Tipback

Tipback from Central Valley Ag on Vimeo.

by Mike Zwingman

by Mike Zwingman

This past Saturday and Sunday, I enjoyed the rare weekend with absolutely nothing to do.  So, like any good citizen of the 21st century, I spent my free time in the Twittersphere.  Reading farmer tweets.

I like keeping up with the Twitter accounts of farmers because it’s such a perfect window into the current bear trap of a farmer’s mind: what is it today or this week or this hour that’s making you nuts?  Often, there’s a theme—something making many of you nuts at the same time—as there was this weekend, and it was an interesting one: tipback.

Overall, there was a lot of frustration and a little freaking out over the issue, so before I continue, I feel compelled to declare to y’all that there’s no need at the moment to freak out, though your frustration is more than acceptable.

Why not freak out?  Because tipback doesn’t necessarily mean lower yields.  We had some pretty primo conditions during ear development this season and ears got off to a great start.  Maybe a little too great.  While conditions haven’t been bad at all since, they haven’t been quite as great and it seems that our plants may have scaled back their plans.  If this was happening during a year in which ears didn’t get off to a macho start, then yep, that would mean lower yields.  But given their strong jump out of the gate this season, some tipback might mean very little to our expectations.

So don’t sound the alarm yet.

Be curious though because while tipback can have environmental causes, it can also occur due to management issues and genetic problems.  Given the very many potential origins of tipback, don’t assume the cause of yours.  Rather, investigate.  The answers you dig up might prove incredibly useful to you going forward.

Tipback due management issues or environmental conditions is a product of the same pathway, though the causes are different.  Essentially, something caused a shortage of sugars around the time of pollination which prompted the plant to abort or not fertilize some kernels as it had to reallocate resources in order to address the shortage.

The environmental causes of such a shortage are various and include an imbalance in moisture and heat, especially when daytime temperatures exceed 86 degrees and/or nighttime temperatures stay above 70 and especially when moisture is low.  Hello, dryland growers—perhaps you recognize yourselves here…

The management causes of such a shortage include deficiencies of nitrogen, potassium, zinc, and/or sulfur, which may be due to a lack of root development.  Plants exhibiting tipback due to management issues might show some visual signs of a deficiency and a quick turn with your spade could reveal issues with root development.

If you suspect management issues caused your tipback, you would do well to compare your plants to the same hybrid grown under different management strategies (which is exactly what you can find at our Answer Plots).  This is the learning part of the process: where you can see what you might do differently in the future to mitigate or avoid the issue altogether.

A final note to file under management issues concerns uneven tipback.  If as you’re investigating you notice that your tipback appears selective or non-uniform, look to your planter.  Likely, downforce or spacing issues caused competition among the plants—some of which won (no tipback) and some of which lost (tipback).

Untitled-2Lastly, there is the possibility that your tipback has been caused by genetics.  Investigating this possibility requires precision because it would be tragic to leave behind what is in actuality a perfectly good hybrid.  To investigate this possibility, you need to compare your hybrid to different hybrids grown under conditions the same as yours (including population, spacing, and planting date).  I see a lot of sales pictures online that are a bit unnerving to me—pictures of big, fat ears of corn next to wimpy little ones, insinuating that one hybrid is better than the other, without any concern given to the variables that might have also affected that outcome.  Even the difference of a single day in planting date can have a significant impact.  Our Answer Plots are an excellent resource in this instance, as they allow you to look at different hybrids grown under very controlled and well-documented conditions.

In 60 days, all of this will sort itself itself out in the yield data of course, but right now is when we learn the why.  And when it comes to the “why” it holds true that the plant never lies.  If you want to know the deal with the tipback you’re seeing this season, the answer is in your field.