Monthly Archives: June 2015

Corn Progressing Through Milk Stage

Milk Stage (R3)

Milk Stage (R3)

Here is dryland corn in Pavo that does look good. We’ve had more rain on the east side of the county. This corn is in the early milk stage (R3) of growth. Plants defined as R3 have kernels with a “milky” interior and explode easily when a kernel is mashed.

We were looking for southern rust.  Southern rust overwinters on corn in Mexico, Caribbean and Central America. Rust has not been found much since the location in Mitchell County two weeks ago. This could be because of not having tropical storms yet, and corn that is being protected with fungicide. This is helping us stay ahead of rust in 2015 unlike last year. Still, we need to be alert after the find of southern rust. We do have increase chance of rain next week and warm temperatures which is more conducive for disease.

What Stage of Growth is Corn Safe?

Much of the corn crop though, is silking to early ear development (R2/R3) which adds roughly 2 to 3 weeks of time to our potential spraying. UGA Extension Pathologist Dr. Bob Kemerait and Agronomist Dr. Dewey Lee say that a crop is likely to benefit from protection from southern rust until the ears reach the hard dough (R4) growth stage. Southern rust is less likely to adversely affect the cron crop if it occurs after the corn has reached the dough stage. Here is a blog post from Mitchell County Agent Andy Shirley of Corn Denting.

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Filed under Corn, Disease

Sugarcane Aphid Populations Increase

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Our earliest planted milo is booting now where sugarcane aphids were found two weeks prior. Infestations have increased to treatable thresholds. This field is 5 miles south of where SCA were originally found and are 100% infested with aphids covering 30-50% of the plants. This level is very high.

In many fields, I only find aphids in 1 or 2 spots. This makes scouting difficult if we want to catch them early. One thing to look for is shiny or glossy appearance on the leaves (as seen above). This is honeydew which is the sugary-rich liquid excreted from aphids and soft b0died insects. Even in a low infested field, you will see a little bits of a glossy substance on the tip of a leaf. Once you see this, turn it over and inspect for aphids. This is where I have found most of our hits in the field.

Threshold/Treatment

Threshold – Several threshold levels are being used in the Delta region for 2015.  One conservative threshold is 25% infested leaves with 50+ aphids per leaf at whorl from preboot stage through dough stage.  In MS, the threshold at pre-boot and boot stages is 20% infested plants with large aphid colonies (100+) and localized areas of heavy honeydew present.  From bloom through dough stage the threshold is 30% infested plants.  I think either of these sets of thresholds will prevent serious yield losses and would suggest using whichever threshold is easiest for you to use.   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.

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 are:

  • Transform WG (Dow AgroSciences) – Transform WG is not fully registered yet, but Georgia, Alabama and several other states haves a section 18 emergency exception approved for 2015 until Nov. 20, 2015. 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. The label allows for 2 applications per season and not more than 3 oz per acre per crop and has a 14 day PHI.
  • Sivanto (Bayer Crop Protection) – Sivanto 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 3, 5, and 7 fl. oz. per acre, so the 4 fl. oz. rate should be effective.  At the 4 oz rate it can be applied up to 7 times during the season but has a 21 day PHI.
  • Chlopyrifos (Lorsban Advanced, Nufos, other) – Lorsban is labeled at 1 to 2 pints per acre. The 2 pint rate has a 60 day harvest interval and 1 pint a 30 day harvest interval.  The 2 pint rate was 80-90% effective in my trial last year but could not be used after the boot stage due the 60 day PHI. The 1 pint rate was variable and only partly effective.  DO NOT USE CHLORPYRIFOS ON SWEET SORGHUM.
  • Dimethoate ( Dimethoate, Cygon) – Is labeled up to 1 pint per acre with a 28 day PHI.  Most dimethoate products cannot be used after head emergence. Dimethoate was variable in my trials and not recommended without further testing.

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Filed under Entomology, Grain Sorghum

Cleaning Out Valor

Tattnall County Ag Agent Chris Tyson put this information on cleaning out valor on his Tattnall County Extension Blog.

