Monthly Archives: April 2017

2017 Sugarcane Aphid Management In Grain Sorghum

Sugarcane Aphids

Here is the newest management prodecdures for sugarcane aphids in grain sorghum from UGA Extension Entomologist Dr. David Buntin:

1) Plant early – Because the aphid migrates northward in the spring, early plantings may avoid may avoid very large infestations.   Late planted double-crop plantings are at greater risk of severe infestations.   

2) Plant a tolerant hybrid/variety – Some hybrids have been shown to have some partial tolerance to the aphid.   This table from the Sorghum checkoff program and ratings for the Georgia Statewide variety trial lists grain sorghum hybrids with some degree of tolerance to SCA.   In my own trials the most tolerant grain types were in alphabetical order Alta AG1201, Dekalb DKS 3707 and DKS 4807, Pioneer 86P20, Sorghum Partners 73B12 and Warner W-7051 (tall, late variety).

http://www.sorghumcheckoff.com/farmer-resources/grain-production/hybrid-selection

http://www.swvt.uga.edu/2016/sysr16/AP103-8-sr-resist.pdf

Sugarcane aphids populate under grain sorghum

3) Use an insecticide seed treatment – My trials last year found that insecticide seed treatment would limit seedling infestations for 30 – 40 days after planting.   All registered neonicotinoid insecticides are effective including thiamethoxam (Cruiser), clothianidin (Poncho, NIpsIt Inside) and imidacloprid (Gaucho, others).   Most grain sorghum seed was treated with one of these seed treatments in 2017.

4) Scout early and often – Fields can quickly be inspected for the presence of aphids by looking are on the underside of leaves.  Once aphids are detected, scout at least once, preferably 2 times per week, because aphid numbers build very quickly.  Shinny lower leaves with honeydew are a clear sign of infestation. 

5) Beneficial insects usually do not control infestations – SCA and their honeydew attract large number of beneficial insect predators such as lady beetles, syrphid fly larvae and lacewings.  A parasitic wasp is present in and caused infested aphids to turn a dark blue-gray color.  No aphid fungal disease has been observed either.  Generally the rapid rate of increase in aphid populations overwhelms the beneficial insects and severe plant damage usually occurs. 

6) Treat when aphids reach threshold levels – The current threshold is 50 or more aphids per leaf on 25% pf plants preboot stage through dough stage.  Once threshold is reach do not delay application because infestations can very quickly go from the threshold level to 100% infested plants and hundreds of aphids per leaf.  

7) Use an effective insecticide – PYRETHROID INSECTICIDES ARE NOT EFFECTIVE and may flare infestations by killing all the aphid predators.  Regardless of the insecticide, rapidly expanding populations are difficult to control.  Foliar insecticide options for SCA in Georgia are:

  • Sivanto Prime (Bayer Crop Protection). Sivanto prime has a full section 3 label and a supplemental 2ee label for lower rates on sorghum and other grain crops. The 2ee rates are 4 – 7 fl. oz per acre. Sivanto was very effective in my trials at rates of 4 to 7 fl. oz. per acre with Control usually lasting 21 days or more. At the 4 oz rate it can be applied up to 7 times during the season but has a 21 day PHI.
  • Transform WG (Dow AgroSciences). Transform WG federal label was re-instated last year but sorghum is not on the full federal label. But Transform WG has an approved Section 18 emergency exception for use on sorghum in Georgia in 2017 but the label has not been issued yet. The label will allow for 2 applications per season and not more than 3 oz per acre per crop and has a 14 day PHI. Transform cannot be used during bloom to protect pollinators. In my insecticide trails last season, rates of 1.0 and 1.5 oz per acre were effective. Use the 1.5 oz rate if aphid populations are increasing rapidly.
  • Chlopyrifos (Lorsban Advanced, Nufos, other).   Chlopyrifos is labeled at 1 to 2 pints per acre. The 2 pint rate has a 60 day harvest interval. The 1 pint has a 30 day harvest interval, but is usually not effective. The 2 pint rate was 60-90% control for about 10-14 days. At the 2 pint rate it cannot be used after the boot stage due the 60 day PHI. DO NOT USE CHLORPYRIFOS ON SWEET SORGHUM.
  • Dimethoate ( Dimethoate, Cygon). Not recommended. In my trials dimethoate is variable in control and control if it occurs is only for a week or so.  

8) Good coverage is key to effective control.  Use tips and GPA for maximum coverage especially lower in the canopy. A minimum of 10 gpa by ground and 5 gpa by air is highly recommended.

