Companion Planting: The Real Story - Montgomery County Master Gardeners, University of Maryland


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Companion Planting: The Real Story - Montgomery County Master Gardeners, University of Maryland

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Companion Planting: The Real Story - Montgomery County Master Gardeners, University of Maryland

  1. 1. Companion Planting: The Real Story Janet Young, PhD
  2. 2. College ofAgriculture andNatural Resources 2
  3. 3. Please Silence Your Cell Phone Thank you!
  4. 4. Companion Planting Outline Definition Disclaimer Brief History Biological Benefits Practical Considerations The Last Word 4
  5. 5. Companion Planting DefinitionGrowing plants near or next to each other to provide a particular benefit to one or both plants. 5
  6. 6. Companion Planting - Disclaimer WHOA! There is very little scientific evidence for certain types of companion planting. This talk does not propose to ensure success with any of the methods presented! 6
  7. 7. Brief History – Ancient Rome Varro, a Roman agronomist - 37BC  Roman Farm Management - Cato  “Full grown walnut trees render sterile all the surrounding land.” Pliny the Elder – 23 to 79AD  Naturalis Historia  “The (highly toxic) plant rue is a ‘very friendly’ companion to figs.” 7
  8. 8. Brief History – ChinaGrowing Mosquito Fern in Rice Fields >1000 YR Hosts a cyanobacterium that fixes nitrogen from air Blocks light from getting to competing plants Mosquito fern Rice 8
  9. 9. Brief History – North America Native American “Three Sisters” Garden  Variant of method used throughout North America  Mounds 12” x 20”, maize first, then squash, beans  Maize=pole ; Beans=N2 ; Squash=mulch/protection Maize Beans SquashCA 9
  10. 10. Biological Benefits Nitrogen fixation – cover crops Physical assistance – shade, mulch, support Pest trapping – attract pest with other plants Host finding disruption – using plant decoys Attract beneficials - predators, pollinators Repel pests – WHOA! 10
  11. 11. Biological Benefits Nitrogen Fixation Plants e.g., clover, collect nitrogen from the air Special bacteria assist the plant in converting this nitrogen to usable nitrogen in root nodules When the plant decomposes, the nitrogen in the roots becomes available to neighboring plants Three Sisters – beans provide this benefit 11
  12. 12. Biological Benefits Physical Assistance Three Sisters: maize, beans, squash Mosquito fern and rice – prevents weeds Salad greens as a cover crop – retain moisture, prevent soil erosion 12
  13. 13. Biological Benefits - Pest Trapping Pelargonium geraniums grown with roses draw away Japanese beetles; geraniums are toxic to the Japanese beetles. Alfalfa grown with cotton draws away lygus bugs. Japanese beetle Lygus bug 13
  14. 14. Biological Benefits - Pest Trapping  Rye is used to protect soybeans from corn seeding maggots.  Sesbania is used to protect Corn seeding maggot soybeans from stink bugs. Stink bugB 14
  15. 15. Biological Benefits Host Finding Disruption How Predatory Insects Find Host Plants Host Plant required by predatory insect for feeding, reproduction Attracted by plant odor, and color green, avoid brown Fly to several leaves of plant to assess suitability if host plant found Chance of success increased if only a host plant is available 15
  16. 16. Biological Benefits Host Finding DisruptionCONCLUSION: adding non-host green plantsamong host plants decreases host findingsuccess, and insect moves to a different area 16
  17. 17. Biological BenefitsHost Finding Disruption Cabbage without clover Cabbage with clover Biologist (2003) 50 (3), p. 132 17
  18. 18. Biological Benefits Host Finding DisruptionHow Predatory Insects Find Host Plants Cabbage root fly searching for host. From: Fig. 4, Biologist (2003) 50 (3), p. 132 18
  19. 19. Biological Benefits Attract Beneficial Insects Flowers and herbs are known to attract pollinators and predators of crop- destroying insects Examples are chrysanthemums, sunflowers, coneflowers, alyssum, and flowers and herbs of carrot family 19
  20. 20. Biological Benefits Repel Pests - WHOA! Chrysanthemum – (may) repel aphids, bed bugs (Cimex lectularius), leafhoppers, spider mites, harlequin bugs, ticks, pickleworms and imported cabbage worms Nasturtium – (may) help to control squash bugs, cucumber beetles, and whiteflies. 20
  21. 21. Biological Benefits Repel Pests - Scientific Evidence? Pests of the Garden and Small Farm, Mary Louise Flint, PhD, UC Davis Department of Entomology “While the concept of companion planting is appealing, research in this area has consistently shown that companion plants offer no pest control benefits under controlled conditions. While many plants have chemical components themselves that repel pests, this effect is localized and benefits are not extended to neighboring plants of different species.” 21
