into improved sunflower germplasm.
H. Insects, Pollinators, and Birds:
Bees are beneficial to sunflower yield because they carry pollen from plant to plant which results in cross pollination. Some sunflower varieties will not produce highest yields unless pollinators are present. All varieties will produce some sterile seed (without meats), but varieties differ in their degree of dependence on insect pollinators. Autogamous sunflower hybrids do not require bees for maximum yield and will yield the same when covered by bags as uncovered. In non-autogamous sunflower varieties, pericarp (bull) development is normal but no ovules or meat develop. Wind is relatively unimportant in cross-pollination of sunflower. Some of the older open-pollinated varieties such as Peredovick set only 15 to 20% of seed without pollinators, whereas many hybrids set 85 to 100% seeds without pollinators.
Insect pests have become major potential yield-reducing factors in sunflower production in the northern Midwest (Table 4). Insects specific to sunflower that feed on the heads include the larvae of three moths; sunflower moth, banded sunflower moth and sunflower bud moth. Sunflower midge has caused widespread damage in some years. Sunflower headclipping weevil, sunflower beetle, sunflower maggot, wireworm, grasshopper, cutworm, sugarbeet webworm, ragweed plant bug, woolybear and painted.lady caterpillar have caused occasional damage to sunflower. Adults of insect pests of other crops (such as corn rootworm beetle and blister beetle) can be found as pollen feeders on sunflower heads, but usually cause little injury.
A. Seedbed Preparation:
Many different tillage systems can be used effectively for sunflower production. Conventional systems of seedbed preparation consist of moldboard plowing or chisel plowing to invert residue and several secondary field operations. Conventional systems have been shown to increase the availability and improve the distribution of potassium and nitrogen and to increase the seed zone temperatures. However, the risk of erosion and expense of the several tillage operations has led to greater interest in minimum or ridge tillage systems.
Both germination percentage and lodging have been shown to increase in ridge-till systems vs. level plantings. Several tillage systems have been used with some success in specific environments. Major considerations are: 1) firm placement of seed near moist soil, 2) absence of green vegetation during emergence, 3) maintaining an option to cultivate and 4) reduce the risk of soil erosion.
B. Seeding Date:
Sunflower can be planted at a wide range of dates, as most cultivars are earlier in maturity than the length of growing season in most areas. In areas of the world with no winters, sunflower has been planted at any month of the year to obtain satisfactory yields. In northern regions, highest yields and oil percentages are obtained by planting early - as soon after the spring-sown small grain crops as possible. In the northern midwest and Canada this is often May 1 through 20 and mid-March through early April in the southern USA. Resistance to frost damage decreases as the seedlings develop into the 6leaf stage, so too-early sowings in the northern USA or Canada can be risky.
A later planting date tends to increase the proportion of linoleic acid in sunflower, especially at southern locations. Damage of sunflower heads by insect larvae may be increased by early planting. Test weight tends to decrease with late plantings. A planting date of early to mid May is recommended in Minnesota and Wisconsin.
C. Method and Rate of Seeding:
A planting depth of 1 to 3.5 in. allows sunflower seeds to reach available moisture and gives satisfactory stands. Deeper plantings have resulted in reduced stands and yields. If crusting or packing of the soil is expected, with silt loam or clay soils, a shallower planting depth is recommended.
Sunflower row spacing is most often determined by machinery available, which might be 30 or 36 in. for corn, soybean or sorghum growers, or narrower rows for sugarbeet growers. In Minnesota trials, sunflower yield, oil percentage, seed weight, test weight, height, and flowering date did not differ at narrow vs. wide rows over five plant populations. Hence, row spacings can be chosen to fit available equipment. Row spacings of 30 in. are most common. There is evidence that earlier, semidwarf varieties may perform better in narrower rows at high populations.
Sunflower stands have the capacity to produce the same yield over a wide range of plant densities (Table 2). The plants adjust head diameter, seed number per plant, seed size, to lower or higher populations, so that yield is relatively constant over a wide range of plant populations. Trials in eastern North Dakota show increases in yields with densities up to 29,000 plants/acre, but most studies have shown less effect of seeding rate. Higher densities are often recommended for irrigated or high rainfall areas.
