Monthly Archives: May 2014

Corn Issues Continue

BobbySmith-Corn 018

Corn is still looking rough in some fields. Michael Murray and I looked at some corn end of last week that was showing nutrient deficiencies. Corn appeared to have signs of nitrogen, sulfur, magnesium and potash deficiency, but tissue analysis show they were sufficient. Another thought was since Counter was used at planting, could it cause problems. You can have issues there if ALS herbicide were used along with Counter, but in this case, ALS were not used.

So far, a nematode analysis has been taken, and we cannot rule this out since reports of stubby root nematode have been common this season. The N:S ratio was 32:1 which should be less that 16:1. In either case, additional S is needed.  Mg and K should be checked again in two weeks to be sure that the plants are continuing to take up enough. Some 28-0-0-5 would help to get back some N and S.

Corn 007

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Soybean Planting Dates

It seems like everyone is scrambling to get caught up since rain has let off. Timing on cotton and peanut planting is not far off, but it could push back planting of other crops and force us to prioritize. I was asked about soybeans and effects of late planting. In this situation, we may need to prioritize. They were going to plant a maturity group 5, 6 and 7. These two slides from UGA Extension Soybean Agronomist, Dr. Jared Whitaker, show the effect of planting date on soybean yield:

The first slide shows overall yield affected by planting date.  Bottom line is that the later you plant the lower the yield potential.

SoybeanYieldPlantingDate

The second slide shows data demonstrating the effect maturity group has on planting date.  Bottom line here is that the earlier maturing varieties lose yield potential much faster as planting date gets later compared to later maturing varieties.

MaturityGroupPlantingDate

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Pecan Budmoth Damage

Pecan Budmoth 028

We’re starting to get caught up from a week of planting trials last week. Grady County Ag Agent, Brian Hayes, was with me when we stopped by Ronnie Herring’s house to look at some damage to his young Elliot pecans. The leaf tips appeared to be scorched and looking closer Brian found a little worm boring into the stem (below).

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Pecan Budmoth SymptomsIt appeared to be pecan budmoth. UGA Extension Entomologist, Dr. Will Hudson has some information in the Southeastern Pecan Growers Handbook:

The pecan budmoth (Gretchina bolliana) is a native pest of pecan and incurs most damage on young, transplanted trees. They overwinter as adults under bark scales then lay eggs on twigs, buds, and shoots in the spring. Once eggs hatch, the larvae feed on and in new buds, shoot apices, and leaves.

The larvae are creamy to dirty white at first, but mature budmoth larvae are one-half inch long, yellow-green, with dark brown head capsules. Once they finish feeding, the larvae pupate in rolled up leaves and damaged buds. It takes about a month for pecan budmoths to complete a generation.

Treatment of mature trees for budmoth is usually not needed or is accomplished through normal spraying of other pests. Control in nursery stock or for newly transplanted trees includes monitoring for budmoth infestation and treated according to need.

Pecan Budmoth

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Pecan Irrigation Schedule

Pecan growers need to be irrigating after a week of no rain. Here are some irrigation recommendations from UGA Extension Horticulturalist, Dr. Lenny Wells:

Pecan trees need as much as 350 gal/tree/day as they are filling the kernels in August and September. While they need good soil moisture throughout the growing season, the demand for water is much less early in the season than later. As the nuts begin to size, the demand for water increases, so growers need to begin applying water at low rates early in the season and increase as the crop develops.

Pecan-Irrigation-Schedule

We are fortunate in the Southeastern U.S.that we normally get enough rainfall throughout the year to account for at least 30-50% of the tree’s water needs. The problem is that the distribution of that rainfall is not always timely to the tree’s needs. The table above summarizes our irrigation schedule recommendations for bearing pecan trees in Georgia. Take note that the irrigation can be turned off for 3 days following rainfall events of 1″ or more per day. Orchards on sandy soils should lean toward the high end of the recommended range, while clay soils can lean to the low end.

We know that young, non-bearing trees (<5 yrs old) do not require near the amount of water applied to mature trees in late season. While we don’t have firm, research-driven numbers to provide for irrigating young trees at this point, we are currently in the process of developing these. In the meantime, the April or May rates applied to mature trees will work season long for young trees because there is no crop demand on them.

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Spring Transition With Overseeded Grasses

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Alan Poppell has done a good job managing this patch of bermudagrass as a field goal kicking practice field on a plantation. Generally, thin-blade grasses work better with overseeding than centipede or St. Augustine grass. But with another cool spring, cool season grasses like this
perennial ryegrass has been slow to die back.

