Corn Pest Management Has the Reserve Team become the Varsity? Advanced Crop Advisers Workshop February 10, 2015 Fargo, North Dakota Janet Knodel NDSU Extension Entomologist Dean Malvick UMN Extension Plant Pathologist Phillip Glogoza UMN Extension Educator - Crops
Major Insect Pests of Corn European corn borer Corn Rootworm White grub Flea & Sap beetles Chinch bug Corn leaf aphid Grasshoppers Corn earworm Wireworm numerous Cutworms Billbugs Common stalk borer Seedcorn maggot Spider mites
MSU Field Crops Entomology Program Handy Bt Trait Table CDD #028 Updated April 2014 Chris DiFonzo, Michigan State University, East Lansing, MI & Eileen Cullen, University of Wisconsin, Madison, WI The most up-to-date version of this bulletin is posted at: www.msuent.com Many corn hybrids contain multiple transgenic traits and seed costs are rising. Meanwhile, refuge requirements dramatically for multi-trait corn, generally dropping from 20% to 10% or 5%, depending on the trait package and company. Some traits still require a structured refuge planted as a block or series of rows, but many hybrids are now sold as refuge-in-the-bag (RIB). Purchasing the right trait package for your pest spectrum, and understanding its refuge requirement, is critical to maximizing profitability and delaying resistance. But this process may be confusing. The table on page 2 of this bulletin summarizes, to the best of our ability, currently available Bt traits, their spectrum of control, and refuge requirements. We make every attempt to provide up-to-date information for each Bt option. However, it is still important for you to take the following steps: *Understand the terminology used by your seed company; *Understand the biology of each trait, the expected level of control, and refuge requirements; *Confirm that the seed you ordered the previous year is the seed delivered to you in spring; *Keep good planting records; *For herbicide applications, Ask Twice-Spray Once, especially if you hire a custom applicator; *Save a representative sample of bag tags = the first thing to check if something goes wrong; *Most important, if you see unexpected damage or poor performance of a trait during the field season, contact your seed dealer immediately so that the field can be visited while the problem is still visible and fresh samples can be taken. Insect targets BCW black cutworm Abbreviations used in the Bt Trait Table Herbicide traits GT glyphosate tolerant LL Liberty Link (glufosinate-tolerant) RR2 Roundup Ready 2 (glyphosate-tolerant) CEW ECB FAW RW SB WBC corn earworm European corn borer fall armyworm corn rootworm stalk borer western bean cutworm NEW Cheat Sheet ------ Event names for proteins expressed in Bt plants Target or Activity Protein(s) expressed Event Trade name corn borer Cry1Ab MON 810 YieldGard CB corn borer + glufosinate tolerance Cry1Ab + PAT Bt11 Agrisure CB/LL corn borer + glufosinate tolerance Cry1F + PAT TC1507 Herculex 1 or CB broad lep control Vip3Aa MIR162 Agrisure Viptera broad lep control Cry1A.105 + Cry2Ab2 MON89034 Yieldgard VT Pro rootworm ecry3.1ab 5307 Agrisure Duracade rootworm mcry3a MIR604 Agrisure RW rootworm Cry3Bb1 + CP4 EPSPS MON88017 YieldGard VT RW rootworm + glufosinate tolerance Cry34Ab1/Cry35Ab1 + PAT DAS-59122-7 Herculex RW glyphosate tolerance mepsps GA21 Roundup Ready glyphosate tolerance CP4 EPSPS NK603 Roundup Ready 2