“I know many folks are through using Valor for the year, but some folks are still using it for soybeans. I got this tank cleanout guide from Hunt Sanders, FMD Specialist for Valent, that I wanted to share with everyone. It tells how to properly clean Valor herbicide from your spray tank using Valent Tank Cleaner. It is very important to properly clean Valor out of your sprayer to prevent injury to other crops.”

CleanOutValor

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Bad Year For Pecan Leaf Phylloxera

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Pecan leaf phylloxera, Phylloxera notabilis, is a tiny aphid-like insect that feeds on foliage of pecan trees. You can only see the insects under a microscope, because they are so tiny. Their feeding causes rapid and abnormal growth of the leaf tissues. The tissue grows rapidly and encloses the phylloxeran. The proper term for the wart is a “phylloxera gall.” The picture above is from the orchard where we are conducting a study on the timing of drench imidacloprid for control of phylloxera. This orchard has a history of pecan leaf phylloxera, but it is certainly bad this year. We are noticing some varieties have less phylloxera than others. Here is an update from UGA Extension Horticulturalist Dr. Lenny Wells:

Pecan Leaf Phylloxera - Dissecting Scope

Pecan Leaf Phylloxera – Dissecting Scope

“Based on the calls I’ve had and observations in orchards, it appears that phylloxera is more prevalent than normal this year. Although the insects themselves are rarely seen, the stem mothers hatch from over-wintering eggs just after budbreak, usually in April, and crawl to the expanding leaves where they settle down to begin feeding. They begin laying eggs inside the protection of the galls in mid-April. As the eggs hatch and the resulting phylloxera begin to feed, the gall enlarges. Usually in mid-May, the now-matured phylloxera emerge from the gall. Some of these may crawl to another spot on a leaf and produces a second generation of galls.  There appear to be 2 species of phylloxera that infect the leaves—one, called Pecan leaf phylloxera seems to prefer immature nursery and orchard trees. The other, called Southern pecan leaf phylloxera prefers mature trees. In any case, the resulting damage will be the same.

While, not very appealing to the eye, leaf phylloxera galls are usually of relatively minor economic importance unless infestations are severe. However, stem phylloxera attack foliage, shoots, and even the fruit of pecans and can be much more damaging. Usually they are seen in the peduncle (the short stem bearing the nuts) at the tip of the shoot or in the nuts themselves. Heavy infestations can cause significant damage to the nut crop and the accompanying weakened shoots reduce tree vitality and may reduce the following year’s production as well.

Stem Phylloxera - Photo by Dr. Lenny Wells

Stem Phylloxera – Photo by Dr. Lenny Wells

Once you see the galls on the tree, it is too late to do anything about the current year’s infestation. Control measures must be taken at or just after budbreak. Commercial orchards can spray imidacloprid or chlorpyrifos products from bud break until the new growth reaches about 1″ in length. Orchards with a history of heavy infestation may require a second application 10-14 days later if chlorpyrifos is used. At present, there are currently no effective methods for control in a yard-tree situation. Soil drench applications with imidacloprid to date have been limited in their effectiveness.

Another unfavorable side-effect of phylloxera is increased likelihood of problems with hickory shuckworm. Shuckworm adults apparently find phyloxerra galls a suitable place to lay their eggs. As a result, damage from first-generation shuckworm can be significant in orchards with heavy phylloxera infestations. Therefore, growers will need to treat for shuckworm in this situation about this time. Intrepid, Dimilin, or Belt are all good options for shuckworm.”

Here is me rating our trail this morning. We will know soon if we have separation in data to conclude a good timing to drench insecticide for phylloxera.

