Wheat Insect Pest Management

1. Wheat Insect Pest Management by Dr. Jack Baldwin Dept. of Entomology LSU AgCenter

2. True Armyworm Fall Armyworm Both have four abdominal prolegs and are about 1.5 inches in length when full grown.

3. Reported to be a pest on seedling wheat in the fall. Brownish color, but varies from green to almost black. Dark head with prominent inverted Y on front. Spines and hairs on body. 4 black spots arranged in square on top of 8th abdominal segment. Fall Armyworm

4. Worm Damage to Seedling Wheat in FallSuspected Pest/s: Fall Armyworm and Cutworm Stand loss (November) Clipped seedlings

5. True Armyworm • Greenish color, but varies. • Brownish head with honeycombed markings. • Smooth body, no hairs or spines. • Orange stripes on both sides of body. • Each proleg has brownish or dark colored band on outer sides.

6. True Armyworm • Primarily an early season (spring) pest. • Strong preference for grass crops: • Known to infest wheat and corn in LA • Source of infestation: • Overwinters in larva stage • Migration • Life cycle: egg to adult requires 41-66 days. Eggs laid in masses of 25 or more

7. True ArmywormObservations and Conventional Trends • Bigger problem in cool, wet springs • Prefers fields with lush, rank growth and lodging. Moth like to lay eggs in moist shady areas. • In LA, infestations usually develop in April. • Feeds at night. During day it hides under soil or under surface debri and thatch. • Scout for pest during early am and late pm, or look for larvae on and under the ground surface. • Feeds on foliage. Appears as notches on leaf margin, or in extreme cases complete defoliation. • Frass appears as black, pepper-like droppings. • Feeding on the heads (beards) and/or clipped heads

8. True Armyworm • When to treat: 5 or more larvae per square foot and foliage loss is occurring. • Protect crop/foliage until physiological maturity (hard dough stage). • Head clipping: • Theory 1: Clip heads after defoliating leaves. • Theory 2: Some years heads clipped and some years they are not. • Suggested threshold of 2-3% clipped heads.

9. Stink BugsRice Stink Bug and Southern Green Stink Bug • Occasional pest, more so in south LA. • Damage developing seed grain with piercing-sucking mouthparts. • At milk stage or earlier (flowering): treat when 10% of seed heads have stink bugs. • At soft dough stage, treat when 25% of seed heads have stink bugs.

10. Aphids English grain aphid Oat bird cherry aphid Corn leaf aphid Yellow sugarcane aphidGreenbug Russian wheat aphid

11. Generation – about a week from birth to mature aphid Adult females give birth to living young; 2-3 per day for 2-3 weeks Piercing-sucking mouthparts; remove plant juices Winged or wingless Soft bodied insects Identification Legs Antennae Siphunculi (cornicles) AphidsGeneral Biology

12. Inject Toxin Russian wheat aphid – does not occur in LA. Greenbug – usually does not develop high populations. Yellow sugarcane aphid – Not as toxic to wheat as to sorghum. Do Not Inject Toxin Corn leaf aphid Oat bird cherry aphid English grain aphid – clusters on grain heads. Transmit BYDV Corn leaf aphid Oat bird cherry aphid English grain aphid Greenbug AphidsPotential pests, but normally not a major problem in LA.

13. Color ranges from green to black Tips of siphunculi, legs and antennae are black. Reddish-orange colored patch on rear of abdomen Direct feeding usually not damaging Oat Bird Cherry Aphid

14. Blue green color; can appear black Black siphunculi, legs and antennae More common on grain sorghum than wheat Direct feeding usually not a problem. Corn Leaf Aphid

15. Long, black siphunculi Black antennae that extend straight back over the abdomen. Dark legs or leg bands Direct feeding can cause damage; usually in flowering/ early grain formation. Dark hit areas in field from flag leaf damage and fungal infected heads. Thresholds are available in some states. English Grain Aphid

16. Light green with dark green stripe down the back Dark tips on siphunculi (tail pipes) and legs Present in wheat all winter and can reproduce at temperatures lower than natural enemies. Injects toxin; results in yellowish spot with dark lesion; ultimately death. Damaged areas first appear as N deficiency/ moisture stress. Greenbug

17. Long, oval, hairy body shape. Lemon yellow to mint green color Siphunculi, legs and antennae are light colored. Injects toxin and can cause serious damage. More damaging to grain sorghum than wheat. Yellow Sugarcane Aphid

18. Russian Wheat Aphid • Present in 16 western states on wheat and barley • First US detection was in Muleshoe, TX in 1986

19. Aphids that have been parasitized by small wasps. Greenbug mummies Aphid Mummies

20. Hessian Fly • Important pest of wheat, but rarely a problem in the deep south states. • Outbreaks in the southeast in 1984-1985 and 1985-1986. • Outbreak in Alabama in 1989. • Detected in southwest Alabama in 2006. • Detected in collections taken from Louisiana in 2000. Larva (Maggot) Pupa (Flaxseed)

21. Insecticide Seed Treatments • Gaucho and Cruiser have wheat labels. • Labeled for aphid control and Hessian fly control • No current LA data at this time to support their use, but they will be looked at this year.

22. Questions