Insects and Related Pests in the Greenhouse

1. Insects and Related Pests in the Greenhouse Presented by Terry Ferriss, PhD University of Wisconsin—River Falls

2. Common Pests in the Greenhouse Aphids Thripse Fungus gnats Shore flies Whiteflies Red spider mites Cyclamen mites Leafminer Mealy bugs Scales

3. Aphids • Description: 1/8” in size • black to green in color • winged and wingless • “tail-pipes” • “Y” shaped vein at wing tip • Feeding: • piercing - sucking mouth • Location on plant: • Found on entire plant (growing tips to roots) • Primarily buds • Underside of leaves • Stems • Signs/Symptoms: • Distorted new growth / chlorosis • Chlorotic pin-point spots on older leaves • Honeydew and sooty mold

4. Honeydew and Sooty Mold Aphids & many other insects frequently excrete: Honeydew” --- shiny, sticky Ants love to eat “honeydew” Sooty mold grows vigorously on “honeydew”

5. Aphids (cont.) Reproduction: • Female nymphs give birth to other females without mating • Males and females appear outdoor as winter approaches – mate • eggs overwinter • 7 day life cycle possible !!!

6. Aphid’s Lifecycle From: Nelson, Greenhouse Mgmt book

7. Aphid From: Nelson, Greenhouse Mgmt book

8. Aphid damage to a chrysanthemum

9. Controlling Aphids • Common crops: • impatiens, dahlia, cineraria , peppers, tomatoes • Management: • Avoid high N fertilization • wash aphids off plant • Aphidied parasitic wasp • Enstar (IGR) • Horticultural Oil • Orthene • Others …..

10. Thrips • Description: 1/32”-1/25” • 2 pairs of wings • dark brown / cigar shaped • may be confused with a speck of dirt on sticky card • Feeding: • Rasping - sucking mouth • Location on plant: • in buds, in flowers, in leaf axils, between bulb scales • Signs/symptoms: • White to silver feeding scars/streaks on new growth (turn tan to brown) • Distorted or malformed foliage/flowers • Stunted growth • Carry virus (TSWV, INSV)

11. Thrips Reproduction: • Can complete in 2 weeks • Warm or cool temps • Pupates in soil

12. Thrips’s Lifecycle From: Nelson, Greenhouse Mgmt book

13. Thrips

14. Thrips damage

15. Controlling Thrips • Common crops: • geraniums, chrysanthemums, impatiens • Management: • Build resistance to chemicals quickly • Sugar bait to increase exposure • CO2 = irritant and increases exposure • Contact chemicals: deliver as small particle size to reach thrips hidden in leaf axils and buds. • (several including Marathon, Avid) • Biological control

16. Is it a fungus gnat or a shore fly???

17. Fungus gnat vs. Shore fly From: Nelson, Greenhouse Mgmt book

18. Fungus gnats • Description: 1/16”-1/8” • adult looks like a tiny mosquito • larvae: worm-like white with black head (1/4 “) • Location : • Larvae are in soil feeding on decaying OM • Adults do not feed but fly around plants and lay eggs in soil • Signs/symptoms: • Larvae can injure roots if high populations • Adults do not cause direct damage to the plant but can carry fungal spores and are very undesirable. • Possible lack of vigor, chlorosis • Common crops: any plant in high organic media

19. Fungus gnat lifecycle (20 – 30 days) From: Nelson, Greenhouse Mgmt book

20. Fungus gnat From: Nelson, Greenhouse Mgmt book

21. Controlling Fungus gnats • Management: • Avoid algae in the area • Keep floors as dry as possible • Clean up spilled media • Eliminate weeds • BT (Bacillis thurengiensis) • Chemical options

22. Shore Fly From: Nelson, Greenhouse Mgmt book

23. Shore Flies • Description: 1/8” • dark in color, looks like tiny fruit fly • Location on plant: • Favor damp areas and algal growth • Signs/symptoms: • No direct injury to plants, but shore flies may carry plant pathogens • Common crops: • Found on any crop around damp areas • Management: • Keep algae growth down, watch fertilizer and water runoff, chemical and biological control

