Below is an update from UGA Extension Economist Dr. Don Shurley:
Here is some information UGA Extension Peanut Agronomist Dr. Scott Monfort put together on runner-type varieties grown in Georgia and Peanut FARM. The USDA Crop Acres Report is estimating Georgia producers have planted 800,000 acres of peanut. This is more than expected. With an expanded planting window, this will help growers manage the increased acreage at harvest but trying to keep track of maturity of these acres may prove to be daunting. One way growers can help track the maturity is through the UFL PeanutFarm Website. Based on research, 2500 aGDDs is near maturity for most medium maturing varieties. We want to start doing maturity checks in the 2350 to 2400 range.
Florida-07: This is a medium-to-late maturing peanut (150 days +)
FloRunTM ‘107’: This is a medium- maturing peanut (135 to 140 days).
Georgia-06G: Georgia-06G is a medium maturing peanut (135 to 140 days).
Georgia-09B: Georgia 09-B is a medium maturing peanut (135 to 140 days).
Georgia-12Y: This is a medium-to-late maturing peanut (140 days +) — May not follow board perfectly.
Georgia-13M: This is a medium-to-late maturing peanut (140 days +) — May not follow board perfectly.
Tifguard: Tifguard is a medium maturing peanut (135 to 140 days).
TUFRunnerTM ‘297’: This is a medium to medium-late maturing peanut (135-145 days)
TUFRunnerTM ‘511’: This is a medium to medium-late maturing peanut (135-145 days)
TUFRunnerTM ‘727’: This is a medium to medium-late maturing peanut (135-150 days)
Peanut FARM – Field Agronomic Resource Manager
PeanutFARM is a group of tools aimed at helping growers manage peanut development and maturity by tracking adjusted growing degree days (aGDD). aGDD’s use upper and lower daily air temperatures, plus the amount of water the crop receives from rainfall and irrigation, to predict the development of the crop. In addition to tracking maturity, aGDD’s are used by PeanutFARM to help schedule irrigation through estimating crop canopy cover and daily water use. This daily water use is then modified using weather data – which can be automatically drawn from state networks or input for individual fields, depending on grower preference. As the grower develops their own profile, each field can be managed separately and processed by PeanutFARM to accurately predict the need for irrigation and optimum harvest time. The purpose of PeanutFARM is to provide the producer with tools to ease both in-season and harvest management decisions.
Below are the three fields I have registered in the PeanutFarm program.
Field Status Report for Jul 2, 2015 for fields planted in Tifton, GA:
Here is a field of Leafy 22 Pearl millet used for grazing. Pearl millet is also used for hay and silage. We need to have 20 – 24 inches in height before cows start grazing. However, leaf spots showed up this past week. The spots are more pronounced in certain areas of the field, but mostly all leaves are covered in spots. The spots turned out to be Pyricularia Leaf Spot or Gray Leaf Spot. This is caused by the fungus Pyricularia grisea. This is a very common and important disease of Pearl millet. I have seen Pyricularia before on Pearl millet. UGA Extension Grain Pathologist Dr. Alfredo Martinez says newer dwarf varieties may have some resistance to Pyricularia. Usually fungicide applications are not recommended for pearl millet. Below is some more information on Pearl millet.
Our early planted sorghum is heading now and is past flowering stage. We are looking at a few different insect pest I want to write about. Some fields have sprayed 3 times now for sugarcane aphids. At this point, we want to watch for aphids in the grain heads. Also we are seeing caterpillars in grain heads. Last week, we were checking for midge.
Midge can be more difficult to scout for. Once grain heads come out, we need to be looking for midge. Once flowering is complete, midge is not an issue. One way to scout is take a paper plate, and slap the head in the plate. Dr. Angus Catchot, entomologist in Mississippi, shows on Scouting For Sorghum Midge With Confidence, a method of putting a gollon ziplock bag over the grain head and thumping it. The midges fly to the top of the bad, and you don’t have to close the bag.
UGA Extension Entomologist Dr. David Buntin says we need to avoid pyrethroids and insecticides that would flare aphid populations. Do not do automatic sprays for this reason.
We are also seeing caterpillars on the grain heads. Most of the caterpillars we are seeing are corn earworms. We were also seeing armyworms. Our threshold is to treat when an average of 1 or more (1/2 inch or larger) of any of these worms are found per grain head. Below is a photo of corn earworms on this head. Flowering is complete here, and they blend in to the grain.
