Tar Spot and Fungicides on Corn: Will it Pay?

One of the hottest topics this past winter revolved around how widespread tar spot would be in the summer/fall of 2025 and how to manage it. The main management decision is whether and when to apply a fungicide. Many of us didn’t make a definite decision, preferring to proverbially kick the can down the road until we had more information. Fortunately, or unfortunately, the time to decide whether to apply fungicides on corn for northern corn leaf blight (NCLB), gray leafspot, and/or tar spot is here.

If you haven’t made the decision yet, here is the pertinent information that plant pathologist Darcy Telenko presented at our annual meeting this past February.

Presence of tar spot:

● Past history- Tar spot was first identified in western NY in the fall of 2021. It could be easily found in Chautauqua, Erie and western Cattaraugus counties in the late fall of 2024. It was found, but was less prevalent in counties to the east. This is important. In previous years, the spores would have blown in from infected residue on corn to the west. Now it will be starting locally.

Weather matters for tar spot:

Scouting- There are no defined scouting procedures for tar spot, but it is important to keep an eye out for early development as it may help to determine when a fungicide should be applied. Although we will not be systematically scouting for tar spot, the staff of WNYCMA will be on the lookout as we visit your fields throughout the summer and early fall. It has been reported that some tar spot was found in Niagara County last week.

If the risk of tar spot in an area is high, there are other considerations to take into account before spraying.

Susceptibility of hybrids planted

● Resistance- Many companies have a rating of their hybrids for resistance to tar spot. There are no hybrids that are 100% resistant, however, a quick look at your seed catalog can help identify if you have any highly susceptible hybrids that may need more protection.

● Research studies of fungicidal treatments, either at planting or with an herbicide application are unlikely to give any significant protection against tar spot.

Value of the crop we are protecting

● The value of the crop to be protected should factor into whether a fungicide is likely to pay. Obviously, corn at $4 per bushel, will take a larger yield response to pay for the fungicide versus $7 corn. A calculator on the Crop Protection Network site can be used to help make that decision. The calculation is similar whether the crop is intended for silage or grain.

● Yield potential of stand. Surprisingly, the health of the crop has little effect on the potential for infection or the % yield loss. In other words, droughty or nutrient deprived corn is no more susceptible than healthy corn. Fungicide applications on stands with poor population due to weather, compaction, etc. are less likely to pay because the yield potential is lower.

How much yield do we stand to lose

● If fields are infested early with tar spot and the weather is cool and dry during pollination, losses can be substantial. In our area, late developing infestations have not resulted in significant yield losses.

How much does it cost to make an application? There are a number of products out there that reduce tar spot symptoms. Costs can range from $30 to $60 per acre depending on whether a farm does one or two passes.

Are fungicides effective? One past research study showed an average $29.2 to $48.5/acre net return under high tar spot disease pressure relative to no fungicide treatment. However, under low disease pressure the average was -$25.8 loss to $1.6/acre net return.

If you do decide to apply a fungicide, what should the timing be?

● Michigan State University Extension recommends fungicide applications from VT/R1 to R3. (Tassel to milk stage) Most pathologists do not recommend spraying before V10. The goal is to protect the ear leaf and leaves above it, which are most important for grain production.

Conclusion:

This year has been incredibly challenging. Fortunately, the current weather- hot and humid with less fog than some years- is less than ideal for tar spot. So far, very little has been found in western NY. If you have historically sprayed for northern corn leaf blight and/or gray leaf spot, an application at tasseling to silking is coming right up. We will continue to monitor corn fields.

Save Some Seed!

As many of us know, large parts of the country struggled with drought in the 2023 crop season.

With the dry conditions nationwide, quality is in question regarding this year's seed stock.

In an article written by Rhonda Brooks in the AgWeb Farm Journal, many growers expressed concern about this year's seed stock supply. Ken Ferrie, a Farm Journal Field Agronomist had several farms send seed samples to be tested for quality. Ferrie expressed that “37% of the samples fall below what he would call good quality levels, and 11% fall into the poor category”.

Another concern of Ferrie’s is pericarp damage. This is when there is a tear in the seed coat at the embryo, likely making the seed more subject to salt burn from starter. Ferrie acknowledges that “seed with a high pericarp-damage score can produce a good stand, as long as you manage the risk from in-furrow fertilizer”.

