Extension Update by Jenny Rees

Wind-damaged Corn: The evening/early morning hours of July 8-9 caused quite a bit of damage to corn fields for some of you reading this. It’s always hard to see crop damage. For field corn, it came at a critical time prior to pollination. The severity and amount of recovery for every field situation will vary depending on the soil moisture at time of the wind, root mass structure, hybrid planted, severity of leaning/bent/snapped plants, and growth stage of the plants. It will also depend on where the bending and snapping of those plants occurred. ‘Recovery’ encompasses the plants righting themselves, re-establishing roots, and re-orienting leaves as they have the ability to bend and grow up towards the sunlight in areas of the plant where plant tissues were not yet lignified (hardened). We know hybrids have been bred to better withstand greensnap. We know that plants that are leaning due to root lodging may have better ability to upright themselves (and have seen this in some fields since the storm). We also know that it is harder for plants near tasseling to upright themselves compared to plants at earlier vegetative stages.

What to expect? It really depends on the conditions outlined above. We all will learn a lot and I encourage us to share what we are observing. For fields very close to tassel with severe bending near ears, we may see pollination, possibly even ear formation issues. There may be fields that were leaning and will have minimal impacts after uprighting themselves. The main research I can find regarding corn lodging yield impacts comes from the University of Wisconsin in 1988. In the study, they manually lodged corn at various growth stages over 2 years to determine yield impacts. Corn lodged at V13-15 resulted in a yield reduction of 2-6%. Corn lodged after V17 resulted in a 12-31% yield reduction.

What to do? Recommend waiting, observing, call your crop insurance adjuster. Don’t apply products right now. Economically, we need to see how each field recovers before putting more into the crop. Plants are already stressed so give them time to try to recover. A respected agronomist shared another point with me-that adding heavy amounts of water right now can add weight onto the plants and keep them sticking together when they’re trying to separate. For those who were planning on fertigation, I’ve seen soil sample results and heard from several people that we’re seeing increased mineralization this year in fields due to the heat. It may be worth a tissue and/or soil test to see if you really need additional nitrogen (final application at brown silk). Regarding fungicides, my recommendation prior to the storm was to wait till at least brown silk (or after) due to low disease pressure, uneven growth stages in fields, waiting for southern rust, and economics; I stand by that after this storm. Fungicides can’t help much with the plant stress being experienced.

Spidermites have been found in low levels in corn, but in some cases, fairly high levels in soybean. Higher levels have been observed in stressed fields (due to off-target herbicide damage and/or beans stressed due to drought). If you’re noticing pockets in fields that appear to be yellow/brown/dying and spreading, check the top side of the leaf for stippling (yellow needle-like pin-pricks) and undersides for webbing and mites. Seeing them in non-stressed beans at low levels as well. Check out this information from Illinois for guidelines on when and how to control: http://bulletin.ipm.illinois.edu/?p=5080.

Gardening Resources: Nebraska Extension is hosting a series of 12 virtual learning sessions for home gardeners to discuss timely issues around vegetable gardening and trees. Each session will include a short (15-20 minute) presentation on the specified topic and opportunities for participants to chat about their issues and “ask the expert”. Sessions will be each Tuesday through September at 7 p.m. CST. Participants can register via go.unl.edu/grobigredvirtual – you can register for all the sessions you’re interested in at one time. You can also view the series via this Facebook post: https://www.facebook.com/events/1195072680839800.