9) Avoid pyrethroid insecticides for other sorghum pests.   For sorghum midge try to avoid routine pyrethroid sprays for sorghum midge.  Instead scout and treat at 1 adult per panicle.  Chlorpyrifos (1 pint per are) for low to moderate infestations.   If pyrethroids are used they can be tank mixed with Sivanto (Do not use Transform during bloom). Early plantings often avoid serious midge infestations.  For fall armyworm in the whorl, the threshold is 50% infested whorls.  Use Belt, Prevathon or Lannate which are specific to caterpillars.  For headworms, corn earworms fall armyworm, sorghum webworm, the threshold is 1 worm per head and use Belt, Prevathon, Beseige or Lannate.

10) Check fields 2-3 weeks before harvest for infestations.   A treatment may be needed if large numbers are in the head to prevent damage to combines.  Hybrids with taller stalks and more space between the grain and upper leaves may make harvest easier by reducing the amount of leaf material going through the combine.  Large infestation producing large amounts of honeydew and sooty mold may interfere with harvest desiccants.  Transform WG can be applied up to 14 days before harvest.  

11) Silage/forage sorghum control. No work was done specifically on SCA control in silage/forage sorghum.   So the same recommendations for grain sorghum also apply to silage and forage sorghum.   Both Sivanto prime and Transform can be used on silage and forage type sorghums.   Grazing / hay interval is 7 days for both products.  Chlorpyrifos at 2 pints per acre has a 60 day grazing forage, hay interval so is usually not an option for forage and hay sorghum.  In forage/hay types, the later cutting were damaged last year.  Spray coverage is difficult when plants get tall.  If aphids are present but below threshold consider a spray application as late as possible before the crop gets too tall.

12) Sweet sorghum. Sivanto prime, Transform and chlorpyrifos cannot be used on sweet sorghum. There currently are no effective treatment options for sweet sorghum. A section 18 request for use of Sivanto prime on sweet sorghum has been submitted to Us-EPA but the request is still pending.

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2017 Glyphosate-Resistant Palmer Amaranth Control

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Pecan Fungicides Begin

Young Trees

All of our pecan fungicides have begun at this point. We have lots of newer planted trees in the county, here are some being sprayed last week. UGA Extension Horticulturalist Dr. Lenny Wells says trees in the first few years need to be sprayed but not on a detailed spray program. For very young trees, a few fungicide applications in a season with some Tin is good. Once the trees approach production age, we need to add a few more sprays throughout the season and get closer to a full spray program.

Timing

In our area, we have been hit so hard with scab that we tend to get our fungicide sprays out real soon. Dr. Wells always says we can wait a little longer than we do. He was down last week looking at a fertilizer situation, and we looked at trees around that were leafing out at different times. He explained the issue with spraying early is not having enough leaf area for the fungicide to contact.

The most difficult part is managing orchards for more than one cultivar, which all are pretty much the same. If Desirables are in the orchard, we have to begin spray on their schedule since they are more susceptible for scab. If an orchard doesn’t have desirables and mostly Stuart, you can wait until those leaves come out. Here is a few pictures of optimum fungicide initiation Dr. Wells and I looked at in an orchard last week.

Left – This is time to spray Desirable
Right – This is too early for Desirable

Optimum time to initiate Stuart fungicide sprays

Fungicide Schedule

Below is an 8-spray fungicide schedule from UGA Extension Horticulturalist Dr. Lenny Wells provided as an example to use for pecan scab management in light of emerging scab insensitivity issues surrounding some fungicides. Since Tin is an integral part of our fungicide arsenal for pecans, and we do see some orchards with insensitivity to Tin, we are recommending saving any Tin sprays for the nut scab period since this material is better on nut scab than it is on leaf scab.

1. Absolute

2. Tebuconazole+Topsin M+Phosphite

3. Absolute+Phosphite

4. Elast/Tin

5. Absolute

6. Elast/Tin

7. Elast/Tin

8. Elast/Tin

If rainfall during the growing season is excessive, more than 8 sprays will be required for management of scab on susceptible cultivars. Therefore, the following program serves as an example of how to accommodate this need:

1. Absolute

2. Tebuconazole+Topsin M+Phosphite

3. Absolute+Phosphite

4. Elast/Tin

5. Absolute

6. Elast/Tin

7. Elast/Tin

8. Quadris Top

9. Elast/Tin

10. Elast/Tin

These examples serve only as two possible options for fungicide programs to manage scab. Many more could be developed. If an orchard has a documented high level of insensitivity to any of the fungicides listed above, the grower should contact one of the UGA Extension for specific recommendations.

