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The Cropwalker - Volume 4 Issue 31

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Crop Conditions

Weather – continues to be on the top wettest from mid-July to mid-August. This is resulting in diseases continuing to grow. Nothing we can really do about it now except watch. Corn continues at a quick pace. Earliest fields starting dent. This is the same as this week last year. Corn silage harvest will be earlier than normal. Get ready now. If it turns dry all of a sudden corn will be ready. Fusarium/DON last year we suggested you look at your hybrids’ rating for fusarium. I have a feeling that did not occur on many farms. However now take a look at the rating of the hybrids you planted. Scout these fields for start of fusarium. Any fields with Western Bean Cutworm (WBC) damage will be more prone to fusarium. Fields with fusarium developing should be harvested as early as possible. A strategy is to get some off and tested. If levels are low in suspect fields, get the corn off. Corn rootworm adults and root lodging are becoming more obvious. Check your fields now for rootworm adults. If you find many, start checking for root damage and decide a strategy for next year. Soybeans top nodes have not produced new pods. Do not believe they will. There are numerous diseases in many fields. Nothing you can do about them now. Having them identified MIGHT be of a help in choosing varieties for next year. Soybean cyst nematode (SCN) is spreading further. If you have this consider a resistant variety for next year. Forages Many farmers have lots. Many growers are trying to put up extra in case next year there is a shortage and there is a possibility of selling forages to Northern Ontario or western Canada. If you have fields that were established in 2019 or earlier strongly suggest you terminate this fall. Many of these fields will have a solid 100 lbs of actual N available for next year’s corn. Some of this will be slow release. August seedings are underway. You can normally safely seed alfalfa until August 20th in most of southern Ontario. Grasses can be successful seeded at least for 2 weeks later. You can insure your summer seeding in case it does not overwinter.


Things to do this week

1.     Remember how you promised to get a manure sample. Do it.

2.    Check your cover crop for emergence and weeds that can be controlled.

3.    Check corn for diseases and western bean cutworm, and soybean fields again for diseases.

4.    Check your variety/hybrid plots for any differences. If you don’t have your own plots, check any in your area.

5.    If you have soil tests back check to see how the levels have changed and plan fall broadcast program.

6.    Take some time off with your family before school starts. If you can’t take time off, at least go out for dinner or order in a great meal.

Comments from Indiana CCA Darel Walker

GDD accumulation is about 4 days ahead of normal at LaPorte Indiana and about 1 day behind normal at Rensselaer Indiana

Commentary: For years I have noticed that often the crop development does not follow GDD very well. This was especially true last year, where we were about average on GDD on August 15 but had an early harvest with very dry corn. Why does GDD not predict corn development well? The main reason is that it only considers temperature and does not factor in sunlight or more precisely solar radiation. Our crop phenologist, Dr. Jon Fridgen, told us that last year was exceptionally sunny and way above average on solar radiation expressed in lumens. When you add a measure of solar radiation to crop models, it does a much better job of predicting crop development than a GDD based system. This year there is concern that the haze coming from the western wildfires could reduce corn yield because it is reducing the quality of solar radiation across a large swath of the corn belt. Most agronomists agree that it will have some effect on corn yield.

More from Darel Walker

Deep Dive on Ear Tip Abortion

My writing style is direct and brief like Earnest Hemingway. But today I want to do a deep dive on corn ear tip abortion because I believe this is a very important concept. This week I talked to a grower who said water was his biggest limiting factor in growing corn. While I agree that is true, I would argue that in NW Indiana, the thing that keeps us from getting above 250 BPA is light, not water. Ear tip abortion is when ear tip kernels are pollinated, but then are resorbed and wither and do not fill. The result is a “possum-nose”, an ear tip with about an inch of cob with no kernels on it. I was taught that you wanted about a 1” possum nose, because if you filled out all the tip kernels, then your corn was not planted thick enough. I still subscribe to this theory. Back in the days when growers planted 25,000, the ears filled out to the tip and we had a huge 10” ear 55 kernels long, but the corn only yielded 180 BPA. In my Cargill days we did field experiments where we planted corn as thick as 51,000 trying to find the secret sauce that would produce 300 BPA corn. When we increased plant population, eventually the number of rows per ear decreases and the ear tips abort so the result is less kernels per ear. This varies greatly by hybrid, but the concept is true. Why does this happen?

