Hit or miss on rainfall for areas in NE Illinois this past week. Enough precipitation to keep the crops going, but few if any tile lines are running. Overall disease pressure continues to be low in both corn and soy fields I have visited, including those that did not receive a fungicide treatment. To date, very low insect pressure has been found in either crop. Not surprising, I’m noting Common Smut on corn field edges damaged by deer feeding. Most of the area corn crop is currently at R4 or the dough stage. The starch in the kernel, initially a liquid, is converting to a more solid or pasty consistency. Cool sunny days are favorable for an extended R4 stage. Much of the Sb crop is at R4 or full pod.

Here in my 3 county area (DeWitt, Macon & Piatt), soybeans for the most part are in mid R5 or “Beginning Seed” stage. Corn planted in the first half of April is late R4 (Dough) or early R5 (Dent) stage. Corn planted at the end of May is R3 (Milk) stage. The past two weeks has brought above normal rainfall to this region and no longer in “Moderate Drought”. Leaf diseases are at a minimum in both corn and soybean fields.

Corn and soybeans are approaching the R5 growth stage. As I type this, we are finally getting a significant amount of rain. Dryer weather, hybrid resistance, and fungicide have kept diseases like gray leaf spot and tar spot at bay in corn. But Goss’ wilt and Northern Corn Leaf blight have just started to show up. Soybeans are loving the rain and could have potential to yield if diseases stay away. One plant was found that had stem canker.

In soybeans, some feeding by Japanese beetles was found closer to field edges, in addition to both minor and advanced spider mite damage (each in different fields). With the recent rainfall and more moderate temperatures, continued damage isn’t expected but will be monitored. In corn, some western corn rootworm beetles were found but in low numbers and with minimal damage. Slightly higher numbers were observed in continuous corn. Little to no disease pressure was observed in visited fields. Corn is at R1-R2 and soybeans are at R4-R5.

Much needed 1.25” of rain this morning. Some soybeans are being sprayed with fungicides and insecticides. Corn spraying is finished for now. Several mornings this week had fog and heavy dew. Will be watching for disease to develop in the corn.

As we slip back into an extremely dry and stressful point in the growing season, more stresses are appearing. Fungicide applications made during last weeks extremely hot stretch brought out symptoms from Triazole sensitivity. SDS is showing up on early planted soybeans in areas of stress or compaction. Corn is showing tip back post pollination in the dryers areas.

Early planted corn fields are in “dough” or R4 stage and later planted fields are in “milk” or R3 stage. Most soybean fields are in the “beginning seed” or R5 stage. In my 3 county area, the 9 straight weeks of being listed in the “moderate drought” category by the U.S. Drought Monitor has reduced our incidence of leaf diseases in corn and soybean fields. This week. a little SDS is just beginning to show up in a few soybean fields. The above SDS photo was from an area of a field with deep soil compaction.

With little rain over the past week, perhaps a few tenths over the weekend, soil conditions in most of Champaign County are on the dry side. However, most fields of both corn and soy look relatively healthy with minimal external signs of drought stress. Measurements from the local Illinois Soil and Water Survey monitoring station show plant-available soil moisture at depths of 8+ inches, and it seems that most crops in the area have been able to reach some of that deeper soil moisture. That said, signs of drought stress including stunted plants and dying lower canopy leaves can be found in compacted areas of fields as well as the few hilltops we have in the county. Tip dieback and ear size was variable in the corn fields I surveyed, and most were in the late R3 (milk) growth stage moving into early R4 (dough). Soybeans were generally around R5 (beginning seed).

Scouting corn this week I’m starting to find some leaf disease, mostly lower in the canopy. To date I have yet to find Tar spot in fields I have visited but am aware it has been confirmed in Indiana Counties east of NE Illinois. Predicting what if any yield drag may arise from our dry June should be easier to determine as we progress through the reproductive stages. An interesting comparison of ear size collected from two different fields. The larger ear was collected from a heavier soil with greater water holding capacity. The second smaller ear was collected nearby growing in a lighter sandier soil on a knoll in the field.