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Disease & Nematode Management Considerations For 2017 Peanut Planting

Peanut growers can use a different products at planting time for the management of diseases and nematodes. Decisions as too what product to use over another, or to use a product at all, can be very confusing. Fighting seedling disease used to be simple- all growers used a fungicide seed treatment, and if they wanted some “stand insurance” they could also spray Abound in-furrow. Today, in-furrow applications are important considerations for the management of tomato spotted wilt, seedling diseases, Cylindrocladium black rot, white mold, and nematodes, not to mention thrips! Below are management options for the growers put together by UGA Extension Pathologists Dr. Bob Kemerait, Dr. Tim Brenneman and Dr. Albert Culbreath:

Note: The rates provided here are on a “per/A” basis. Typically, the full rate can be placed in single rows; the rate is typically halved per twin row. For example, Abound, 6.0 fl oz/A in-furrow for single rows becomes Abound, 3.0 fl oz/A in each of the twin rows:

Management of Tomato Spotted Wilt

Tomato Spotted Wilt Virus

A number of products can be used to manage thrips on peanuts. However, only one product, Thimet (ai: phorate) is effective in reducing the risk to this disease. The reduction in risk to tomato spotted wilt is not related to the thrips control that it provides, rather is seems to be associated with the response of the plant to Thimet. Thimet likely activates defense-response genes in the peanut plant that help to protect the plant from the virus. Growers who want to plant early (before May 1), or who want to use cultivars with spotted wilt risk points greater than those of Georgia-06G, might especially want to consider to using Thimet for management of tomato spotted wilt.

Management of Seedling Diseases

Peanut seed and young seedlings are susceptible to attack from a number of fungal pathogens. The two most important fungal pathogens causing death of peanut seedings in Georgia are Rhizoctonia solani and Aspergillus niger. Fungicide seed treatments are a critical tool to manage seed rots and seedling diseases; currently nearly all seed is treated with Dynasty PD. Dynasy PD is composed of azoxystrobin, fludioxonil, and mefenoxam. However, growers can also protect the developing plants from seedling diseases with in-furrow fungicide applications of fungicides like Abound (5.7-11.4 fl oz/A), Proline (5.7 fl oz/A), and Evito (2.3-3.5 fl oz/A). These fungicides are typically used to compliment seed already treated with a fungicide seed treatment.

Aspergillus Crown Rot

The most effective in furrow spray for stand establishment has been Abound, although Proline also has activity on these pathogens and Evito is labeled for this use as well. The benefits of these products have not been as consistent in recent years, and research is underway to determine the factors involved.

Management of Cylindrocladium black rot (CBR) and early-season white mold

Proline (5.7 fl oz/A) applied in-furrow has been an important treatment for the management of CBR. Though this disease has been less widespread in recent years, an application of Proline in-furrow is still useful where there is a threat of CBR. When favorable conditions, such as very warm weather, occur early in the season, in-furrow applications of Proline also offer some protection from early-season white mold. The extent of the protection is likely less than that provided by banded applications of Proline 3-5 weeks after planting. Decisions to use Proline in-furrow should be made based upon a) risk to CBR, and b) risk to early-season white mold (although there are effective alternatives for white mold).

Mycelium and sclerotia (yellow bee bee’s) from white mold

Management of Nematodes

Nematode-resistant cultivars continue to hold up well against even high populations of root knot nematodes. However, growers electing to plant a susceptible cultivar like Georgia-06G in fields infested with the peanut root-knot nematode should consider the use of a nematicide. Popular nematicides for peanut production in Georgia include Telone II (4.5-6 gal/A), Velum Total (18 fl oz/A) and AgLogic 15G (7 lb/A). To prevent injury to seed and seedlings, fumigation with Telone II should occur 10-14 days prior to planting and when soil conditions are not too dry (powder) nor too wet (mud). Fumigation with Telone II can provide excellent control of nematodes but DOES NOT control thrips. Growers who use Telone II must still apply something for management of thrips.

Velum Total is a combination of fluopyram for management of nematodes and also imidicloprid for management of thrips. Growers who use Velum Total do not need to add any additional thrips control product in the open furrow. (Note that imidicloprid does not reduce the risk to tomato spotted wilt.) Also, use of Velum Total does provide additional early-season management of leaf spot diseases. The extent of this protection from leaf spot is such that growers should be able to skip the 30-day after planting fungicide application for leaf spot, unless they have planted a very susceptible cultivar like ‘Georgia-13M’ or TUFRunnerTM’511’.

