Soggy saga of planting season

Tony Nye - OSU Extension

The soggy saga continues and farmers are once again waiting for some drier weather to finish the planting season.

The persistent rains and saturated soil conditions have resulted in replanting and delayed corn planting. The weather forecast indicates the likelihood of more rain through Sunday so the many soggy fields may not be drying out soon.

With that said, area farmers have made great strides lately but as one drives around the area there are many fields yet to be planted.

We are at a point in this year’s growing season that one must be careful what one asks for. We don’t want the rain to completely stop but rather take a break long enough to finish planting.

According to the USDA/NASS, Ohio crop progress for the week ending May 21, corn was 73 percent planted, which was 24 percent ahead of last year and the same as the five-year average.

So given the timeline, do producers who need to finish planting corn need to switch from full season to shorter season hybrids? Agronomists would suggest probably not — in most situations full season hybrids will perform satisfactorily (i.e. will achieve physiological maturity or “black layer” before a killing frost).

Peter Thomison, Ohio State Corn specialist points out results of studies evaluating hybrid response to delayed planting dates indicate that hybrids of varying maturity can “adjust” their growth and development in response to a shortened growing season.

A hybrid planted in late May will mature at a faster thermal rate (i.e. require fewer heat units) than the same hybrid planted in late April or early May).

According to Thomison, in Ohio State and Purdue University studies, agronomists observed decreases in required heat units from planting to kernel black layer which average about 6.8 growing degree days (GDDs) per day of delayed planting.

Therefore a hybrid rated at 2800 GDDs with normal planting dates (i.e. late April or early May) may require slightly less than 2600 GDDs when planted in late May or early June, i.e. a 30 day delay in planting may result in a hybrid maturing in 204 fewer GDDs (30 days multiplied by 6.8 GDDs per day).

There are other factors concerning hybrid maturity, however, that need to be considered.

Although a full season hybrid may still have a yield advantage over shorter season hybrids planted in late May, it could have significantly higher grain moisture at maturity than earlier maturing hybrids if it dries down slowly.

Moreover, Thomison suggests there are many short-to mid-season hybrids with excellent yield potential. Therefore, if you think you may end up planting into early June, consider the dry down characteristics of your various hybrids. In recent years we’ve seen a range of drying conditions.

In years with hot, dry conditions in September, some mid- to- full season hybrids had grain moisture levels at harvest similar to those of short season hybrids because of rapid dry down rates. However, in other years, cool, wet conditions after maturity slowed dry down and major differences in grain moisture at harvest were evident between early and full season hybrids.

Thomison suggests late planting dates increase the possibility of damage from European corn borer (ECB) and western bean cutworm and warrant selection of Bt hybrids (if suitable maturities are available) that effectively target these insects. In past OSU studies, Bt hybrids planted after the first week of June consistently out-yielded non-Bt counterparts even at low to moderate levels of ECB.

While you wait to get back in the fields, spend some time to research your hybrid options as we head into June.

If you are one of the lucky ones that is finished or close to being finished, the weather has been a perfect storm for slug issues.

With a few reports already coming into the Extension office, a reminder is in order about possible slug problems in no-till crops, especially in fields with a history of slug damage. With the weather conditions over the past month, many fields are just now being planted.

Slugs have been hatching and beginning to grow; this will result in many fields just germinating or emerging when slugs start to feed. This combination of feeding slugs and small plants can result in much more plant injury than normal. Slugs can also damage un-germinated seed.

Thus, growers with a history of slug problems who are just now planting into those fields should watch their crops closely over the next few weeks. Although all fields should be scouted, focus on those with a history of these pests, where weed control was less than effective, or with a lot of residue left on the field.

Slugs are nocturnal so you may not catch them in the act of feeding unless you inspect plants after dusk. If you see feeding damage on plants, sift through residue and look under stones in the field. One scouting technique is to use an asphalt shingle laid out on the ground, painted white to keep it cooler.

Slugs will collect under it during the day. There are no research-based thresholds for slugs in field crops.

However, if the level of damage concerns you, a rescue treatment may be in order. There are few products available, but three of them are Deadline MP, Iron Fist, and Ferrox, which are all baited pellets which must be broadcast and ingested by the slugs.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 29 years, currently serving Clinton County and the Miami Valley EERA.

Tony Nye

OSU Extension