DiFonzo&Cullen s Handy Bt trait table Updated April 2014 Insects controlled (bold) or suppressed (italics) Above-ground------------In soil Herbicide tolerant? Refuge %, location in the MIDWEST Bt protein(s) Agrisure Trait Family Agrisure CB/LL/RW Cry1Ab mcry3a ECB CEW FAW SB RW LL 20% in field/adjacent Agrisure 3000GT Cry1Ab mcry3a ECB CEW FAW SB RW GT LL 20% in field/adjacent Agrisure Artesian 3011A Agrisure Viptera 3110 Agrisure Viptera 3111 Agrisure 3122 E-Z Refuge Agrisure Viptera 3220 E-Z Refuge Agrisure Duracade 5122 Cry1Ab mcry3a ECB CEW FAW SB RW GT LL 20% in field/adjacent Cry1Ab Vip3A BCW CEW ECB FAW WBC SB Cry1Ab mcry3a BCW CEW ECB Vip3A FAW WBC SB Cry1Ab Cry1F BCW ECB FAW mcry3a Cry34/35Ab1 WBC CEW SB Cry1Ab Cry1F BCW CEW ECB Vip3A FAW WBC SB Cry1Ab Cry1F BCW CEW ECB mcry3a ecry3.1ab FAW WBC SB --- GT LL 20% within ½ mile RW GT LL 20% in field/adjacent RW GT 5% in the bag --- GT 5% in the bag RW GT LL 5% in the bag Agrisure Duracade Cry1Ab Cry1F Vip3A BCW CEW ECB RW GT LL 5% in the bag 5222 mcry3a ecry3.1ab FAW WBC SB Herculex Trait Family Herculex 1 (HX1) Cry1F BCW ECB FAW --- LL 20% within ½ mile WBC CEW SB Herculex XTRA Cry1F BCW ECB FAW RW RR2 20% in field/adjacent (HXX) Cry34/35Ab1 WBC CEW SB (most) Optimum Trait Family Optimum Cry1F mcry3a BCW ECB FAW RW LL RR2 20% in field/adjacent TRIsect WBC CEW SB Optimum Cry1F Cry1Ab BCW ECB FAW --- LL RR2 5% within ½ mile Intrasect WBC CEW SB Optimum Cry1F Cry1Ab BCW ECB FAW RW LL RR2 20% in field/adjacent Intrasect XTra Cry34/35Ab1 WBC CEW SB Optimum Cry1F Cry1Ab BCW ECB FAW RW LL RR2 5% in field/adjacent Intrasect XTreme mcry3a Cry34/35Ab1 WBC CEW SB Optimum (AM) Cry1F Cry1Ab BCW ECB FAW --- RR2 5% in the bag AcreMax WBC CEW SB Optimum (AMRW) AcreMax Rootworm Cry34/35Ab1 --- RW RR2 10% in the bag Optimum (AM1) Cry1F BCW ECB FAW RW LL RR2 10% in the bag (RW) AcreMax1 Cry34/35Ab1 WBC CEW & 20% - ½ mile (CB) Optimum (AMX) Cry1F Cry1Ab BCW ECB FAW RW RR2 10% in the bag AcreMax Xtra Cry34/35Ab1 WBC CEW SB Optimum (AMXT) AcreMax XTreme Cry1F Cry1Ab mcry3a Cry34/35Ab1 BCW ECB FAW WBC CEW SB RW RR2 5% in the bag YieldGard / Genuity Trait Family YieldGard VT Triple Cry1Ab Cry3Bb1 ECB CEW FAW SB RW RR2 20% in field/adjacent Genuity VT Double Cry1A.105+Cry2Ab2 CEW ECB FAW --- RR2 5% in the bag PRO RIB Complete Genuity VT Triple Cry1A.105+Cry2Ab2 CEW ECB FAW RW RR2 10% in the bag PRO RIB Complete Cry3Bb1 Genuity SmartStax Cry1A.105+Cry2Ab2 BCW CEW ECB RW LL RR2 5% in the bag RIB Complete Cry1F Cry3Bb1 FAW SB WBC Cry34/35Ab1 Refuge Advanced Trait Family REFUGE Cry1A.105+Cry2Ab2 BCW CEW ECB RW LL RR2 5% in the bag ADVANCED Cry1F Cry3Bb1 FAW SB WBC Powered by SmartStax Cry34/35Ab1
Common Stalk Borer Papaipema nebris Description Moth: wing spread just over one inch forewings brown to gray with small white spots. Eggs: globular, ridged and laid in the creases of rolled or folded leaves of weeds (grasses) Larva: Brown with white longitudinal stripes and a distinctive purple area in the middle of the body 1 1/2 to 2 inches long when full and are uniformly dirty gray found boring into the stems of plants, particularly grasses, ragweed and corn.