A question that often arises is, “If I use Velum Total, do I get any protection against seedling diseases as well?” The “bottom line” to this question is that use of Velum Total should complement a seed treatment and be good “stand insurance” and we would not add anything else. The biggest factor by far to reduce the impact of seedling disease is the quality of the seed and putting that seed in the right soil conditions at the right time.

AgLogic 15G (7 lb/A) is for management of thrips and nematodes. AgLogic does not reduce the risk to tomato spotted wilt. The rate is lower than what was historically used for Temik 15G (10 lb/A). Additional research is needed to assess the efficacy of the 7 lb/A rate on management of nematodes. In high risk field it may be advisable to use a combination of these nematicide options.

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Updated Climate Outlook For Summer 2017 And Beyond

Just as we started planting peanuts this week, some growers stopped for lack of moisture. It is very dry and has been for a while. Our last good rain was 3 weeks ago, and subsoil moisture is also low. We’ve been discussing potential weather this year and most talk about the expected heat. But what about other predictions? UGA Extension Climatologist Pam Knox has an update.

In spite of the cold outbreak in mid-March across the Southeast, year-to-date temperatures are in the top five warmest on record for most parts of the peanut-growing region. The average temperatures from January 1st on have been an average of five degrees above normal. The result of that early warming in spring was that many plants came out of winter dormancy almost three weeks earlier than usual.

Rainfall across the area has been somewhat variable, with the year-to-date totals showing below average precipitation, although the first week of April brought flooding rain to many places in the Southeast. The early dryness has caused deficiencies in soil moisture which have led to the development of “abnormally dry” conditions across the region according to the Drought Monitor, although those have been somewhat reduced by the rain last week. Streamflow in many rivers has also been below normal because the early-growing plants sucked up any available moisture that fell, leaving less to move into the ground or run off.

The short-term and long-term outlooks show that temperatures are likely to continue to be above normal. In the near term, our weather is likely to be dominated by high pressure, which will keep skies sunny and temperatures on the warm side. A few passing fronts may drop some showers but no big rain events are currently expected, which may bring abnormally dry soil conditions to the area, especially as warmer temperatures lead to higher evaporation rates.

Over the rest of the growing season, the likelihood of above-normal temperatures continues all the way into next winter. This is based on trends towards warmer temperatures that have occurred across the region from the 1970’s on as well as the absence of a strong El Nino or La Nina. Prediction of precipitation is difficult in neutral conditions, and NOAA’s Climate Prediction Center shows equal chances for below, near and above normal precipitation in the next year, indicating their lack of skill. However, they do provide a hint of above normal rainfall in the western Gulf of Mexico region which may be tied to unusually warm waters which are present now in the western Gulf.

ENSO conditions are currently in the neutral phase, which means that no La Nina or El Nino is present. While spring is a tough time to predict the phase of El Nino in the coming fall and winter, climate forecasters currently believe that an El Nino is likely by mid- to late summer. With this in mind, the forecasts for the Atlantic tropical season predicted that there will be fewer than usual storms, because the developing El Nino’s strong subtropical jet stream will “blow the top off” of any developing storms, keeping them from getting strong enough to become full-fledged storms. I think that with the Gulf of Mexico having such warm water temperatures now, we may see some early storms develop in that region, potentially bringing rain to the Southeast as the storms move out of the Gulf. Later in the season – if the El Nino develops as expected – less tropical storm activity is likely, leading to a potential for another dry fall. Of course, as we saw last year with Hurricane Matthew, a single storm can cause all kinds of havoc with winds and flooding rain, so even in a season that is not very active, you can still get tropical impacts.

The bottom line: expect warmer than normal temperatures to continue through most of the growing season (with some breaks for cool incursions from time to time), more rain early in the growing season,and a potential increase in dry conditions later in the year in areas that are not directly affected by any passing tropical storms.

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2017 Pecan Beginner’s Course

The 2017 Pecan Beginners Course will be held at the UGA Tifton Campus Conference Center in Tifton. GA on Tuesday, April 18, 2017. There is a registration fee of $10 . Registration at the door will be $15 until we reach capacity of 300 people. Please pre-register so that we will have a head count for the meal. Lunch and refreshments will be provided.

