Organic Sweet Corn Production

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					Organic Sweet Corn Production

 Ruth Hazzard, Extension Vegetable Program,
  University of Massachusetts, Amherst MA

Mid Atlantic Fruit and Vegetable Convention
                Hershey, PA
               January 30, 2007
Organic corn can look like this….
It doesn’t have to look like this…
       Fertility for Organic Corn
• Major nutrients removed by sweet corn:
  – 155 lb/acre nitrogen (ears = 55 lb/acre)
  – 20 lb/acre phosphorus
  – 105 lb/acre potassium

• To supply these needs combine:
   – Adjust P, K and pH over time
   – Broadcast amendments pre-plant
   – Organic fertilizer in the planter
   – Side-dress or top dress at 12-18 inches if needed
• Greatest N demand is 30-75 days after planting
           Sources of Nitrogen
• Organic matter in soil
   – Built up over time (compost, manure or cover crops)
   – Seasonal release: 20 lb N per acre per 1% OM
• Compost
• Bagged organic fertilizer
   – Expensive as the main source
• Manure
   – Waiting period: 90 days to harvest for corn
   – Bagged manure pellets easier to handle
• Legume or legume/grass mix
   – Fallow year: clover, alfalfa
   – Overwinter cover crop: Hairy vetch with rye or oat
Hairy vetch -- with rye or oat
    vetch gives 100+ lb N/acre
   Oat or rye – take up leftover N
      Use pre-side dress nitrate test
• Take soil sample when corn
  is 12 inches tall
• 24 hour turnaround time at
  soils lab
• Sidedress if Nitrate N < 25
  ppm
• Add 20-40 lb N/acre
• Choices: blood meal,
  Chilean nitrate, seed or
  plant meal
             Crop Establishment

Special Challenges for organic corn:
   – Seed is not treated with insecticide or
     fungicide
   – Seedling pests and pathogens
     reduce germination
   – Crop stand losses reduce yield
   – Weeds germinate with the corn and
     are difficult to control in the row
• Solutions??
Transplant corn???
        Can it be cost
         effective to
       transplant corn?
– Avoid seedling pests
– Avoid trying to germinate seed in
  cold soils
– Complete, even-aged plant stand:
  100%!
– Crop is far ahead of the weeds
– Little or no hand weeding, fewer
  cultivations
– Harvest earlier than direct seed w/
  row cover
– Higher yields and lower weeding
  costs
   Grower-built
  seeding system
Jon Satz, Wood’s Market
  Garden, Brandon, VT




                          Two plates –slide and drop into
                          tray
                          3/16 inch Lexan drilled 3/16 inch
                          holes
                          Two seeds per cell
                          Cell size: 128
      Growing sweet corn transplants
• Two seeds per cell
• Cell size - no smaller than
  128’s
• Not longer than 14-16 days
  from seed to transplant
• Floor of greenhouse is OK –
  use edges, extra space
• Ready when root ball can be
  handled
• Don’t let it go too long
   – (tap root bound – field
     growth stunted)
Transplanting

       • Cultivate just before TP
       • Handle like any other
         transplant
       • Carousel transplanter is
         popular -- for speed
         and handling
       • Spacing depends on
         variety: 12-14 inches
       • Early corn: cover with
         floating row cover
              Variety selection
• Qualities to look for
   – Strong emergence
   – Good tip cover throughout ear growth
   – Ease of picking
   – Taste
   – Consistent ear quality
• Certified organic seed difficult to find in good
  varieties
• Untreated seed of standard hybrids is acceptable
  Weed Management – Direct Seeded
              Corn

                    • 1. Prep field just before
                      planting
                    • 2. Blind cultivation
                      before emergence
Chain drag          • 3. Early cultivation – in
                      row weeds
                    • 4. More vigorous
                      cultivation at 12-18
                      inches, throw soil, side
                      dress.