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Filed under Entomology, Pecans

Southern Corn Rust Identified In Area

R3-Corn

Southern corn rust has been identified in Mitchell County by Agent Andy Shirley. This is our most destructive disease in corn. Our current weather patterns do increase the risk. Any corn that is approaching or even passed tassel growth stage is worth protecting if yield potential is there. Below is an update from UGA Extension Agronomist Dr. Dewey Lee:

“Even though this southern rust infection is earlier than usual, most of our corn crop is a little head of schedule. While this might not be much comfort, it does mean we might have saved at least one spraying. Last year, it was extremely difficult to stay a head of southern rust because the infectious time was longer than normal due to favorable conditions for infection.  Some corn in the southern areas of the state is as far along as the R3/R4 stage. This makes it easier to control rust and reduce the impact since it is much closer to maturity.  Much of the corn crop though, is silking to early ear development (R2/R3) which adds roughly 2 to 3 weeks of time to our potential spraying.

If you have good yield potential (and most irrigated growers do), I would consider spraying a combination of fungicides to provide both a curative and preventative type of action. There are great choices today from lots of sources. You may not have a current infection taking place, but spores are active and an application of a combination of fungicides will be great insurance and likely prevent yield loss. As long as southern rust is active, I would consider staying on a 14 day spray schedule or shorter. This disease can certainly undermine all your efforts this year and significantly reduce corn yields.”

Southern Rust

Southern Rust

Common Rust

I have seen some common corn rust in some fields. This is NOT the bad rust that causes yield losses. This rust is a cooler season rust that most likely infected during cool nights a few weeks back. It causes damage on BOTH sides of the leaf whereas southern rust shows up primarily on the tops of leaves. This rust is darker  brick red as well in color. Southern rust is a more orangish color.

Common Rust - Photo by Rome Ethredge

Common Rust – Photo by Rome Ethredge

 

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Filed under Corn, Disease

Peanut Insecticide Burn

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These peanuts are planted 33 days old and look good. We’re starting our fungicide programs and also thinking about applying landplaster. This field had 3 inches of rain last week, which nearly flooded it. Shortly after, this burn along the tips was showing up. It is burn from soil insecticide, Thimet put out at planting. Thimet moves systemically through the plant. UGA Extension Peanut Entomologist Dr. Mark Abney says Thimet has very little water solubility; therefore, with the high amount of rainfall all at once, the plant took in more insecticide. With this injury, we will see some yellowish burn on the outside of the leaves and spots will also be on the outside of the leaves. It’s usually on lower leaves. This burn isn’t bad and plants will grow out of it with no issues.

Peanuts-Thimet 012

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Filed under Entomology, Peanuts

Controlling Deer

Many fields planted throughout plantation land see lots of wildlife damage, mostly from hogs. Effingham County Agent Sam Ingram put together some information on Controlling Deer through his blog. Here is a field of soybeans last year on a plantation where deer have damaged. This kind of damage early on can certainly decrease yield potential.

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Deer may prefer these areas because of greater comfort. If this is the case, a grower may plant excess plants in these areas to allow for grazing and to limit the deer from encroaching past these areas. This is more of a sacrifice area than control.

Control options or deterrents are available, but efficacy or effectiveness is not proven for any of them:

  1. Milorganite® is used by many producers by application around the perimeter of the fields as a deterrent. Producers believe this product has worked well in fields in the beginning, but if the deer become accustom to the product or a rain shower washes the product it loses its effectiveness.
  2. Hot sauces- similar idea as the Milorganite® with it being placed around the perimeter. Similar limitations to the effectiveness with weather issues and the deer becoming accustomed to the product.
  3. Electric fence- This deterrent or barrier is the most troublesome to put in place but for fields with heavy deer pressure it may be worth the expense. Some factors to consider is the access to power or solar power and the understanding that a producer may have to repair/re-stake the fence throughout the season.

For more information on the potential yield loss and control options, here are thoughts from UGA Soybean and Cotton Agronomist Dr. Jared Whitaker:

“Some producers have said hot sauces or milorganite give some control. Unfortunately, we do not have any research behind the effectiveness of these remedies. But, looking at the potential loss in yield, every situation is different. If the deer graze the plant past the cotyledon, we lose all yield potential for that plant.”

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Filed under Soybeans