Swede Midge |
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Background
The swede midge, Contarinia nasturtii (Kieffer), (also known as the cabbage midge or crown gallfly), is a Eurasian pest of crucifers, especially those grown in clay soil. The swede midge is an exotic cecidomyiid fly, one of a diverse family with over 1200 species native to North America. It was detected in Niagara County, NY in September 2004.
In 2001, Canadian researchers discovered that this exotic pest was causing damage that was costing Ontario farmers approximately 85% of their broccoli crops. Farmers had observed heavy losses in broccoli since 1994 and had erroneously attributed the problem to a molybdenum nutrient deficiency. University of Guelph researchers surveyed crucifer crop fields by mailing out yellow sticky cards to farmers in Ontario and Québec that, when returned, held swede midges. Swede midge has been found in 23 counties in Ontario and 26 counties in Quebec.
In 2004, Cornell scientists placed experimental lures in crucifer fields near the Canadian border, and swede midge was detected. They estimate that New York state, which leads the U.S. in production of cabbage, could lose a major portion of this $87 million annual crop in addition to the state’s $6 million yield in other crucifer crops if the swede midge is not properly managed. The first detection of swede midge in the U. S. was made in Niagara County, New York in September 2004.
New York increased surveys for this pest in 2005. As a result, additional positive samples were collected in the counties of Erie, Genessee, Monroe, Orleans, and Wyoming. Delimiting surveys were expanded into adjacent counties for the 2006 season. Additional detections were found in Cattaraugus, Chautauqua, Lewis, Madison, Oswego, St. Lawrence, and Wayne. This brings the total number of counties positive for Swede Midge in New York to thirteen.
As a result of CAPS survey efforts in New York during 2007, there are 8 new county records with detections made for Swede Midge during this trapping season: Livingston, Steuben, Onondaga, Chenango, Otsego, Jefferson, Franklin, and Suffolk are all positive. This brings the total to 21 counties in New York infested with the pest from 2004 to present.
A Technical Working Group has been formed for Swede Midge. The Chairman is Dr. Jim Smith of CPHST. He and the other two members from CFIA met in December 2007.
Symptoms
"Blind heads" are typical of swede midge infestation. This
condition is the disruption or lapsing of growth at the terminal growing
point of the plant. In older plants, swede midge larval feeding can
cause twisted or missing broccoli or cauliflower heads, split terminals,
crinkled heart leaves or other distortions. Flower buds may not open
and their tissue can swell and distort. The main stem may become deformed
to the extent of splitting into extra stems. Plants infested as seedlings
produce no marketable yield, and if infested in the early stages of
development, productivity of the crop is severely reduced. Symptoms
may mimic molybdenum deficiency, hormonal herbicide damage, genetic
variability, heat stress and frost damage.
Distribution
It has been reported in Austria, Belgium, Czechoslovakia, Denmark, France,
Germany, Great Britain, Ireland, Italy, the Netherlands, Norway, Portugal,
Sicily, Sweden, and the Ukraine. The periodic outbreaks of the swede
midge in Great Britain have caused concern for the extensive damage
these small insects have caused to crucifers and rutabagas (“swedes”).
Hosts
Primary hosts of C. nasturtii are members of the family Brassicaceae,
including broccoli, cauliflower (B. oleracea var. botrytis),
cabbages (B. oleracea var. capitata), and radish (Raphanus
sativus).
Detection
and Reporting
If you suspect this pest occurs on crops in your area,
either by evident damage or specimens collected, please notify your
state's department of agriculture, your state's land grant university's
cooperative extension service, or your local USDA, APHIS, Plant Protection
and Quarantine office.
Links
- Canada Agricultural Situation Plant Health Measures to Limit Spread of Swede Midge 2002 (Foreign Agricultural Service)
- North American Plant Protection Organization (NAPPO)
- HYPP Zoology Page
- Cornell
University News Release (2/3/2003)
- Cornell University Cooperative Extension IPM Fact Sheet
Swede Midge in Canada
- Distribution and development of the swede midge, Contarinia nasturtii, in Ontario, Canada
- List of Regulated Countries and Regulated Areas within Canada for Swede Midge
- Swede Midge - Contarinia nasturtii
- Swede Midge Certification Program (SMCP)
Contact:
Dr. Alan Dowdy
Program Manager
301-734-5356
E-mail: Alan.K.Dowdy@aphis.usda.gov