2004 Crop Production Considerations Todd Vagts ISU Extension Crop Field Specialist

Todd Vagts Talking Points Rotation changes? Corn – Soybean Yield Comparisons –Soybean Yield Plateau? Pest Considerations –Soybean –Corn

Todd Vagts The Rotation Decision? Traditional Corn-Soybean Corn-Corn-Soybean Continuous Corn Problems and Considerations

Todd Vagts Why Corn-Bean Rotation Higher Yields (?) –Rotation Effect… Lower fertilizer costs (?) Less pest problems (?) –Weeds, insects, disease Less crop residue to manage Farm program (?)

Todd Vagts -10% -7% ( )

Todd Vagts CS | C (1) | C (2) | CC

Todd Vagts -9%

Todd Vagts

2 nd Year Corn Potential 7 to 10 percent yield reduction compared to 1 st year corn Additional 2 to 4 percent yield reduction with 3 or more years of corn

Todd Vagts

Rotation Yield Gains and Losses 2 nd Year Corn –8% Yield reduction X (149 bu/A) = 11.9 bu 11.9 bu/A X $2.48 = $28.56 (Disadvantage) Soybean following 2 nd Year Corn –6% Yield Increase X (43.9 bu/A) = 2.6 bu 2.6 bu/A X $6.04 = $15.70 (Advantage)

Todd Vagts Costs to Corn-on-Corn 2 nd year corn and 3 rd year soybean Corn Yield Reduction Soybean Yield Gain -$ $15.70 = -$12.86

Todd Vagts Nutrient Requirements

Todd Vagts Nutrient Costs

Todd Vagts

Nutrient factors

Todd Vagts Costs to Corn-on-Corn 2 nd year corn and 3 rd year soybean Corn Yield Reduction Soybean Yield Gain Fertilizer Cost -$ $ $12.00 (2 years) = -$24.86 (2 year)

Todd Vagts Yield and Rotation Yield benefit to rotation most evident in lower yield environments (25%) –Yield benefit declines under high yield environments for both corn and soybean (15% or less) Corn-Soybean rotation maximizes corn yield but not soybean yield –The Corn Soybean Rotation Effect, Joe Laurer Paul Porter and Ed Oplinger. University of Wisconsin.

Todd Vagts Calhoun County Soybean and Corn Yields Comparison

Todd Vagts

5-Year Average Soybean Yield

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5 Year Average Yield

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Greater Advantage to Corn “High corn yields relative to soybean yields”

Todd Vagts Yield Trends Iowa Calhoun County

Todd Vagts Yield Trend Iowa Calhoun County

Todd Vagts 6-Year Yield Trends Iowa 1997 – –

Todd Vagts 6-Year Yield Trends Calhoun County 1997 – –

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Yield Trends for Iowa 6 Year Increments

Todd Vagts Yield Trends for Calhoun County 6 Year Increments

Todd Vagts Have Soybean Yields Reached a Plateau? For Calhoun County, when compared to similar time periods in the past – No Answer is more difficult to determine for the state

Todd Vagts Economics

Todd Vagts Shift Acres from Beans to Corn? 2/09/04 Dec. corn futures $2.83 Less basis, N. Iowa 0.35 Harvest hedge price 2.48 Nov. soybean futures $6.49 Less basis, N. Iowa 0.45 Harvest hedge price 6.04 R. Wisner ISU Econ.

Todd Vagts Corn/soy: Harvest hedge price $2.48 Less variable prod’n 170 bu./A Net/bu Net/A. over variable cost $ Corn/corn: Harvest hedge price $2.48 Less variable prod’n 145 bu./A. (ISU farms avg. diff.) 1.55 Net/bu Net/A. $ Corn, Corn, SB rotation

Todd Vagts Corn/soy: Harvest hedge price $2.48 Less variable prod’n 149 bu./A. (5-Yr Ave. Yield Calhoun County) 1.21 Net/bu Net/A. over variable cost $ Corn/corn: Harvest hedge price $2.48 Less variable prod’n 136 bu./A. (91% of C/S) 1.60 Net/bu Net/A. $ Corn, Corn, SB rotation Returns to Corn Production

