Archive for the ‘Fertilization’ Category
Posted by romeethredge on February 11, 2015
Small grains have looked rough this year for several reasons. Oats have suffered as they are more susceptible to cold and we’ve had another cold winter. Also, we’ve had leaching rains that removed nutrients. Most recently we are seeing some Barley Yellow dwarf virus (BYDV) transmitted by aphids. The darker aphid, Bird cherry- oat, is worse about causing this in small grains. We are seeing a good many of them now.
I talked to Brooks county Agent, Stephanie Hollifield and they have them there as well in oats and she’s seeing symptoms of BYDV. She has a good write up concerning this on her blog with some good photos at this link, Oats & Barley Yellow Dwarf.
Here’s some info on aphids from Dr. David Buntin (Entomologist at UGA Griffin) handy for your review: (more details available here: http://extension.uga.edu/publications/detail.cfm?number=B1190).
Aphids are small, soft-bodied insects that can be found in wheat anytime during the growing season. The most common aphids found on wheat are the bird cherry-oat aphid, rice root aphid, greenbug, corn leaf aphid, and English grain aphid. The first four occur mostly in the fall and winter. Only the greenbug causes direct feeding damage that appears speckled brown and discolored with some leaf curling. The other aphids usually do not cause obvious feeding damage. The English grain aphid is mainly present in the spring and can reach large numbers on flag leaves and developing grain heads. Damage from this pest can reduce kernel size and lower grain test weight. For the most part, beneficial insects such as lady beetles are not active during the winter and only exert some control over aphids during the spring in wheat.
Aphids also vector a viral disease named barley yellow dwarf (BYD) and a related disease called cereal yellow dwarf. Wheat and barley can be severely damaged, but oats are most susceptible to this disease. BYD is present in most fields in most years throughout Georgia. Yield losses of 5-15% are common but losses can exceed 30% during severe epidemics. Infection can occur from seedling emergence through heading, but yield loss is greatest when plants are infected as seedlings in the fall. Although all aphids can potentially transmit certain strains of the virus, infections in the Southeast are mostly associated with infestations of bird cherry-oat aphid and rice root aphid. Planting date is the single most important management practice, with early plantings generally have greater aphid numbers and greater BYD incidence than late plantings.
Systemic seed treatments, imidacloprid (Gaucho, Attendant, Axcess), thiamethoxam (Cruiser), and clothianidin (NipsIt Inside), are available for controlling aphids in the fall and winter and may reduce infection rates of BYD. These seed treatments are more effective in the northern half of the seed treatments have been inconsistent in control and are not recommended for routine use.A single, well-timed insecticide application of the insecticide lambda cyhalothrin (Karate Zeon, Silencer, and similar products) or gamma cyhalothrin (Declare) also can control aphids, reduce the incidence of BYD and increase yields. The best time for treatment in northern Georgia usually is about 25 – 35 days after planting although an application at full tiller also may be beneficial. In southern Georgia, the best treatment time usually is at full-tiller stage in early to mid-February. But, scout fields for aphids at 25 – 35 days after planting and during warm periods in January to determine if an insecticide application is needed. A lambda cyhalothrin or gamma cyhalothrin treatment at full tiller can be applied with top-dress nitrogen. OP insecticides, such as dimethoate and methyl parathion, also will control aphids but are not effective in preventing barley yellow dwarf infection.
To sample aphids, inspect plants in 12 inches of row in fall and 6 inches of row in winter. In spring, inspect 10 grain heads (+ flag leaf) per sample. Count all aphids on both the flag leaf and head for making control decisions. Sample plants at 8 to 16 locations per field.
Treat when populations reach or exceed the following thresholds at various stages of development:
Seedlings: 2-3/row ft,
30-60 days after planting: 6/row ft;
6-10 inch plants: 1 to 2/tiller
boot to heading: 5/stem
heading to dough stage: 10/stem
hard dough to maturity: damage not economic.
Posted in Agriculture, Fertilization, Forages, Wheat | Tagged: Barley Yellow dwarf virus, oats, wheat | Leave a Comment »
Posted by romeethredge on January 30, 2015
NRCS representative, Anita Tabb, here in Donalsonville, reminded me that 2015 is the “International Year of Soils”.
The soil that God created is a miraculous thing. It’s what plants grow in. Someone the other day said, “Most food comes from plants”, yes, but really all food comes from plants or animals and organisms that eat plants. Those plants mostly grow in soil.
My ABAC College professor, Mr. Sibbett, said “Dirt is what’s under your fingernails, soil is where plants grow.” I still lovingly call it dirt sometimes.
Here’s a good general 2 minute video about soil.
Posted in Crops, Fertilization | Tagged: soil | Leave a Comment »
Posted by romeethredge on January 26, 2015
We don’t want to over-fertilize wheat with N in the fall when wheat is planted as it may cause excessive growth and result in winter injury. We need most of it in late January and February as one or two sidedressings – depending on tillering. Total N will be between 100 and 130 lbs per acre.
