Monthly Archives: July 2017

2017 Stored Grain Protectants

For the first time in many years, we have many new products on the market. Here is an update from UGA Extension Entomologist Dr. Mike Toews and Auburn Entomologist Dr. Kathy Flanders:

Products for Empty Bins

  • Centynal EC – This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
  • Defense SC (labeled for empty bin use only) – This is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
  • Suspend SC – This is a good product for treating empty bins and elevator boots. Note that the active ingredient in Centynal EC, Defense SC and Suspend SC are identical so these are not good rotation partners.
  • Tempo SC (labeled for empty bin use only) – Tempo is a good product for treating empty bins and elevator boots, but is not labeled for application directly to grain.

 Products for Application to Grain

  • Actellic 5E (labeled for corn only) – This product has been the standard for many years, but it is expensive. A full rate will provide protection from weevils for 9-12 months. Reducing the rate will decrease the longevity of the protection. Our data suggest that Actellic is susceptible to heat degradation in the drier when grain temperatures exceed 120 F.
  • Centynal EC (labeled for corn and wheat) – Centynal EC is a new formulation that will provide 3 to 6 months of protection from weevils at the 0.5 ppm rate or 6 to 12 months of protection at the 1.0 ppm rate. This material is heat stable in the drier (tested up to 150 F).
  • Diacon (labeled for corn and wheat) – Diacon is an insect growth regulator that is effective for killing nearly all immature grain moths and beetles, except weevils. The 4 oz per 1000 bu rate is sufficient for tank mixing.
  • Diacon IGR PLUS (labeled for corn and wheat) – This product is a premix of Centynal EC and Diacon. See comments above for rates and activity.
  • Malathion (labeled for wheat and corn) – Although widely used in the past, this product is no longer recommended due to well documented resistance in many stored grain insect populations.
  • Sensat (labeled for corn and wheat) – This product is new to the market, but has been in our evaluation program for several years. Test results show excellent weevil control for up to 12 months. No dryer stability data at this time.
  • Storcide II (labeled for wheat only) – Storcide II is an industry standard for stored wheat, but is not labeled for use on corn. Protection will degrade with heat and time.
  • Suspend SC (labeled for corn and wheat) – This product is an older formulation that must be completely suspended before measuring and requires frequent agitation. It provides 3 to 6 months of protection from weevils.
  • Three-way tankmix (only tested on corn) – UGA tests from 2014-2016 showed that a threeway tank mix of Centynal (8.5 oz) plus Diacon IGR (4 oz) plus PBO-8 Synergist (13.5 oz) will provide 6-9 months of protection from weevils. This is a moderately priced option for growers in markets where other products are unavailable or cost is a limiting factor.

Regardless of the product used, be mindful that grain protectants are not a silver bullet. Shelled corn should be dried to a maximum of 15% moisture content before dropping it in the bin.

Chemical applications should only be made to clean grain that will be stored for more than 3 months. Apply protectants at the bottom of the auger in a course spray to maximize coverage as the kernels are moving up to the top of the bin. Long-term grain storage requires appropriate moisture content, proper housekeeping, use of a spreader when filling bins, and managed aeration.

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Scout Cotton For Corn Earworms

UGA Entomologists Dr. Phillip Roberts and Dr. Mike Toews put this information together on corn earworms in cotton.

During the past week we have received a few reports of escaped corn earworm CEW) larvae in Bt cottons which exceed recommended thresholds. Bt cottons are not immune to CEW and never have been. All Bt cottons should be scouted for CEW and growers should be prepared to react in a timely manner if thresholds are exceeded. We have planted Bt cottons for over 20 years.  The technology has moved from a single Bt gene to two gene and now three Bt genes. The addition of Bt genes was for two reasons primarily; 1) to improve efficacy and increase the spectrum of activity and 2) for resistance management. The slide below is a general rating for Bt cottons for various caterpillar pests.

Activity on CEW varies by technology, however all technologies should be scouted. Entomologists in Georgia and other areas of the cotton belt believe we are seeing changes in the susceptibility of CEW to some Bt genes. We have been fortunate in Georgia in that only a small percentage of Bt cottons have required treatment for escaped CEW in recent years. However we have observed changes in performance of Bt corn in recent years, i.e. seeing more damage to corn ears. We are also seeing more feeding on squares in Bt cotton which was very rare 5 years ago. One aspect of Bt cotton that we must not forget is that all Bt cottons continue to provide excellent control of tobacco budworm.

