Corn development has slowed over the last week due to the cool nights and moderate day temperatures. You will notice there is now a wider gap in accumulated GDD between the southern and northern counties when compared to the seven-day forecast. The forecasted temperature for the next seven days remains moderate. According to predicted accumulated GDD, the earliest planted corn in the southern counties of my area should be in full dent by the beginning of next week.

Harvesting corn for silage is on the minds of many producers. Detailed information on harvesting corn for silage can be accessed at the following web site: http://www.uwex.edu/ces/crops/uwforage/Silage.htm

Estimate your corn’s yield potential. For those wanting to get a head start on estimating potential corn grain yield, you can make some simple counts to get within a ballpark range of where it may be.

The start of second generation Bean Leaf Beetle emergence in soybeans should be occurring now. If you scouted 1^st generation BLB and you were over the treatment threshold (1st generation threshold for 2nd generation treatment) you should be out in the field looking for beetles and damage now. If you did not scout 1^st generation beetles, use the thresholds in Table 1 to make management decisions. Most damage from 2^nd generation BLB will be from feeding on the pod, look for this when scouting.

 

Crop value ($/bushel)	Treatment cost per acre (insecticide + application)
	$7	$8	$9	$10	$11	$12	$13	$14	$15
	beetles per foot of row
$5.00	5.5	6.3	7.1	7.9	8.7	9.5	10.3	11.0	11.8
$6.00	4.6	5.2	5.9	6.5	7.2	7.8	8.5	9.2	9.9
	beetles per sweep
$5.00	3.5	4.0	4.5	5.0	6.5	7.2	7.7	8.3	8.7
$6.00	2.9	3.3	3.7	4.1	5.4	6.0	6.4	6.9	7.3

Last week I mentioned that the Soybean Aphid had progressed as far west as Webster County. Well, the westward movement continues as I and Jerry Chisek found a field with the aphid in eastern Calhoun County and the aphid was reported at the ISU research farm in B.V. County. I would not expect any yield problems from the aphid this year due to its late arrival, but I would expect that we will be finding this potentially damaging pest much earlier in soybeans next year. Look for the aphid on the underside of new soybean trifoliate leaves.

Alfalfa Webworm (garden webworm) has been a problem in many alfalfa fields in Iowa and Nebraska. This is a very uncommon pest, but this year the numbers and damage are high enough to warrant scouting and possible treatment in many fields. Cutting the alfalfa may be the best control strategy for most fields. After cutting, keep a close eye on the field for continued injury from this pest. This week’s addition of ISU’s Integrated Crop Management newsletter has much more detailed information on the alfalfa webworm in IA. http://www.ipm.iastate.edu/ipm/icm/2001/8-20-2001/webworms.html

Visit this week’s addition of Integrated Crop Management for many other crop and insect management related issues in Iowa. http://www.ipm.iastate.edu/ipm/icm/default.html