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AgAlerts 2001 From Griggs County
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Issue # 14, August 27, 2001
Reports of worms in sunflower heads have been
received this week. These insects are the larvae of the banded sunflower
moth. I scouted one field and found high levels of this insect. This
seems to have been a very favorable summer for moths and butterflies.
First there was thistle caterpillars, then alfalfa caterpillars, then imported
cabbage worms and this list continues.
Damage: The moths lay eggs on the bracts of
the buds before flowering. The newly hatched larvae move from the bracts to the disk flowers of the sunflower head, where they enter pollinating disk
flowers to feed. In some instances, when the eggs hatch while the disk flowers are immature, young larvae will feed on bract
tissue prior to feeding within the disk flowers. The larvae feed on the disk flowers until they have developed to the third
instar. This early feeding may reduce the total number of mature sunflower seeds produced by the sunflower head.
Studies simulating damage of disk flowers showed that although there was a slight increase in individual seed weight, plants did not compensate for the number of damaged disk flowers during
seed filling.
Once the larvae reach the third instar they feed on seeds, usually consuming the entire kernel of each seed fed on. The larva
typically enters near the top of the seed and leaves by way of the same puncture after the kernel is eaten.
Each larva may destroy several (six to seven) mature seeds in addition to the disk flowers consumed by the early instars.
Small areas of silken webbing on mature sunflower heads indicate the presence of banded sunflower moth larvae within the head.
Seed damage done by larvae of the banded sunflower moth resembles damage caused by the red sunflower seed weevil.
However, the banded sunflower moth normally consumes the entire kernel, whereas the seed weevil larva consumes only about
one-third of the kernel. Also, the exit hole in the seed created by the banded sunflower moth is slightly larger than the one made
by the seed weevil larva and is usually located on the top rather than on the side of the seed.
(click on photo to enlarge)
Estimating soybean yields can be done three weeks prior to harvest. There are four steps needed to determine an estimated yield.
1. Plant Count: Count the number of plants in 1/1000 of an acre by counting the number of plants in a row for a defined distance. The following table gives the number of feet of row for various row spacings.
| Row Spacing | Feet of Row |
| 30 inch | 17' 5" |
| 15 inch | 34' 10" |
| 7 inch | 75" |
2. Number of Pods per Plant: Count the number of pods per plant on a minimum of 10 plants.
3. Number of beans per Pod: Calculate the average number of beans per pod. If you do not want to count all the pods, use an average of 2.5 beans per pod.
4. The Formula: [(Plant Count)x(Number of Pods/Plant)x(Number of Beans/Pod)]/150= Estimated bu/A
An educational workshop on harvesting and handling soybeans and other identity preserved crops will be held at Unity Seed, Inc. in Casselton on Thursday, August 30th starting at 8:15 a.m. and running through lunch. Representatives from both John Deere Co. and Case IH will be doing live field adjustment demonstrations. Other topics to be covered include maintaining varietal purity and harvesting and storage considerations for identity preserved crops. Unity Seed is located one mile west of the north edge of Casselton.
Birdshield is a new product labeled for
blackbird control in sunflower and corn in North Dakota. The active
ingredient is a concentrate formulated from food grade products. The label
recommendations are as follows for corn and sunflower.
Corn: Apply at a rate of one pint per acre by aerial
application. Begin application 10 days before the crop begins to ripen or
birds begin feeding. Reapply at 5 day intervals until harvest.
Harvest 5 days after last application.
Sunflower: Apply at a rate of one pint per acre by aerial
application. Begin application when birds begin feeding on the crop.
Repeat as necessary to keep repellency. Harvest 7 days after last
treatment.
The cost is about $5.93 per acre plus
application. The National Sunflower Association is very interested in how
this produce is working. Early reports from Association directors around
the state are favorable. I anyone has used or going to use this product,
the National Sunflower Association is interested in the results. If you
would like more information from the National Sunflower Association on the
reports they have been receiving, contact:
Max Dietrich
Production Coordinator
National Sunflower Association
Bismarck, ND
Tel: 701-328-5104
email: maxd@sunflowernsa.com
Please Contact Our Office For Additional Information
E-mail: griggs@ndsuext.nodak.edu
Go to the 2001 AgAlert Index Page