Silverleaf Whitefly in Cotton Update

WhiteflyBlogPic

Photo courtesy of: Joseph LaForest, University of Georgia, Bugwood.org

Here’s some information from Dr. Phillip Roberts, UGA Extension Cotton Entomologist:

Silverleaf whitefly (SLWF) adults have been observed in low numbers in cotton.  To date very few immature whiteflies have been observed in cotton.  We are not aware of any field which has exceeded threshold for SLWF.  Most reports include observations of individuals or a few adults when searching plants for corn earworm.  However, the presence of SLWF in a field is worth noting and management of all insect pests must consider the presence of SLWF.  All efforts should be made to minimize the need to treat SLWF with insecticide.

Management Considerations:

  • Scout for the presence of SLWF adults.  It is important to know if SLWF is present!
  • Conserve beneficial insects, do not apply insecticides for any pests unless thresholds are exceeded (beneficial insects will also suppress corn earworm).
  • If SLWF is present in a field, avoid use of insecticides for other pests which are prone to flare SLWF.
  • Scout fields frequently for adults and immatures once fields are infested with SLWF.
  • Be timely with SLWF insecticides when thresholds are exceeded (many learned in 2017 that it is difficult to play catchup with SLWF).
  • Be very aware of SLWF infestations in hairy leaf varieties and late planted cotton, these are high risk fields.

There is no question that agents, scouts, consultants, and growers are looking more closely for SLWF this year based on the problems we had in 2017.  Historically if we see SLWF in cotton during the month of July we should anticipate problems with SLWF, especially on late planted fields, and manage appropriately.  Infestations do not come close to where we were a year ago.  In 2017 treatable populations first occurred during the last week of June and many acres were treated in July; so we are in a much better situation this year compared to last.  It will be important that all fields are monitored closely for SLWF and hopefully proper proactive management can minimize damage and the need for SLWF insecticides.

 

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Target Spot

TargetSpot

Photo credit:  Jason Brock, University of Georgia, Bugwood.org

Target spot has been observed throughout South Georgia and is known to cause the most issues in fields with rank growth.  Growers with a crop between the first week of bloom and the sixth week of bloom may consider protecting their crop with a fungicide.  However, not every grower will benefit from this application and should scout fields prior to making this management decision.  This disease is characterized by leaf spots with concentric rings (shown above).  Defoliation begins at the lower leaves and progresses up the stalk.  Conditions are favorable for the disease and early detection is critical.  Once defoliation has reached more that 25% a fungicide application may no longer be feasible.

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Irma’s Aftermath

We were very fortunate in Thomas County since the eye passed east of us. Our winds were in the 40s with gusts in the 70s. There is still obvious damage to our field crops. Here are some pictures of what we have now:

Peanuts

The only negative effect will be altering our digging time, if the field needed to be dug in that time period. We had some peanuts already inverted, but they are drying and will be picked this week. The soil is drying with a few days of sunny weather.

Cotton

It’s about 50/50 with wind damaged fields. Where wind hit hard, cotton is all tangled up. And any bolls/lint that fell off the plant is for sure lost. This is going to affect us on our picking efficiency and spraying. UGA Extension Cotton Agronomist Dr. Jared Whitaker says, “One thing to consider is that cotton that is just beginning to open is the heaviest it will be throughout its life and when opening proceeds, it will allow the plant to stand up.  However, one thing that I’ve seen that I haven’t in the past with blown over cotton is the “rooting out” around the stem at the ground level due to winds from several different directions. This could complicate the issue of cotton standing up and exacerbate the issue of standing up.”

There is more damage to younger cotton that will not be known at this time. Right now, you see a lot of reddening of the plant at the top. This is from stress, but multiple factors can cause this stress. We looked a blown over field today where it was obvious whiteflies were not treated. You will also notice stemphyllium leaf spot this time of year with loss of potassium. But the wind can also cause this symptom, and will hurt cotton in providing energy to those bolls.

Pecans

UGA Extension Horticulturalist Dr. Lenny Wells’ preliminary estimate is that about 30% of the state’s total pecan crop has been lost. This has become the most damaging wind event ever seen by the Georgia pecan industry. Again, most of the damage east and north of us. In Thomas County, we are a little under that 30% based on what I am seeing.

We mostly have limbs / nuts lost, but also some trees down. These are similar trees we lost with Hurricane Hermine – mostly in that 5 – 15 age range. Here is some more information from Dr. Wells:

Growers should take photos of their damage and report it to their local FSA office in order to receive financial assistance with cleanup. Cleanup funds normally pay 75% of the USDA-set cost of a mature tree ($300) up to a maximum of $200,000 per entity. Younger trees will be valued at varying levels depending upon age. In addition, the Tree Assistance Program (TAP) will pay for tree loss when 15% or more of the orchard is destroyed. This pays 65% of the cost of the tree up to a maximum of $120,000 per entity.