From our experience, poor quality seed is also more susceptible to imbibitional chilling injury, which has resulted in poor and uneven stand emergence.

He explained that it would be beneficial to keep a small sample of seed from each lot until the crop has emerged and stand counts have been taken. Roughly 2 pounds of seed from each lot should be kept in a cool, dry place and labeled with seed variety and lot number- if possible keep a seed tag with the sample.

Hopefully, everyone will have a great stand and this sample can be discarded. If issues arise, this sample can be sent out and tested to rule out seed quality issues.

Filling out WNYCMA planting records will help scouts determine if a stand is underperforming based on planted population and the stand counts taken in the field.

If you need help filling out planting records please contact your consultant, or access training documents on the WNYCMA website in the “News” tab under “Entering Records on WNYCMA.com” OR “Entering Planting Records On Mobile Devices”.

References

Brooks, R. (2024, April 29). Ferrie: With Poor Quality A Concern, Hold Back Some Seed Corn.

AgWeb. https://www.agweb.com/news/crops/corn/ferrie-poor-quality-concern-hold-back-some-seed-corn

Dos and Don’ts to coping with this year’s weather:

Time to Change Plans?

By, Dan Steward

Here we are well into May with a great deal of spring fieldwork yet to be done. Since things rarely seem to go as planned in farming, here are a few pointers to consider as you dodge raindrops to get the crops in.

Dos and Don’ts to coping with this year’s weather:

• Don’t be inflexible. Your cropping plans for the year are just that: plans. Plans can always be changed based on new information. Here is some new information: rain seems to keep coming and the date on the calendar keeps getting later and later. This past winter was very hard on alfalfa stands on marginal ground. This was likely due to the wet weather starting in the fall and assisted by the freezing and thawing leading to heaving March. Now is a good time to evaluate your stands.

• Do consider delaying seeding fields until the summer or next year. With very few seedings planted, this is a very viable option to consider. If you have not already fall-killed or rutted up the hay fields you planned on putting to corn, you may want to leave them in hay and not seed any fields. The other option is to summer seed fields. Fall-killed wet, heavy ground fields are also candidates for seeding instead of corn. The advantage to picking this strategy is that you decrease your spring fieldwork by a significant amount and likely keep the same hay yield potential on your farm. The disadvantage? It will set your rotation schedule back another year.

• Do plan on applying nitrogen on grass stands. Many farmers were able to get nitrogen out on their grass fields without rutting up the fields too badly. Many did not. Assuming it gets dry enough to get across the fields in the next week, it will still pay to spread nitrogen. It is likely that some yield has already been lost due to the shortage of N. However, grass puts on the majority of its yields as it approaches maturity and will still respond to N. Keep your planned N rates the same. If the nitrogen is not taken up on this cutting, it will be available for the second cutting. If fields get dry enough, plan on applying N up to approximately May 10th. (Maybe even later if you are at a high elevation on wetter soils.)

• Don’t put in your haylage too wet. Since this is not the first wet spring in the northeast, we can learn from the past. A similar year in the mid-90’s, the grass grew like you would expect in a wet year, but when it came time to harvest, it was still wet and overcast and the cut hay just didn’t dry. By feel it seemed dry, but the koster tester didn’t lie; it was still wet. Those who ignored the tester put up a lot of wet, butyric haylage that year. Coupled with the low sugars due to lack of sunshine, and the high lignin due to the cold, wet weather, not much milk was made on that haylage. You are better off having high NDF forage that cows will eat than a bunk of unpalatable slop.

• Don’t mud in your corn. The harm caused by plow or a tillage layer and/or sidewall compaction is irreparable. You are better off putting in corn 10 days late, then mudding it in.

• Do try to trade in your long season grain hybrids for shorter season corn. It’s not too early to consider switching to shorter season hybrids for grain. The decision for silage or high moisture corn fields can probably wait until the end of May. If the seed is not already in the ground when you receive this newsletter, grain growers should probably back off by five days in hybrid maturity, and another five if planting is delayed until early June. Also, consider switching from corn to soybeans. If your silage or high moisture corn planting is delayed until early June, consider reducing the maturity. As previous years’ data shows, there is usually no yield hit to staying with long-season hybrids right up until June, but often harvest has to be delayed by 2-3 weeks, or grain moisture will be much higher.

