Monthly Archives: June 2015

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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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.

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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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Sugarcane Aphids In Sorghum

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In summer of 2014, this new invasive pest of grain sorghum appeared in Georgia. We knew it would be back this season, probably earlier, and it has. The first documented 2015 appearance on sorghum was identified this past week in Brooks County and now Thomas County. Yesterday I checked waist high sorghum and found aphids and cast skins on a few plants. You can see the white cast skins on the leaf. The aphids are black, which is likely from a parasitic wasp. UGA Extension Entomologist Dr. David Buntin says Aphelinus sp. wasp is reported in the Delta and Texas region but was not seen here last year. We mailed the leaves to him to observe for this wasp. Wasps have hatched from some aphids that appear more brown. You can also see an exit hole.

Sugarcane Aphid Mummies & Cast Skins

Sugarcane Aphid Mummies & Cast Skins

Identification

White Sugarcane Aphid

White Sugarcane Aphid

We need to begin scouting and actively managing sorghum fields for the sugarcane aphid.  SCA is difficult to manage cost effectively but planning and scouting are our best hope in managing this pest successfully and preventing losses. The sugarcane aphid can be identified by the pale cream to yellow color with no bumps or tubercles on the body, but with black feet and black cornicles (small tubes located on the end of the abdomen).  A hand lens or microscope evaluation is most likely required to confirm physical characteristics and positive identification. The sugarcane aphid will feed on the sorghum leaves and stem, resulting in reddish colored lesions from the injury.

Management & Thresholds

To see recommendations on management from Dr. David Buntin, visit my previous blog post: Managing Sugarcane Aphids In Sorghum.

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Filed under Entomology, Grain Sorghum

Irrigating Young Pecan Trees

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We were having a conversation recently about irrigation on young pecan trees and what those requirements were. UGA Extension Pecan Horticulturalist Dr. Lenny Wells has information from research on young pecan tree irrigation below:

“Young pecan trees require two key ingredients for establishment…

  1. Water
  2. Elimination of weed competition.

There is no published data on required irrigation amounts for young pecan trees that I have been able to find. So, we began a study in 2014 to determine this for trees grown under Southeastern U.S. conditions. Looking at trees in the year of planting (1st year trees), we used microsprinklers that supplied either 6.7 gallons per hour (gph) or 14.3 gallons per hour (gph) and compared these with non-irrigated trees. Trees were irrigated 3 times per week (M,W, F) at 4 hours per application. Preliminary results show that young pecan trees respond to more water than expected. Trees receiving 80 gallons per week had significantly more growth than non-irrigated trees. But, trees receiving 172 gallons per week had even more growth than those receiving 80 gallons per week.

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Many people try to water young trees by hauling water to them once a week. While this is better than nothing, and will keep the tree alive, the trees require more water for the best results on most soils in our area. While 80 gallons per week improved growth over non-irrigated trees, it appears that young pecan trees require as much as 172 gallons per week for optimal growth on a loamy sand soil. Heavier clay soils may not require quite this much, while deep sandy soils may require even a little more.”

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Filed under Irrigation, Pecans