             Lely
 Bezzerides
and Spyder
weeder – in
 row cultiv.
for seedling
    corn
Goal: control in-row weeds




    Without hand weeding!!!
Reggi weeder comes to sweet corn…
Late whorl: throw soil to bury remaining
     weeds and hold stalks in wind.
Insect management
European corn borer
(Ostrinia nubilalis, ECB)
             ECB life cycle
*Larvae over-winter in corn stalks
& other host plants

           *Adults emerge in early May and
           mate in weedy or grassy areas


         *Females lay eggs on
         underside of leaves
Newly-hatched larvae




          Young larvae feed
          first in whorl and
          young tassel
Borers move down, tunnel
into stalk and into the ear
                            Damage to
                               shank




Full-grown ECB larva and
damage to ear from ECB
that tunneled through the
side of the husk.
Managing ECB
      Pheromone or
      blacklight traps
      indicate when moths
      are active.
Managing ECB: organic options
               1. Foliar sprays
               2. Trichogramma
                  ostriniae
               3. Row Cover
Using foliar sprays to control ECB


Scout field at pretassel stage
Check 50-100 tassels in groups
of 5 or 10
Look for larvae or fresh feeding
damage
Calculate % with 1 or more ECB
present ( = ‘infested’)


                                   “pretassel
                                   stage”
   Using foliar sprays to control ECB




Spray if field has > 15% infestation

Use Bt (e.g. Dipel DF, with sticker) or spinosad (Entrust)

Scout 4-5 days later to see if 2nd application is needed
               Cost of spray products
Product            Price            Label Rates       Cost per Acre
                                      (oz/acre)

           per package     per oz   Low       High Low Rate High Rate
Dipel DF       $18.40/lb    $1.15     16         32   18.40     36.80
Entrust          $455/lb   $28.43    0.5          2   14.22     56.86
Row cover on sweet corn




         •Use 50 foot wide sheets
         •Gives 7-10 days earlier
         harvest
         •Excludes ECB moths & eggs
•Remove (and replace) for weeding.
•Leave plenty of room to grow.
•Hold edges with soil
        Tichogramma ostriniae
•   Minute parasitic wasp
•   Female inserts eggs into ECB eggs
•   Larvae feed and develop in ECB eggs
    – Egg mass turns black
•   Adults emerge and search out new
    eggs
•   Wasps reproduce and disperse
    during the season




Photo by Joe Ordonez,           Photos by Sylvie Chenus, Entomology, Cornell
NYAES, Cornell
      Methods for Trichogramma
               release
Select release field in
  advance:
  --target early corn
  --bare ground, plastic or
  transplants

Notify supplier in advance of
  expected release dates

Monitor ECB flights with
 pheromone traps
  Methods for Trichogramma release –
            on farm trials
First release (~June 6):
 --after moth flight has
   begun
--when corn is 12 inches
   tall
--30,000 to 60,000 wasps
   (1-2 cards) per acre
Methods for Trichogramma release
Second release:
-- one week later
      (~June 15)

Third release (optional):
-- one week later
       (~June 21)

Scout as usual for borers,
spray if needed

Tested 2003-2006 in Mass
sweet corn fields
  What did the growers say about
          Trichogramma?
• Release fields still needed sprays, but fewer sprays
• Trichogramma was easy to release
• Release of Trichogramma saved sprays later in the
  season
• When you consider cost, take into account the
  benefit to later corn
• Timing is important – need to understand it better
• Will use it again
                                 ECB Late Season Trap Captures, Hatfield MA

                         40
                         35
Moths caught per night




                         30
                         25
                         20
                         15
                         10
                          5
                          0
                              July 24th   July 31st   August 6th   August     August   August
                                                                    14th       20th     28th
                                                  2003     2004     2006 w/ Trich.