• Don’t miss this great opportunity to get your equipment ready. In other words, try to find something positive out this frustrating spring.

It has been frustrating, but we have to do the best with the hand we are dealt. In 2011, patience was aptly rewarded. That year had an exceedingly wet May allowing only 24% of the corn to be planted in NY by the 22nd and 43% by the 29th. But then conditions turned exceedingly dry from mid-June through July before the drought was relieved in August. That year, the long-season corn planted in late May or early June yielded by far the best because it wasn’t mudded in. As a bonus, it didn’t silk until the first week of August when the drought was relieved. The earlier planted corn silked in the middle of the drought and had pollination issues.

The 2021 growing season marked WNYCMA’s nineth year of organizing and facilitating corn grain trials.

The 2021 Corn Grain Trial results are in and full results are available at: https://wnycma.com/testplots.

Western New York Crop Management would like to extend a big thank you to the seed companies: Brevant Seeds, Hubner Seed, Local Seed Co., LLC, Pioneer, Seedway, LLC, Syngenta-NK Brand, and WinField United for the seed and financial support; Torrey Dairy Farms, Inc., Hildene Farm, Inc., CY Farms, Field Craft Farms, LLC, and Verratti Farms, LLC for providing the equipment, time, and land; and to the staff at WNYCMA for their hard work. The cooperation of these three groups of people made it possible to do these trials. If you would like to host a corn grain plot on your farm, please contact your crop consultant. Thank you and and we look forward to successful harvest this year.

The results of our 2020 Corn Grain Test Plot are in.

All of our plots have been harvested and the data has been analyzed. To view the results please go to our test plot results page.

Special thanks goes out to the farms that hosted our test plots.

Grain Plots:

• Field Craft Farms, LLC
• Hildene Farms, Inc.
• Horizon View Enterprises, LLC
• Torrey Farms, Inc.
• Verratti Farms, LLC

Silage Plots:

• Edelweiss Farm LLC
• Field Craft Farms, LLC
• Hi-Land Farms
• Maple Lawn Dairy, LLC
• Sregnuoy Farms LLC
• Swiss Valley Farms LLC

More thanks go out to everybody that helped plant, grow and harvest these plots.

Our 2020 Corn Silage Variety Test Plot Results Are now available

To view the results please go to our test plot results page.

Recently I got a call from a farmer who wanted help in getting his planter leveled in the shop.

I visited the farm and proceeded to go over how to level the planter in the shop with a particular tractor.The real answer really is the shop is not a  good place to do that job. You really need to be in the field with the planter in the ground planting. It is best to be level or slightly higher in front.  The main frame is what you should look at first. The best way to eyeball it by running along side or riding in a four wheeler. If it was level last year it might not be this year due tractor tire wear or wear on the bushings in the hitch. If the planter is low in front it may push residue in front or not close the slot well in back .If for some reason one has to switch tractors this has to be looked at again. No two tractors are the same.Sometimes a very mellow field will allow a tractor to settle more and more adjustments have to be made.

 Good Luck  STAY WELL     DAVE SHEARING

Cold Soils & Risk of Imbibitional Chilling Injury in Corn

It's May 1st. The forecast shows some unseasonably cool temperatures this coming week. By the calendar we should be safe to plant corn now, right? Indiana growers were asking the same question about two weeks ago. The following are some excerpts from an article on imbibitional chilling injury by Dr. Bob Nielson from Purdue that may help you make a decision:

While farmers are free to plant corn whenever they choose to do do, there are risks associated with "early" planting (Nielsen, 2020). The primary risk is that associated with "cold" soil temperatures. Soils that hover around 50 degrees (F) for days or longer after planting delay germination and slow emergence of the young seedlings. More importantly, soil temperatures lower than about 50F increase the risk of "imbibitional chilling" injury to germinating seeds.

"Imbibition" refers to the initial uptake of water by seed during the first 24 to 48 hours after being planted into moist soil. The resulting rehydration causes the seed to swell and the germination process to begin. Imbibition occurs naturally, with no physiological processes involved (e.g., dry wood will imbibe water). It also occurs whether soils are cold or warm and therein lies the potential for "imbibitional chilling" injury.

