It has been a tale of the “haves and have-nots” with regard to rainfall. The far southern areas of Macon and Piatt Counties are at near-to-above-normal rainfall levels, with the majority of the three counties hovering around 50% of normal rainfall.

In the dry areas, grasshopper populations are increasing. Some foliar feeding by Japanese beetles and grasshoppers is visible, but so far the levels are below the threshold for control.

For a more upbeat report, I would encourage you to read my coworker Steve Brand’s report. Last week, in the area Steve covers in Northern Illinois, many fields received between 3 and 5 inches of rainfall. In areas including Kendall, Grundy, and Will, the rainfall totals measured in tenths. As many corn fields are at or nearing VT and R1 (tassel and silk stage), an expected result of the moisture stress is kernel abortion. Moisture stress at this time can interfere with pollen shed and silking synchronization. In addition, high temperatures coupled with low humidity can desiccate exposed silks.

Can farmers evaluate the pollination process? After successful pollination and fertilization of the ovules, the silk will detach from the developing kernel. Evaluating pollination success can be done with the ear “shake test.” Carefully unwrap the husk and gently shake the ear; the silks from the fertilized future kernels will readily drop off.

As long as we have kernels and green tissue for photosynthesis, we can remain hopeful for the corn crop. Our soy crop, while visibly shorter this year in the dry fields, can recover more readily if forecast moisture alleviates growing conditions in this area.

Spotty storms this week have dumped 1″–3″ of rain across Marion County after our longest stretch without precipitation since March. Our soils didn’t get dry exactly, but this moisture will help see the crop through the heat. This rain also helped even out some stands of double-crop soybeans in spots where the seed didn’t quite make it through the straw down into the soil and had yet to germinate. Most double-crop soybean fields I’ve seen are at V2 and looking good. First-crop soybeans are R1–R2 unless they were planted or replanted late. There were still planters rolling the first week of July, and those are more on pace with the double crops.

Corn in the area is still in vegetative growth stages, but you can feel the tassel forming down in the whorl, so VT is on the horizon.

The rains have finally arrived in northern IL, with a handful of widespread storm events and more starting this weekend and pushing into next week. Most areas have reverted to D0 or D1 drought status, and crops are doing well. Will County is the only area still in a D2 drought. With the rain and cooler temperatures in the forecast, disease may finally start to creep into our corn and soybean plots. This late in the season generally won’t have a large impact on yields, but scouting is still recommended through ear fill in corn, as well as scouting for white mold and frogeye in soybeans.

Corn is tasseling across the I-80 corridor. The DeKalb area was around 80% of fields at VT/R1, with the stragglers around V12/13 and spiking. Corn blotch leafminer is showing up in the lower leaves of multiple fields I scouted between DeKalb and Crystal Lake. This is also the kind of weather tar spot thrives in — wet, with intermittent rains and cooler temperatures overall. I would not be surprised if it is already in fields in northern IL or develops quickly with the upcoming forecast. Scouting is your best measure to know if it’s in your fields, as always. Corn overall is healthy, and I have not seen any fields with wind or hail damage despite the severe weather we have been seeing.

Soybeans are pushing quickly through growth stages. Most bean fields I scouted are in R3 and nearing R4 very quickly, if they aren’t already there. Disease pressure is low currently, with small amounts of Japanese beetle damage, but nothing that will lead to economic loss. I will be scouting heavily for white mold, SDS, frogeye, and other fungal diseases in the coming weeks if the water has turned on and stays on.

Depending on location, we have received between 1.5 and 4 inches of rain in the last week. It had previously been very dry in some areas, while others were lucky enough to get some pop-up showers. We now have the conditions for diseases to start showing up in corn or soybeans, but this will also depend on their disease susceptibility or disease scores. A few Northern corn leaf blight lesions were present in corn, but I was more concerned with the spread of gray leaf spot from the lower leaves. Japanese beetle infestations have ramped up, especially in later-planted soybeans. If farmers have decided to make fungicide/insecticide applications, they will start on corn this week as it has reached the VT growth stage. Early-planted soybeans have canopied and will soon reach the R3 growth stage. If warranted, they will also receive fungicide/insecticide applications at R3.

More hit-and-miss rainfall last week in NE Illinois as additional corn acres begin to reach VT (tassel). Areas that received rainfall are faring considerably better than those that did not. Corn growing in fields with gravelly knolls and lighter or sandy soils that did not receive recent rains is showing significant stress. Fungicide applications have started in the area. In scouting visits to R1 corn fields, the only disease noted was sporadic Northern corn leaf blight. This disease is recognizable by the cigar- or canoe-shaped lesions formed on leaf tissue. The causal pathogen for this fungal disease overwinters on corn leaf debris. Hybrid resistance is normally adequate for management of the disease, but substantial losses can occur with early infection and susceptible hybrids.

Interesting, but normally not economically important, leaf feeding was also noted in the corn. The corn blotch leaf miner is a small fly that deposits eggs on either the upper or lower corn leaf surface. After hatching, the larva tunnels in the leaf, feeding on the inner leaf tissue as it grows, leaving behind mines or transparent galleries. Eventually, the larva chews its way out of the leaf, drops to the soil, and pupates. I’m finding very limited leaf feeding, despite the presence of Japanese beetles, and no diseases at this point in the growing season in the soybean fields visited.