Cornell University

This semester I was lucky enough to have room in my schedule to continue working a few days a week at ACS. My summer internship is over but I’m still working part time as this year has been extremely busy and there is always work needing to be done. My “summer internship” ended on sort of a slow note; much of the busy scouting was over and the next thing to focus on was CSNT’s (Corn Stalk Nitrate Test). This test is done right before harvest and it requires cutting whole plants (around 15) from different areas of the field to get a representative sample. We cut the stalks 6 inches up from the ground and then again 8 inches up from that cut, giving us an 8-inch piece of stalk. We then quartered those 8-inch stalk pieces and kept only 1 of the 4 quarters for each stalk. We put those pieces in a paper bag and sent them to the lab to be analyzed. The results from this test are important to farmers because it lets them know how much nitrogen was taken up by their plants which is a relationship to how much they applied; either over applied, under applied or applied the correct amount. With regulations on CAFO dairies only getting stricter, this allows farmers to adjust their application based on what the plant actually took up. The PSNT allows them to know what they need to apply pre-harvest but the CSNT lets them know how well they did following the recommendations determined by PSNT.

The dry matter test for corn was also a test we did a lot of and that consisted of us running the sample plants through a small wood chipper into a big garbage bag, and from that sending a smaller sample to the lab to be analyzed. Doing this before harvest gives farmers an idea of how much feed they are going to have after harvest is in and allows them plan accordingly if they think they need to purchase more. For the majority of farmers we dealt with this year, having too little corn was not a concern unless they weren’t able to get it planted during our very wet spring.

As harvest got to be underway, the next stage of busy work started and that was post-harvest soil sampling. Depending on the field, either whole fields were sampled as one sample or multiple sections within that field were sampled. Some fields are near water courses and have “manure setbacks” which is an area in the field that runs along the watercourse where manure cannot be spread. These sections are generally sampled separate to be sure that the N and P content of the soil are not of concern.

The soil sampling will continue into the winter months which means sampling even in the snow if that’s how the weather turns out. Thousands of samples will be taken from New York, Pennsylvania and Vermont, then be sent back to the lab and analyzed just in time to give farmers recommendations for next planting season.

At several of our farms we began to see some Northern Corn Leaf Blight in their fields and once our other clients caught wind of it, we were scouting full time for blight. Northern Corn Leaf Blight is identified by grey, cigar shaped lesions on the leaves of the corn plant and it generally shows up in the late season, from around the V12 stage and on. Due to the staggered planting this year because of the wet conditions, we did see some blight in corn that was younger, around the V8 stage. The majority of the blight that we saw was in fields that were no-till planted; the fungus is able to overwinter in the corn residue on the surface so in no-till applications it’s much more prevalent. When temperatures rise, the fungus become active and its spores are splashed up onto the leaves of the corn plant. It needs 6 to 18 hours of water on the leaf’s surface to infect the plant so during wet years like we’ve had this year or when the temperature cools and the dew takes longer to burn off, the fungus begins to be a problem.

Northern Corn Leaf Blight on left and Anthracnose Leaf Blight on right.

Another fungal disease we saw was Anthracnose leaf blight which is similar to Northern Corn Leaf Blight and causes similar foliar damage. Both fungal diseases cause the most damage when they’re seen in the crop during the period of two weeks before tasseling stage and the two weeks after tasseling stage.

The best way to control both of these diseases is to increase tillage practices to bury the stubble or plant resistant hybrids. The fungal disease is still seen in the resistant hybrids but the damage isn’t substantial and doesn’t cause any yields losses.

Nearing the end of my internship, I decided to continue to working with ACS during the semester throughout the rest of scouting season and harvest.

Our late season scouting focused mainly on fungal diseases and some pests as well. At this point the corn was around the tasseled stage, VT, and usually way over my head which made scouting pretty miserable.

One of the more common late season pests that we saw was the Fall Armyworm. Several of our clients are produce farmers and the majority of the Fall Armyworm damage we saw was in their sweet corn. They aren’t as common in field corn; however, we did see a number of field corn acres that showed damage symptoms, luckily none bad enough require action. The late timing at which the pests arrive is what makes them a problem; the corn is usually too tall to get a sprayer rig in the field that can spray for the worms. They cause the same type of foliar damage as the Armyworm you see in the early season but they will feed on the ear as well.

