Monthly Archives: June 2017

June 30, 2017 · 5:01 PM

Pawnee Nut Drop

UGA Extension Pecan Specialist Dr. Lenny Wells has this to say about Pawnee nut drop:

We have seen a fairly large Pawnee drop over the last week. It is not uncommon for Pawnee to shed a few nuts this time of year but this year’s drop looks a little heavier in places. Still, I don’t think its anything much to worry about in most cases. Most of the Pawnee trees I have seen with a heavy drop under them still have a heavy crop on them. The drop probably helped them more than hurt them. The trees should be able to produce better quality and have a better chance of a return crop.

Aborted Pawnee nuts prior to drop. Photo by Dr. Lenny Wells

Stages of Pecan Nut Drop (Sparks and Madden, 1985)

As the graph above shows, pecans undergo 4 separate fruit drops during the growing season, most of which are related to pollination problems. Pawnee is about a month ahead of most of our other varieties, so this drop would coincide with the 3rd drop in the graph above (which is based on Desirable). This drop occurs just before rapid fruit expansion and is due to the failure of the endosperm to develop properly. This drop is known to be accentuated by self-pollination. The low chill hours of this past winter and the resulting effect on budbreak (see Warm Winter and Pecans) could have affected cross pollination, leading to more self-pollination. If so, we may see a similar drop on other varieties in a few weeks.

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June 30, 2017 · 4:56 PM

Weather & Disease Update

It’s hard to say we don’t want more rain, but more and more we’re saying just that. We’re having showers nearly every day or every other day, sometimes as much as an inch and a half. It’s starting to show up in the field where cotton is getting ‘wet feet.’ Some of our rain has come with strong winds. Our largest field of tobacco took a hit from these winds knocking plants to the ground in some places. The only hope is to stand it back up as best as possible. It is still causing issues with topping since the flowers on the ground began growing straight up.

We have a good crop of tobacco this year, but it was hit hard from strong winds and rain. Some areas completely blown to the ground.

Flowers turned from wind affects topping

From UGA weather station in Cairo, here are the rain numbers since the beginning of May.

Disease Update

Here is our latest disease update from UGA Extension Pathologist Dr. Bob Kemerait:

Southern Corn Rust: I was stunned when agents in our disease diagnosis class visiting a field in Morgan County found a very active spot of southern rust. Unbelievable because until yesterday, it had ONLY been found lightly in Seminole and Marion Counties. Obviously, as we expected, southern rust could be present anywhere in Georgia now. Why it has not “exploded” yet is a mystery to me given the conditions we have had, but CLEARLY the spores have spread across the state.

The corn in that field as at hard-dough/early dent, so it does not need to be treated; however growers with later planted corn not yet at R6/dough stages should be aware there is at least some threat.

Target spot of Cotton: Perfect weather but I am NOT calling for an automatic fungicide application at first or at third bloom. BUT I am saying that every cotton grower SHOULD be aware that these can be important and critical timings. As cotton approaches bloom, I hope growers can put some eyes and boots in the field and begin looking for it, lower leaves first. Weather is very favorable- growers with a history of disease in the field and those with high-input, strong yield potential should be the growers with the greatest chance for benefit. Target spot will not steal the entire crop, but it will take away a valuable portion of the crop.

Consider: Growth stage (blooming yet?) history of disease, reports from scouting, (have early symptoms been found?), what’s the weather like now and what is the forecast? What is the value to the growing in a preemptive application “to be done with it”?

White mold and leaf spot in Peanut: We are seeing some of both. Growers, don’t get behind!

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Filed under Corn, Cotton, Disease, Peanuts, Tobacco, Weather

June 28, 2017 · 9:20 PM

PGR Rainfast

We are 2nd and 3rd week into squaring now, and we’re starting to put out our plant growth regulators. I had an unexpected 1 inch rain at the house yesterday afternoon.With all the rain we are having, we need to keep in mind the ‘rainfast’ of our PGRs. Below has written out each of our mepiquat and mixed products. Generally, when a surfactant is used, we can cut the rainfast in half. Pentia is more expensive, but with a 2 hour rainfast (1 hr with surfactant), we may find it beneficial our current conditions.

