With soybean well into the reproductive stages and corn just hitting tasseling this week, now is the time to scout for key insects and diseases, particularly with the recent high moisture conditions.
Weather Temperatures this past week were 2-4 degrees cooler in the region, and we accumulated only 117 growing degree days (GDD base 50). The forecasted reference evapotranspiration rate (FRET) is 1.5-1.6 inches for most of the region for the week ending July 26 which is slightly above normal. Temperatures will be pleasant through the weekend turning to above-normal next week with highs in the lower 90s, and an additional 150 GDD50 are predicted for the coming week. The 6-10 outlook calls for above-normal temperatures for the end of July and the first part of August.
This past week, much of Michigan received the highest weekly rainfall totals so far this growing season, although portions of the southwest region missed most of that. Those areas are 10-50% below normal for rainfall while “the winners” are actually slightly ahead of normal over the past month. The drought monitor (July 20 release) reflects the widespread rainfall events in Michigan and across the Midwest—19% of Michigan is now in D1 (moderate) drought (down 34% from last week) and only 3% is in D2 (severe) drought. However, portions of the western Corn Belt continue to suffer from severe drought, and drought conditions have continued in the northwestern region of the Lower Peninsula. The forecast for the coming week is for 0.10-0.75 inch of rain in the southwest. The medium-range outlooks show near-normal chances of rain for the end of July shifting to slightly above-normal chances
Corn and soybean have entered key reproductive stages. Many corn fields are beginning to tassel while later-planted fields are likely a week or more behind. Incidentally, on a drive to Madison, Wisconsin, this week, I observed a similar range of development in northern Illinois and southern Wisconsin while most fields between I-80 and I-88 were fully tasseled. We are heading into the period (VT through R1) when a fungicide application for tar spot is most effective (see below).
Soybean in early planted fields and those with lower maturity group varieties is nearing R3 (beginning pod, pods 3/16 inch at one of the four uppermost nodes on the main stem) and all fields visited had reached at least R1 (beginning flower, at least one open flower at any node on the main stem). With the recent rains and higher humidity, the Sporecaster app for white mold is currently showing high risk of white mold in the southwest portion of the region and medium risk on the eastern side. I selected 15-inch rows spacing for all but one location (30-inch for Constantine) and irrigated management for Berrien, Cass and St. Joseph counties. The app is free to download from Google Play for Androids and the App Store for iPhones/iPads. You can enter information for all your fields and select row spacing and irrigation.
For fields with a history of white mold, a fungicide application at R1-R2 (beginning to full flower) is recommended as the pathogen (Sclerotinia sclerotiorum) infects the flowers. MSU soybean senior educator Mike Staton’s article, “Fungicide use for managing white mold in soybeans,” outlines the key strategies in managing this disease. Tighter row spacing, higher plant populations, susceptible varieties and long periods of high moisture below the canopy all favor the development of white mold.
One of the on-farm trials being conducted with the Michigan Soybean Committee is looking at the “plant health” yield benefit from a fungicide application (Delaro Complete). If you are considering investigating that practice, the company recommends an application at the R3 growth stage and, as always, be sure to leave at least one to two check strips. You should then create separate files/tasks in your yield monitor when harvesting so you can compare yields in the treated and non-treated areas and then decide whether the application paid for itself.
Source: msu.edu
Photo Credit: gettyimages-klosfoto
Categories: Michigan, Crops