Fitting bio-fumigant cover crops into intensive vegetable production systems for integrated crop management Mathieu Ngouajio, Michigan State University Mathieu Ngouajio Dept. Horticulture
Add N (legume) Enhance mycorrhiza Add organic matter Enhance Microbial activity Reduce soil compaction Suppress weeds Attract beneficial insects Suppress diseases Recycle nutrients Suppress nematodes Reduce erosion Increase water infiltration Mathieu Ngouajio, Michigan State University Department of Horticulture
Synthetic chemicals Methyl bromide Methyl iodide Telone Vapam Vorlex Plant residue Mainly plants that produce glucosinolates
Secondary plant metabolites Produced by 15 plant families Mainly the Brassica (or mustard) family. >100 glucosinolates have been identified ( R) N OSO - 3 R C S C 6 H 11 O 5 R=Side chain Glucose Sulfur Mathieu Ngouajio, Michigan State University Department of Horticulture
Myrosinase enzymes are responsible for the degradation of glucosinolates But Myrosinases and glucosinolates are located in different compartments in the cell Tissue Damage triggers the reaction Tissue Damage
Isothiocyanate is the most important breakdown product of glucosinolates Used in Commercial fumigants R R C S C Thiocyanate N OSO 3 - S C 6 H 11 O 5 N R S N Isothiocyanate ITC C
Isothiocyanate has shown activity on many plant pests R N C S Isothiocyanate Diseases Insects Weeds Nematodes
Brassica Species are called Biofumigants because they release isothiocyanate upon damage of their tissues The process of incorporating fresh residues of Brassica Species in the soil is called Biofumigation
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Species selection Appropriate seeding rate Seeding time (tolerate freezing temperature down to 28 F) Initial fertilizer if soil is poor Allow the cover crop to grow up to flowering stage (do not allow seed set)
Others Turnip Rape Broccoli Etc
Cover Crop Range Rate Used Oilseed radish 10 to 25 15 Oriental mustard 4 to 6 6 Yellow mustard 10 to 14 8 Brown mustard 10 to 14 8 Sudangrass 40 to 80 60 Rate: Lbs/A Broadcast and incorporated Large scale: Drilled
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Oct. 13, 2003 Oct. 13, 2003 Mini tiller
Oct. 13, 2003 Oct. 13, 2003
Cover crops incorporated at flowering stage June 23, 2006 About 45 Days after planting
Use multiple passes of a disc or a rototiller
Simultaneous flail mowing and incorporation
Flail mowing + incorporation Flail mowing + incorporation Rototiller Disc No killing no incorporation
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The cover crop should be scheduled in the rotation system and planted in fall of the year before onions Onions Tomatoes Snap bean Cucumbers Carrots Cucumbers Cucumbers
# per 100 cm3 soil 2250 2000 1750 1500 1250 1000 750 500 250 Muck research farm 2005: Onion More beneficial microorganisms in the cover crop plots 0 Oilseed radish Oriental mustard Yellow mustard Brown mustard Sudangrass Control MSU Plant Diagnostic Lab
520 500 Plants/ 25 ft 480 460 440 420 a abc ab ab bc c 400 Oilseed radish Oriental mustard Yellow mustard Brown mustard Sudangrass Control
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Cover crop Celery J F M A M J J A S O N D Celery growing season
Cover crop Celery J F M A M J J A S O N D Celery growing season
25 20 15 10 5 0 2005 Hamilton yield Cereal rye Oilseed radish Oriental mustard Yellow mustard Control Yield (kg/plot) b a a ab b b a a a b BT AT The Brassica species improved celery yield in 2004 & 2005
Nematodes/100 cm3 350 300 250 200 150 100 50 Plant Parasitic Nematodes Hamilton 2004 Celery Fewer nematodes in the oilseed radish and yellow mustard plots 0 Control MSU Plant Diagnostic Lab Oriental Mustard Oilseed Radish Cover Crop Rye Yellow mustard
Decatur 7 Cover Crops Control seeding April 5 Collaboration with Dr. Bird Lab Hamilton 5 Cover Crops Control Seeding April 14 & 28
Decatur site About 7 acres Mathieu Ngouajio, Michigan State University Department of Horticulture Hamilton site About 3 acres
Yield (Lb/20 plts) 33 31 29 27 25 23 21 19 17 15 Brown mustard Control plots have lowest yield Marketable Yield: Hamilton a a a a Oriental mustard Oilseed radish Brassica cover crop Yellow mustard b Control
27 Marketable Yield: Decatur 25 Yield (Lb/20 plts) 23 21 19 17 ab ab a ab ab a b 15 Brown mustard Oriental mustard Oilseed radish Yellow mustard Defender radish Mustard mix Control Brassica cover crop Control plots have lowest yield
3 EXPO. Dec 2007
Cover crop Eggplant J F M A M J J A S O N D Eggplant growing season
2007 800 700 Yield (bushels/a) 600 500 400 300 200 100 0 Methyl bromide Oilseed radish Oriental mustard Yellow mustard Treatment SoilBuilder Control
The biofumigants improved various vegetable production systems
They should be used in combination with other management tools. They should be considered as a cover crops first and any biofumigation effect should be a plus.