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June 27, 2017 · 4:09 PM

Aphid Fungus

For the first time, I am getting to see what ‘consistent aphids’ looks like in the field. Normally, aphid populations are sporadic, seen only in ‘hot spots.’ This season, they are prevalent in our oldest and youngest cotton. We looked at a field this week where every single plant was affected by aphids in the top 3 – 4 leaves (below). The only reason we don’t talk much about it is UGA research on treating aphids has never found a consistent yield response. The best thing is to limit stress on the plant, and our rainfall is helping us here.

Leaves of 8-leaf cotton curl due to stress of aphids

Classic symptoms of aphids in our cotton variety trial.

Aphid Fungus

But the real new is that yesterday, we confirmed the ‘aphid fungus’ in Thomas County. UGA Extension Entomologist Dr. Phillip Roberts already reported the ‘aphid fungus’ being spotted in Tifton this week. This means, aphids will soon crash.

We observed the aphid fungus, (Neozygites fresenii), which causes aphid populations to crash on the Tifton Campus on June 26, 2017. We have also received some early observations from both north and south of Tifton. The presence of grey, fuzzy aphid cadavers is indicative of the naturally occuring fungus (below). Once observed in the field we would expect aphids to crash within a week. We typically first observe the fungus in fields with high aphid infestations; and more specifically areas of those fields which were initially infested. All scouts should be on the lookout for the fungus and be sure to report to growers.

Aphid fungus – Photo by Dr. Phillip Roberts

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Filed under Cotton, Entomology

June 16, 2017 · 7:12 PM

Cotton Irrigation At Squaring

Some of our pivots have not been running these past few weeks thanks to steady rainy days. For being so dry at planting, this is hopefully going to get us off to a good start in the field. Below is a photo of rep 2 from our variety trial. We have some plants squaring already.

Remember, stressing cotton during squaring has more negative effects than we realize. Cotton does not rebound if stressed from no irrigation through squaring. Last year, we lost so many squares from drought stress. This is something UGA Extension Irrigation Specialist Dr. Wes Porter says we have to be careful about.

Data on this using the UGA Checkbook Method where pre-bloom irrigation was eliminated found no difference in non-irrigated cotton. The reason for this is that cotton grows vegetatively and reproductively at the same time. During its vegetative growth, cotton is setting nodes. If it is stressed during this time, less nodes are set.

Dr. Porter has been looking at soil moisture sensors and the irrigation apps we can download on our phone. Research does show that the Smart Irrigation App is keeping us from putting out more water than is needed during both drought and rainfall situations. This is interesting because these apps do not monitor soil moisture, and the Smart Irrigation App is no charge to download. We go one step further when we use soil moisture sensors.

Aphids???

I saw some ants crawling up some plants. I then checked for aphids. The ants eat the ‘honeydew’ produced by the aphids, called ‘farming aphids.’ UGA Extension Entomologist Dr. Phillip Roberts says there are some aphid hot spots that may develop in fields now. We just need to watch.

Aphids under leaf of squaring cotton

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Filed under Cotton, Entomology, Irrigation

June 16, 2017 · 6:57 PM

Pecan Fungicide ‘Rainfast’

With rain and humidity, we are having ideal conditions for scab. Some growers essentially continue to spray around the clock. A common question is, “How long does my fungicide need to dry before rain?” This is a question pathologists have worked on for some time, but there are many variables involved making it difficult to generate data. UGA Plant Pathologist Dr. Tim Brenneman recently offered the following suggestions based on his studies with pecan and also on similar studies he has conducted in peanut:

Highly systemic materials like phosphite must be absorbed into the plant. It may require as much as 1/2 a day for this process to take place so that the material can be highly effective. While DMIs and strobilurins or combination products like Absolute, Top Gard, Quadris Top, and Quilt have some systemic activity they are not as systemic as the phosphites. Still, they would need a little time to be effective, so several hours to half a day would be ideal. A surfactant (80/20 or other) would increase the uptake speed of these materials and would likely provide some benefit in the conditions we’ve had over the last week or so. However, do not include a surfactant with Phosphite.

While the DMIs and Strobis have some systemic activity they still function largely as protectants. Other materials like Dodine (ELast) or Tin are pure protectants. These materials (Dodine and Tin) would be the most prone to wash off when rain arrives shortly after spraying. Dodine does adhere tightly to the plant cuticle, which likely helps it. Rainfall that occurs less than one hour after spraying makes the fungicide pretty well ineffective. Any rainfall within 24 hrs after spraying with a pure protectant will likely reduce the effectiveness of control to some extent. For each additional hour between the spraying and rainfall you gain additional control.