Common Stalk Borer Papaipema nebris Life History one generation per year eggs deposited in August-September in weeds and grassy patches along fencerows, ditch banks, and grass waterways passes the winter as egg eggs hatch in May-June tunnel into nearby plants, becoming full grown in July. They then pupate, usually just below the soil surface, and emerge as moths in August. Stalk Borer Degree Days (DD) Model 41 F base temperature accumulated from January 1. Use daily average temperature (max + min/2) 41 = daily DD
Common Stalk Borer Papaipema nebris Damage tunnels into the stalks of small grains, grasses, and corn. Feeding appears as irregular holes while while leaves were in whorl The heads of individual grain plants turn white prematurely Corn feeding occurs most frequently in rows adjacent to areas that were weedy the previous August. Damage usually of little economic significance. Threshold Guide None established "rescue" treatment if applied when the larvae are moving from weed hosts to corn treatments after tunneling are not effective
Flea Beetles Corn flea beetle Chaetocnema pulicaria Red-headed flea beetle Systena frontalis Description Adults: Corn flea beetles are small, shiny, black beetles, approximately 1/16-inch long, with enlarged hind legs. Red-headed flea beetles are shiny black with a reddish head are about 1/8 to 1/4- inch long. These small beetles have hind legs modified for jumping. The size and jumping behavior are the basis for the name flea beetle.
Flea Beetles Corn flea beetle Chaetocnema pulicaria Damage Chew on corn the leaf, usually parallel to the veins. They feed on both the upper and the lower epidermis of corn leaves, but they do not chew completely through the leaves. rarely result in economic injury. Flea beetle injury -- "windowpane effect" transmit the bacterium Erwinia stewartii (= Pantoea stewartii), the causal organism of Stewart s wilt (more likely a problem in Iowa- Illinois than in NW MN-ND) Threshold Guide average of five or more beetles per plant prior to the 4-leaf stage
Flea Beetles Red-headed flea beetle Systena frontalis Damage Chew on corn the leaf, "windowpane effect" Clip silks as they emerge from ear tip and high adult densities may result in poor pollination and reduced kernel set. Silk clipping after pollination causes no problems. rarely result in economic injury. Threshold Guide threshold of 25-50% of the plants with clipped silks during pollen shed silks must be chewed to within 1/2-inch of ear tip, hot dry weather more critical.
Picnic or Sap Beetles Family Nitidulidae Description Adults: black or brown, commonly with four prominent orange or yellow spots on the wing covers Adults found in the ears and stalks of corn that has been damaged by the corn earworm and corn borer. Larva: The larvae are active, white to creamcolored worms with brown heads.
Picnic or Sap Beetles Family Nitidulidae Life History: may winter as larvae or adults in decaying vegetation, debris, and fruit buried in the soil. emerge in the spring and lay their eggs on spoiling or rotting vegetation. Later they can lay eggs in the silks and kernels of damaged corn. The larvae feed in this decaying material until they are full grown, then they drop to the soil to pupate. two or more generations each year.
Picnic or Sap Beetles Family Nitidulidae Damage: they do not normally attack healthy plants, but work on injured spots on growing plants. Both species of beetles follow injury to ear corn. Since they lay eggs in the silks, the larvae feed in the ear and are suspected of being primary pests. Control: Control is rarely justified in commercial field corn. In seed production fields treatment may be warranted when there are ten or more adults per ear tip on 25% of the plants during the blister or milk stage.
Corn Leaf Aphid Rhopalosiphum maidis Description: bluish-green or gray, The adult females give birth to living young Colonies typically in the curl of the leaves, upper part of the cornstalk, and large numbers down in the whorl and on the unemerged tassel. Infested plants are quite sticky from accumulations of the honeydew.
Corn Leaf Aphid Rhopalosiphum maidis Damage: Heavily infested corn leaves may wilt, curl, and show yellow patches. Tassels and silks may be covered with honeydew, which may interfere with pollination. There is no conclusive evidence that leaf aphids cause barren stalks, but there is circumstantial evidence that barrenness occurs in about 40 percent of the heavily infested cornstalks. Damage is most severe between the latewhorl and pollination stages.
Corn Leaf Aphid Rhopalosiphum maidis Scouting Procedure: Corn leaf aphids are found in the whorl of younger plants and later on the tassel and upper leaves. To monitor aphid populations, examine 100 plants (5 sets of 20) for corn leaf aphids during the whorl stage (3 weeks prior to tassel emergence). Rate the infestation for each plant using the following system: 0 - No aphids 1-1 to 100 aphids per plant 2 - More than 100 aphids Note presence of predators, mummies, and fungal infected aphids
Corn Leaf Aphid Rhopalosiphum maidis Treatment Decisions: If 50 percent of the plants have more than 100 aphids per plant AND plants are under drought stress, treatment may be justified. The presence of numerous predators, parasites and fungal killed aphids suggests that natural controls may be reducing the number of aphids.
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