When scouting Bt for CEW cotton scouts should examine the top 12 inches of the plant for eggs and larvae and also examine one bloom, one bloom tagged boll (be sure to look under bloom tag), and an additional boll lower in the canopy. If any damage is observed on the plant the entire plant should be searched. It is important to size larvae as small (< ¼ inch) or large (> ¼ inch). Once larvae reach ¼ inch in length it is likely those larvae will survive on the Bt plant and continue to feed. When we observe escaped CEW larvae they are often associated with fruiting structures near the uppermost white bloom.  So make sure you check blooms, bloom tagged bolls, and small bolls closely. The slide below shows various images of CEW in cotton.

The threshold for CEW larvae in Bt cotton is when 8 larvae ¼ inch or greater in length are found per 100 plants. When treating escaped CEW in Bt cotton coverage and penetration of the canopy with sprays will be important.  We must get the insecticide to the target as larvae will likely be down in the plant canopy. Control of larvae in bolls and under bloom tags will be difficult.

Pyrethroids have been the standard treatment for CEW for many years.  In parts of the cotton belt pyrethroid activity on CEW has deteriorated. For example some states in the Mid-South do not recommend pyrethroids for control of CEW due to pyrethroid resistance and field control failures. We annually monitor CEW susceptibility to pyrethroids in Georgia using adult vial tests. Basically we capture adult CEW moths in pheromone traps and place those in pyrethroid treated vials and monitor survival. During recent years and especially during 2016 we observed increased survival of CEW in these tests which suggests susceptibility is changing. However, we have not observed or been made aware of any field control issues when pyrethroids have been used for CEW control. With that said, we have made few field applications of pyrethroids for control of CEW in any crop during recent years. Bottom line is it will be important for us to check behind pyrethroid applications targeting CEW. There are non-pyrethroid alternatives that will provide very good control of CEW.  The slide below illustrates CEW survival in pyrethroid treated vials.

 

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Pecan Fruit Thinning

If you have over 60% of the terminals bearing fruit, the trees will benefit from thinning. This will improve quality this year and generate a better return crop next year. UGA Extension Horticulturalist Dr. Lenny Wells says early to mid-October harvest varieties should be about ready for thinning next week. Most of our varieties should respond when thinning next week and at least the first half of the following week. Sumner possibly even a little later. To know exactly when to thin you will have to slice nuts open and look at the development of the ovule inside the nut

When do you thin?

In most years, there is a window of only 10 – 14 days in which fruit thinning can be done successfully. Research has shown that… nuts should be removed when the ovule (cavity inside nut in photo below) is 50% to 100% expanded, but before the kernel enters the dough stage. Thus, the calendar date for fruit thinning of pecan will vary with cultivar and location, as well as from year to year.

After the female flower has been pollinated and fertilized, the ovule (the tissue that becomes the kernel) begins to expand and lengthen from the tip of the nut toward the stem. As the ovule expands, the space inside is filled with a watery substance called liquid endosperm. After the ovule extends to the stem end of the nut, and the nut reaches full size, the shell begins to harden from the tip backward. When the ovule is completely expanded, the kernel begins to fill and nuts pass from the water stage to the gel stage, to the dough stage.

Ovule (cavity) on the right is 70-80% expanded where left cavity is just starting.

To observe of nut development, slice through the nut to expose the ovule. When the nut is removed from the tree, an oval shaped scar is left on the shuck. Cut the nut lengthwise at a right angle along the long axis of the oval scar. A straight, lengthwise cut exposes the expanding ovule and liquid endosperm within the nut. Thinning should occur when the ovule or kernel has extended to half the distance toward the stem end of the nut. The larger the nut size, the earlier in the ovule expansion period thinning can take place, because larger nuts are easier to shake off the tree

How much to remove?

The amount of nuts to remove varies with nut size, cultivar, crop load, and environmental factors. Judging the tree’s crop load is another important factor in the decision to thin. This is a practice that takes experience. The percentage of nut-bearing terminals can be developed by observing the number of fruiting terminals counted from an observation of 50-100 random terminals on a tree.

