Field Observations Thru June 30


The time for 2nd cutting is getting closer, for some fields 2nd cutting has happened.  Continue to monitor fields for potato leafhopper.

Click here for alfalfa insect scouting calendar

Click here for more information on Potato Leafhopper


Our corn growth varies greatly throughout the county.  Most of the county is between V2 and V6. However, there are some fields at V8 and beyond.

Click here for more information on the V3 – V4 growth stage

Click here for more information on the V5 – V6 growth stage

If you  haven’t scouted your fields lately, check them now for slugs.  Slugs have been very active this year, even when we had warmer temps.  I know several fields throughout the county that have been treated.

Click here for slug information


Beans just aren’t looking very good, for a variety of reasons – emergence problems, stand counts, too much water, not enough rain, SLUGS (!), poor root development, etc.  Make sure you are scouting your fields now to determine plant health.  A 4 year comparison of Ohio eFields on-farm research has shown that soybean plant populations as low as 80,000 plants per acre can produce yield equal to or greater than plant populations of 120,000 and 160,000.

Click here to see research summary.

As I mentioned above in the corn section, if you  haven’t scouted your fields lately, check them now for slugs.  Slugs have been very active this year, even when we had warmer temps.  I know several fields throughout the county that have been treated.

Click here for slug information


Wheat maturity is delayed a bit this year.  Mother nature, growth regulator applications or fungicide applications all could play a part in this.    If you are planning on double-crop soybeans remember to pay close attention to herbicide restrictions prior to planting.  Table 23 from the Ohio Weed Control guide lists these restrictions.

County Rainfall Update

Soybean Water Requirements

The image above shows the critical stages of soybean development.  Stress (moisture, heat, etc.) can have an effect on our final yields.  Most soybeans in Knox County ranges from the 2nd to 4th trifoliate.  A few fields are approaching R1.

The table below shows the water requirements for a soybean plant throughout the growing season.  Currently are soybean plants are using .08 to .14 inches per day.

Corn Water Requirements

The image above shows the critical stages of corn development.  Stress (moisture, heat, etc.) can have an effect on our final yields.  Most corn in Knox County ranges from V2 – V6.  A few fields are in the V8 + range.

The table below shows the water requirements for a corn plant throughout the growing season.  Currently are corn plants are using .1 to .2 inches per day.

Weather Update: Unsettled Weather Continues

Over the last two weeks, a more active pattern has brought numerous rounds of showers and thunderstorms across the Buckeye State. Many areas, from west central to southeast Ohio have received 2 inches of rain or more, with pockets of 4-6 inches across western Franklin, Fairfield, and Perry Counties. This has resulted in a decline in drought areas from 78% to 33% as of Thursday, June 22, 2023 (US Drought Monitor), leading to some improvement in crop conditions. However, large portions of southwest, northwest, and northeast Ohio have received less than normal precipitation over this period (Figure 1), intensifying drought conditions across these areas. Our CFAES Rapid Response Team continues to manage the early drought response resource site and encourages readers to continue to submit observations and impacts for your location by visiting


An upper-level low-pressure system is sliding east across the lower Great Lakes with showers and isolated storms on Monday and Tuesday. Temperatures are expected to remain cool on Tuesday with highs in the 70s and overnight lows in the 60s. Tranquil weather will return for Wednesday with highs in the mid-70s to low 80s across the state. A warming trend will continue for Thursday through Sunday, with highs generally in the 80s, pushing 90°F across the south. With warmer temperatures and increased humidity, isolated showers and storms are also possible throughout this period. The current forecast shows 0.25-0.5” is expected this week across northern counties, with totals over 1” near the Ohio River.

The Climate Prediction Center’s 8-14 Day Outlook and the 16-Day Rainfall Outlook from NOAA/NWS/Ohio River Forecast Center indicate that probabilities for temperatures and precipitation are leaning above average for the period July 3 – 9, 2023 (Figure 3). Climate averages include a high-temperature range of 83-86°F, a low-temperature range of 62-66°F, and average weekly total precipitation of 0.85-1.15 inches.

Weed of the week – Poison Hemlock

Family: Parsley, Apiaceae.

Habitat: Wet sites, gardens, roadsides, wastelands, pastures, and meadows.

Life cycleBiennial, forming a rosette the first year and producing flowers and seed in the second.

First Year Growth HabitBasal rosette of finely divided leaves with a pungent odor.

Second-Year Growth Habit: 2-7 feet tall, branched plant with flowers.

