SAFFLOWER INTRODUCTION

Transcription

1 . INTRODUCTION SAFFLOWER Safflower is an annual, broadleaf oilseed crop in the same plant family as sunflower. Because safflower production is recommended in areas with warm temperatures and sunny, dry conditions during the flowering and seed-filling periods it is well adapted to the semiarid regions of the Great Plains. Specifically, safflower production is not recommended for areas with more than 15 in. of annual precipitation or growing seasons with fewer than 120 frost-free days and less than 2,200 growing degree days (calculated as the average daily temperature minus 50 F). Temperatures as low as 20 F are tolerated by plants while in the rosette stage, but safflower is very sensitive to frost injury from stem elongation until crop maturity. The deep-rooted characteristic of safflower allows drawing water from up to 8 to 10 foot depth. Safflower seedlings have a central stem that does not elongate for 2 to 3 weeks, and develops leaves near the ground in a rosette, similar to a young thistle. The slow growth of seedlings often results in a weedy crop. Thus, in the emergence through early rosette growth stages (25-40 days depending on weather), safflower is susceptible to significant yield-limiting competition from other plants. In later growth stages, safflower can out-compete most late spring-emerging weeds for soil moisture and light. The most effective approach to manage weeds in safflower is to practice appropriate crop rotation, which reduces aboveground and seedbank weed abundance. Establishing a competitive crop also is important to reduce weed abundance. To establish a competitive safflower stand, lbs/a of pure live seed should be seeded in rows spaced 14 in or less at a shallow depth (< 1 in). Deep seeding, >1.5 in, significantly delays and reduces seedling emergence allowing weeds to get ahead of the safflower. The plant structures of most modern safflower varieties are suitable for row cultivation to control weeds. Row spacing of 22 in are utilized in row crop systems. As a general rule, if a field is not heavily infested and if perennial weeds are not a serious problem, adequate weed control can be achieved through cultivation and represents a viable option for organic safflower production. In a cereal grain crop rotation, safflower provides the opportunity to control grass weeds and deplete grass seeds in the soil seed bank. The broadleaf weed seed numbers should be reduced under cereal grain production. Safflower producers have listed wild oats, kochia, Russian thistle and volunteer cereals as their most troublesome weeds. The herbicides labeled for safflower production generally provide good grass weed control and varying degrees of broadleaf weed control. Because safflower can be severely injured by soil residues of broadleaf herbicides commonly used in small grains, caution must be used when growing safflower with wheat, oat, or barley. Eptam, Dual II Magnum, Sonalan, Gramoxone, and various brands of trifluralin are federally labeled for use in safflower production. In addition to Treflan, trifluralin is marketed as Tri-4 HF, Trifluralin 4EC, and Trifluralin HF. Goal is also listed for vegetation control in fallow periods prior to seeding safflower (60 day preplant restriction). Defol is listed as a harvest herbicide. It is important to apply soil incorporated herbicides to soils that are not too wet as it is difficult to thoroughly mix herbicides in moist soils that are too tacky. Many soil incorporated herbicides require a minimum 5-day interval between the first and second incorporation operations to ensure maximum performance. The herbicide recommendations presented here are to serve only as a preliminary guide. Consult current product labels for complete information on methods of use, crop rotation precautions, and safe handling procedures. Read and follow all label instructions. Edited by: 118 Dr. Fabián D. Menalled Dept. of Land Resources & Environ. Sci. Montana State University Bozeman, MT

2 WEED RESPONSE TO SAFFLOWER HERBICIDES Preplant/Preemergence Weeds Eptam Dual Treflan Grasses barley, volunteer G - P foxtail, green G-E G G oats, volunteer G - G oats, wild G P-F F quackgrass F-G - P sandbur G-E G G wheat, volunteer F-G - F Broadleaves bindweed, field P - P buckwheat, wild F - F cocklebur, common P - P knotweed, common F - G kochia P F F-G lambsquarters, common G F F-G mallow, common P F P mustard, wild P - P nightshade, hairy G F P nutsedge, yellow F F-G P pigweed, redroot G G G purslane, common G G G smartweed, Pennsylvania P P P-F sowthistle, annual F - P sunflower, wild P P P thistle, Canada P - P thistle, Russian P P F-G Control: E = Excellent, G = Good, F = Fair, P = Poor or no control Responses of weeds to any of the listed herbicides may be altered by growing conditions, weed populations, type of irrigation, genetic variation, soil type, ph, organic matter, time of application, and application rate. Ratings may vary from season-to-season and geographic areas. Weed control generally decreases as the season progresses. 119

3 WEEDS LISTED ON SAFFLOWER HERBICIDE LABELS Preplant/Preemergence Grass Weeds Eptam Dual Treflan Annuals barnyardgrass X X X bluegrass, annual - X X brome, downy - - X cheat - - X crabgrass X X X crowfootgrass X - - cupgrass, prairie X - - cupgrass, southwestern X - - cupgrass, woolly P - X foxtail, giant X X X foxtail, green X X X foxtail, millet X - X foxtail, yellow X X X goosegrass X X - lovegrass (stinkgrass) - X X millet, wild proso P X - panicum, fall X X X panicum, Texas P X X red rice X - X rescuegrass - X - ryegrass, Italian - X X sandbur, field P X X shattercane P X X signalgrass X X X sorghum, volunteer P - - sprangletop - - X volunteer grains (barley, oats, wheat) - X - wild oats - X X witchgrass X X - Perennials bermudagrass - S - johnsongrass PS S - nutsedge, purple - X - nutsedge, yellow X X - quackgrass - X - X = control, S = seedling control only, P = partial control, - = weed not listed on label Level of control considered acceptable for inclusion of a weed on labels may vary among herbicide manufacturers. Absence of a weed from a label does not necessarily mean complete lack of control. High label rates, or repeated applications, may be necessary to achieve level of control claimed for some weeds. 120