This money is not available immediately but your FSA office will gather your report. Requests for cleanup funds are made to Congress and they will then appropriate the funds so it may take a while.

Growers have many questions regarding how to handle fallen trees and the mass of green nuts blown from the trees. The success of righting blown down trees varies considerably with age of the tree. Trees less than 8-10 years old (trunk diameter < about 10 inches) can generally be righted with pretty good success, if leaning less than 45 degrees. Success rate is highly variable when leaning more than 45 degrees.  Success of righting these trees will be much greater when trees are pruned back as if they were to be transplanted with a tree spade because the newly-limited root system must be able to support the tree that remains. The larger the tree, the more you should prune off when righting.

Uprooted trees or those lying flat on the ground should be removed, especially large, mature trees. Such trees often never perform as they should and will be likely to be blown down again at a later date. Uprooted trees usually exhibit visible broken roots on the side opposite of the direction of fall. The major roots on the opposite side of the tree are also generally broken as well. Such trees usually have much more root damage than is apparent.

I’ve had many questions about salvaging the green nuts blown onto the ground and having them de-shucked. In most cases, the expense involved in this will outweigh  the benefit. While there are a significant number of nuts on the ground, in most cases, the volume will be less than most growers think. Pawnee shucks were splitting or open and many of these nuts came out of the shuck and are on the ground. Many would have been ready for harvest this week so these nuts can be salvaged once the debris is cleaned up. Early October harvest nuts like Caddo, Oconee, Elliott, Moneymaker etc. may be far enough along to attempt de-shucking if growers are inclined to do so. However, they need to bear in mind the cost of an additional harvest, transport, cleaning, and de-shucking when making this decision. Later varieties like Desirable, Stuart, Cape Fear, Sumner,. etc. are likely not mature enough for de-shucking even though the kernels may be filled out. If the nut does not pop out of the shuck when stepped on or rolled with your foot or if the shell is still white and the markings have not developed growers should not attempt de-shucking.

There is potential for further damage to appear at a later date from nuts getting knocked around in the storm. This often bruises or damages the shuck and affects development or maturity of the nut and may lead to stick-tights. However, my early observations are that this bruising is minimal. I do not see a lot of bruising as of yet on the shucks so I am hopeful  but it is still a bit early to tell whether or not we will escape this type of damage.

All in all, the Georgia pecan industry has suffered a significant blow but it could have been much worse than it is given the severity of the storm.

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2017 Forestry & Wildlife Program – October 3rd

We are very excited to announce the 4th annual Thomas County Forestry & Wildlife Program. Contact our office at 225 – 4130 if you plan to attend.

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Terminating Fungicide Sprays In Peanuts

Our peanuts are once again taking 140 – 150 days to mature. We’re digging in the 130’s only if peanuts are turning loose in the hull. This is a good crop, and we want to get all the weight and grades we can. UGA Extension Pathologist Dr. Bob Kemerait helps us out each yeah with an update on terminating fungicide sprays:

  1. Grower is 4 or more weeks away from harvest and currently has excellent disease control.
    • Suggestion – I recommend the grower apply at least one more fungicide at least for leaf spot control.
    • Suggestion – Given the low cost of tebuconazole, the grower may consider applying a tank-mix of tebuconazole  + chlorothalonil for added insurance of white mold and leaf spot.
    • NOTE: If white mold is not an issue, then the grower should stick with a leaf spot spray only.
  2. Grower is 4 or more weeks away from harvest and has disease problems in the field.
    • If the problem is with leaf spot – Grower should insure that any fungicide applied has systemic/curative activity. If a grower wants to use chlorothalonil, then they would mix a product like thiophanate methyl (Topsin M) or cyproconazole (Alto), with the chlorothalonil. Others may consider applying Priaxor, if they have not already applied Priaxor twice earlier in the season.
    • If the problem is white mold – Grower should continue with fungicide applications for management of white mold. If they have completed their regular white mold program, then they should extend the program, perhaps with a tebuconazole/chlorothalonil mix.  If the grower is unhappy with the level of control from their fungicide program, then we can offer alternative fungicides to apply.
    • If the problem is underground white mold – Underground white mold is difficult to control.  Applying a white mold fungicide ahead of irrigation or rain, or applying at night, can help to increase management of this disease.
  1. Grower is 3 or less weeks away from projected harvest and does not currently have a disease issue. Good news! This grower should be good-to-go for the remainder of the season and no more fungicides are required.  SEE NOTE BELOW ABOUT HURRICANES.
  2. Grower is 3 or less weeks away from harvest and has a problem with disease.
    • If leaf spot is a problem and 2-3 weeks away from harvest, a last leaf spot fungicide application may be beneficial. If leaf spot is too severe, then a last application will not help.  Tank mixing chlorothalonil with a systemic fungicide, like thiophanate methyl or other appropriate systemic fungicide, could be beneficial.
    • If white mold is a problem and harvest is 3 weeks away, then it is likely beneficial to apply a final white mold fungicide. If harvest is 2 weeks or less away, then it is unlikely that a fungicide will be of any benefit.