LeavesAlternate, pinnately compound, finely divided, toothed, and glossy green.

Stems: Branched, waxy with purple blotches; hollow between nodes and grooved.

FlowerJune – August (second year). Clusters of small white flowers with 5 petals in a loose, umbrella-like cluster, 2-7” across.

Root: Fleshy taproot.

Similar plants: During the first year, poison hemlock resembles wild carrot, but has a strong, pungent odor. Further, young leaves of wild carrot are more finely divided and its stem is hairy. At maturity, poison hemlock can be difficult to distinguish from water parsnip and water hemlock. Look for purple blotches on the stem to identify poison hemlock. Water hemlock (Cicuta maculata), which is also highly poisonous, has a magenta-streaked stem and lanceolate leaflets with sharply-toothed edges. Water parsnip (Sium suave) is not poisonous and has toothed lanceolate leaflets.

The problem is….This plant is highly poisonous to both humans and animals. Poison hemlock is a large and impressive plant which has been planted as an ornamental in some areas. It grows quickly in fertile soils.








Stem – Note distinctive purple speckling







Click here for control options


Pest of the week – Slugs


Identification and Incidence: Slugs are not insects, they are molluscs and more closely related to snails and clams than to insects. In field crops, slugs are particularly prevalent in no-till or reduced-till fields with heavy residue and little soil disturbance. They can eat virtually all crops and inflict most of their damage during crop establishment and early growth in the spring and fall. This damage tends to be most severe under cool, wet conditions, which slow crop growth and favor slug activity. Slugs typically feed at night and hide in residue or soil during the day. They range in color from pale cream to gray to shiny black and range in size as adults from less than an inch to over 2 inches in length. Small juvenile slugs can damage seeds and seedlings reducing stand and may defoliate established stands that may delay plant development. Slugs damage soybean by destroying the germinating seed prior to emergence and causes significant defoliation.

Sampling: Inspect several areas of the field and determine percentage of plants being fed upon and percentage defoliation. Another approach to finding slugs is to place artificial shelters across a field (1 X 1 foot shingles, old boards, or anything to create a dark, cool, moist environment). Several days after putting them out, slugs can be found under the shelters during the day. Research suggests that if you consistently find one to two slugs per shingle in the early season that you may end up with damage. In autumn, scouting for eggs can also reveal details on populations to expect in spring.  Research has not been able to identify consistent relationship between the amount of slug damage to soybean plants and yield loss.

Economic Threshold: Treatment may be necessary if defoliation is greater than 40 percent on slow growing plants or if plants are being killed.

Management Options: Several bait formulations of metaldehyde or chelated iron are labeled for slug control. Research indicates that ground beetles and other predators can be significant allies in the fight against slugs; populations of these predators will be strongest in fields that avoid preventative insecticide applications.

Click here for Slug Factsheet



Dicamba Deadline Reminder

Source: Dr. Alyssa Essman

Crop progress is highly variable this year. Some early planted crops have emerged and have had decent growth following recent rains. Dry weather has delayed the emergence of some later planted crops. This means there will also be variability in growth stages, which can have implications for POST application timings. The deadline to apply dicamba over-the-top (OTT) in Ohio is coming soon. For OTT applications of the dicamba products labeled for this use, the cutoff is up to and through June 30th, or the labeled growth stage. Below are the cutoff dates and/or soybean growth stages for the different products.

  • XtendiMax – R1 growth stage or through June 30th, whichever comes first.
  • Engenia – no later than June 30th
  • Tavium – V4 growth stage or through June 30th, whichever comes first.

A soybean plant is at the V4 growth stage when there are four open trifoliates. The R1 growth stage occurs when there is one open flower somewhere on the main stem. See here for detailed descriptions and pictures of soybean growth stages. Table 8 and table 18 of the weed control guide have information related to the maximum crop size and harvest intervals for POST applications in corn and soybean, respectively. As always, it’s important to scout fields before planning applications and follow the herbicide label guidelines.

Corn Outlook Update Following USDA’s June WASDE Report

Purdue ag economists James Mintert and Nathanael Thompson discussed the updated corn outlook following USDA’s June World Ag Supply and Demand Estimates (WASDE) report on the latest Purdue Commercial AgCast video podcast. The latest corn crop condition ratings were discussed along with implications for 2023 U.S. corn yield, production and carryover stocks. Corn export prospects were also featured with a comparison to South American and Black Sea region exports. The discussion concluded with an overview of corn basis and basis forecasts using the recently revamped Purdue Crop Basis Tool.