Ideally, all fungicides should be applied prior to rain events. If circumstances prevent you from getting a spray on in time and you have to spray after a rain event, the DMI/Strobi combinations would be the best choice.

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Image

Cotton Market Update

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June 16, 2017 · 6:56 PM

June 16, 2017 · 5:58 PM

Southern Rust In GA

Southern corn rust has been identified in Georgia (on June 5th) by Rome Ethredge in Seminole County. Corn was in the silking (R2) state. This is likely some of the earliest southern rust to affect our state. UGA Extension Pathologist Dr. Bob Kemerait has this update for growers:

Weather condition for the past few days and over the next few days is predicted to have a significant chance of rain and humid conditions. These conditions are quite favorable for the development and spread of rust diseases to include southern corn rust and Asian soybean rust.
As of today, 5 June- Asian soybean rust has been found on kudzu in Miller County and on corn in Seminole County.
My recommendations: Corn in southern Georgia that is approaching tassel stage (or has reached) is now at some risk to southern corn rust. The risk is likely not urgent yet, but finding rust now (fairly early in the season) and coupled with the current weather conditions does increase risk.
Grower spraying for southern corn rust: tebuconazole is effective, but combination products that include multiple modes of action (e.g. strobilurins, triazoles, SDHIs) have a broader spectrum of activity against disease AND have a longer protective window (e.g., 3 weeks versus 2 weeks.)

Insects

The picture above is corn in Thomas County that is also silking. We are very fortunate with our rain these past few weeks. During this stage (70-80 DAP) corn is still using 0.3 inches of water / day. We also need to watch for stink bugs. It is common to treat during the ear elongation / tassel state (VT) is 1 SB per 2 plants is present. Because they can hide from you, it is easiest to drive down the rows and check.

During policantion and blister statges (R1-R2), SB feed through the husk and damage individual kernels. Treat if you see 1 per plant.

Pyrethroids are fine to use when we’re seeing southern green SB. If brown SB are prevalent, use a high rate of bifenthrin to get about 75-90% control.

1st Instar Brown Stink Bug

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June 2, 2017 · 6:07 PM

Peanuts And Valor Injury

We plant a lot of peanuts on plantations here in Thomas County. As we were finishing up peanut planting, manager at Wild Ridge Plantation Jason Sanders made a great video of them planting near the Florida line. They filmed it with a drone camera. Jason did a great job making this video. I think I need to get my ‘video band’ down to Wild Ridge and get a band shot from this drone camera.

Our peanut crop is looking good since we’ve had a few weekly rains. Fungicide programs are starting up now, and we’re still needing some rain. We had a few showers this week, but not much to count. UGA Extension Weed Scientist Dr. Erick Prostko has this update on valor that I want to share:

Peanuts that were planted approximately the last two weeks in May were in a great place to get hammered from Valor because of the Sporadic heavy rainfall events (below). If you received one of these heavy rainfall events on Valor treated peanuts when they are cracking and small (~2 weeks after cracking), injury will occur.

Georgia Rainfall Totals from May 20 – May 24, 2017

Peanuts typically recover from this injury without a yield penalty. In a 2009 research trial, more than 5″ of rainfall occurred in the 30 day period after peanut planting. Peanut injury was significant but yields were not reduced even at a 2X rate.

Valor injury to peanut. Photo by Dr. Erick Prostko

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June 2, 2017 · 5:18 PM

June Drop On Desirables

Here is an update from UGA Extension Pecan Specialist Dr. Lenny Wells:

Pollinated pecans begin to form

We have had a heavy bloom of female flowers and a good early nut set on ‘Desirable’ this year, but anyone that has been around pecans for long knows this cultivar has a nut drop in June each year. When this occurs the trees may drop as much as 30-60% of the nuts on the tree. The June drop continues to about 40-45 days after pollination, and is due to the lack of successful fertilization of the egg and sperm. This is an inherent characteristic of ‘Desirable’ in particular and this self-thinning is also the reason this cultivar can have consistent production from one year to the next

‘Stuart’ will also have a June drop but it is usually not as severe or as noticeable as the ‘Desirable’ drop. There is nothing you can do about this drop and there is nothing wrong with the trees when it occurs. If seeing this drop bothers you I recommend not going into the orchard to look until its over. Desirables always drop down from 4 and 5 nuts per cluster to 0, 1 and 2 nuts per cluster. The trees will still have good production. I began seeing this last week and it will likely continue for a week or so.

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