One of the four fields we checked yesterday is at dough stage of development. Dr. Buntin says when we get to dough stage, we do not have the concern for sugarcane aphids. We still need to check for aphids in the grain heads, because of issues with harvest equipment from aphid honeydew. Here is a photo of some aphids in the grain head. This field is in the dough stage and past flowering, so pre harvest intervals are more difficult as we move to heading.
Some milo fields have been sprayed three times for sugarcane aphids. It is difficult to assess thresholds following a devastating 2014 season where aphids hurt us before we knew what was going on. However, Dr. Buntin believes we should be able to get SCA with two sprays during the season. We have learned to scout by not only checking aphids on a plant, but walking fields and looking for honeydew. It is easier to see honeydew on the leaves from a distance and you can check more than one row at a time. Where honeydew exists, this indicates a high aphid population – one that is treatable. Below is a photo of sooty mold on leaves. Sooty mold grows on the honeydew left from aphids. This is another indicator, however, I have not seen sooty mold show up until now. This is not an issue for the plants, just sign of aphids.
Here is an update from UGA Extension Irrigation Specialist Dr. Wesley Porter:
Our ample rainfall seemed to stop early later in May and into June. With the lack of rainfall we also had an excess of heat. Typically, peanuts do not require much water early in the season, but the lack of rainfall and extreme continual heat may have pushed some producers to turn their pivots on. I would say this was a good decision and recommended practice. We had depleted much of our non-irrigated soil moisture due to the hot and dry period.
As of June, we have began to pick up some rainfall from scattered mid-afternoon thunderstorms. These rains are beneficial and very welcome. However, high intensity rainfall does not do a very good job of refilling your soil water profile. Do not bank fully on these high intensity events to fully provide the required water you need.
Based on the split planting of peanuts due to the warm early season weather we will be moving into one of two stages during July, either ramping up to peak water use and then dropping off, or just getting ready to move into peak water use. The graphic below should give us an idea of where we will stand for the 4 weeks of July. Keep track of rainfall, and supplement it with irrigation. On rainfall events from 0.25” to 1” it is good to assume a 90% efficiency, and on events over 1” it’s probably safest especially if it is a high intensity event to assume around a 75% efficiency. Make sure not short yourself on soil moisture as this can be detrimental. Overwatering can hurt just as much as under-watering too. Remember this requirement is IRRIGATION and RAINFALL! Irrigation may not even be required in the first few weeks!
It is again time for pecan leaf sampling. UGA Extension Horticulturalist Dr. Lenny Wells says the recommended period for this is from July 7-August 7. The reason for this window of time is that the nutrients are at their most stable point here at mid-season. This gives us the best idea of the nutritional status of the trees. Prior to this some nutrients are increasing in the leaf, while others are decreasing and soon several key nutrients will begin declining in the leaf as the maturing fruit acts as a sink. For leaf sampling procedures, see the blog below from last July:
What should we be looking for in leaf samples? We may get a range of recommendations based on the results depending on the laboratory chosen. There have been recent changes to a few key nutrient threshold levels that we need to be aware of as we look at tissue results. Mike Smith from Oklahoma State was the lead author on a paper a couple of years ago that re-addressed leaf nutrient concentrations for pecans. His results led to the following recommendations and these ranges are the levels you should go by when making fertilization decisions:
Nitrogen (% ): 2.5 – 3.0
Phosphorus (% ) 0.14 – 0.30
Potassium (% ) 1.00 – 2.50
Sulfur (%) 0.20 – 0.35
Calcium (% ) 0.70 – 1.75
Magnesium (% ) 0.30 – 0.60
Boron (ppm) 15 – 50
Copper (ppm) 6 – 30
Iron (ppm) 50 – 300
Manganese (ppm) 100 – 2000
Zinc (ppm) 50 – 150
Nickel (ppm) Greater than 2.5
If trees have a pretty heavy crop load and leaf N is below 2.75, I would recommend the application of another 30-50 lbs N – depending on the total amount applied to date. With a heavy crop, K should be around 1.20, because the fruit begins to pull a lot of K from the leaves as they develop. Its difficult to reach 0.14% on leaf P in many cases. Most of the time soil P is adequate but uptake is a problem. If soil P is sufficient but leaf P is low, applying P as a banded application rather than a broadcast application is more effective in increasing P absorption.
Zn levels are often artificially high in commercial orchards due to the application of foliar Zn. There may be nutrient residues present on the leaf that are not actually present inside the leaf itself. To get a true reading, samples should be washed off with a 0.1% phosphate-free detergent and rinsed in de-ionized water prior to analysis. Since this is not practical for most producers, just know that if you have been spraying foliar Zn or other micronutrients and get very high results in samples, it is likely due to residue.