by Elizabeth A. Tomlin

“Know your yields!” advises Karl Czymmek, Senior Extension Associate, PRO-DAIRY, Department of Animal Science Cornell University.

Czymmek, in a presentation prepared with Professor Quirine Ketterings, Nutrient Management in Agricultural Systems, Cornell, led a discussion during the 2019 annual CNY CCE Corn Day conference correlating yield and good nitrogen (N) management decisions, a component of  “Decision Agriculture.”

Research shows that high-yielding fields may not need extra N, as for whatever reason, high-yielding fields are found to be more efficient at using N.

Czmmek pointed out that if you only need 50 pounds of N instead of 150 when you side-dress, it’s going to impact both your wallet and the environment.

The N issue becomes more important each year in New York, as environmentalists are interested in correlating N to Harmful Algal Blooms (HAB) in the Finger Lakes.

“Some people are looking at nitrogen as a driver of the toxicity levels.”

Producers can see that the soil in their fields differs from one area to the next — and even within one field conditions vary. Matching crop varieties to those specific soil conditions is advised.

Of course, weather conditions, soil and topography, such as elevation, all impact yield.

“Of all nutrients essential for crop growth, nitrogen is most difficult to manage due to varying crop nitrogen demands throughout the season — and inability to accurately predict nitrogen supply.”

Measuring yield for individual fields can be done by using check-strips, combine/ chopper yield-monitors and other new technology devices, such as drones and even satellite images.

“There’s a lot of opportunity.”

Yield-monitors must be calibrated often and cleaned of previous data to be accurate. This can result in a difference of many tons in data of yield recorded.

Re-calibration is required for each crop/ variety being harvested, and for changes in dry to wet conditions.

“Check and zero the mass flow sensor every morning so that the sensor identifies crop flow accurately.”

Cleaning yield-monitors is critical for obtaining accurate data.

State-wide research is ongoing, with data being collected by Cornell. Farms are invited to take part in this study. For more information contact CNY Field Crop Specialist Kevin Ganoe at .

Michael Hunter, Field Crops Specialist, CCE North Country Regional Ag Team, discussed no-till weed control programs and serious issues with developing resistance.

“A lot of times when we’re talking about no-till, we deal with cover crops as well.”

No-till is on the rise in New York each year.

“We really need to be careful with weed identification. It becomes more and more important as we understand the weeds that we have and the weeds that we’re dealing with. The longer we get into the no-till corn production, the more we will see a shift in weed populations.”

Scouting is critical.

Burn-down programs will be essential in most no-till corn production and cover crops, resulting in increasing reliance on pre-plant burn-down applications and post-emergence weed control.

“A lot of times our post-emergence weed control program is brought in to clean up our perennials that we’re missing.”

A serious, predicted shift in weed populations includes increased perennial weeds, such as dandelions, horse-nettles, bindweed and milkweed.

Hunter says this is important and farmers need to be on top of it.

Horseweed (aka Marestail), wild mustard, shepherd’s purse, lambs quarter, pig-weeds and Eastern black nightshade are expected to be more populous.

“We’ve got a couple of new pig-weeds we’ve got to start dealing with in New York State.”

Small seeded weeds, commonly found in no-till fields, feature three herbicide resistant weeds; Glyphosate resistant marestail, tall waterhemp and Palmer amaranth.

“You may want to pay close attention to this,” Hunter advised attendees, citing an update in information. “We’re getting resistant marestail throughout the state now.”

Indications show that most populations of Glyphosate resistant marestail will also be resistant to Group 2 herbicides.

Marestail has two different types and two growth stages. “It can come in late summer/fall, and act more as a winter annual — those are tough because of no-till — and in the spring, you’ll have the ones that were winter annuals that will be taller, then you’ll have the shorter ones as well.”

Hunter explained that he interviewed one New York crop producer that had been inundated with marestail due to the speed that it took over his fields. Marestail will easily travel more than 100 miles on wind currents.

“I continue to tell farmers that it is not a case of ‘if ‘resistant marestail will become a problem in their fields but a matter of ‘when’,” emphasized Hunter.

Tall waterhemp and Palmer amaranth are both encouraged by no-till practices.

“The one thing that tall waterhemp and Palmer amaranth don’t like is intensive tillage. They do very well under no-till conditions.”

Tall waterhemp has been found in western New York and now has been discovered in Oneida County on the Herkimer County border. An increase in populations is expected.

Palmer amaranth, ranked by the Weed Science Society of America as the most difficult weed to control in the U.S., was discovered in Seneca County during October 2018.

“This is one that we didn’t want to see in New York State. It’s the most troublesome weed in the country to deal with.” Palmer amaranth causes a devastating impact on crop yields. It is extremely prolific — a single Palmer amaranth plant may produce a million seeds per season — and it reportedly has stems tough enough to damage farm equipment.

Both Palmer amaranth and tall waterhemp are species of pigweed.

Scouting and accurate identification is critical to controlling these weeds.

“We’ve got to take action. We can’t just ignore this, because those spots are just going to get bigger.”

Research is ongoing at Cornell using seeds from plants detected in New York to determine exactly what herbicides they are resistant to.

Multiple resistance is documented in several states and Canada.

Hunter said there will be increased pressure on soybean and corn producers to control these weeds.

“We really have to start thinking as we move forward in weed control about herbicide resistant management. We’ve really got to start mixing up our tank mixes, using multiple sites of action. You don’t want this to show up on your farm.”

These seeds may be transported into New York through several methods; on combines brought in from other states, through cotton seed movement for dairy rations, in seed mixes and by migrating water fowl.

Studies show that pigweeds are a preferred food of ducks and the small seeds from these weeds remain in their digestive tract for 36 to 48 hours, providing them enough time to fly hundreds of miles before passing seeds that are still viable. Maps portraying tall waterhemp sites in New York do correlate with maps depicting snow-geese population sightings.

Used combines also provide transport of these seeds. Folks bringing in used equipment, especially from the mid-south, are invited to have Cornell field crop teams come in to collect chaff and weed seeds brought in on that equipment. These seeds will be analyzed, screened and used for research.

Hunter also discussed managing cover crop. Winterkill works with oats. Mowing and herbicides are options.

Planting green was addressed. “Entomologists will tell you not to do it,” Hunter remarked, citing a variety of challenges including pests, such as seedcorn maggots, armyworms and black cutworms that will thrive in those environments, weed interference and other management issues.

Glyphosate is the preferred choice for burndown in cereal rye. Stages of growth impact effectiveness when burndown is applied. Gramoxone can be effective, but timing is critical. Gramoxone shows increased control when atrazine is added to the mix. Air temperature also impacts effectiveness.

Hunter encourages producers to carefully evaluate whether they actually need glyphosate or gramoxone for burndown and to consider what they are using in their tanks. “We can use some pre-emergence herbicides that have burndown residual products that also have some burndown capabilities as well.”

Data is being collected by Cornell for further studies.

For more information contact your local CCE Field Crops team.