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As soybeans begin to mature, areas to target for IDC management reveal themselves

Iron deficiency chlorosis Iron deficiency chlorosis (IDC) is a technical phrase for plants that have yellow leaf tissue between veins because they have not been able to take up enough iron ( Figure 1 ). Iron is needed for plants to make chlorophyll - the green pigment that plants use to capture the sun's light energy. Through photosynthesis plants use this energy to combine carbon dioxide from the atmosphere and water from the soil to make carbohydrates. IDC is favored by saturated soils with high calcium carbonate and soluble salt (and sometimes nitrate) contents.   Figure 1. Iron deficiency chlorosis (IDC) symptoms on soybean (photo: Angie Peltier) Each spring, after that period of poor growth and development caused by IDC, soybean plants in northwest Minnesota typically outgrow all but the most severe IDC symptoms. Provided that there aren't too many factors other than IDC contributing to lower yield, a careful review after harvest of yield maps may help one to pick
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NW MN IPM Survey Results

This article was written by UMN Extension educators Angie Peltier and Anthony Hanson. Soybean growth & development Between August 8 and 19, soybean growth stages from Wilkin County, Minnesota and north were either beginning seed (R5) or full seed (R6; Figure 1 ). Just last week during the August 10 Strategic Farming: Field Notes program , Extension soybean agronomist Dr. Seth Naeve explained that these are very different stages of soybean growth and development across the state. Soybeans at the R5 growth stage are still growing vegetatively while completing reproductive milestones, while soybeans at the R5.5 growth stage are no longer growing vegetatively and are thereafter devoted only to reproduction. It is recommended that soybeans continue to be scouted for soybean aphids through the beginning seed growth stage (R5) and until the pod cavities are filled with seeds (early R6). Soybean aphid’s ability to affect yield also decreases significantly at R6 to 6.5 as yield is already