I argue it is because of lack of sunlight! At the higher populations we cannot get sunlight to the leaves and produce enough energy to maintain tip kernels. Studies have shown consistently we can increase corn yield by adding artificial lighting to corn. Just think of the size of the ears you get on the outside rows. This is called border effect and is precisely the result of getting extra light to the corn leaves. Water is not the limiting factor, it is sunlight. The reason we struggle to produce a corn yield above 250 BPA here is because of cloudy weather we typically experience here in late July because of Lake Michigan. To help you visualize this, I like to use the power plant and lightbulb analogy. On a cloudy day, our energy plant (the corn leaves) is only operating at 50% and can only produce so much power. The ear is a collection of 500 or so little light bulbs we call kernels. On a cool, cloudy day in milk to dough stage we may only have enough power to light 400 light bulbs, so the corn plant says, “I am going to let these tip kernels go so I can keep the other 400 lit”. This is exactly what happens to corn after pollination when we don’t have adequate solar radiation.

So, what can we do about it? We have learned that some hybrids are better at keeping ear tip “light bulbs” lit. Advanced Agrilytics leads the industry in hybrid testing to identify products which can retain ear tip kernels when plants are under stress including the stress caused by cloudy days. If you want to learn more about this, give me a call. I will gladly share with you what we are learning through our hybrid comparison trials.

Q I have applied manure and planted a cover crop. I am told that this cover crop will prevent N from leaching. Does that mean I can use less N next year where I have manure plus cover crop vs. where I just applied manure?

Ans There is limited research on this question. The research that does exist, suggests that whether you use a cover crop or not the amount of N credit for the next crop is the same. This begs the question if cover crops prevent N from leaving the farm but there is no credit to the next crop, where does it go? Does it leach later in the season or does it go off in the air. I think it may help build organic matter and the difference in residual held in the cover crop is too small to be measured. Few factors that may help answer the question are; what is the C:N ratio of the cover crop (cereal rye can capture N, but with a high C:N ratio at planting, will tie up additional N in the spring), what was the total plant biomass, and when does the plant start to break down.

Q I am seeing soybean fields with less than normal number of seed pods. Should I be worried?

Ans No. Right now, there is nothing you can do about number of pods. Reality is that the plant will find some place to store nutrients produced in the leaves and stems. If there are fewer pods than normal the plant will put more nutrients into the existing beans.

Corn rootworm problems/solutions

We are seeing a bit more corn rootworm damages this year compared to last year. I believe we will see more as the season unfolds. Right now, the only solution to beating this insect is 1 year in 3 for corn. For those who cannot do that, the best option will be Force granular insecticide applied in a T band. The traited hybrids are not giving us control. The seed treatment neonics at best gave some control. And with the hassle of getting them, they are not worth the bother. If you have corn rootworm problems this year you will probably have them again next year. I checked with Syngenta and was told they plan to carry Force again next year. If you plan to go this way suggest you get your order in now as supply will be limited. Then start looking for rootworm insecticide hoppers. You may have to go to the US or try to find some lying around that are no longer used. Can I apply in-furrow with the seed? My experience has been this gives some control but not as much as applied in a band over the row. Can I Use Lorsban? The research in the late 70’2 early 80’s indicated that while Lorsban was registered for rootworm it gave very poor control compared to the other products. Lorsban is discontinued and I only mentioned it since there is some old stock around that can be sold. What about spraying the adults before they lay their eggs? This has been tried in the US. There was a time when rootworm adults were so high in numbers that farmers sprayed them so they would not interfere with pollination. The logical thought was can we spray adults to reduce damage for the next year. There was a massive project where all the corn in about 10 square miles was sprayed for rootworm adults. The result. No difference the next year. The reality was that the adults emerged over 4–6-week period and it was impossible to spray to control them. Another alternative is to find an older planter with insecticide hoppers and use it to plant some acres. Or work with someone else who has insecticide hoppers. You plant for them and they plant for you.

