The article is about the pest the sunflower midge and it's penetration into North Dakota crops in 1984. The method to gain data was the survey method

Busaccaand, J.D.

Kopp, D.D.

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1984 SUNFLOWER MIDGE SURVEY J.~. Busacca and D.O. Kopp The sunflower midge, Con turinia schulzi Gagne', has been a pest of cultivated sunflowers, Heliunthus annuus L., in the Red River Valley of the North since 1971 . This insect has been sporadic in terms of when and where it has been a problem. During some years midge damage has been widespread; in others the damage has been restricted to a rather small area. During the late 1970s, the sunflower acreage and midge damage increased significantly. In 1979 and 1980, the midge caused significant localized economic damage over a large por­tion of the Valley and caused widespread concern about the feas ibil it y of growing sunflowers in some of the hardest hit areas. In 1981, NDSU entomologists conducted a survey which determined the range and extent of damage caus­ed by the midge (Grinaker, 1981) . This survey concen­trated in midge-affected areas of North Dakota and ad­jacent areas of Minnesota. In 1982 and 1983, participa­tion in the survey was expanded to include en­tomologists from Agriculture Canada, University of Minnesota, South Dakota State University and Nort h Dakota Department of Agriculture, who intensified the survey in their respective states and provinces. Re ults of these surveys (Kopp and Busacca, 1983 and Busacca and Kopp, 1984) showed the range of the midge had ex­panded slightly since 1981 and that the areas of heavy midge damage had shifted. Methods and Materials This year's survey was conducted in a manner similar to the previous years'. Sunflower fields were examined for the presence of midge larvae or larval damage, and if present, a rating value was given to reflect the economic severity of the infestation. The field rating system is shown in Table 1. The 1984 sunflower midge survey was conducted during the last week of August through mid-September. A total of 427 fields were evaluated in southern Manitoba, eastern North Dakota, western Minnesota and northeastern South Dakota. Busacca is assistant professor, Department of Entomology, and Kopp is entomologist, Cooperative Extension Service. Table 1. Field Rating Scale for the Sunflower Midge Survey o - Midge not detected in the field. I - Midge presen t - Midge larvae present or evidence of midge larval activity in fi eld margins and of no economic significance. 2 - Moderate midge infesta tion - Sunflower heads showing deformation in the field margins with damage extending less than 100 ft. from the field margins. Yield reduct ion apparent in the margins but li ttle damage th roughout the field. 3 - Severe midge infestation - Sunflower heads deformed throughout large areas o f the field and beyond 100 ft. in from the margins. Yield reduct ion expected throughout the field. Results and Discussion The area in which the sunfl ower midge was detected has expanded westward in North Dakota. The new area involved included the eastern half of LaMoure and Dickey Counties and all of Ransom, Sargent and Richland Counties (Figs. 1 and 2). There has been no significant expansion to the north of this new area com ­pared to the 1983 survey. The 1984 range remained similar to the 1983 range in Canada. Midge population were not detected in South Dakota this year. The midge was fo und throughout Minnesota in all sunflower grow­ing areas. This year's survey also showed that although the range of the midge seemed to be expanding in some areas, the damage it caused declined from levels of 1983. ]n most o f the fields surveyed this year, damage was restricted to the flower bracts. Very few fields had gnarled heads and gnarling was restricted to a few plants near the field margin. There were so few midge in many areas in Minnesota and along the western boundary of North Dakota that it was difficult to detect their presence . The apparen t increase in the range of the midge in southern North Dakota is partially the result of intensified survey efforts there during 1984. The results of this year's survey should be encourag­ing for many sunflower growers. Midge damage to 25 SUNFLOWER MIDGE SURVEY 1983 Midge I Damage Moderate Pr e.en t to Severe • Winnipeg Fig. 1: Sunflower Midge Survey 1983. sunflowers had con tinued to decline since 1981 and we did not observe a single field that sustained economic loss from the midge during 1984. This trend suggests that the sunflower midge should not cause significant damage to the 1985 sunflower crop. This conclusion does not mean that the sunflower midge will never be an economic problem again. The midge evolved with wi ld sunflower and only recently developed population levels high enough to cause economic loss to cultivated sunflowers. The midge will be present as long as there are sunflower plants for the insect to complete its life cycle on; therefore, it will con­tinue to be a potential pest. Warm, moist conditions favor survival of the midge. If severa l warm, moist years occur in a reas of heavy sunflower prodution, midge populations could increase and cause some damage in those areas. ACKNOWLEDGEMENTS We express our sincere gratitude to the fo llowing en­tomologists for their cooperatio n in conducting this SUNFLOWER M IDGE SURVEY 19S4 Midge Present § Damage Moderatl to 511.,.,._ FIELD RATING ~Innlpeg MAN "I -"'I. "" ~ = 1 ~ I \-j-NO lFarao L / , -, I ~ ~ ~ f-r SO ~ ~ L­'" ~ I ~MN fJ~H ~ Fig . 2: Sunflower Midge Survey 1984. survey: Drs. David Smith , Jay McCullough and Andy Kolach, Manitoba Agriculture; Dr. David Walgenbach, South Dakota University; Mr . David Noetzel, Univer i­ty of Minnesota; David Nelson, North Dakota Depart­ment of Agriculture; and William V. Lipp, North Dakota Cooperative Extension Service. Appreciation is also expressed to Steve Stark of th NDSU Cooperative Extension Service Agricultural Communication Depart­ment for preparing the figu res. LITERA TU RE CITED Busacca, J.D. and D.O. Kopp. 1984. 1983 Sunfiower Midge Survery. North Dakota Farm Res . Bimont hly 41(6):20-21. Grinaker, G. 1981. Sunflower Midge-A Look At Its Life Cycle. The Sun fl ower 7(8):24-25. Kopp, D. D. and J.D. Busacca. 1983. Sunfiower Midge-1982. North Dakota Farm Res. Bimonthly 41(2) :3-4. 26 

1984 Sunflower Midge Survey

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