         Releases were made in early corn: June 6, 15, and 21.
          Source and cost for
         Trichogramma ostriniae
Per acre, per release:
Two cards (30,000 wasps/card)           $30.00
Shipping                                 $ 5.50
Total per acre:                         $35.50
Total for three releases (per acre):   $106.50

Source: IPM Laboratories, Locke, NY
                 315 - 497 - 2063

Order ahead – call when you plant the corn!
                  ECB summary

• Cultural: disk or plow fields in fall or early spring to
  kill overwintering larvae
• Two generations per year – early corn may have only
  ECB, later corn has ECB plus CEW
• Use Row Cover on early corn.
• Use Trichogramma
• Monitor flight with your own traps or Extension
  network
• Scout for ECB larvae at pretassel stage; spray if
  >15%; use Bt or spinosad
Caterpillar Entry Sites


      Tip entry: CEW and
                 some ECB



        Side entry: ECB and
                   FAW
Corn earworm




               The most
               difficult pest
               for organic
               sweet corn
  CEW flight
     paths:
  northward,
 along coast,
up river valleys
Corn earworm

  Monitor
  flights with
  pheromone
  traps
  placed in
  blocks with
  fresh silk
                     Corn earworm--
                   Spray Thresholds for
                       New England
                    Intervals based on pheromone trap captures
                                                        Spray
                   Moths/Night      Moths/Week         Interval
Spinosad will
                      0-0.2             0-1.4         No Spray
control
moderate             0.2-0.5           1.4-3.5          6 Days
levels of CEW
                      0.5-1             3.5-7           5 Days
if used at
recommended         1.0-13.0            7-91            4 Days
spray intervals,
good coverage,        >13               > 91            3 Days
etc.
Alternative to Sprays for
CEW




Direct silk application with a mixture of corn or soy oil with
Bt or spinosad controls caterpillars that enter the ears
through the silk channel.
Zealater oil applicator, custom designed for this purpose.
Labor: approx 8 hours per acre
Zealater oil applicator
             Two Liter tank and shoulder
             strap, tubing with quick
             connects, and ‘oil gun’ with
             needle tip.
             Adjustable rates, 0.5 ml per
             ear is recommended
             Parts are all resistant to
             corn oil (no rubber or
             neoprene)
             Available from Johnny’s
             Selected Seeds, $93.50
             Developed at UMass and
             Hampshire College with
             grower input.
 Results of Trials, 1994-2003
Combination of Bt and Corn oil gave best control

Achieves significant improvements (20-60% cleaner)
to ear quality under varying pest conditions

Possible to achieve desired quality under low to
moderate CEW pressure

Difficult to achieve desired quality under high CEW
pressure
 Materials
• Must be OMRI listed
• Must be labeled as a
  pesticide OR be listed
  as exempt
• Exemption must
  include both FIFRA and
  food tolerance.
                                   Materials
                     Choices for carrier:
                        • corn or soy oil,
                        • JMS Stylet oil (mineral oil)
                        • carrageenan

Choices for toxin:
      Bt, spinosad, or neem
Use lecithin as emulsifier for dry products (Bt, spinosad)
Total mixture delivered to tip: 0.5 ml per ear
    Testing Materials, 2004-2005 Trials
Methods
•   Variety: Delectable
•   Harvested Sept 12 (2004) or Sept 20 (2005)
•   Oiled at wilted silk, 4-6 days after first silking (90-130 DD)
•   Rates based on plant populations of 16,000 plants ears per
    acre.
•   3X3 Factorial, RCBD, 4 Replicates


Toxins                              Carriers
1. Bt (1/2 lb/acre Dipel)           1- Carrageenan
2. Spinosad (2 oz/acre Entrust0     2. JMS Stylet Oil
3. Neem (Azadirect)                 3- Corn oil
             Pesticides – avg. feeding damage rating

                                         Feeding Damage in Tip
                      1
Mean Damage Rating




                     0.8

                     0.6
                           a                         ns                   2004
                                    ns                           a
                     0.4                                                  2005
                                                                     ns
                                                 b
                     0.2