The Importance of Residue Management

To get your wheat off to a great start, residue management has a significant impact on seedling emergence and drill performance. Uneven residue leads to hair pinning on the no-till drill and warm/cool zones on the soil surface. These zones then lead to uneven emergence and plant stages. In the fall, sunlight hitting the soil surface has a significant impact on soil temperature. So, what can you do to spread that soybean stalk evenly? 1) Don’t buy a header bigger than what the combine can spread the residue. 2) Keep the chopper knives sharp or replace them every 3 to 4 days. 3) Ensure the crop is being fed into the chopper evenly. In Europe, wheat combines are sold on their ability to chop and spread residue. When you are harvesting soybeans with a lot of residues, you need to be able to spread this residue. In the U.S., the majority of combines are sold into just 4 states; these states do very little with residue management as crop rotation is mostly corn/soybeans with conventional or minimal tillage. There are aftermarket or manufacturer kits available to do a better job of spreading the residue. One example is the John Deere Powercast Tailboard or consider machines with European influence.

Question When is it too late to plant a cover crop?

Answer It depends on the cover crop. You can plant cereal rye well into October and expect a benefit. Some cover crop promoters will spread fall cereal rye until December (usually after corn). Oats needs about 4 weeks to get significant top growth to make it worthwhile so you can plant oats up to mid-September or so. Rye grass for forage should be planted no later than first of September in hopes of getting a cut this fall and again next spring.

Should I spray dicamba now to control weeds in my wheat stubble?

Short answer is NO. There is too big a risk of off target movement at this time of year. Wait until soybeans and other broadleaf crops have reached maturity prior to considering an application with dicamba.

Big hitters on the soil test results;

1)    Soil pH. If you are above 7, there will be no buffer pH reported. If you are below 6.5-7, the lab will report a buffer pH. The buffer pH is used to determine how much acidity is in the soil. The difference between the buffer pH and the target pH is used to determine how much lime (carbonate) should be applied to raise your soil pH.

a.     Why raise your soil pH if it is acidic? 1) improved nutrient availability and uptake, 2) some plant species (i.e., alfalfa, blueberries, soybeans, and the like), can not produce optimal yields on acidic soils. Acid soils make some nutrients more available to the point these nutrients are toxic.

Figure 1 - Fertilizer Efficiency at Various soil pH values

2)    Soil Organic Matter – Optimal levels are based upon soil texture. If you are below the optimal level for your soil texture, it may be time to consider some crop production management changes. You should compare your OM levels over time. You could even get a soil map and see what OM levels were in your area 60 years ago.

3)    Magnesium – If you are below 200 ppm, you should be considering a magnesium product in your fertilizer plan, as there are likely pockets in the field below 100 ppm. If you are below 100 ppm, you MUST be adding magnesium to your fertility plan.

4)    Phosphorus –

a.     Olsen/Sodium Bicarb test – Is the accredited test for Ontario, all OMAFRA/University extension research is expressed using this test. If you are looking at soil fertility research of other parts of North America, ensure you are comparing apples to apples when it comes to the underlying soil phosphorus test.

b.    On my soils, I like to see at least 30 ppm of phosphorus, (realizing you can grow great crops at 25). Rule of thumb has historically been 20 ppm. If you are no-tilling or strip tilling, or run heavier bulk density soils, you are more likely to see benefit from getting your soil test levels higher OR applying a starter fertilizer than those doing full width conventional tillage.

