Researchers looking for alfalfa blotch leafminer George Heimpel Entomology Univ. of Minnesota. The ABLM is a small fly that has been present at sub-economic levels in Michigan for at least eight years and has invaded Wisconsin and Minnesota within the last three to four years where it is now causing economic damage. Because ABLM has apparently been present in Michigan longer than in Wisconsin and Minnesota, and because damage appears to be lower in Michigan, it is possible that the parasitic wasps that controlled populations in the eastern U.S. and Canada have spread into Michigan, but not other Midwestern states. ABLM mines have a characteristic shape and are easy to identify. The mines generally start towards the middle of the leaf, move to the side of the leaf, and terminate at the tip, where they form a silvery-gray blotch that turns brown with age.
Mines typically cover approximately half of the surface area of a normal-sized alfalfa leaf.
Look for at least one more cool frontal passage and the chance for showers and thunderstorms late in the week. The most recent medium-range forecast guidance suggests that the trough currently across the region will gradually weaken with a gradual return of warmer and more humid air into the state, likely by early next week. New long lead outlooks New NOAA long lead outlooks continue to be influenced by falling sea surface temperatures in the central and eastern equatorial Pacific. The cool water has not yet been in place long enough to alter hemispheric jet stream flow, but this could occur in the next month or two. The forecast also calls for slightly greater than normal odds of below normal temperatures during the August through October period.