Corn Nutrient Problems

We have seen more corn nutrient problems than usual. There’s been Phosphorus deficiency, especially where pop up fertilizer wasn’t used. It is harder for the plants to take up in cool conditions. Also there’s been some Magnesium deficiency, with striped leaves and it’s sometimes a temporary striping condition when we get fast growth. Magnesium is more available to plants at higher pH’s. A plant tissue analysis is often needed to figure out these problems.

Then corn also needs Zinc, and we’ve seen a little Zinc deficiency in some fields. We don’t need much Zinc due to the fact that the plant doesn’t need much and because we may grow peanuts in the same field next year and they are sensitive to too much Zinc. Often growers can use a micronutrient pack in preplant fertilizer to suppply enough of the micronutrients. Zinc is more available to plants at lower pH levels. So overliming may actually cause Zn problems in corn.  I saw a case this week where they have new ground where they burned old trees and brush and they limed the field well and where these burn piles were, the Zinc deficiency problem is worse. We often get higher pH’s in ashy burn pile areas. A foliar spray or 2 of Zinc will often rectify the problem.

 

 

Question of the Week – Phosphorus and Anthocyanins

Last week I had a photo of purple corn beside some normal looking corn. In this field the grower did not use pop up fertilizer ( fertilizer put close to the young plants that usually contains Phosphorus). He did use a good dose of preplant Phosphorus. At this spot in the field he changed corn hybrids and that is what we see here. One row is one variety and the other one is another variety. We ran a tissue analysis and a soil test here and the nutrients in the soil, including P were at sufficient levels. However the plant tissue was deficient in Phosphorus. We know that cool temperatures like we were having makes it difficult for plants to take up phosphorus. We also know that different corn hybrids sometimes respond differently to low nutrients in the tissue.

Another kink here is that the seed company says that the corn hybrid here that is purple sometimes has a buildup of anthocyanins, causing changes in plant color, with warm weather followed by cold rain and weather.  Since the tissue came back low we can say here the color was likely caused by low P due to cool conditions and the hybrid response to it.

Here’s a photo with the purple corn in the foreground and the green corn in the background.

Corn Straightening Out

Corn is finally straightening out.  We’ve had some good weather right here recently. Some corn we checked today is in the V5 stage and is getting tall. Weeds are growing well too and palmer amaranth is emerging. Lots of corn sidedressing is going on and some fields that haven’t had it are looking somewhat deficient.  Weed controls are going out as well when the wind permits.

Wheat Condition Good – Ahead of Schedule

Wheat is really moving along.

I looked at many fields today and all are jointing and many have some flag leaves out. I even saw a couple of heads trying to show themselves. I didn’t find any Stripe Rust, thankfully. There is still plenty of powdery mildew out there, and if it climbs to within a couple of leaves of the flag leaf, we may have to spray an early fungicide. We usually like to delay fungicide applications until the heads are out to get disease control on them as well as the flag leaf.

I’m not too worried about recent leaching rains on the fertilizer except for on deep sandy soils where some may need some additional fertilizer if it was done right before the rains, but each situation needs to be carefully considered and some tissue testing may need to be done.  Fertility looks good in fields I was in today to the point where there was some slight lodging where the fertilizer truck turned around near the edges. These were not sandy fields.

Slight lodging(falling) where fertilizer truck turned around and put a little extra.

Dolomitic Lime has Magnesium

We’ve had some discussions lately about liming and liming materials. Sometimes Hi Cal (Calcitic ) Lime has been used at times as a calcium source for peanuts before planting and it works pretty well and it also raises pH. We don’t want pH too high however, we start getting over 6.7 and we begin seeing some induced problems with things like Manganese (Mn) deficiency.

Dr. Glen Harris, UGA Extension Soil Fertility Scientist, has the following to say about liming and changing soil pH.

Dolomitic lime (that has 6 % or more Mg) is still the most common liming material used in

Georgia and provides magnesium (Mg) as well as calcium (Ca) and a pH adjustment.

Calcitic lime (less than 6% Mg) is becoming more popular and may be used in cases where high

soil Mg levels occur, it has been used as a calcium source in peanuts preplant.

If calcitic Lime is used for consecutive years, soil test Mg levels should be tracked closely with soil testing.

As soon as soil test Mg levels start to drop out of the high range into the medium range, the use of dolomitic lime should be resumed. The reason for this is that dolomitic lime is the most economical source of Mg fertilizer.

Good Calf Crop – Now Mangage Grazing

Nicholas Smith with his excellent calf crop. It looked almost like 2 calves for every cow out there. They were watching the irrigated field of rye that will soon be ready to enjoy. Nick is holding them out for a while to get some more growth on it.

Here’s excerpts from an excellent publication by Dr Dennis Hancock, UGA Extension Forages Scientist. The full article can be found here, http://www.georgiaforages.com/ then go to FERTILIZING AND GRAZING WINTER ANNUAL STANDS

In Georgia, our biggest competitive advantage in the beef cattle industry is our ability to grow and graze

forage during the winter months. One of the most important parts of a winter forage program is, of course, the

cool season annual grasses. However, it takes skill (and a healthy dose of common sense) to manage winter

annuals so that the forage produced matches the stocking rate. Now that your winter annuals are in the ground

for this season, this article presents seven keys to optimizing the production and management of your winter

annual forage.

Avoid Grazing Too Early

There is a big difference between “can” and “should”. Grazing of winter annuals can begin as soon as

the plants are well‐established and have accumulated 3‐4 in. of growth. However, grazing should begin only

after the plants accumulate 6‐8 in. of growth. The plants will survive if they are grazed too early, but they will

never fully recover. Some recent research that Dr. Gary Hill and I have been doing in Athens and Tifton suggests

that starting to graze too early (i.e., at ~4 in.) reduces the total forage yield in the season by at least one third.