24. Shore Fly’s Lifecycle From: Nelson, Greenhouse Mgmt book

25. Whiteflies • Description: 1/16”-1/8” • wings covered with white waxy powder • yellow-orange body • Breed in oxalis and other weeds • Life cycle of 4-5 weeks • Location on plant: • Underside of leaves (10 young lvs) • fly when disturbed • Feeding: • Piercing-sucking mouth part • Signs/symptoms: • Chlorosis • may leave honeydew

26. Whitefly’s Life cycle From: Nelson, Greenhouse Mgmt book

27. Whitefly From: Nelson, Greenhouse Mgmt book

28. Whiteflies (cont.) • Sweet potato WF vsPoinsettia WF SPWF:moves slower / larger enstar / flies further / grayer PWF: reproduces 30% faster • Common crops: poinsettia, geranium, tomato, pepper, fuschia

29. Controlling Whiteflies • Management: • Weed control • Enstar (IGR) • Encarsia formosa • Horticultural oil • Chemical control (in nymph or adult stage) • Marathon • Pyrethrum • others

30. Red Spider Mite(2 –spotted red spider mite) • Description: .007”-.015” • Red or orange in color • Location on plant: • Underside of leaves and on flowers • Favorable conditions: • Low relative humidity and high temperatures • Signs/symptoms: • Chlorotic stippling on upper leaf surface • Yellow / bronzing of foliage – dry lvs • If severe will see webbing cthr.hawaii.edu

31. Red Spider Mite Lifecycle From: Nelson, Greenhouse Mgmt book

32. Red spider mite Photo: NCSU Photo: mumsanddahlias.com gardenscure.com

33. Controlling Red Spider Mites • Common crops: • English ivy, marigold, foliage plants, ivy geranium • Management: • Wash underside of leaves • Humidity / temp control • Parasitic mites • Biological sprays • Miticides effective only on adults kenyon.edu

34. Cyclamen Mite • Description: .007”-.015” • Location on plant: • Growing tips • Signs/symptoms: • Distorted or stunted new growth, • blackened shoot tips • Common crops: • African violet, new guinea impatients, ivy, clematis • Management: • Rouge out infested plants, chemical control

35. Cyclamen Mite From: Nelson, Greenhouse Mgmt book

36. Leafminer • Description: 1/16”, • stout bodied flies that are black and may have a bright yellow thorax • Location on plant: • Leaves • Favorable conditions: • High nitrogen levels • Signs/symptoms: • Punctured leaves where females lay eggs • “Mines” through leaves after eggs hatch • Common crops: • marigold, chrysanthemum, petunia • Management: • Resistant varieties, chemical/biological controls

37. Leafminer’s Lifecycle From: Nelson, Greenhouse Mgmt book

38. Leafminer

39. Leafminer damage From: Nelson, Greenhouse Mgmt book

40. Mealybug • Description: 1/8”-1/4” • soft-bodied insect covered in a white, waxy secretion • Location on plant: • Leaf axils, leaf midribs, underside of leaves • Signs/symptoms: • Honeydew on leaves, • leaf yellowing and leaf drop, • cottony white masses in leaf axils and underside of leaves, • new growth is distorted

41. Mealybug • Common crops: • Foliage plants • Signs / symptoms: • “spitballs” in leaf axils and along veins • Stunted growth • Chlorosis of adjacent plant parts • Feeding: • Piercing-sucking mouth part • Management: • Rouge out infested plants, • wash off plants, • chemical control (nymphs are most susceptible), • biological control

42. Mealybug Lifecycle

43. Mealybug From: Nelson, Greenhouse Mgmt book

44. Scales • Description: 2-5mm • soft and white to hard and dark bodied • Feeding: • piercing sucking mouth • Location on plant: • Stem, flowers, fruits, roots, crown • Signs/symptoms: • Silver streaking honeydew on plant, • Chlorosis • Common crops: • woody interiorscape plants, amaranthus • Management: • Destroy infested plants • chemical and biological controls

45. Scales’s Lifecycle From: Nelson, Greenhouse Mgmt book

46. Scales

47. University of Wisconsin—River Falls Thank you Terry Ferriss, PhD