Corn

Tar Spot of Corn in Ohio Again this 2019

By: Pirece Paul, OSU Extension and Felipe Dall Lana da Silva, OSU Plant Pathology

Tar Spot, a new disease of corn caused by the fungus Phyllachora maydis, was reported for the first time in Ohio at the end of the 2018 growing season. At that time, it was found mostly in counties close to the Indiana border, as the disease continued to spread from the middle of country where it was first confirmed in 2015. Over the last few weeks, there have been several new, confirmed report of Tar Spot in Ohio, this time not only in the northwestern corner of the state, but also from a few fields in central and south-central Ohio. As was the case last year, disease onset was late again this year, with the first reports coming in well after R4. However, some of the regions affected last year had more fields affected this year, with much higher levels of disease severity. It could be that Tar Spot is becoming established in some areas of the state due to the fungus overwintering in crop residue from one growing season to another. This is very consistent with the pattern observed in parts of Indiana and Illinois where the disease was first reported. We will continue to keep our eyes out for Tar Spot, as we learn more about it and develop management strategies. You can help by looking for Tar Spot as you walk fields this fall, and please send us samples.      Tar Spot Continue reading →

Managing Corn Harvest this Fall with Variable Corn Conditions

By: Jason Hartschuh, CCA, Elizabeth Hawkins, James Morris, Will Hamman, OSU Extension

Thanks to the weather we had this year, corn is variable across fields and in some areas we will be harvesting corn at higher moistures than normal. Stalk quality may also be variable by field and amount of stress the plant was under, see the article Stalk Quality Concerns in this weeks CORN Newsletter. This variability and high moisture may require us to look harder at combine settings to keep the valuable grain going into the bin. Each ¾ pound ear per 1/100 of an acre equals 1 bushel of loss per acre. This is one ear per 6, 30 inch rows in 29 feet of length. Continue reading →

Stalk Quality Concerns

By: Peter Thomison, Pierce Paul, OSU Extension

2019 may be an especially challenging year for corn stalk quality in Ohio. Stress conditions
increase the potential for stalk rot that often leads to stalk lodging (Fig. 1).  This year persistent rains through June caused unprecedented planting delays. Saturated soils resulted in shallow root systems. Corn plantings in wet soils often resulted in surface and in-furrow compaction further restricting root growth. Since July, limited rainfall in much of the state has stressed corn and marginal root systems have predisposed corn to greater water stress.

Continue reading →

Drydown in Corn: What to Expect?

By: Peter Thomison, Ohio State University Extension

Many corn growers may encounter slower than normal drydown this fall due to late crop development associated with June planting dates. Much of Ohio’s late-planted corn may not achieve black layer until mid-October or later when drying conditions are less favorable for drydown. Once corn achieves physiological maturity (when kernels have obtained maximum dry weight and black layer has formed), it will normally dry approximately 3/4% to 1% per day during favorable drying weather (sunny and breezy) during the early warmer part of the harvest season from mid‑September through late September. By early to mid‑October, dry-down rates will usually drop to ½% to 3/4% per day. Continue reading →

Corn Earworm in Field Corn; Watch for Molds

By: Kelley Tilmon, Pierce Paul, Andy Michel, OSU Extension

There have been recent reports of high corn earworm populations in certain grain corn fields.  Corn earworm is a pest with many hosts including corn, tomatoes and certain legumes.  In Ohio it is typically considered a pest of sweet corn rather than field corn, but this past week substantial populations have been found in certain field corn sites.  Corn earworm moths are most attracted to fields in the early green silk stage as a place to lay their eggs.  These eggs hatch into the caterpillars that cause ear-feeding damage, open the ear to molds, and attract birds.  With a wide range of planting dates this year, different fields may be at greater risk at different times. Continue reading →

Assessing The Risk of Frost Injury to Late Planted Corn

By: Peter Thomison, OSU Extension

Lately I have received questions as to whether corn at various stages of development, especially the blister (R2) and dough stage (R3) stages, will mature before the 50% average frost date. According to the National Agricultural Statistics Service, as of August 18, 37 percent of Ohio’s corn acreage was in the dough stage (R4) compared to 70 percent for the five year average, and three percent of the corn acreage was in the dent stage (R5) compared to 21 percent for the five-year average. Many areas of the state corn are considerably behind the five-year average because of late planting. Late maturation of the corn crop had led to questions about the likelihood for frost damage and whether more fuel will be needed to dry corn.

Physiological maturity (R6), when kernels have obtained maximum dry weight and black layer has formed, typically occurs about 65 days after silking. At physiological maturity (kernel moisture approximately 30-35%), frosts have little or no effect on the yield potential of the corn crop. Continue reading →

Estimating Yield Losses in Stressed Corn Fields

By: Peter Thomison, OSU Extension

Many corn fields are still silking (and some are just past the mid-vegetative stages)….so, it may seem a little early to discuss estimating grain yields. However, according to the most recent  NASS crop report, for the week ending Aug. 8, 2019,  25% of the corn crop has reached the dough stage (compared to 63% for the 5 year average). Corn growers with drought damaged fields and late plantings may want to estimate grain yields prior to harvest in order to help with marketing and harvest plans. Two procedures that are widely used for estimating corn grain yields prior to harvest are the YIELD COMPONENT METHOD (also referred to as the “slide rule” or corn yield calculator) and the EAR WEIGHT METHOD. Continue reading →

Drought and Heat Stress

By: Peter Thomison, OSU Extension

One of the corn production scenarios agronomists least like is an exceptionally wet spring followed by a hotter and drier than normal July and August. The spring of 2019 was one the wettest on records throughout much of the state and now, as the dry weather that started in July persists, such a scenario seems to be a possibility in many Ohio corn fields. A combination of warm temperatures and inadequate rainfall is beginning to stress corn fields across Ohio. Continue reading →

Western Bean Cutworm: It’s Time to Scout for Egg Masses!

Results from week four of The Ohio State University Western bean cutworm (WBC) monitoring network has resulted in an increase of moths captured in the majority of Ohio counties; which means now is the time to get out and scout for egg masses.  Last week’s trap count included WBC adults captured from July 15 – July 21. A total of 26 counties monitored 79 traps across Ohio. Overall, trap counts increased, resulting in a total of 2001 WBC adults (287 total last week) and a statewide average of 25.3 moths/trap (up from 3.8 average last week) (Figure 1). A WBC statewide average of 25.3 is similar to what we observed in the WBC peak week in 2018 (25.1) (Figure 2).


Figure 1. Average Western bean cutworm adult per trap followed by total number of traps in the county in parentheses for week ending July 21, 2019 Continue reading →

Ponding and Saturated Soils: Results of Recent Ohio Corn Research

By: Alexander Lindsey and Peter Thomison, Ohio state University Extension

Persistent rains during May and early June have resulted in ponding and saturated soils in many Ohio corn fields and led to questions concerning what impact these conditions will have on corn performance.

The extent to which ponding injures corn is determined by several factors including (1) plant stage of development when ponding occurs, (2) duration of ponding and (3) air/soil temperatures. Continue reading →