Bermuda 005UGA Extension Turf Weed Scientist, Dr. Patrick McCullough, sometimes suggests herbicides to be used to aid in transition from cool season to warm season.

With temperatures steadily increasing this week, the ryegrass will start to dieback. With cool temperatures slowing transition, using a herbicide such as Katana or metsulfuron to knock back perennial rye would help. Here is a link to the turfgrass section of the Georgia Pest Control Handbook.

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Minimizing Injury From At-Plant Herbicides In Cotton

Comments about cotton injury caused by residual at plant herbicides recommended for management of glyphosate-resistant Palmer amaranth are starting. Since many herbicide recommendations are driven by herbicide resistance, sometimes we have to live with a small amount of crop injury.  Colquitt County Ag Agent, Jeremy Kichler, has done work in Pigweed management while he was in Macon County. Here are a few tips from Jeremy’s blog, Colquitt County Ag Report, to help minimize cotton injury from at plant residual herbicides:

  1.  Plant higher vigor seed
  2. Shallow planting depth increases injury potential
  3. Plant into a moist soil (preplant irrigation may be needed)
  4. Apply proper residual herbicides within 24 hr of planting
  5. Avoid irrigation within 30 hr of planting (36 hr if cold)
  6. Avoid irrigation 24 hr before and 48 hr after emergence
  7. Irrigate to develop the perfect cotton stand; however, limit irrigation events during the first 2 weeks after planting to as few as possible after activating residual herbicides

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Yellowing Corn

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After raining almost every day last week, I saw field corn that was yellowing. All plants had same symptoms and ranged from V2 to V5 growth stage. Some lower leaves were solid yellow indicating N deficiency and certainly nutrients have leached with rains. The stripes in leaves pictured below resemble Magnesium deficiency. For Mg, UGA Extension Fertility Specialist, Dr. Glenn Harris, says you can  spread Kmag, spray Epsom salts, or put Epsom salts through the pivot.

Corn 009

Seminole Ag Agent, Rome Ethredge, discovered field corn with Sulfur deficiency and nematodes. With corn yellow, he discussed 4 primary reasons we are seeing this now:

  1. Leaching rains have depleted nutrients such as Nitrogen and possibly Sulfur, and it’s time to add more but it’s too wet to run the spreaders or liquid rigs to put it out.
  2. Another reason is the erratic cool weather, with some very cool nights.
  3. Wet soil. The soil is staying so wet that we are loosing soil oxygen and that is bad for roots.
  4. Nematodes – which goes along with poor growing conditions. Nematodes affect the roots and therefore plant growth and health.

A last reason that we is not counted is that where over the top herbicide applications have been made, that many times further yellows corn for a few days as well.

 

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Fusarium Head Blight

Wheat-Fusarium 002

Mitchell County Ag Agent, Andy Shirley, and I were looking at some wheat around Ochlocknee yesterday and noticed some bleached and discolored heads infected with Fusarium Head Blight/Scab. Decatur County Agent, Justin Ballew found some last week around Bainbridge and Seminole Ag Agent, Rome Ethredge, posted some photos and information on Fusarium Head Scab on his blog. The problem has to do with weather conditions during  time of flowering and it doesn’t spread. Below is some information from UGA Extension Grain Pathologist, Dr. Alfredo Martinez-Espinosa:

“Historically, scab (Fusarium spp /teleomorphs Gibberella spp and Microdochium nivale) infections have been extremely low in Georgia. The pathogen requires warm (78-86 F consistently), humid/wet weather coinciding with wheat at flowering stages for infection to occur. Fusarium conidia and/or ascospores infection are most common at wheat anthesis.

Recently, while the weather has been wet across the state, the temperatures have remained low and therefore diminishing greatly the risk for infection. It is still worth to scout for the presence of scab in areas where flowering have coincided with wet/moist weather. Scab is best recognized on emerged immature heads where one or more or the entire head appears prematurely bleached. Usually a pinkish/orange mycelium is present, which will develop dark fruiting bodies (perithecia). Diseased, bleached spikelets are sterile or contain shriveled/discolored seed (usually with a tint of pink or orange).

An additional problem is that the fungus produces a compound in the grain that may be toxic to livestock and man. For control, avoid rotation with other cereal crops, specifically corn or sorghum.

Wheat-Fusarium 003

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