Head moths can ruin the beauty of sunflower fields

ORIGINALLY WRITTEN BRADLEY GOERING
It can be quite a welcome site driving down a country road and looking off to the west and seeing a horizon of yellow. If you are familiar with this crop, you know I am referring to a field of blooming sunflowers.

Two years ago, our area flourished with bountiful yields as sunflowers were planted early and harvested in mid- to late August. Then last year was a bomb in most areas because of dry conditions and worse-the head moth.

Only a handful of fields in our area didn’t have a lot of damage last year due to head rot caused by the moth. With so few fields without damage last year, a number of farmers decided against planting the crop this spring.

The lesson learned is that populations of the head moth vary greatly from year to year so that the crop has to be monitored closely to reduce potential losses.

These critters are grayish in color, one-half inch long, and cigar shaped when they are not in flight. With wings expanded, they are three-fourths of an inch from wing tip to wing tip.

Last year presented several challenges. High winds and too many acres prevented timely spraying of the moth. As the flower begins to open and head moths are present, the farmer should call out the airplane.

If the field had a germination problem that lead to an uneven stand, it presents the issue of uneven flowering.

When the crop duster is spraying and only 40 percent of the flowers are opening, you have the potential for 60 percent of the plants being hurt by the pesky insect.

The head moths feed on the nectar and pollen. Eggs are deposited among the florets on the face of the flower head.

Ninety percent of the eggs are laid within seven days of the onset of flowering. Within 40 hours, the eggs hatch into larvae, which feed and damage about six seeds.

The larvae develop over two to three weeks and tunnel through immature seeds or the receptacle during July and August. Once this happens, the sunflower is susceptible to head rot and a great loss of yield potential is the result.

Control is done by using something like Warrior, Parathion or Baythroid to get the source-which is the head moth.

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