D. Fertility and Lime Requirements:
Research has shown that sunflower responds to N, P and K. Nitrogen is usually the most common limiting factor for yield. Nitrogen fertilizer tends to reduce oil percentage of the seed, change the amino acid balance, and increase leaf area of the plant. Yield increases from N fertilizer rates up to 175 lb/acre have been observed, but rates considerably lower than this are usually recommended. Nitrogen recommendations in dryer regions can be made from estimates of nitrate nitrogen in the soil, but in wetter regions, this is not feasible. In the wetter regions of eastern and southern Minnesota and Wisconsin, recommendations are based upon soil organic matter and previous crop history. Recommendations of approximately 18 lb N/acre after fallow or legume sod, 60 lb N/acre after small grain or soybean and 80 to 100 lb N/acre after corn or sugarbeet are common. On higher organic matter soils, amounts should be lowered. Nitrogen can be supplied from mineral or non-mineral sources (manures, legumes, compost). Row placement of P and K may be important in sunflower for maximizing efficiency of fertilizer use, as it is with many species.
More yield increases are reported as a result of applications of P than from K in Europe and North America. Recommendations for applications of P and K should be made from soil tests and the yield goal for each field. Recommendations range from 40 to 70 lbs P2O5 and -60 to 140 lbs K2O /acre for soils testing very low in P or K, depending on soil yield potential. These recommendations decrease as soil test P and/or K increase. Response to P is not expected if soil P exceeds 30 lb/acre nor to K if the K test is greater than 300 lb/acre.
Sunflower is not highly sensitive to soil pH. The crop is grown commercially on soils ranging in pH from 5.7 to over 8. The optimum depends upon other properties of the soil; no pH is considered optimum for all soil conditions. The 6.0 to 7.2 range may be optimal for many soils.
E. Variety Selection:
The development of a cytoplasmic male-sterile and restorer system for sunflower has enabled seed companies to produce high-quality hybrid seed. Most of these outyield open-pollinated varieties and are higher in percent oil. Performance of varieties tested over several environments is the best basis for selecting sunflower hybrids. The choice should consider yield, oil percentage, maturity, seed size (for non-oilseed markets), and lodging and disease resistance. Performance results from the Upper Midwest are usually available annually from North Dakota State University, University of Minnesota, and South Dakota State University.
F. Weed Control:
As a crop, sunflower yields are reduced, but rarely eliminated by weeds which compete with sunflower for moisture and nutrients and occasionally for light. Sunflower is a strong competitor with weeds, especially for light, but does not cover the ground early enough to prevent weed establishment. Therefore, early season weed control is essential for good yields. Annual weeds have been the primary focus of weed control research. Perennial weeds can also present problems but are usually not specific to sunflower.
Successful weed control should include a combination of cultural and chemical methods. Almost all North American sunflower plantings are cultivated and/or harrowed for weed control, and over 2/3 are treated with herbicides. Postemergence cultivation with a coilspring harrow, spike tooth harrow or rotary hoe is possible with as little as 5 to 7% stand loss when sunflowers are at the four to six leaf stage (beyond cotyledon), preferably in dry afternoons when the plants are less turgid. One or two between row cultivations are common after the plants are at least 6 in. tall.
Several herbicides are currently approved for weed control in sunflowers. Information on chemical weed control in sunflowers is available at most county extension offices.
G. Diseases:
The most serious diseases of sunflower are caused by fungi. The major diseases include rust, downy mildew, verticillium wilt, sclerotinia stalk and head rot, phoma black stem and leaf spot. The symptoms of these diseases are given in Table 3. The severity of these disease effects on total crop yield might be ranked: 1) sclerotinia, 2) verticillium, 3) rust (recently more severe), 4) phoma, and 5) downy mildew. Resistance to rust, downy mildew, and verticillium wilt has been incorporated into improved sunflower germplasm.
H. Insects, Pollinators, and Birds:
Bees are beneficial to sunflower yield because they carry pollen from plant to plant which results in cross pollination. Some sunflower varieties will not produce highest yields unless pollinators are present. All varieties will produce some sterile seed (without meats), but varieties differ in their degree of dependence on insect pollinators. Autogamous sunflower hybrids do not require bees for maximum yield and will yield the same when covered by bags as uncovered. In non-autogamous sunflower varieties, pericarp (bull) development is normal but no ovules or meat develop. Wind is relatively unimportant in cross-pollination of sunflower. Some of the older open-pollinated varieties such as Peredovick set only 15 to 20% of seed without pollinators, whereas many hybrids set 85 to 100% seeds without pollinators.
Insect pests have become major potential yield-reducing factors in sunflower production in the northern Midwest (Table 4). Insects specific to sunflower that feed on the heads include the larvae of three moths; sunflower moth, banded sunflower moth and sunflower bud moth. Sunflower midge has caused widespread damage in some years. Sunflower headclipping weevil, sunflower beetle, sunflower maggot, wireworm, grasshopper, cutworm, sugarbeet webworm, ragweed plant bug, woolybear and painted.lady caterpillar have caused occasional damage to sunflower. Adults of insect pests of other crops (such as corn rootworm beetle and blister beetle) can be found as pollen feeders on sunflower heads, but usually cause little injury.
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