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Ruth Hazzard-Late blight for 2010c

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					Late Blight: being prepared for 2010



      NOFA winter Conference
          January 2010

      R. Hazzard, UMass Extension

       www.umassvegetable.org
       What happened in 2009?

1. IDEAL WEATHER
 – Rain – - 7 solid weeks (June & July, early
   August)
 – Cool, cloudy conditions; long leaf wetness




                         Photos courtesy of Jim Dill, U Maine
Photos courtesy of Tom Zitter & Meg
McGrath, Cornell Univ.
Photos courtesy of Tom Zitter & Meg
McGrath, Cornell Univ.
          What happened in 2009?
2. Inoculum spread throughout New England
  – Bonnie Plants starts plugs in Alabama, ships
    north
  – One greenhouse/state grows plants on
  – Big box stores sell plants to home gardeners.
                          Photos courtesy of Jim Dill, U Maine
                 Rapid spread

• June 16-18 – late blight reported PA, NJ
• June 25 –      late blight reported Geneva NY
  big box store
• June 25-26- late blight found in big box stores
  in ME, CT, MA, NH
• June 26 –      alerts sent to growers
• July 10- 13 –confirmed infected field tomatoes in
  CT and MA ---„snowball‟
• July 14-21-    confirmed in 5 counties in MA
           Sporangia
            dispersal
      Survive in cool,
               cloudy
       Travel on wind
       Move for miles




70-80 F ideal
Infections produce millions more spores
                    How fast can
                    late blight kill
                       crops ?


July 23




          July 30
       Mating Type
            A-1       A-2

            Oospore
        (survives winter)


  New        US – 8 (earlier years)
England       US - 14/17 - 2009
Strains –     Sporangiophore
   A2        Zoospore (flagellated)
             What about 2010?

• Late blight pathogen can only survive on
  living tissue
• Infected potato tubers are the key, most
  likely source
  – In storage
  – Left in ground, below frost line
  – Compost pile
Late blight infected tuber
    Goal # 1: no late blight inoculum!

• Destroy/kill infected potatoes (culls)
   – Freeze & thaw on surface
   – Bury deep
   – Feed to livestock
• Purchase certified disease-free potato seed
   – 1% tolerance
• Scout last year‟s fields, compost piles, for
  volunteer potatoes; destroy promptly.
• Rotate potato and tomato to new fields
   Goal # 1: no late blight inoculum!

• Tomato greenhouse from 2009?
  – let it freeze!
• Grow your own tomato starts from seed
• If you purchase bought-in transplants,
  isolate for 1 week & watch for symptoms
• Visit big box stores in May – scout their
  plants – report if diseased
Resistant /tolerant varieties
Tomatoes
  – „Legend‟ tomato from Oregon (Territorial Seed
    Co).
  – NC breeding program: Mountain Magic, Plum
    Regal (Bejo Seeds – Johnny‟s)
  – „Juliet‟, „Stupice‟, 'NC 03220' (Org. Seed
    Alliance, WA)
  – Others: Matt‟s Wild, Ferline, Fantasio
Potatoes
 Kennebec, Sebago, Allegany, and Chieftain
                Cultural practices
• Rotate potato and tomato crops to new fields
• Trickle irrigation (not overhead)
• Stake and weave with moderate pruning for
  drier leaves




                              Early blight
     Septoria leaf spot
   The „other blights‟…come every year
• Septoria survives in crop debris
• Early blight & Septoria move up the plant,
  reduce yield




 Early blight
 Grow greenhouse or hoophouse tomatoes

• Heat and vent in evening to reduce leaf
  wetness overnight
  – Will help with Botrytis, Fulvia leaf mold, Late
    blight
  Know the late blight risk in your area

• Listen to reports about late blight
  UMass Vegetable Notes (MA)
     • www.umassvegetable.org
     • Subscribe to Email list (free!)
• Report / get diagnosis of suspected LB
• Weather conditions – 18 „severity units‟
  accumluate
          Use protective fungicides
           if Late blight risk is high
-late blight is present within 40
miles
-weather conditions have
been/are favorable
    wet, cool, cloudy
    Blitecast >18 severity points
-take action to protect the crop –
before infection.
   Organic products with late blight on label
Stimulate plant resistance:
  Serenade ASO (Bacillus subtilis) 6 qts/A
  Serenade MAX (Bacillus subtilis) 1-3 lb/A
  Sonata (Bacillus pumilis) 2-6 qts/A
Kill spores (no residual)
  Oxidate (hydrogen dioxide) 40-128 fl oz/100 gal
Prevent spore germination (increase resistance?)
  Copper fungicides
Mode of action??
  Sporan EC (rosemary, clove, thyme oils) 1-3 pints/A
  Sporatec (rosemary, clove, thyme oils) 1-3 pints/A
“Copper is an essential nutrient for plant growth and
  disease resistance, although direct toxicity was long
  thought to be the mechanism responsible for disease
  control with copper.

Fertilizer and pesticide applications containing Cu can
  provide effective control of many diseases by stimulating
  plant disease mechanisms.

This aspect of the effect of Cu is frequently overlooked.”

     “Mineral Nutrition and Plant Disease”, L Datnoff, W.
  Elmer, D. Hubner. 2008


Another good reference:
• “Handbook of Plant Nutrition‟, A. Barker & D Pilbeam,
  2007
Considerations in copper management

• Copper is essential micronutrient for
  plants, animals and humans.
• Interaction with organic matter, manure,
  pH, other minerals is complex.
• Copper rapidly forms organic complexes,
  binds to humus, does not leach
• Deficiency is more common than excess in
  NE soils
   What about Copper Soil Toxicity?
• Typical level, UMass Soils Lab samples =
  0.2 to 0.3 ppm
• Toxicity to plants occurs at 30-60 ppm
   – Vineyards, orchards after years of use
• 2 lb/acre copper fungicide adds estimated
  0.5 to 1.0 ppm in soil
• 2 organic fields tested after sprays every
  5-7 days= 0.3, 0.8 ppm - needs more
  study
    OMRI Listed Copper Fungicides

                  • Champ WG
                • Nu Cop® 50 WP
*registered in NY,Massachusetts, & other New England states
          If you sell your crop, use one of these


Home garden: look for any copper hydroxide
         or copper sulfate product
               Using copper:
    Rates of application for NuCop 50WP
Potato: 1.5 to 4 lb/acre

Tomato: 2-3 lb/acre
  3 lb/acre = 1.1 oz/1,000 sq ft.

apply at 7-10 day intervals, more frequently when
  disease is severe


Note: Champ WG may be used in greenhouse
      What about personal safety?
• Read and follow the label
• What you need to wear when using copper:
  – Eye protection (goggles)
  – Long sleeved shirt and pants
  – Shoes and socks
  – Chemical resistant gloves
• Don‟t work in the crop for 24 h
• May be applied up to 24 hr before harvest
  – Pickers should be careful not to rub their eyes
    if handling fruit with residue.

				
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