I have had many reports of corn leaf aphids over the last couple of weeks, including several in pre-tassel corn. Corn leaf aphids are usually found inside of the upper whorl (unlike other species which are primarily found on the undersides of leaves), and are darker in color than other species we see in corn. This year, the wide variety of planting dates has resulted in corn that is all over the place in terms of stage – these aphids are particularly a problem if they are present in large numbers during pollination. (Fortunately, where we have adequate moisture and cool temperatures during pollination, this effect will be minimized). Consider an insecticide if 50% of plants have aphid colonies (~50-100 aphids) prior to or during R1. Once pollination has passed, it takes much greater numbers to cause yield loss.

April planted corn has fully pollinated. Both corn and soybeans have had fungicide and insecticide applications. The late May planted soybeans are not there yet and only at R2. Mid May soybeans have canopied. Stink bug feeding and bacterial leaf diseases showing up in corn. Could use more rain soon.

Widespread precipitation across the area has been a big benefit to the crop. Most of central IL did not have much reported damage from the derecho on the night of the 15th. Rain amounts varied, but most of the area received some much needed rain from Beryl and the storms following. Now to keep our eyes on what could be optimal conditions for disease progression especially considering that the planting dates are wider than normal.

Continue to scout soybean fields for regrowth on waterhemp. Be on the lookout for aphids in corn fields. Scout corn fields once a week for disease presence. Soybeans are adding regrowth of vegetation but will return to R1/R2 in the near future. Be ready for applications when we reach R2 growth stage.

Southern Illinois is wet. SIUC’s Belleville Research Center has measured over 12″ of rain so far in July, with >6″ coming Monday of this week. Fields that aren’t flooded are still heavily waterlogged. Most corn fields are at VT/Silking. About a quarter of fields were still in vegetative stages and one field with browning silks but that was an outlier. First crop soybeans are either starting to flower or are fully in R2 already. Double crop soybeans are V3-V4 and trying to get above the wheat stubble.

LaSalle County experienced a good amount of precipitation this week from the several large storm systems that moved through the area. Luckily, we have not seen any severe damage from these storms. I also have not noticed much standing water in fields. Corn at the IVCC + Extension plots is tasseling or getting close to it. Soybeans are flowering. The IVCC + Extension plots are a little behind in development compared to fields in a lot of LaSalle County. Corn in many fields is tasseling, silking, or has been successfully pollinated.

An active week on the weather front in Northeast Illinois. Several storms packing high winds roared through the area. Despite this, to date, I have heard few reports of down corn. Regional corn fields are at varied maturities because of planting dates. The earliest planted has reached R2 (Blister), the developing kernels appear as clear fluid containing whitish blisters on the cob, silks are brown and drying rapidly. Most soy is also at R2 (full bloom) and closing canopies in 30″ rows. Fungicide applications are underway by plane, helicopter and drone (and likely ground rigs when field conditions permit). I noted isolated incidence of Gray Leaf Spot and Tar Spot this week, I plan on revisiting those corn fields within the week to reassess. On some corn plants lower leaves exhibit the inverted V symptoms of nitrogen deficiency. Leaf senescence occurs naturally and is identified by corn leaves losing greenness due to a reduction in chlorophyll. Not all nutrients are lost, some assimilates are “remobilized” and transferred to the ear and kernels so that grain fill can be sustained and completed. While a natural process, lower leaf senescence and its counterpart, top dieback, can also be initiated by crop stresses and bears watching in future field visits.

Monday night’s derecho brought significant rainfall to the area. Most parts of Logan, Menard, and Sangamon counties received 1.5 to nearly 3 inches of rain. This rain, combined with the rain received from Hurricane Beryl, caused some low-lying areas to have standing water. Thankfully, there does not appear to be any signs of wind damage. Nearly all of the corn across the three counties has tasseled, and pollination is beginning. Soybeans also look good, almost all in the R2 to R3 stages. Waterhemp continues to be a prevalent issue. Japanese beetles are also present, but damage has yet to reach the economic threshold in the fields I have walked through.

Compared to my last trip around Coles County at the end of May, conditions are considerably wetter now in mid-July with an estimated 5-6 inches of rain since the beginning of the month, according to the Midwest Regional Climate Center. Most fields are at or near water holding capacity, and although not widespread, standing water could be seen in areas of low-lying fields at the time of this survey (7/16). That said, much of the corn and soybean crop still looked healthy and will likely continue that way if the current forecast holds, and no significant rainfall is experienced in the area over the next 5-7 days. Most corn fields were at least showing tassels, and the most advanced fields were around R2. Most soybean fields are somewhere around R2-R3 with a few stragglers still in late vegetative or early reproductive stages. I saw one field of double-crop soybeans emerged and at V1-2. Insect damage still appears to be minimal, but Japanese beetles and some corresponding defoliation (< 5%) were seen in a number of soybean fields. Except for in the areas of standing water, disease symptoms were also minimal at the time of the survey. Although if wet conditions persist, that may change in the coming weeks.

Majority of crops are in excellent condition. Received 1 to 2 inches of rain last night with no storm damage. Moderate temperatures forecast for the next week should be beneficial.