Start Light, End Heavy

Along those same lines, it is best to begin with a light stocking rate and gradually increase it as the

growing conditions improve and forage growth rate increases. A good way to do this is by restricting the

animal’s time on the paddock, rotating animals between paddocks, or using strip grazing techniques. But, later

in the season, the growth rate of the winter annuals will be much more rapid. If a light stocking rate is

maintained, much of the forage will get rank and overly mature. Ideally, more animals would be added to

increase the stocking rate. Of course, that usually is impractical. So, increase the stocking rate by reducing the

number of acres grazed. In practice, this means shutting animals out of some pastures or paddocks and letting

those areas grow up for hay or baleage. Be sure that you select those areas in advance, so that you don’t put N

fertilizer out if you don’t need the extra forage.

Know Your Forage

Our winter annual species differ a lot in their tolerance of grazing. Ryegrass and rye are generally very

tolerant of repeated grazing and generally regrow rapidly. On the other end of the spectrum, barley and triticale

do not regrow well after grazing. Wheat and oats are more intermediate, as they are quite a bit slower to

regrow than rye or ryegrass and have poor tolerance to heavy continuous grazing.

 

Yellow Areas in Peanut Fields?

We are seeing a good bit of yellowing areas in peanut fields.  It’s worse where we have high pHs.  We suspect most of this is the micronutrient Manganese (not Magnesium) deficiency. This is due to the fact that Manganese is not as available to the plant at a high pH.  We may want to spot spray manganese in these areas if we are 3 weeks or longer to digging.  In the fields where I took these photos this week, the pH in some areas was 6.5 to 7.1.  The narrowing band on the chart below from my old soil science book indicates the lessened availability when the pH gets higher.

Here are some comments from Dr. John Beasley, UGA Extension Scientist,  concerning this situation.

“ It looks as if the primary issue is manganese deficiency. If you look closely, the yellowing only
goes down 3-4 nodes from the terminal. Most of the leaflets are showing the
typical Mn deficiency symptom of interveinal chlorosis. You could soil
sample to confirm pH levels in those areas. Manganese
deficiency is associated with a high pH (6.5 or greater). The symptoms are
also associated with a flush of new growth due to more frequent rainfall events
and “slightly” cooler temperatures. If the fields showing the
conditions are within 3 weeks of harvest there is no economic advantage to
treating them. If the fields are greater than 3 weeks from harvest, spot
spraying the affected areas with manganese sulfate is recommended.”

Here’s some information from the UGA Plant Analysis Handbook concerning correcting Mn deficiencies in Peanut.

Manganese deficiencies may occur on sandy soils with a pH greater than 6.3. If
Mn deficiency occurs, apply a broadcast spray of Mn using 1/2 pound Mn per acre
as manganese sulfate or 0.15 to 0.25 pound Mn per acre as chelated Mn in 20
gallons of water per acre. If symptoms persist, the spray should be repeated at
2 week intervals. In most cases, multiple applications will be required. High Mn
levels are generally due to low soil pH.

UGA Grazing School – Cancelled for this year

 This has been cancelled for this year

September 18-19^th  the 2012 Grazing School will be held in Tifton, GA at the Tifton Campus Conference Center. Basic information about the Grazing School, including an outline of the program and times, is posted here:http://www.caes.uga.edu/commodities/fieldcrops/forages/events/GS12/GS12.html . The complete agenda and speaker list will be forthcoming.

This two-day workshop will focus on soil fertility, forage crop establishment, plant growth, animal nutrient requirements, and management-intensive grazing. Training will take place in both classroom and field settings. Multiple classroom lectures addressing plant and grazing management will be combined with hands-on activities at the UGA farms in Tifton. Demonstrations of fencing and watering options will highlight valuable management practices for livestock producers.

Cost of the two day program is yet to be determined but is set at our costs (usually $150-180 for the first person, $50 per extra participant from the same farm) and includes lunches and breaks on each day, a nice dinner on the first night, a grazing school handbook, a forage and weed ID handbook, and a copy of Southern Forages 4th Edition textbook. Participants are responsible for lodging.  Please note: registration is limited to 35 participants and is accepted on a first-come, first-served basis. You may want to register quickly. These spots fill up fast.

NOW is the Time to Apply K Fertilizer

We are experiencing some stand losses in bermudagrass. It is extremely important to maintain proper K fertility, not only for good yields, but also for resistance to disease. Below is some data from a recent study in Mississippi that shows the relationship.

NOW is the perfect time to fortify your stand’s K status. Applying K now can help promote excellent stolon and rhizome production. It also encourages healthy preparations for winter dormancy. For more on this subject go to County Agent Andrew Sawyer’s blog at http://thomascountyag.com/2012/08/10/time-to-apply-potassium/

Question of the Week – Fertility

Last week I had a photo of Cotton tall and short in streaks in the field. It was caused by a lack of fertility in those short cotton areas. There were peanuts in this field last year and the tall cotton is where the peanut hay was and so more nitrogen and organic matter was present. Also no preplant N was applied. So that increased the problem, here.

This week I want to know what is causing this leaf symptom in cotton?

Corn Sidedress Injury

This week we have been looking closely at field corn for disease and stink bugs.  There are other leaf symptoms that we see that we don’t need to be confused with something we need to be treated.

This is sidedress injury on corn.  When sidedress fertilizer is applied,  it often burns the leaves where it is caught in the whorl.  When they unfurl it looks like this.  You can see the burn in a kind of line across the leaves.   Also you will see it on most of the plants at the same level above the ground since it happened at a certain point in time.