We saw much more of the fungal diseases than we did of the late season pests. Common rust was a major one and along with the rust we saw a lot of Eyespot. Rust is casued by the fungus Puccinia sorghi and just like the potato leaf hopper, the spores of the fungus are blown north by winds and storms and they end up here in our crops. The fungus dies in the winter with our cold climate but its able to overwinter in the southern temperate climate and each year it makes its way north. Usually the Common rust doesn’t cause any substantial yeild losses but the Southern rust is one that can cause a lot of damage. We were told to indiciate any form of rust that we found in the field, which leaves it was present on and what percentage of the plants in the particular field had it.

(Fall Armyworm on left, Eyespot in center, Nitrogen burn on right)

Eyespot is another fungal disease that favors a cooler climate than the rust but still the humid conditions. Its able to overwinter in the corn stuble and its seen more commonly in fields that have been planted in continuos corn. Luckily none of the corn we scouted showed severe symtoms of Eyespot and it wasn’t a huge issue for our farmers.

Nitrogen burn from sidedressing the corn was something else we saw a lot of but there nothing that can be done about that. The late season scouting continued and increased instances of blight began to worry some of our farmers.

Once the corn had reached around the V3 stage, the push to get PSNT’s (Pre-Sidedress Nitrate Test) done for our farms was on and I spent the majority of my days pulling samples. For the sample you take multiple 12” cores from all over the field to get a representative sample to use for nitrogen recommendations. Due to the very wet growing season we’ve had, a lot of corn is light green to yellow (an indicator for N deficiency) especially in the lower spots, which triggered a lot of our farmers to request these PSNT’s. Once the samples were pulled it was imperative that we kept them cool and got them back to the lab as soon as possible to make sure the sample and recommendation was as accurate as possible.

While the sampling and scouting was taking place, the alfalfa was growing back after first cutting and we began to notice the problem of the Potato Leaf Hopper. The Potato Leaf Hopper is a pest that normally feeds on the vegetative part of the potato plant, hence its name, however due to the lack of potatoes grown in New York it tends to feed on alfalfa instead. If the damage is intensive, the alfalfa plant turns a yellow to brown color and becomes necrotic. These pests can wipe out a pure alfalfa stand in a matter of days, depending on the height of the plant. The reason for this major outbreak of the Potato Leaf Hoppers is because of the great number storms that have moved their way up from the south and dumped rain on us all season. These small green pests are carried by the winds of the storm and end up here when the storm dissipates. Then when we get a few hot dry days after the storm, they reproduce like crazy and the problem starts.

We scouted the Potato Leaf Hoppers with sweep nets; generally doing 20 sweeps total throughout the entire field to get a good idea of the overall pest pressure. Then a decision would be made based on how many Potato Leaf Hoppers we found and the maturity of the alfalfa; using the Cornell guidelines as a reference. If we found that the pressure of the Leaf Hoppers was enough to call for some sort of action to be taken we would advise the farm to spray their alfalfa or mow it if it was close enough to harvest time.

After we got our PSNT’s taken care of and the Potato Leaf Hopper under control, the scouting continued with a focus on fungi and blight.

The first two weeks of my internship at Agricultural Consulting Services in Ithaca started off slow; we spent a lot of time training and getting ready for “scouting season” as they called it. I printed off hundreds of field maps for dozens of farms and organized them in manila folders in my big Rubbermaid map box. When I wasn’t printing maps I was at a training session on weed identification or Phosphorous indexing or countless other things, all in the anticipation for this dreaded “scouting season” everyone kept talking about. Then it hit, corn was popping out of the ground and “scouting season” had begun. My 40-hour weeks turned to 60-hour weeks and it’s been that way for the past month and a half.

Photo of army worm on left and black cutworm on right.

Two of the biggest pests we looked for while scouting young corn were black cutworms and armyworms. Both were more prevalent in fields where a cover crop had been throughout the winter months. The adult moths lay their eggs in the standing cover crop and when it is plowed into the soil, the eggs hatch and then you have their larvae, the worms, present in the soil. The cutworms, like their name implies, literally chew (cut) right through the stem of the corn plant and then feed on the seed in the soil below. The armyworm does more vegetative damage while the plant is standing. When these pests were found, an analysis of the damage was done based on the percentage of plants injured and then a mode of action was taken, generally spraying.

Weeds were also on our radar when scouting in hopes to control them early to give the young corn the advantage from the VE to around V4 stages. Due to a lot of our farms planting non-gmo (not Round-up Ready) corn, weed identification was crucial, especially within the grasses, because Round-up couldn’t be used. For example, mistaking nutsedge as a grass and recommending a herbicide to control that grass wouldn’t kill the nutsedge, essentially wasting the farmers money.

Once the corn reached around the V4 stage we began to shift from weeds into more of a pest based scouting and focusing more on alfalfa and the potato leaf-hopper which started a whole new phase of our scouting season.