Register at the following link: Pecan Beginners Course Registration

The program for the course is found below:

9:00        Welcome                                                                                           

9:10        Cost of Pecan Production                                                                            

Lenny Wells, UGA Horticulture

9:30        Pecan Varieties                                                                                                                                               

                Patrick Conner, UGA Horticulture            

10:15     Break

10:45     Pecan Irrigation                                                                               

Lenny Wells, UGA Horticulture

11:15     Pecan Tree Planting & Establishment                                   

Lenny Wells, UGA Horticulture

12:00     Break for Lunch               

                Meal Sponsored by Savage Equipment                                 

1:00        Pecan Insect Management                                                                                                         

Will Hudson, UGA Entomology

1:45        Pecan Fertilization

Lenny Wells, UGA Horticulture

2:30        Break

2:50        Pecan Disease Management

                Jason Brock, UGA Plant Pathology

3:20        Pecan Weed Control

Timothy Grey, UGA Crop & Soil Science

4:00        Pecan Equipment

Lenny Wells, UGA Horticulture

Please contact Debbie Rutland @ 229-386-3424 for further infromation

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Planting Peanuts

A few growers have started planting peanuts late this week as subsoil moisture comes more of an issue. Most growers will want to pull the trigger next week. We’re planting right now with some fungicide and inoculant in furrow. Here is a few pointers from UGA Extension Agronomist, Dr. Scott Monfort and Dr. Scott Tubbs:

Soil Temperature

It is recommended that the average daily soil temperature remain above 68 degrees for 3 consecutive days and without cold temperatures in the forecast for the next week before making the decision to start planting peanut. With a warm winter so far, the temperatures had been in the “acceptable” range of conditions … during the last week of March.

armer temperatures are expected to return during the week of April 10-16, and I anticipate the 4-inch soil temperature will warm quickly to a point acceptable for planting by the middle of that week. There are no other cool spells showing in the extended weather forecast through April 21, so I anticipate peanut planting should be in favorable conditions sometime next week including adequate soil moisture because of this past week’s rainfall.

It is important to watch for additional rainfall in the forecast, especially under non-irrigated conditions, in order to activate herbicides after planting. Even with soil temperatures above 68 degrees, it will often take peanuts 7-14 days to emerge from the ground in these conditions (with cooler night temperatures still causing some fluctuations in soil temperatures). In ideal conditions, growers would want to plant with adequate moisture, sustained 68 degrees at the 4-inch soil depth, no cool temperatures expected in the 10 day forecast, but some rain expected within one week of planting in order to ensure optimal peanut emergence and herbicide activation to give the best possible growing conditions from the beginning. Hopefully we can get some peanuts in the ground a few days on either side of Easter this year and catch a rain the following week to get this season off to a great start.

Inoculants

Last year was a very hot and dry year. In those conditions, the survivability of the living Bradyrhizobia bacteria needed to inoculate peanuts is generally reduced. Thus, there may less than adequate nodulation of peanut in some fields or some parts of fields if relying solely on native soil Bradyrhizobia to infect the roots of peanut for N-fixation this season. This is true even if planting in short rotation where peanut was planted within the last few years.

I would recommend growers strongly consider the investment in a peanut inoculant at-planting this year, especially in fields that did not have any cover crop residue on them last year to minimize direct heat impact and reduce evaporation of soil moisture in the upper portion of the soil profile. It has been stated before by my predecessors and colleagues, an inoculant application is one of the most cost-effective “insurance policies” at a grower’s disposal.

Depending on the product used and contract price received for peanuts, it usually takes in the neighborhood of 100 lb/ac yield increase to cover the cost of the product. It is common in my research trials and in reviewing research from colleagues to get greater than 100 lb/ac yield increase on average over multiple years of trials even in a standard rotation. More importantly is to consider the cost of NOT applying an inoculant and having a nodulation failure where there is not adequate N-fixation. The cost of applying the amount of N needed by peanut would greatly exceed the cost of applying an inoculant over the course of many, many years. The risk of not getting a return on investment for an inoculant compared to the risk of potentially losing a large proportion of yield potential one year is not an equal level of risk in my opinion.

Keep in mind that the product is listed on the label to be delivered at around 1.0 fl oz per 1,000 linear row feet (may differ slightly depending on which product is selected). This is developed for single row application! Inoculant application is not like adjusting seeding rate, where you are pulling half of the amount out and moving it over to the adjacent twin furrow. With an inoculant, the applied amount needs to be per furrow according to label instructions. Therefore, a twin row planting inoculant application will double the amount of inoculant applied compared to a single row planting. I have no data at this time to support using a half-rate of inoculant per furrow to keep the total application rate per acre the same as a single row planting.

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