                      0
                               Bt               spinosad         neem
                                                Pesticide
            Carriers – avg.feeding damage rating

                                      Feeding Damage in Tip

                      1
Mean Damage Rating




                     0.8
                     0.6     a                      b                    2004
                                                              a
                     0.4                                           ab    2005
                                  a
                                              b
                     0.2
                      0
                           Carrageenan     JMS Stylet Oil     Corn Oil
                                              Carrier
                              Marketable Ears, 2004
          100
           90
           80
           70
Percent




           60
           50
           40
           30
           20
           10
            0
                None




                              spinosad




                                                        spinosad




                                                                                  spinosad
                        Bt




                                                 Bt




                                                                          Bt
                                         neem




                                                                   neem




                                                                                             neem
                       Carrageenan                JMS Stylet Oil               Corn Oil

                                                Treatment


     Note: 2005 had very little earworm; 2004 was a better test of efficacy
     (control = 36% marketable.)
Goal: best caterpillar control with least
       ‘cone tip’ or other injury.
                   Percent of Ears that Have Cone Tip
          100
          80



Percent
          60                          a                       2004
          40                                          b       2005
                      c
          20

           0
                Carrageenan    JMS Stylet Oil    Corn Oil
                                  Carrier



                      Percent of Ear that is Cone Tip

          20

          15                              a
Percent




                                                              2004
          10                      a                           2005
           5                                              b
                  b                               b
                          c
           0
                Carrageenan    JMS Stylet Oil    Corn Oil
                                  Carrier
                       Percent of Ears that Have Cone Tip
          100

           80

Percent
           60                                                        2004
           40          a        b       a               a        b   2005
                                             a
           20

               0
                           Bt          Spinosad         Neem
                                      Pesticide


                           Percent of Ear that is Cone Tip

          20

          15
Percent




                            a                                        2004
          10
                                                                     2005
                   a                   a                     b
          5                                 c          a

          0
                       Bt             Spinosad         Neem
                                      Pesticide
                                        Best Materials
                                  1. Corn oil plus spinosad
                                      – Best combination of efficacay
                                        and ear tip quality
                                  2. Corn oil plus neem
                                  3. Carrageenan plus spinosad
                                     --must be injected into tip
                                  4. Corn oil plus Bt



Dipel DF rate, ¼ lb/acre @ 16,000 ears/acre = 28.3 g or 3 tablespoons per
liter of oil.
Spinosad rate: 2 oz/acre @ 16,000 ears/acre = 0.25 oz or 4 teaspoons per L
oil
Dissolve Bt or spinosad in a small amount of water before adding to oil.
Timing: when silk starts to wilt and pollination is complete
except at the very tip. This provides best balance of insect
control with full ear growth.
The best way to determine timing: silks have detached from
all kernels except at the tip ( this occurs at 5-7 days after silk
initiation, depending on temperature)
Filled tip   Unfilled tip   Cone tip
Further note on oil treatments
 Oil treatment reduces
 tip damage from ECB
 as well as CEW but
 does not control side
 damage (ECB, FAW)
 Supplement oil
 treatments with silk
 sprays and/or
 Trichogramma
    Fall Armyworm
(Spodoptera frugiperda, FAW)
Monitoring Fall Armyworm

                Pheromone trap for
             flight
              Field scouting for
             damage and
             caterpillars
               Spray at 15%
             infestation
              Use spinosad
 Is clean, beautiful organic corn possible?

• Yes, but it’s not easy to get clean corn all season
     • Plan ahead
     • Use as many approaches as possible.
     • Pay careful attention to monitoring and timing.

• AND ALSO….
     • Know your market.
     • The price and the customers are worth the
       effort.
                     Thanks to…
• Funding:
   – Northeast SARE
   – Organic Farming
     Research Foundation
   – New England Vegetable
     and Berry Growers
     Asociation
• Field Work and Statistical
  Analysis
   – Pam Westgate
   – Amanda Brown