Trees with almost 100% of the shoots bearing fruit and a cluster size greater than three are overloaded and should benefit from thinning. Optimum crop load varies with cultivar and may range from 50-70% fruiting shoots. Varieties with small nut size can be thinned more lightly than those with large nut size. For example, optimum crop load on cultivars greater than 70 nuts per pound may be 60-70% fruiting shoots. Nuts in the size range of 50-70 nuts per pound, like Cape Fear or Stuart, have an optimum crop load of 50-60% fruiting shoots. While varieties with large nut size of less than 50 nuts per lb may have an optimum crop load of only 45-50% fruiting shoots.

Additional Tips

The major mistake growers make when first time attempting to fruit thin is not removing enough nuts. When shaking begins, don’t be alarmed by the number of nuts that fall. Trees should be shaken two to three seconds at a time, evaluated, and then shaken again if needed. This process should be repeated until the operator has a feel for how hard to shake to achieve the desired results.

Increased profit potential through enhanced size, quality, and return crop has so far been shown with mechanical fruit thinning on Cape Fear, Creek, Pawnee, Schley, Stuart, Sumner, Kiowa, Cheyenne, Shoshoni, and Mohawk. This does not mean that the practice is not profitable on other cultivars, but simply that it has not been adequately tested for those cultivars not mentioned. It is likely that most pecans with fruiting characteristics similar to those previously mentioned would respond favorably.

 

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Forage Insect Update

We have had an interesting year so far in our hay crop. Our dry Spring kept us from truly getting started, and the current rain is keeping growers from cutting. We have hundreds of acres that hasn’t been cut yet. If it has been cut, it’s mostly been cut once. There is a very small amount of hay that has been cut twice.

This may be one reason we are seeing stem maggot in some fields. I stopped by this field Wednesday, and a large section appeared frosted. Stem maggot has done lots of damage here. The good news is we have yet to see fall armyworms. This too may be cause the rain.

UGA Extension Forage Specialist Dr. Dennis Hancock has given an update on some other insect issues throughout the state:

Bermudagrass Stem Maggot

Damage from bermudagrass stem maggot

Reports of the bermudagrass stem maggot have been coming in from all over the Coastal Plain and into the southern 2-3 counties in the Piedmont. I suspect with the abundant rainfall in most places, we will see BSM pressures similar to the heavy pressure we saw in 2013. Producers need to employ the standard suppression technique (labeled pyrethroid of their choice 7-10 days after cutting and again 7-10 days later, as needed). Moderate N fertilization rates, and good K fertilization minimizes disease and this seems to minimize BSM activity (but it doesn’t eliminate it). In the past, we have recommended spinosad, as well. Current research indicates this is not as effective as we believed it to be. Pyrethroids are our best option currently. We have a new Extension bulletin on BSM found at Bermudagrass Stem Maggot Research Update.

Fall Armyworms

Reports of fall armyworm are also starting to come in. Producers need to scout and spray if the threshold is reached. The newest bulletin is Caterpillar Pests in Pastures and Hayfields.

Where BSM activity is high and FAW pressure is imminent, consider using Besiege (Lambda-cyhalothrin for the BSM and active FAW; Chlorantraniliprole for residual control of FAW).

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Timing N, Ca, and Boron On Peanuts

Peanuts are looking really good now. We are between pegging and developing seeds at this time. We are on our second and third fungicide applications across the county. We are starting to see evidence of caterpillars. I saw some three corner alfalfa hoppers yesterday as well.

UGA Extension Fertility Scientist Dr. Glen Harris wrote a good piece of information on timing nutrients in peanuts. (Since I already wrote about applying landplaster, I moved the calcium to the bottom since it is a lot to read.)

Timing is everything right? Well, that’s not exactly true when it comes to applying these fertilizer nutrients on peanuts. Rate, source and placement, to round out the “4Rs” of fertilizer management, are important too. When it comes to timing though, if you are too early or too late you could come up short on providing these key nutrients to peanut.

Nitrogen – If peanuts are inoculated or in a short rotation, they should not need any nitrogen fertilizer. This includes putting nitrogen in a starter fertilizer or spraying foliar nitrogen. However, in the case of an inoculation or nodulation failure, nitrogen fertilizer will be recommended as a “rescue” treatment. The timing for fixing this problem is critical and should be detected and fixed around 30 days after planting or soon thereafter. It only takes 60 lb. N/A to fix the problem. Yes, peanuts normally fix more N than that, but recent research as shown that 60 lb. N/A is enough. Split applications and rates up to 180 lb. N/A yielded no more peanuts than the 60 lb. N/A treatment. Ammonium sulfate also seems to be the product of choice in this situation.