NOTE:  If harvest is likely to be delayed by threat from a hurricane or tropical storm, then the grower may reconsider recommendations for end-of-season fungicide applications.

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Hull Scraping Peanuts: Looking For A Starting Point

With a good crop and a lot of acres, this year will likely resemble 2012. We officially got started with peanut hull scrapes today. There was nothing ready sooner than 14 days. I only looked at 1 irrigated sample, and you would think they were all irrigated. We looked at samples of peanuts that we scraped weeks ago, and some were sprouting then. We haven’t had rain on these much since then, and those peanuts I believe have pretty much shut down.. If we have a 1/5 inch rain, that won’t be a big deal, but much more than that will be an issue. The issue in the west part of the county is that we need a little rain before we start digging. The east side of the county is getting rain through August.

Sprout

06G Maturity

Something we need to think about is the trend in 06G’s the past five years. They are listed as a medium maturing at 130 to 140 days. But we are seeing the 06G grade being higher as we push 150 days. Everything I’ve seen, along with many other agents, is o6G’s going 140, 145, and 150 at this time. Remember, there are factors that will set the peanuts behind a week or so that have occurred throughout our crop this year: 1) Valor injury, 2) germination issues / slow emergence 3) bad stands 4) gramoxone at-cracking sprays. Any of these events will knock peanuts back a week and a half. So that normal 134 day quickly turns into 145 assuming normal progressgion. With so much rain this season, this explains why we DON’T go by days after planting.

We’re seeing more normal progression of the crop with no split crops in our dryland fields.

Peanut Profiles

Our profiles are looking good, with much fewer if any split crops. Again, this is another reason to lets make sure we get these mature and get some good grades. In some dryland fields, we are definitely seeing where half the peanut will be yellow and the other half black. This is sometimes a characteristic of dryland peanuts, indicating off-and-on rain. We still judge the peanut by the darkest color on the profile board.

Dryland peanuts

There are some peanuts turning loose in the hull, but not terrible. Still, this is a cause for us to pull the trigger soon in these fields. It’s a difficult call because each week too early can be 200 – 300 lb yield loss.

Still our biggest issue is the number of acres we have and finding and starting point.

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Peanuts Getting Close

Peanut profile on August 7. Peanuts were planted on April 12, putting them at 117 days.

We are passing 120 days on our early peanut crop, and will start hull scraping soon. We’ve done a few hull scrapes and found we are still a few weeks away – even with rain and high temperatures. Based on the average days to maturity of the last few years (140 – 150), we actually have a few more weeks where we can add some weight to the crop. This means we need to make sure we stay on our fungicide programs and watch insesects. UGA Extension Specialists Dr. Scott Tubbs has good information on what we should expect:

A harvestable peanut typically needs at least 40-50 days of development after initiation to gain enough weight for yield. It has been common for the majority of the peanut crop to reach optimum maturity between the 140-150 days in recent years in Georgia. Therefore, a fertilized bloom or developing peg at the 100 day after planting point in the season should theoretically “make it into the basket”. Anything that initiates after that point is questionable unless the crop is pushed late for digging, which can then start to cause losses of the earliest formed pods either from deteriorating peg strength or germination of the seed in the hull if its funiculus has detached from the hull.

Using Aug. 8 as a reference point, any peanut planted on April 30 or earlier will have reached the 100 day point, and will be at the critical point for increasing any additional pod set that could become harvestable. Essentially, the early planted crop is already set. For peanuts planted in the month of May, there is roughly the equivalent number of days left to set additional pods in the crop as the date of planting in the month. For instance, if you planted on May 14, then you would have about 14 more days to set additional pods that could become harvestable by the end of the season. Everything beyond that 100 day old point becomes a matter of maintaining the maximum yield potential by filling the pods that have already established.

Weather conditions in central Georgia show favorable chances for continued rain, which is overall good for the crop. However, it can cause delays in timeliness of applications for weeds, insects, and diseases issues. At least for the next few weeks, take advantage of good operating conditions in the field when you have them to get herbicide, fungicide, and insecticide applications out.

However, if your crop has been challenged up to this point in the season, the good news is that there is still time to make up for it and produce harvestable pods if you planted in the month of May. Watch maturity profiles closely, especially when you get past 120 days , and don’t be afraid to push those peanuts later (beyond 145 days) if the maturity profile calls for it and the overall vegetative conditions (vines, leaves, and pegs) are relatively healthy.

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