Todd Vagts Corn/soy: Harvest hedge price $6.04 Less variable prod’n 50 bu./A Net/bu Net/A. $ Corn/soy: Harvest hedge price $6.04 Less variable prod’n 38 bu./A Net/bu Net/A. (excludes aphid spraying cost) $ Shift Acres from Beans to Corn? Disease, Nematode, aphid problems 2/09/04

Todd Vagts Economic Summary Return to corn –C/S Rotation $189 ($1.27/bu) –C/C/S $120 ($0.88/bu) Return to soybean –Low Yield $121 ($3.18/bu) –High Yield $194 ($3.87/bu)

Todd Vagts Other Factor to Consider Greater percentage of farm in one crop – increases risk Corn requires greater input expenses

Todd Vagts Pest Management Considerations Corn –Western Bean Cutworm –Grape colaspis Soybean –Soybean Aphid –Bean Leaf Beetle –Cyst Nematode –Soybean Rust (?)

Todd Vagts Eggs: Small, whitish, clusters that turn purple prior to hatch Larvae: New larvae  ¼” long and dark brown, lighten to pale brown as they mature. Full size is 1½” Adults: White band along most of the leading edges of forewings LARVA ADULT EGGS Corn Pests –western bean cutworm

Todd Vagts Injury:  Different from other cutworms; ear feeders  Economic damage may occur when multiple cutworms feed on an ear  Injury allows pathogens into the ear Corn Pests –western bean cutworm

Todd Vagts Corn Pests – western bean cutworm

Todd Vagts

Pyrethroids (RUP) Ambush ® * Asana ® XL* Capture ® 2EC Baythroid ® 2E Mustang ® Max Pounce ® 3.2EC* Warrior ® Organophosphates (RUP) Lorsban ® 4E Penncap-M ® Carbamates Sevin ® XLR Plus See “Integrated Crop Management” ( or product labels for correct application rates. Insecticides for western bean cutworm *Mite risk

Todd Vagts Description  Honey-brown leaf beetle  Fine tan & brown lateral stripes on grooved wing covers  Larvae are small, “C”-shaped, grubs Corn Pests – colaspis beetles

Todd Vagts Corn Pests – colaspis beetles Grubs feed on roots Above-ground symptoms may include stunting, wilting, purpling of the stem and leaves, and tip and leaf-edge browning Damage extent unknown

Todd Vagts Soybean Aphid

Todd Vagts Where is it now? Spread of Soybean Aphid in the US, Spread to S & W continues Outbreaks in 2003 primarily in western half of NC states Treatment occurred in DE & MD in 2003 Slide from K. Ostlie, Data from R. Venette, unpublished data

Todd Vagts Soybean aphid Description –Very small, yellow aphid, 1/16 inch long –Distinct black ‘tailpipe-like’ structures on end of abdomen –Wingless and winged forms –Appear in colonies of adult females and offspring –Females give birth to live females

Todd Vagts (Buckthorn) (Soybean)

Todd Vagts How fast can a soybean aphid reproduce? [data generated in the lab by Ragsdale et al., Univ. of Minnesota] Temp 68 o F 77 o F 86 o F 95 o F Lifespan(days) (die)Doublingtime(days) deadTotal#babies Firstbabies (# days) Chris DiFonzo, Michigan State University

Todd Vagts Soybean Aphid Impacts on Yield & Yield Components: 5 MN Fields in 2001 Slide from K. Ostlie, University of MN

Todd Vagts Sooty Mold

Todd Vagts Natural Enemy “Lag” Time Spray Timing Critical – Aphid Resurgence Factor Bob Ellingson and David Hogg, UW Entomology

Todd Vagts Product Performance & Canopy Distribution Lorsban Furadan Pyrethroids Volatile distribution through canopy. May “fume” into untreated check strips Systemic, a.i. activity within plant in addition to contact activity Cannot work its way through canopy beyond contact activity. Coverage in closed canopy critical for efficacy against aphids at lower and inner locations on plant. Eileen Cullen – UW Extension, Entomology

Todd Vagts Product Performance & Temperature Lorsban Furadan Pyrethroids Optimal performance at higher temps. (may increase “fuming” action) Also relatively better at higher temp Exhibits a Negative Temp Relationship: Works better under cool conditions below 90 o F. Eileen Cullen – UW Extension, Entomology

Todd Vagts Product Performance & Residual Lorsban Furadan Pyrethroids Short residual, measured in days. Longer residual than organophosphates. Some additional feeding exposure, due to systemic activity Longest residual, 2 weeks or more Eileen Cullen – UW Extension, Entomology

Todd Vagts What to look for in 2004 Look to areas of the north  MN and Wisconsin  Areas with buckthorn and cooler temperatures Watch the weather  North Wind  Bring winged aphids in  Temperature  Favorable environment for survival and reproduction.