Developing seed (R5 Reproductive Growth Stage)

Boron – Since boron is important for pollination and fruiting, the recommended timing for B applications on peanuts is early bloom. And since it is a micronutrient that foliar feeds well, the recommended practice is to include boron with early fungicide sprays. Can you apply boron to the soil at planting? Yes, but this timing may be considered too early since like nitrogen, boron can be highly mobile in soils, i.e. leach out and not be available later when needed. And how late is too late to apply boron? Again, since peak pod fill for peanuts occurs 60 to 90 days after planting, once peanuts are 80 days old or older, the chances of applying boron and getting a yield increase decrease dramatically. And what about rate? The UGA recommendation for B on peanuts is 0.5 lb. B/A. This can be applied in one application or split into 2, 0.25 lb. B/A applications. Rates higher than 0. 5 lb. B/A in a single application can cause burn to the foliage. Rates less than 0.25 lb. B/A, for example 6 ounces of a 5 % liquid B that only provides 0.025 lb. B/A, are considered ineffective and not economical.

Boron burn on peanuts

Calcium – The two most common ways of supplying calcium to the pegging zone of peanut are lime at planting and gypsum (calcium sulfate) at early bloom. Again, timing of applying these two is critical and is linked to the solubility of calcium in these materials. The calcium in lime is not as soluble as the calcium in gypsum so it must be applied earlier to give it time to get in the pegging zone. Applying lime at early bloom is too late.

What about applying gypsum at planting? I get this question all the time. While in some years you could probably get away with this, in other years, like this year for example, applying gypsum at planting would have been too early and not a good idea. Heavy rains on sandy soils can actually “leach” (dissolve and move downward) the calcium right past the pegging zone (top 4 inches). If you applied gypsum too early or if you got 4 to 6 inches of a “leaching rain” soon after application, then you may consider reapplying the gypsum.

Of course, you may want to take a hard look at if you needed gypsum in the first place by looking at your calcium levels and the calcium to potassium ratio in a soil sample from the pegging zone. And what if you are about 60 days after planting and don’t want to run over lapped vines and discover you need some calcium? The period from 60 to 90 days after planting is considered “peak pod fill” and research has shown that applying 10 gal/A of calcium chloride thru the pivot with irrigation water can provide some much needed calcium to developing pods. This treatment will not raise the soil test calcium levels like lime or gypsum will but can be effective.

And what about foliar feeding calcium? The answer for timing of that one is easy…never! Calcium simply does not translocate form leaves to developing pods plus you could never get enough calcium to the pods from a quart per acre foliar calcium even if it did work.

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Weather Outlook For July And Beyond

We are blessed with rain these past two months. In some cases, we have more than we want. Drought is almost entirely gone from the Southeastern US at this time. Rainfall across some parts of Georgia were abundant, with rainfalls up to 300% of normal. The rainfall and clouds have also kept the temperatures down below normal by blocking out the sun’s energy. Below is an outlook of what we may expect from here on from UGA Extension Climatologist Pam Knox:

The outlook for July and beyond shows that there is a continued chance of above normal rainfall for the next month, although that abates somewhat later in summer. Temperatures are expected to be closer to normal than in previous seasons, although there is not much skill in making summer forecasts, especially when ENSO conditions are neutral (not El Nino or La Nina). The neutral conditions do make it likely that the Atlantic hurricane season will be more active than usual, so some areas could see a lot of rain from any storms that do materialize, but of course we don’t know where those will go, so areas right along the path could see a lot of rain while others outside the path could see none, similar to what happened in 2016 with Hurricanes Hermine and Matthew across the Southeast. Because of the increased chance of rainfall and the cooler temperatures, I expect that irrigation will be less needed than in some previous years, but of course it depends on the growing stage of the peanuts and the type of soil they are in as well. Whatever rain does come is likely to be in hit-or-miss showers which may cause widely variable conditions across short distances.

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Spider Mites In Cotton

With this heat, it gets dry quick. I found a few plants with evidence of spider mites yesterday. This of course is not good since it is early. When we are scouting fields, look for spider mites. Look for the reddening on the “V” part of the leaf. UGA Extension Entomologist Dr. Phillip Roberts says early detection is critical.

**The best management practice is to NOT flare spidermites with unnecessary insect sprays. If our retention is good (plant bugs), stink bug threshold is low, and aphids have crashed, we need to hold back. It’s about to get hotter, and dry weather makes them worse too.

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