The sunflower is the only row crop in North America that coexists with its native ancestors. When extensive commercial planting of sunflower began in the 1970s, many of the insects which evolved in native perennial sunflower seed species transferred to the cultivated crop. Red sunflower seed weevils deposit eggs in sunflower seeds and larvae feed on the developing sunflower kernels destroying a portion of the kernel. The larvae make an exit hole and exit the seeds in late summer. Research indicates that most seeds are only partially fed upon.
“Several years ago, a set of trade standards were developed for nonoil sunflower kernels. These standards stipulate there should be no more than 10 percent broken kernels; not more than 0.5 percent heat damage; and not more than two percent insect damage.
Economic populations of seed feeders such as the red and gray seed weevils, head moth and banded sunflower moth can inflict very serious damage if not controlled. But they commonly consume just a portion of the kernel, so those seeds often are not separated from other seeds during combining. “It’s very difficult to remove all insect damage from in-shell sunflower,” affirms Jim Krogh, president of Agway, Inc., of Grandin, N.D. “Yet it’s also difficult to explain to today’s consumer why there’s a hole in the seed they bought. The hole is unsightly; the kernel tastes bad. It’s a bad deal all around.”
Since it is an edible product, economic thresholds for confection flowers are much lower than for oil-types. One to two weevils per plant should trigger prompt insecticide treatment, based on current recommendations.”
Author: Lilleboe, D.
Title: Optimizing the quality of your confection crop
Source: The Sunflower. April/May 1998. Available online at: https://www.sunflowernsa.com/magazine/details.asp?ID=77&Cat=10