When we plant wheat we don’t plant enough seed for each plant to just make one head. We want several heads from each plant. This time of year the plants are tillering or growing these multiple stems so that we’ll have more grain heads per plant in the field. Tillers — grain heads– kernels– yield.
Last week I did some tiller counts and we are behind in many fields, so we need to split our sidedressing. Often the wheat rows are 7.5 inches wide so we measure 19 inches down the row to get a square foot and count total tillers in that area. Once we know the average number of tillers per square foot we can make some decisions about wheat sidedressing. We want close to 100 tillers per square foot and if we are below that we generally go ahead with half our fertilizer sidedressing the last week in January and the rest the second week of February.
In this photo you can see there are 3 tillers on this plant.
If we have 100 or so tillers per square foot and good growth and don’t see much yellowing of the older foliage, we can wait until the 2nd week of February to put out all of our sidedress fertilizer.
Timing of N fertilization should be based on the pattern of uptake by the crop. Demand for N is relatively low in the fall but increases rapidly in the spring just before stem elongation. Therefore, make the fall applications of nitrogen at planting, and the remaining N prior to stem elongation. Use a lower rate of fall applied nitrogen at planting on heavier-textured soils and the higher rate on sandy soils.
Other nutrients should be applied according to a soil test preplant.
Since 65% of the total P uptake and 90% of the total K uptake occurs before the boot stage, these nutrients should be applied according to soil test before planting and thoroughly incorporated into the rooting zone
Posted in Fertilization, Wheat | Tagged: fertilization, wheat | Leave a Comment »
Posted by romeethredge on April 26, 2014
Our rainy conditions have leached some nutrients in corn fields and one of them is Sulfur. Sulfur is a nutrient that is not needed in high amounts but is needed by plants, especially corn. Sulfur is classified as a secondary element. In one of my soils classes at UGA we talked about that when we burned lots of coal, sulfur dioxide was put into the air and made it to our fields, but now we have to supply more than long ago.
Sulfur is essential in forming plant proteins and deficient plants look very pale yellow especially in new growth areas as it is not well translocated to new growth as some nutrients are. Cold wet soils delay the release of sulfur from organic matter as well.
Also, we can run into a problem when our N:S ratio is too high. In other words we need a certain amount of sulfur to go with our nitrogen and if we don’t have it then the Nitrogen doesn’t do as much good for the plants as it should.
In corn we want this ratio to be less than 16:1 or we don’t have enough sulfur in the plants. This tissue sample taken last week in a very yellow corn field shows this problem.
Posted in Corn, Fertilization | Tagged: corn, fertilization | 2 Comments »
Posted by romeethredge on April 18, 2014
Some of our corn is just coming up good but most is at V2 and the oldest is at V5 growth stage. Most of it has a yellow color for several reasons, here are the top 4 in my mind.
Leaching rains have depleted nutrients such as Nitrogen and perhaps Sulfur and it’s time to add more but it’s too wet to run the spreaders or liquid rigs to put it out.
Another reason is the erratic cool weather, with some very cool nights such as the unseasonable 38.5 degrees F on April 16th at the Donalsonville weather station.
A third reason is the wet soil. The soil is staying so wet that we are loosing soil oxygen and that is bad for roots. The plants are affected.
Reason number 4 goes along with the poor growing conditions, nematodes. Damage from nematodes in corn shows up much worse when we have poor growing conditions. Nematodes affect the roots and therefore plant growth and health.
A last reason that we won’t count is that where over the top herbicide applications have been made, that many times further yellows corn for a few days as well.
Posted in Corn, Fertilization | Tagged: corn | 6 Comments »
Posted by romeethredge on March 8, 2014
Last week I had a photo of a corn planting rig and my question was about the set of round coulters out in front of the set where the seeds are coming out. That set of coulters go into the soil about 2 inches deeper than the seed will be placed and about 2 inches to one side. There is a tube inside the coulters that pours out liquid fertilizer , we call it pop up. The placement is so that the young seedling will get it very quickly. But we don’t put it right in the seed furrow so as not to burn the seedling with the strong fertilizer. This is the preferred 2 by 2 starter fertilizer placement for field corn. It usually is mostly Phosphorus with some Nitrogen. Phosphorus is important for young seedlings , especially with cool soils.
I remember my ABAC Soil Science professor, Mr. Sibbett, teaching us about this in his, sometimes crude way. “Plants have trouble taking up phosphorus when it is cool, conso…dam…quently, we need some phosphorus close to the seedling. There…dam… fore starter fertilizer is important.” They broke the mold after making him.
Here is this week’s question.
I was called out to identify a floating pond weed yesterday. Here are 2 photos, what is it?
