Iowa crop update for June 27 to July 11

July 12, 2016 5:09 PM
Blog Post

Iowa State University Extension and Outreach field agronomists report crop conditions in your area of the state.

Joel DeJong: Corn is starting to tassel in the Northwest corner of Iowa. Rainfall has been OK, but sandier soils are showing some stress, which can be expected at this time of year. Soybeans are blooming. Weeds have been treated in most cases, but there is evidence of some small ones still beneath the canopy. Oats are turning and the second alfalfa crop has been harvested. Grasshoppers can be found in significant numbers in grassy areas in many places. Overall, the crop looks quite good at this point in time.

Paul Kassel: Corn that was planted on and before April 17 is starting to tassel and some of it is showing silks. Corn that was planted on and before May 7 is at the V17 stage. The corn that was replanted the week of May 16 looks good and is about at the V14-15 stage. Some April planted soybean is V8/R2. I have not seen any R3 stage soybean, but some of the April planted soybean crop might be close. Some waterhemp is starting to recover from the glyphosate and fomesafen applications that were made about two weeks ago.

Parts of Sac, Buena Vista, and Pocahontas counties are listed as ‘abnormally dry’ on the U.S. Drought Monitor. These areas did not receive a lot of rain recently and are still a little on the dry side. However, there continues to be a really wet area in northwest Dickinson county. 

Brian Lang: We are finding a few NCLB lesions here and there. The primary recommended timing for treatment (based on scouting) is the VT-R1 stage.  I get asked here and there about treating earlier.  My initial response is: “Did you scout the field?”; “Are at least 50% of the plants exhibiting a NCLB lesion anywhere on the plant from the third leaf below the ear leaf on up?” There is no need to treat before VT just because a few lesions where found. There are two very good reasons to not treat early: (1) All leaves on the corn plant are not fully developed yet. The foliar fungicides only protect what they land on. Treating now (~V16 stage) would have 3-5 leaves at the top of the plant not treated/not protected. This means a second application would be needed to protect those leaves which are very important contributors to grain fill. (2) Foliar fungicide applications recommend the use of a surfactant. I get extremely concerned about applying a surfactant on corn in late vegetative stages (prior to VT). Purdue University has written quite a bit about Arrested Ear Development and its causes.  If you are nervous about potential NCLB problems this season, you could start scouting fields now. Don’t wait for VT to scout. 

Mark Johnson: Much of the corn in central Iowa has been pollinating the last 4-6 days, with a little before that and a little not quite there. Soybeans are mainly R2 to R3. Much of the second cutting of hay has been put up. I’ve come across very little as far as insects are concerned. I have encountered some very light NCLB, but haven't seen or heard of any serious enough to apply fungicide. Doesn't seem to be much disease pressure, in general. 

Rains have again been spotty, but many areas getting 0.7 to over 1.5 inches over the last 12 days. Many areas could use more, but crops look good so far.

Southwest and West Central
Clarke McGrath: In southwest and west central Iowa, soybean spraying is about wrapped up, with a few fields being hit again for waterhemp, ragweed, and/or marestail issues. We’ll be able to recognize these fields over the next week or so, since the hot mixtures we have to use to attempt to slow down weeds (notice “slow down”, not control) will burn the beans pretty badly. It is the time of year where we need to double-check rotation restrictions and preharvest intervals for anything we spray. Once in a while we see late applications that get us into trouble, so just a reminder. Beans look decent for the most part. Narrow rows are mostly canopied and wide rows might make it before too long. Corn is mostly tasseled. The uneven corn syndrome that we saw across a lot of the regions had been hidden to a degree, as the corn grew through vegetative stages. However, now that we are tasseling we can see that growth still lags in some spots in many fields. In another week or so, we should see about everything tasseled, which should mask the tough spots to a degree again. The next time we really see them stand out might be on the yield monitor. Retailers are getting planes and choppers lined up for fungicide applications, and we will likely see those starting soon. There have not been many reports of insect or disease activity; hopefully we can keep it that way.

South Central, Southeast, East Central
Rebecca Vittetoe: In southeast/south central Iowa, corn is VT or R1 and soybeans are at R2. Most of my area has been classified as being in a moderate drought according to the U.S. Drought Monitor, but we received some much needed rain last week that really helped to perk the crops up.

Prior to the rain, I was getting quite a few reports of spider mites showing up in soybeans. Not seeing or hearing much on foliar diseases in corn or soybeans.

Meaghan Anderson: Corn is moving right along, with much of it tasseling (VT) in this area, and soybeans are mostly in full bloom (R2). Rainfall last week brought some relief to the hot, dry conditions in the southern/western counties, and crops look good in east central Iowa. Unfortunately, some wind came with the rainfall and affected fields across a large part of east central Iowa.

Corn blown over near Langworthy, Iowa on July 6, 2016.
Photo by Meaghan Anderson

 Affected fields appeared to have mostly root lodged, but some fields were affected by greensnap. While out evaluating for greensnap and lodging, farmers should check roots for feeding from corn rootworms. Some soybean fields in the Washington County area were sprayed for spider mites last week, but I’m hearing very few reports of disease or insect issues.

Virgil Schmitt: In the last two weeks, most areas in east central and southeast Iowa received over 3 inches of rain, which was especially welcome in my southern counties. Storms did blow some corn down. Most of it was root lodging in my area and not green snap, so most damaged fields should recover.

Corn is V17 to R1, and I have seen a few fields with brown silks. Soybeans are mostly at R2. Disease levels are generally low. Hay looks good and second cutting is progressing. Oats are turning color.

Find your local ISU Extension and Outreach field agronomist here!

Related Links:
Iowa Crop Update for June 20 to June 26