Disease Control Update

This is an update to the disease advisory posted at:
http://www.agr.state.nc.us/markets/commodit/horticul/grape/discont.htm
Please check this site for disease information and identification.

Always read the label for restrictions and other information.

Several people have asked for an outline of what diseases are important at different times throughout the season.
Pleae note that I am not a Plant Pathologist. This information is taken from talks at several meetings I attended. Any comments would be welcome.

Bud Break Early Shoot Growth

n Phomopsis - important for cane and rachis infections
- Mancozeb,captan
n Powdery Mildew (PM) - moderate risk - wait for forecasted rain?
- Sulfur (variety/temperature restrictions)
n Black Rot (BR) - slight/moderate risk if present last year
- Mancozeb
n Downy Mildew (DM) - no
n Botrytis - no



10" Shoot Growth (2wk Pre-bloom)

n PM - Important to prevent infection
- Sulfur (variety/temperature), SI, Abound?
n BR - can be important if wet and carryover
- Mancozeb, Nova/Bayleton(SI)
n DM - Inoculum mature, important if wet/carryover
- Mancozeb,captan (Abound?)
n Phomopsis - important for cane and rachis infections
- Mancozeb,captan
n Botrytis - no ?


Immediate Pre-bloom

n PM - Critical
- Abound, SI, Sulfur ? (variety/temperature)
n BR - Critical
- Abound, Nova/Bayleton(SI), Mancozeb
n DM - Critical
- Abound, Mancozeb,captan
n Phomopsis - Rachis/berry infection if high pressure
- Mancozeb,captan, (Abound?)
n Botrytis - almost ?


Bloom

n PM, BR, DM - Critical, Phomopsis
- Same as prebloom
- This spray should still be effective (2nd)
n Botrytis - Important if wet and a susceptible variety
- Vangaurd, Elevate, Abound(?)

First Post-bloom (Pre-bloom +10-14 days)

n PM - Critical
- Abound, SI ? , Sulfur ? (variety/temperature)
n BR - Critical
- Abound, Nova/Bayleton(SI), Mancozeb
n DM - Critical
- Abound, Mancozeb,captan
n Phomopsis - Rachis/berry infection if high pressure
- Mancozeb,captan, (Abound?)
n Botrytis - Important if wet and a susceptible variety
- Elevate, Abound(?)

Second Post-bloom (1stPost-bloom+7 ? 14 days)
n PM - Important
- Abound, SI ? , Sulfur ? (variety/temperature)
n BR - Important
- Abound, Nova/Bayleton(SI), Mancozeb (66 d PHI), Ziram (?)
n DM - Important if established and wet
- Abound, Mancozeb (PHI?),captan, Ridomil?, Copper?
n Phomopsis - Rachis/berry infection if high pressure
- Mancozeb,captan, (Abound?)
n Botrytis - Important if wet and a susceptible variety
- Vangaurd, Elevate, Abound(?)

Mid-Summer Sprays
n PM - Important to keep maintained
- Sulfur ? (variety/temperature), Abound?, SI ? ,
n DM - Can be important if established and wet
- Captan, Copper, Ridomil?, Abound?
n BR - Fruit should be resistant unless high pressure
n Phomopsis - No
n Botrytis ? No

Verasion
n PM - Important to maintain clean foliage
- Sulfur ? (variety/temperature), Abound?
n Botrytis - Can be important if wet and susceptible variety
- Vangaurd, Elevate
n DM - Can be important if established and wet
- Captan, Copper, Ridomil?, Abound?
n BR - No
n Phomopsis ? No

After Harvest
n PM - Important to slow infections next year
- Sulfur ? (variety/temperature)
n DM -?
n BR - ?
n Phomopsis - ?
n Botrytis ? No

First Year Disease Management
- Disease control is easiest the first year because fruit should not be present. BUT DON"T BE SLACK! Disease pressure will build up and be a BIG problem the next season.
- Foliar diseases - powdery and downy mildew
o Approx. 6 sprays beginning at 12" shoot growth.
o SI fungicide (e.g. nova) plus mancozeb - first two sprays (April and May)
o Sulfur and mancozeb can be applied for the third spray if variety used is tolerant and it is between 65-90 F (June)
o SI fungicide (e.g. nova) plus mancozeb - fourth and fifth sprays (July and Aug)
o Sulfur and mancozeb can be applied for the final spray (see note above)


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Eric Bish
Extension Associate / Small Fruit & Viticulture
North Carolina State University
256 Kilgore Hall / Campus Box 7609
Raleigh, NC 27695-7609
919-515-3705 (office&mobile)
919-515-2505 (fax)
eric_bish@ncsu.edu