5)    Potassium –

a.     The accredited test is ammonium acetate. If you are looking at soil fertility research of other parts, ensure you are comparing apples to apples when it comes to the underlying soil test.

b.    High potassium values can exacerbate magnesium deficiency. Understand why you have poor plant growth before putting on additional fertilizer.

c.     Some have bought into the base saturation concept of hitting a targeted 2% potassium. This can be misleading, as you can hit your targeted base saturation value and still be short on total ppm to meet crop requirements. Focus on ppm when it comes to potassium, after accounting for soil texture, then consider if that nutrient is causing an imbalance by looking at ratios of nutrients.

d.    If making applications to build soil potassium levels, it is imperative you know what clay type you are working with. Different clay types have different abilities to fix cations like potassium. In some clay soils it may be more advantageous to “spoon” feed potassium through banding and yearly broadcast applications than attempting to raise levels once every three years.

IPNI Plant Nutrition Today

Potassium availability impacted by clay mineralogy

North Dakota Clay Mineralogy Impacts Crop Potassium Nutrition and Tillage Systems — Publications

Clay mineralogy is important in directing potassium rate to corn and other crops in North Dakota. It also has an impact on tillage systems and their success and proper management.

6)    CEC – Cation Exchange Capacity is a calculated metric based on the levels of potassium, calcium and magnesium in the soil. It is an estimated soil texture based on the levels of those nutrients. 0-10 is consider sands, 10-15 loams, 15 plus clay-based soils, as a rule of thumb.

Red Clover and Technology

If you have red clover in the crop rotation and use a NDVI-based imagery service like Climate Fieldview or Corteva’s Granular Insights, I suggest you consider ground truthing one of their images this fall. This should allow you to see if you can write a variable rate nitrogen script the following year for corn for areas with strong catches vs. none and making up the difference in the spring.

A few questions this week on forages from one reader, here’s a few articles from December 2019.

Which management practices favour alfalfa over grasses? - Joe Lawrence - Cornell

Figure 2 - Factors Before Planting Impacting Alfalfa-Grass Ratio
Figure 3 - Factors After Planting Impacting Alfalfa-Grass Ratio

Forage Management Quick-Hitters – Joe Lawrence – Cornell

1)    Disc vs. Mower – Discbine can pick up more yield (due to lower cutting height), but it means you pick up more ash (reducing feed quality) and stress the grasses more.

2)    With grasses – You will get more total yield for the season by raising the cutting height due to faster regrowth.

3)    Avoid the Vacuum Effect – Which means the discbine picks up ash from the soil and incorporates it in the feed. Curved blades are worse than straight blades.

4)    Stem Crimping – Is a requirement for dry hay. Use wide rows without crimping for rapid dry down for silage.

5)    Grass Maturity – Once you see the head, the quality is dead.

6)    Grass Quality 1.0 – Are less forgiving than alfalfa when it comes to crude protein, rapidly dropping closer to maturity.

7)    Grass Quality 2.0 – There are bigger differences between species of grass than varieties of grasses when it comes to forage quality.

8)   Impact of Weather on Corn Silage – Weather impacts hybrid digestibility greater than the differences between hybrids within a specific hybrid type (i.e. Grain corn, leafy silage, BMR). Higher rainfall in August means lower digestibility.

9)    Total Starch – Is impacted by dry matter and the ear to Stover ratio. You can have a leafy hybrid with lots of Stover, and minimal cob, meaning lower total starch content.

10) Adapted Corn Hybrids – Can ensure proper maturity + moisture when it comes to silage rather than increasing risk. Can gain 3-4 points in starch content using proper dry matter (cob to stover ratio is in proper portions).

Grass Species Ratings – Joe Lawrence – Cornell

Figure 4 - Grass Species Ratings from Joe Lawrence - Cornell

"It is the glistening autumnal side of summer. I feel a cool vein in the breeze, which braces my thought, and I pass with pleasure over sheltered and sunny portions of the sand where the summer's heat is undiminished, and I realize what a friend I am losing."

– Henry David Thoreau