Posted in Agriculture, Corn, Fertilization, Wildlife | Tagged: corn, fertilization | 4 Comments »
Posted by romeethredge on February 28, 2014
We are spreading a lot of fertilizer in preparation for corn planting and its important to make sure you are getting a good pattern in the field. Most newer spreaders calculate the rate per acre for you, in other words, you may know how many pounds of material you are putting out per acre.
But we are also concerned with the spread over the area. We want an even spread with no heavy or light streaks. This UGA publication at the link below covers how to evaluate your fertilizer spreader in detail. Also most spreaders come with a good guide to help with this process.
Last week we checked out this spreader with Brad Thompson and with a few adjustments it is spreading evenly and doing a good job. We put out containers to catch fertilizer behind the spreader and put grates in them to keep bouncing out down to a minimum and then later poured them into vials so that we could line them up and see if there were problems.
We also ran the next through to see how much fertilizer came from next door to the run we were measuring, overlap.
Here, below we see how much overlap we have.
Fertilizer flying out onto the field.
Empty the pan into vials according to location of the pan.
Checking out the levels in the vials to see how good our spread is.
Posted in Agriculture, Fertilization | Tagged: fertilizer | Leave a Comment »
Posted by romeethredge on November 15, 2013
Preplant Nitrogen fertilizer will depend mostly on what was just harvested from the field this season. UGA Extension Grain Agronomist, Dr. Dewey Lee, says the amount of N we need depends on previous crop. Below are recommended N amounts:
Cotton – 35 to 40 lbs/ac
Corn or Fallow – 30 to 35 lbs/ac
Soybeans – 15 to 20 lbs/ac
Peanuts – 0 to 15 lbs/ac
Tillers produced in the fall generally produce the most grain per unit area. It is important not to over-fertilize with N in the fall as it may cause excessive growth and result in winter injury.
Total N will be between 100 and 130 lbs per acre. We need most of it in late January and February as one or two sidedressings – depending on tillering.
Timing of N fertilization should be based on the pattern of uptake by the crop. Demand for N is relatively low in the fall but increases rapidly in the spring just prior to stem elongation. Therefore, make the fall applications of nitrogen at planting, and the remaining N prior to stem elongation. Use the lower rate of fall applied nitrogen at planting on heavier-textured soils and the higher rate on sandy soils.
Other nutrients should be applied according to a soil test preplant.
Since 65% of the total P uptake and 90% of the total K uptake occurs before the boot stage, these nutrients should be applied according to soil test before planting and thoroughly incorporated into the rooting zone.
Posted in Fertilization, Wheat | Tagged: fertilization, wheat | Leave a Comment »
Posted by romeethredge on October 11, 2013
Bermudagrass Stem Maggot is a new pest that has only been in the US for a few years. This is the first time I’ve been sure that I’ve seen it in deep southwest Georgia. This Alicia Bermuda pasture has stem maggot damage as well as Leaf Rust due to the leaching and use of potassium causing a deficiency that goes along with the leaf rust. The Stem borer feeds into the stem and usually kills the top 2 or 3 leaves on the plant. There’s not a lot you can do about it but go ahead and make a cutting. there is ongoing research on insecticide sprays. You can go to a factsheet and a video by Dr. Dennis Hancock, UGA Forages Scientist, concerning this problem by going to our UGA Forages site. http://www.georgiaforages.com/
Posted in Entomology, Fertilization, Forages | Tagged: entomology, forages | Leave a Comment »
Posted by romeethredge on August 8, 2013
A big fertility issue with peanuts this year that was caused by the unusually wet weather is delayed gypsum/(landplaster) applications.
Dr. Glen Harris, UGA Extension Soil Scientist, gives us the latest info concerning this.
The recommended time to apply gypsum is early bloom, which normally occurs around 45 days after planting (or maybe as early as 30 days after planting). Many peanut fields were simply too wet to apply gypsum at this time. How late is too late to apply gypsum ? Again, since the “peak pod fill” period is 60 to 90 days after planting, and this is time when developing are “sucking in” calcium dissolved in the soil solution directly through the hull, once you get to 100 days after planting, it is definitely too late to apply gypsum. What about 60 days after planting ? Well, 60 days after planting is better than 70 days after planting… which is better than 80 days after planting (you get the idea).
Two other things to keep in mind if you are considering a late (60-90 days after planting) gypsum application though are 1) will you do more damage running over lapped vines than you gain by adding calcium?, and 2) Did you really need a gypsum application in the first place? Remember that if you had at least 500 lb/a of soil test calcium in the pegging zone (top 3 to 4 inches of soil) AND a calcium to potassium ratio in this soil sample of at least 3:1 or better, AND you are not producing peanuts for seed….than you technically did not need a gypsum application at all. I hear about many soil samples being in the 700, 800, 900 even 1000 lbs of Ca/a and with all the rainfall we have had there should be plenty of soil water in the pore space to dissolve the soil calcium and get it into the nuts.
Posted in Fertilization, Peanuts | Tagged: fertility, peanuts | 2 Comments »