When the seed swells as it rehydrates, its internal cell membrane structure is damaged. When seeds (and soil) are warm, the membrane damage is quickly repaired by the physiological activity associated with germination and "life goes on" normally. When seeds (and soil) are cold, their cell membranes are less elastic, the cell membrane damage due to swelling is more severe, and the physiological repair of the damage is slowed or stopped. Left unrepaired, this damage to cell membranes and the subsequent leakage of cell contents can result in death of the seed.

Past research on the nature and causes of imbibitional chilling injury to seed does not clearly identify the environmental conditions "in the real world" that result in a high probability of the problem. The literature implies that soil temperatures simply lower than 50F are a key factor. It is not clear from past research whether the injury can occur with only a few hours of exposure to sub-50F soil temperatures or whether it requires lengthier exposure to cold temperatures. What is known is that this type of chilling injury is most likely to occur during the first 24 to 48 hours after planting seed into moist soil because that is when imbibition (and corresponding seed swelling) occurs.

Identifying and Diagnosing the Problem in the Field

Identifying and the diagnosing the problem in the field is often challenging for several reasons. First of all, germination and emergence of corn in cold soils will naturally be slow. The first visual indicator of germination (other than the seed swelling) is the appearance of the radicle root between 35 and 60 Growing Degree Days (GDD) after planting (Nielsen, 2019).

Tip: Calculating GDDs using soil temperatures is preferred over air temperatures for predicting corn development progress prior to about the 6-leaf growth stage (V6). The reason is that the seed & young seedling responds more directly to soil temperature as long as the main growing point of the corn plant (apical meristem) remains below ground (until about V5-V6).

When soil temperatures hover around 50F for days or longer after planting, accumulating 35 to 60 GDD may take 1 to 2 weeks. Initially, dead seed due to imbibitional chilling injury do not look much different than live seed taking their normal "sweet time" to germinate in cold soils. However, once 60 GDD or more have accumulated, then seed that seems to be "dormant" compared to others that exhibit radicle roots, coleoptiles, and lateral seminal roots may well be the result of imbibitional chilling injury. Sometimes, instead of immediate cessation of the germination process (i.e., "dormant" seed symptom), the radicle root and coleoptile emerge from the seed coat before ceasing further development (Fig. 2).

Another challenge in diagnosing imbibitional chilling injury as the cause of poor stands of corn is that eventually the dead seed or seed that germinated but simply ceased further development will naturally begin to decompose. Consequently, if you wait too long to investigate a problem field, you might be tempted to diagnose seed or seedling disease as the cause of the poor stand.

Daily, or hourly, soil temperature records coupled with knowledge of a field's planting date are useful for "pointing the finger" at imbibitional chilling injury. Because imbibition occurs within the first 24 to 48 hours after planting into moist soil, one can imagine that timing of planting relative to the onset of several days of cold soil temperatures influences the risk of imbibitional chilling injury. Anecdotal stories abound in the coffeeshops about fields planted 3 days ahead of a cold snap emerging just fine... fields planted 2 days ahead of the cold snap experiencing some emergence problems... fields planted 1 day ahead of the cold snap having more problems... and fields planted the day of the cold snap having major problems.

Factors Influencing Risk of Imbibitional Chilling Injury

• Intensity and Duration of Cold Soils. Obviously, 40F soil temperatures represent a higher risk than 50F temperatures. A single day of cold soils is likely less risky than multiple, consecutive, days of cold soils.
• Soil Moisture. Daily soil temperature fluctuation is more dramatic in dry soils than in moist soils. That means higher daily maximums and lower daily minimums.
• Plant Residue Cover. Daily soil temperatures fluctuate less in no-till fields that have a lot of surface residue from previous crops or current cover crops. In particular, soil temperatures in such fields will not drop as rapidly or dramatically in response to a cold snap as will bare fields. That's the good news. The bad news is that soil temperatures in fields with heavy surface residues are generally lower to begin with than bare soils early in the season and so early planting of corn in no-till fields is somewhat more risky in general.
• Seed Quality? One can speculate that seed lots with lower than desirable cold germination ratings might be more susceptible to imbibitional chilling injury.

Here is the link to the full article. https://www.agry.purdue.edu/ext/corn/news/timeless/ImbibitionalChilling.html