Todd Vagts Aphid Population Development - MN

Todd Vagts Wind Direction

Todd Vagts Temperature (Ames)

Todd Vagts Iowa Aphid Treatment Yield Response

Todd Vagts IA Soybean Aphid Treatment Yield Response

Todd Vagts IA – Response by Aphid Count

Todd Vagts Threshold aphids per plant increase - assumes aphid numbers are on the increase - provides a 7-day lead time (call in equipment, deal with weather delays) - use through R4 (full-pod stage) Cannot overemphasize DROUGHT Chris DiFonzo, Michigan State University

Todd Vagts How many aphids per plant cause that much yield loss….. + a 7-day lead time? [Based on data from University of Minnesota plots in 2003] Price$/bu $5.00 $6.00 $ % 3.3% 2.8%50 4.8% 4.0% 3.4%40 6.0% 5.0% 4.2% % of Yield potential, bu/acre % of Yield potential, bu/acre#bu Chris DiFonzo, Michigan State University

Todd Vagts 82 Aphids How Many Aphids?

Todd Vagts 850 Aphids

Todd Vagts 49 Aphids

Todd Vagts 11 Aphids

Todd Vagts Monitor weather forecast Cool to mild forecast may enhance aphid reproduction capacity –Warming trend may slow or stop aphid reproduction Northerly fronts may blow aphids in from north Precipitation may or may not help

Todd Vagts Yellow or red; with or without four square marks on wing covers Always with a small, black triangle behind the head Soft and gray when adults first emerge Bean leaf beetles

Todd Vagts Key feature: Small, black triangle behind head Soybean Pests – bean leaf beetles

Todd Vagts Timing of Bean Leaf Beetle Generations /26 6/26/9 6/16 6/23 6/30 7/7 7/14 7/21 7/28 8/4 8/11 8/188/25 9/1 9/8 9/15 date mean bean leaf beetles Overwintering 1 st Generation 2 nd Generation

Todd Vagts Economic damage from pod feeding and by transmission of bean pod mottle virus Soybean Pests – bean leaf beetles L. Sweets Pod Injury Foliar symptoms of virus

Todd Vagts Bean Leaf Beetle Population Trend bean leaf beetles / 50 sweeps Highest abundance recorded in 14 years!

Todd Vagts Bean Leaf Beetle Management Different strategies based on pest complex A) Bean leaf beetle only B) Bean leaf beetle + bean pod mottle virus

Todd Vagts Timing of Bean Leaf Beetle Generations

Todd Vagts Insecticides for bean leaf beetle management Pyrethroids (RUP) Ambush ® 2EC* Asana ® XL* Mustang Max ® Pounce ® 3.2EC* Warrior ® Organophosphates Lorsban ® 4E Penncap-M ® (RUP) Carbamates Sevin ® XLR Plus See “Integrated Crop Management” ( or product labels for correct application rates. * Mite risk

Todd Vagts Soybean Cyst Nematode

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Soybean Rust

Todd Vagts Soybean Rust Potential Yield Losses –In countries in which soybean rust is an established problem, losses range from percent. The severity of losses varies depending on susceptibility of the soybean variety, time of the growing season in which the rust becomes established in the field and weather conditions during the growing season. Management –Current management strategies are through the use of resistant varieties and foliar fungicides applied during the growing season. Two to three fungicide applications may be necessary depending on disease severity.

Todd Vagts Soybean Rust Hosts –Soybean, kudzu, yellow sweet clover, medic, vetch, lupine, green and kidney bean, lime or butter bean and cowpea or black-eyed pea. Survival –Rust pathogens survive on living plant material. It may be able to survive the winter months on hosts such as kudzu in the southern United States. Soybean rust spores could then be carried north on wind currents and by storms.

Todd Vagts New Developments Section 18 approval for Gaucho (insecticide) on soybean seed –Bean leaf beetle –Soybean aphid