Cole Crops, Root, Bulb and Leafy Vegetable Edition
by Jennifer Allen, Vegetable Crop Specialist, OMAFRA, Guelph 

• Emergency Use Registration for White Mould
• White Mould in Carrots
• Degree Days

ONTARIO, QUEBEC, NOVA SCOTIA, PRINCE EDWARD ISLAND AND THE PRAIRIE PROVINCE’S CARROT GROWERS Receive Emergency Use Registration for WHITE MOULD

J. Chaput, OMAFRA, Minor Use Coordinator, Guelph

The Pest Management Regulatory Agency (PMRA) recently announced the approval of an emergency use registration for SCHOLAR 50WP (fludioxonil) for control of white mould (Sclerotinia) on stored carrots in the provinces of Quebec, Nova Scotia, Prince Edward Island, Manitoba, Saskatchewan, Alberta and Ontario.  Scholar WP was already labelled in Canada for control of post-harvest diseases on pome fruit and stone fruit.  Furthermore a complete minor use submission is underway with the Agriculture & Agri-Food Canada, Pest Management Centre (AAFC–PMC) minor use program to seek eventual, full registration of SCHOLAR for white mould control on stored carrots in Canada.

White mould (Sclerotinia sclerotiorum) is a serious disease of carrots and many other crops around the world.  In Canada, white mould is considered to be one of the major limiting factors to the successful long-term storage of carrots.  Losses of 50-100% have been reported by growers in Canada in recent years.  Since the loss of the fungicide Benlate several years ago, carrot growers have had no post-harvest fungicide treatments to reduce losses to this disease.

The emergency use registration of Scholar 50WP Fungicide will help in the interim to manage white mould on stored carrots, however management of white mould still requires a comprehensive IPM and resistance management program with access to all available tools and strategies.  The following is provided as general information only.  Users should consult the complete label before using Scholar 50WP.

Scholar 50WP Fungicide can be used for control of white mould on stored carrots in Quebec, Ontario, Nova Scotia, Manitoba, Saskatchewan, Alberta and Prince Edward Island until December 31st, 2009 only.  Scholar 50WP can be applied once as a post-harvest dip or drench immediately before storage.  Mix 227 g of product in 378 L water.  This amount can treat up to 90,000 kg of carrots.  

IMPORTANT:  FOR DOMESTIC USE ONLY, NOT FOR USE ON CARROTS INTENDED FOR EXPORT.

Follow all other directions for use on the Scholar 50WP Fungicide label carefully. 

Scholar 50WP Fungicide should be used in an IPM program and in rotation with other management strategies to adequately manage resistance.

We wish to thank Shauna Mellish, Prince Edward Island Department of Agriculture for preparing the rationale documents on behalf of Ontario, Quebec, Nova Scotia, Manitoba, Saskatchewan, Alberta and PEI carrot growers as well as Dr. Rick Peters, AAFC, Charlottetown, Dr. Jennifer Allen, OMAFRA, Mario LeBlanc, MAPAQ, the personnel of Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Nova Scotia Agriculture for their input, support and assistance.   We also wish to thank the personnel of the respective provincial ministries of Environment in Ontario, Manitoba, Quebec, Alberta, Saskatchewan, Nova Scotia and PEI and  Sygenta Crop Protection Canada Inc. for their support of this registration and the personnel of the Pest Management Regulatory Agency for evaluating and approving this important pest management tool.  Special thanks are expressed to the PEI Dept. of Agriculture who generously covered the submission fee for this emergency use registration. 

For copies of the emergency use label contact Jennifer Allen, OMAFRA Vegetable Crops specialist at Guelph (519) 826-4963, Jim Chaput, OMAFRA, Guelph (519) 826-3539 or visit Syngenta Crop Protection Canada at www.syngenta.ca.

Albert Tenuta, Field Crops Plant Pathologist with OMAFRA recently reported the presence of white mould in soybeans.   Unlike other diseases that have the same name but are caused by different organisms, white mould of soybeans is caused by the same fungus that causes white mould in carrots, Sclerotinia sclerotiorum.  

Conditions that favour white mould development include rain and moist soil conditions, cool temperatures (>29°C) and high relative humidity.  Conditions exactly like we are experiencing in southern Ontario.  Sclerotinia sclerotiorum can infect many field and horticulture crops including soybeans, carrots, dry beans, canola and cabbage (just to name a few).

Key management strategies include: crop rotation to non-host crops for 2-3 years in fields where white mould has been an issue; planting on raised beds and wider row spacing to encourage air movement among plants; weed control to reduce potential hosts; removal and destruction of infected plant material from the field; rapid cooling prior to storage; and sanitation of all storage components before the carrots are harvested.  

While there are no products registered for control of white mould in the field, the emergency use registration of Scholar 50 WP as a post-harvest dip or drench will be a useful tool for the 2009 growing season.  It is important to note that this registration is solely for the use on domestic product onlly.  If you intend to export your carrots, this product can not be used. 

Mycelia growth on soil between rows (blue arrow)	Mycelia and sclerotia on carrots taken from storage (red arrow)

Degree Days 

Here are the degree and growing degree-day accumulations for April 1 – July 21, 2009. Orange highlighted cells indicate pests that have reached 3rd generation status.

Area	Onion Maggot	Cabbage Maggot	Carrot Rust Fly	Carrot Weevil	Tarnished Plant Bug	Leaf-hopper	GDD
Bradford/ Holland Marsh*	1479	n/a	1612.6	1087.2	535.1	851.1	1346
Sarnia	1543.2	1250.6	1676.4	1162.2	618.7	928.7	1411
London	1591.2	1292.9	1726.7	1199.1	627.5	957.1	1434
Waterloo	1435.7	1146.4	1569.0	1056.2	512.5	826.9	1309
Windsor	1910.10	1601.6	2049.0	1506.3	888.3	1251.2	1776

Degree-day information for pests.

	Degree Days
	1st Generation	2nd Generation	3rd Generation
Onion Maggot	210	1025	1772
Cabbage Maggot	314-398	847-960	1446-1604
Carrot Rust Fly	329 – 395	1399-1711	n/a
Carrot Weevil	138 – 156 455 (90% oviposition)	No model available	n/a
Tarnished Plant Bug	40	n/a	n/a
Aster Leafhopper	128	390	n/a

DISEASE FORECASTS   

BOTCAST — Disease severity index  is 58.  Risk of developing Botrytis is low to moderate.  Monitor fields regularly and if field has more than 1 lesion/leaf, apply a recommended fungicide.        

DOWNCAST—Predicted no sporulation infection periods for the last four days.  Risk of downy mildew on onions is moderate.  

BREMCAST—Predicted no sporulation infection periods in the last three days.  Risk of downy mildew on lettuce is moderate at this time.    

Data provided thanks to funding from the Holland Marsh Growers’ Association, Bradford Co-op Storage Ltd., Muck Crops Research Station, Department of Plant Agriculture, University of Guelph., Lake Simcoe Conservation Authority, Bayer CropScience, BASF, DuPont, Engage Agro and Syngenta.