4 WEEDS LISTED ON SAFFLOWER HERBICIDE LABELS Preplant/Preemergence Broadleaf Weeds Eptam Dual Treflan Annuals beggarweed, Florida P - - carpetweed X X X chickweed, common - X X corn spurry - X - fiddleneck - X - galinsoga X - - goosefoot - - X henbit - X X knotweed - - X kochia - - X lambsquarters, common - X X morningglory, tall - X - nettleleaf, goosefoot - X - nightshade, black X X - nightshade, hairy P X - pigweed, prostrate - X X pigweed, redroot X X X pigweed, tumble - X X puncturevine - - X purslane, common P X X pusley, Florida X X X shepherds purse sicklepod - X - sida, prickly - X - thistle, Russian - - X X = control, S = seedling control only, P = partial control, - = weed not listed on label Level of control considered acceptable for inclusion of a weed on labels may vary among herbicide manufacturers. Absence of a weed from a label does not necessarily mean complete lack of control. High label rates, or repeated applications, may be necessary to achieve level of control claimed for some weeds. 121

5 SAFFLOWER Herbicide Application and Remarks Defol 5 Rate: 4.8 qts/a sodium chlorate Time: 7 or more days before harvest, when safflower heads are fully mature. Rotation: A defoliation herbicide that reduces crop moisture and desiccates weeds prior to harvest. Defol 5 may be applied by aircraft or ground equipment. Foliage should be thoroughly covered. When using this product under dry land conditions, injury may occur to rotational crops. Do not graze treated areas. Dual II Magnum Rate: 1.0 to 2.0 pts/a, rate dependent on soil texture and O.M. % metolachlor Time: A selective preplant surface applied, preplant incorporated or preemergence to the crop. Rotations: Dual II controls grass and some broadleaf weeds. Dry weather following preemergence application may reduce effectiveness. Barley, oat, rye and wheat have a 4 1/2 month planting restriction and alfalfa a 4 month restriction. Under high moisture conditions, crop injury may occur following application of Dual. Eptam (7E) or Rate: 3.4 pts or 15 lbs granules /A just before planting Eptam 20 G EPTC Time: Preplant incorporate into top 2-3 inches of soil immediately after application. Rotations: Eptam controls grass and some broadleaf weeds and will not control established weeds. In cases of safflower crop failure, run a bio-assay before planting. Use equipment proven to incorporate thoroughly to the recommended depth. Consult label for proper equipment and adjustments. Improper incorporation may cause crop injury. Gramoxone Extra Rate: 2.0 to 3.0 pts/a paraquat dichloride Time: Preplant or precrop emergence and after weeds have emerged but before crop emergence. Rotation: Minimum carrier 10 gal ground and 5 gal air. Always combine with nonionic surfactant or crop oil concentrate. A nonselective, nonresidual foliar herbicide. Good coverage is essential. No restrictions. 122

6 SAFFLOWER - continued Herbicide Application and Remarks RESTRICTED USE PESTICIDE. Wear/use appropriate gear for application. Sonalan 10G Rate: lb/a in coarse soils, lb/a in medium soils, ethalfluralin lb/a in fine soils Time: Rotation: Spring or Fall application, Sonalan should be applied and incorporated before planting. A preemergence herbicide to control several annual grasses and broadleaf weeds including foxtails, wild buckwheat, common chickweed, kochia, common lambsquartes, and nightshades. Sonalan controls wild oat, expcept for seeds germinating below the zone treated with herbicide. Several rotational crop restrictions exist. Do not plant small-grains for 12 months after application of Sonalan. In Montana and Wyoming plant only canola, safflower or sunflower as rotational crops in the crop year following the crop treated with lb per acre of Sonalan. Spring seeded barley can be planted in the crop year following the crop treated with 7.5 lb per acre of Sonalan. For other crops, the land should be fallowed for a year. Two incorporation passes are necessary, the first one as soon as possible after application and the second one 5 days later. Make only one broadcast application per year. Treflan MT or Rate: 1 to 2.5 pts or lbs/a depending on soil texture, soil O.M. and Treflan TR 10 time of application trifluralin Time: Preplant incorporated fall or spring. Rotations: May be applied to standing stubble or soil that has been pre-tilled. Existing weeds and crop residues should be reduced to manageable levels. Uneven incorporation can result in erratic weed control or crop injury. Sugarbeets, red beets, spinach, millet, corn, oat, and sorghum should not be planted for at least 12 months or 18 to 20 months if land is not irrigated. TR 10 should be incorporated within 24 hours. Unless specified otherwise TR 10 requires two incorporations. The second should be delayed a minumum of 5 days. Tri-4 HF, Trifluralin 4EC, Trifluiralin HF are other brand names of liquid trifluralin. Note: Guidelines and weed spectrums may differ with brand labels for liquid trifluralin. 123