Question: I raised Mammoth Sunflowers this year, and they were beautiful. I would like to try to do it for a living, what spray should I use for the bugs that get into the seeds?
Hardiness Zone: 9b
Marcia from Alturas, FL
Answer: Marcia,
There are a couple of different insects that specifically go after the seeds on sunflower plants. One is the Sunflower Seed Weevil (the Red or Gray variety), and the other is the Sunflower Midge.
In the larvae stage, Sunflower Seed Weevils have cream or yellow colored bodies that are legless and c-shaped. The larvae usually emerge in mid to late summer to feed on the seeds. There are several non-chemical methods used by commercial growers here in the Midwest to control the weevils. They include yearly crop rotation, early planting, fall plowing to destroy over wintering larvae and trap cropping.
If you're are not familiar with the term, trap cropping is planting a border consisting of a row or two of "bait" sunflowers around the perimeter of your main sunflower crop. These "bait" sunflowers should be planted so they bloom 10-14 days ahead of the rest of your crop. The emerging larvae will naturally migrate toward the first sunflowers that bloom and produce pollen. When they become concentrated in one area of the field, it is easier and more economical to manage them. When your trap crop becomes infested with weevils, you can then spray them with the appropriate chemical control. What you spray will depend on whether or not you're going to sell the sunflowers as cut flowers, or for consumption by animals, etc. Laws regarding insecticide use on commercial flowers can vary from state to state, so I would contact your local county extension agency for more information on the rules governing the commercial growing and selling of sunflowers in Florida.
The Sunflower Midge larva has a small (0.07 inch) cream colored body that is tapered to the front and rear. The larvae emerge in early July to feed on the sunflowers' developing heads and seeds.
Most conventional insecticides are not effective against the Sunflower Midge, because the larvae crawl inside the seed soon after hatching so they are protected from topically applied chemicals. By delaying planting until late May or early June, you can significantly reduce the amount of crop loss due to midge damage. Again, your country extension agent should be able to give you more detailed advice on controlling these pests in your area.
Good luck!
Ellen
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