  22. 22. Biological Benefits Repel Pests - Scientific Evidence?  “The Myth of Companion Planting”, Linda Chalker- Scott, PhD, Extension Horticulturist, Washington State University “There is no scientific basis, however, for any of the several lists that exist describing ‘traditional companion plants’. Like horoscopes, these lists may be fun to use, but they should not be perceived or promoted as scientifically valid any more than astrology.”I 22
  23. 23. Biological Benefits Repel Pests - True? Tomatoes love marigolds What does this mean? Should one plant marigolds in between (intercrop) tomato plants? 23
  24. 24. Biological Benefits – Repel Pests – True? The Problem  Nematodes are unsegmented roundworms, usually microscopic in size  Plant-parasitic nematodes can kill Galls from root-knot nematodes crops - University of MD Extension FS 825  Plant-parasitic nematodes are found in soil and are very difficult to control 24
  25. 25. Biological Benefits – Repel Pests – True?The Experiment Cowpeas seeded in a field with nematodes Marigolds then planted next to the cowpeas in one part of the field Nematode numbers, cowpea height, number of leaves, seeds/pod measured– African Crop Science Conf Proc,.v. 8:1075, 2007 25
  26. 26. Biological Benefits – Repel Pests- True!The Results Marigolds DID control nematodes in soil Cowpea yield was doubled if plants were intercropped with marigolds in fields with nematodes– African Crop Science Conf Proc,.v. 8:1075, 2003 26
  27. 27. Biological Benefits – Repel Pests- YESThe Conclusions Authors stated that a bio-nematicide may be released into the soil through the roots of the marigold plants – African Crop Science Conf Proc,.v. 8:1075, 2003 More recent studies show that marigold roots release the chemical alpha-terthienyl -- University of Florida Extension In the Florida study only a cover crop of marigold proved protective 27
  28. 28. Biological Benefits – Repel Pests- True!The Conclusions (cont’d) Therefore, marigolds may be beneficial to tomatoes (IF they are grown in soil with plant- parasitic nematodes) 28
  29. 29. Practical Considerations Use what we know works!  Nitrogen fixation – cover crops  Physical assistance – shade, mulch, support  Pest trapping plants  Host finding disruption  Plants that attract pollinators and beneficial predatory insects (know thy friends and avoid killing them!)  Some plants known to repel pests from neighboring plantsCO 29
  30. 30. Gardening Plans - Three Sisters From: 30
  31. 31. Gardening Plans - Three Sisters From: 31
  32. 32. Three Sisters Garden Corn is planted the last day of April. Beans and squash are planted mid- May.From: 32
  33. 33. Three Sisters Garden Plants are growing well the first week of June.From: 33
  34. 34. Three Sisters GardenPlants are well establishedby the end of June. Zucchini squash Butternut squash From: 34
  35. 35. Three Sisters GardenA More Mature Three Sisters GardenFrom: part-2-companion-planting/ 35
  36. 36. Companion Planting - Final Words Try using what we know works Experiment in your own garden Be open to trying folk lore remedies Don’t believe everything you read And most important of all, have fun! 36
  37. 37. Companion Planting – Selected Research References Companion Planting: Basic Concepts and Resources by ATTRA, funded by USDA, pub/summaries/summary.php?pub=72 Companion Planting: Ecogardening Fact Sheet #10, Cornell U., 1994: Companion Planting: Insects Can See Clearly Now the Weeds Have Gone - by Stan Finch and Rosemary Collier, Horticulture Research International, Wellesbourne, UK anting/biologist_jun03.pdf Marigold (Targetes erecta L.) as interplant with Cowpea for the control of nematode pests, by T.I. Olabiyi and E.E.A. Oyedunmade, African Crop Science Conference Proc. V. 8, p. 1075-78, 2003: The Myth of Companion Planting scott/horticultural%20myths_files/Myths/Companion%20plants.pdf Three Sisters (agriculture): 37
  38. 38. Companion Planting – Popular Books  Cunningham, Sally Jean. Great Gardening Companions. Rodale Press, Inc., 1998.  Mayer, Dale. The Complete Guide to Companion Planting. Atlantic Publishing GroupInc., 2011.  Riotte, Louise. Carrots Love Tomatoes. Storey Publishing, LLC., 1998.  Riotte, Louise. Roses Love Garlic. Storey Publishing, LLC., 1998.  Roberts, Margaret. Companion Planting. Briza Publications, 2011. Note: There is very little scientific evidence for certain types of companion planting discussed in these very popular books. Listing here is for informational purposes, and in no way ensures success with any of the methods presented!M WHOA! 38
  39. 39. This program was brought to you byThe Master Gardeners Program of Montgomery County University of Maryland Extension