With cooler and wet conditions, iron chlorosis has been showing up in a number of soybeans fields around Manitoba.
IDC is the plants inability to uptake iron due to high soil pH, high carbonate levels and high salt levels. Initially the soybean leafs will turn yellow and as symptoms progress growers may note interveinal yellowing. The dark greens veins of the soybean leaf is a tell tale sign of IDC. If symptoms are severe you will see necrotic tissues on the leaves and short stunted plants. If growers do see this occurring in fields the best thing to do is to take the long way home from town for about a week until you get a bit of warmer weather so the beans can grow out of this condition. For future years growers can use the IDC ratings listed in the soybean table of seed Manitoba to help choose a variety for a particular field that is rated higher for tolerance to IDC.
Submitted by Dennis Lange, MAFRD FPA (Altona)
More information on soybean production can be found at http://www.gov.mb.ca/agriculture/crops/production/soybeans.html