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.

It’s hot! Temperatures exceeding 90 degrees for consecutive days in NE Illinois. Despite the ambient temperature both corn and soy fields are holding up well, but additional rainfall would be welcome. Most corn fields are at or near R3, the milk stage. Some ears have visible aborted kernels at the ear tip. There has been minimal to no leaf disease in corn fields that I have visited, but plan on staying diligent and listening to local reports and regional reporting resources including the Corn ipmPIPE for Tar Spot https://corn.ipmpipe.org/tarspot/ to be aware of areas where crop disease has been detected. The soy crop has responded to recent rains with increases in vegetative growth and most fields are at or near R3 or Beginning pod. When scouting fields, it is still not too late to look for symptomology of herbicide damage in fields.

I’ve received several reports of corn rootworms breaking through pyramided Bt traits over the last couple of weeks. Most of these are in the usual areas north of I-80, but I was able to collect a population from Sangamon County last week and had reports from Putnam and Bureau. Continuous corn is virtually always the culprit in these cases. We are always looking for both western and northern corn rootworm populations to bioassay; if you have large numbers of adults and wouldn’t mind us coming out to collect them, please don’t hesitate to contact me.

With my area still listed as being in “Moderate Drought”, crops are still looking good. Most soybean fields are in the “full pod” or R4 stage. I surveyed 50 consecutive soybean fields on my drive and 13 (26%) of those fields had weed escapes present across the field and volunteer corn was not considered a weed escape. This is another effect of this year’s dry spring weather on the effectiveness of residual and post-emergent herbicides. Most corn fields are in the late “milk” or R3 stage or beginning “dough” or R4 stage. There is some tipback on the corn ears present. Very little leaf disease is showing up in area crop fields, which is common in a drought.

It was a good sign to see that the corn canopy was collecting as much sunlight as possible with little sunlight hitting the ground. We can’t complain, but would love more rain for corn grainfill. The insecticide application eliminated Japanese beetles and most disease. If you visit field edges where fungicide coverage was a scarce, you will find tar spot on lower leaf and gray leaf spot moving up the plant. Soybeans are hanging in there with no more insect pressure thanks to a recent insecticide application. Septoria brown spot is in the lower canopy.