|MAREK, LAURA - Iowa State University|
|LEE, D.K. - University Of Illinois|
|THAPA, SANTANU - University Of Illinois|
|HAHN, VOLKER - University Of Hohenheim|
|BRADSHAW, J.D. - University Of Nebraska|
Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2016
Publication Date: 6/14/2016
Citation: Prasifka, J.R., Marek, L., Lee, D., Thapa, S., Hahn, V., Bradshaw, J. 2016. Effects from early planting of late-maturing sunflowers on damage from primary insect pests in the United States. Helia. 39(63):45-56.
Interpretive Summary: Delayed planting is common method to limit damage from insect pests in sunflower and other crops. However, planting early can improve yield quality or quantity, potentially making up for any direct losses from insect pests or costs of insecticide applications. Over two years in North Dakota, Nebraska, Iowa and Illinois, sunflowers were planted early, including hybrids with typical or late maturity. Total seed damage and damage by two of three seed-feeding pests was not increased for hybrids that bloomed two to four weeks later than two elite hybrids popular in the United States. Damage from the red sunflower seed weevil was greater in late-maturing sunflowers, which is typical for this pest. Pest populations are currently low compared to decades past and insecticides are usually very effective in reducing damage; consequently, making decisions on planting time to avoid sunflower insect pests may be unnecessary, except for areas with a history of problems with severe pests that cannot be managed using insecticides (e.g., sunflower midge).
Technical Abstract: Delayed planting is recommended to reduce damage from sunflower insect pests in the United States, including the sunflower moth, Homoeosoma electellum (Hulst) and banded sunflower moth, Cochylis hospes Walsingham. However, in some locations, planting earlier or growing later-maturing hybrids could improve yield (quantity or quality) of oilseed sunflowers which would partially offset any added costs from insect pests or their management. Because the abundance or distribution of some sunflower insects has changed since recommendations for delayed planting were developed, experimental plots were grown over two years in four sites in the central United States. Planting was two to four weeks earlier than normal and included hybrids that flower two to three weeks later than elite commercial hybrids. The sum of seed damaged by sunflower moth, banded sunflower moth, and red sunflower seed weevil, Smicronyx fulvus LeConte, (i.e., total percentage) was influenced by location, but not the relative maturity of tested entries. However, when damage attributed solely to the red sunflower seed weevil was analyzed, more damaged seed were found for late-maturing entries in North Dakota and Nebraska. In addition to the 2012–2013 trial data, current pest populations are lower than when delayed planting was first recommended and insecticide use during sunflower bloom is both common and effective. Together, these observations suggest factoring insect pests into planting time decisions may be unnecessary, except for areas with a history of problems with severe pests that cannot be managed using insecticides (e.g., sunflower midge, Contarinia schulzi Gagné).