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Prepare for the 2018 Tropical Storm Alberto

Pam Knox, Interim Director, Georgia Weather Network

Long-time residents of Georgia may remember the devastating floods of Tropical Storm Alberto in July 1994. The rain was so intense that Georgia’s one-day rainfall record was set during that storm, with 21.10 inches recorded at Americus for a 24-hour period ending on July 6, 1994 as the storm stalled over the state. In spite of that incredible record and the resulting damage, the National Hurricane Center did not retire the name of Alberto. This year, Alberto is the first name on the list of Atlantic tropical storm names for the season which begins on June 1.

The latest 5-day outlook for the Atlantic tropical region from the National Hurricane Center indicates that there is an 80% chance of this year’s Tropical Storm Alberto to develop in the Gulf of Mexico in the next five days, even before the season officially begins. While it is not likely to bring extreme winds and storm surge to the area, it is expected to bring copious rain to an area that has already received up to six times as much rain as normal in the last week, covering most of Georgia except the northwest corner. Another six inches is expected across a wide area of Georgia in the next seven days from the slowly moving storm. While this is not likely to be as wet as the 1994 TS Alberto, the storm and rainfall is still going to cause tremendous problems for us here in Georgia, along the coast and inland across most of the state.

Now is the time to think about what you need to do to get ready for the rain, whether or not it organizes enough to be designated as a named tropical storm. If you have weekend activities planned along the Gulf Coast for this Memorial Day weekend, be prepared for intermittent heavy rains, gusty winds, high waves and rip currents in the water along the coast from New Orleans to the west coast of Florida. If you are inland, prepare for localized flooding which will be worse because the ground is already saturated in many areas. Move equipment and livestock out of low-lying areas. Expect some trees to fall because of the wet soil conditions, even if the winds are not that strong. This may mean blockage of roads or disruptions in power, so check your generators now if you need supplemental electricity for your operations. If water covers the road, do as the National Weather Service recommends and “Turn Around, Don’t Drown.” You won’t be able to tell if the road has been undercut or washed away, and water has a tremendous potential to move cars and trucks even when only a few inches deep. The Extension Disaster Education Network (EDEN) has several useful publications on preparation and recovery at https://eden.lsu.edu/educate/resources.

I have heard from a number of you that the rain and cloudy conditions we have had the past two weeks has caused a lot of problems for producers, leading to splitting blueberries, increased fungal diseases, slow growth of crops, and the inability to get into the field to do side dressing of corn, application of fungicides and other treatments, and planting. Unfortunately, I don’t see a shift in this current pattern, and above normal rainfall is likely to continue for the next several weeks, although there will be some drier periods that may allow you to get work done.

I do not plan to send out another email, but for updated information you can follow my retweets at @SE_AgClimate or my shares on Facebook at SEAgClimate. My number one source of updated weather information is always my local National Weather Service office, but you can also get information from many commercial vendors as well as the National Hurricane Center. Do not count on your smartphone weather apps to give you the most current information, since many of them are only updated once or twice a day. Keep monitoring for changing conditions, since above normal sea surface temperatures in the Gulf of Mexico could lead to a rapid drop in pressure and increase in winds as the center of the storm gets close to land, or the storm could move in a different direction under weak steering currents.

Yellow Peanuts

Here’s an explanation of WHY this is happening from Cristiane Pilon, Ph.D. Assistant Professor – Row Crop Physiology

Three major environmental conditions may be playing a role in the peanut plant development (leaf yellowing) these past days: sunshine, humidity, and to a lesser extent, temperature. Leaves have small pores (known as stomata) that allow water vapor to be released (transpiration) and carbon dioxide to enter (photosynthesis). Environmental signals will trigger stomata to open or close. Low light intensity, high humidity, and low temperature usually signal the plants to close their stomata. Water and nutrients move from roots to shoot through transpiration. For this process to take place, a difference in water potential between the soil and atmosphere surrounding the plant is needed, creating a gradient and driving water and nutrients upward (against gravity). The drier the air around the plant, the higher the transpiration, if water is available. The opposite is also true. High relative humidity surrounding the plants does not allow for this difference in gradient, stomata remain close and transpiration is reduced. This is probably what is happening with the high humidity promoted by the rain we got these past days. Without enough light and stomata close, photosynthesis also decrease. This condition can create yellowing in the leaves and slow down growth. I have checked the integrity of the leaf photosynthetic structures and they are normal. The issue is on the efficiency to capture and move energy to complete the photosynthesis process. Since the physiological structures are not impaired, the plants should be able to recover when weather changes and we get more sunshine to decrease and increase temperature.

Managing Pecan Scab Pressure/Leaf Roll Mites

Lenny Wells UGA Pecan Specialist

With 10 successive days of rain behind us and no relief in site and a potential tropical storm bearing down on us, pecan growers are under the gun for scab pressure right now. Most days have provided some breaks in the rain showers that have allowed growers to get out and spray at least a portion of their acreage. But, the question is what to spray with when growers can get into the orchard.

We are currently transitioning from worrying about leaf scab as the leaves should be hardening off soon to worrying about nut scab as the nuts begin the sizing period. One of the best materials to be using at this stage with the pressure we are having would be one of the DMI/Strobi mixes (Group 3 + Group 11) like Absolute or Quadris Top if  you have not used them 2 or 3 times already. The problem we are running into is that most growers are coming off of spraying this chemistry in their last couple of sprays. If this is the case, what should growers go to at this point?

The answer would largely depend on what has been used already but in the scenario above—if you have already used a couple of group 3 & 11 mixes—you have a few options. The right choice will probably depend on variety.

For moderately susceptible varieties like Sumner, Stuart, Schley, Oconee, etc. you could go with something like a 2 qt rate of Phosphite alone or a group 3 fungicide (Tebuconazol, Propiconazol, Tetraconazol, etc.) + either Phosphite orTin

For highly susceptible varieties like Desirable, Pawnee, Caddo, Cunard, a better option would be something like 25 oz Elast and 1 qt of Phosphite.

Regardless of what you use, it is probably a good idea to tighten that spray window to 10 days minimum on scab susceptible varieties.

We have also had a number of calls about leaves curling at the edges a seen in the photo below:

This is a result of feeding by pecan leaf roll mite. Their feeding causes galls at the outer margin of the leaflet, which causes the edges to curl up and sometimes turn brown. This distorts the leaflet but does not usually cause defoliation. Most of the time this damage is only cosmetic and does not require treatment.

Disease Update (Row Crops)

Bob Kemerait – UGA Extension Plant Pathologist

Plenty of disease issues to consider now.  Please let me know if you have questions.

  1.  To date, no soybean rust has been found this year in Georgia.
  2. To date, no southern corn rust has been found this year in Georgia.  (We have found a small amount of common rust, which is not a concern for growers.)
  3. We have had reports of northern corn leaf blight being found in counties such as Seminole and Terrell.  Northern corn leaf blight CAN be a problem, especially when a grower plants a susceptible variety and weather conditions are favorable.  (Weather conditions are favorable now.)  Growers DO NOT NEED to treat for northern corn leaf blight if they only find a few lesions (long, cylindrical, grey, cigar-shaped lesions) here and there.  BUT if the lesions are commonly present on lower leaves, then treatment with a fungicide is important to consider.  Treatment, if needed, for northern corn leaf blight is best achieved applying fungicides before tassel (perhaps as early as V6-V10) and using products with mixed-modes of action.
  4. Rhizoctonia seedling blight is a common problem on our cotton right now and significant stand loss has occurred.  Jason Brock showed me cotton samples yeterday from Colquitt, Cook and Turner Counties with nearly 100% pure cultures of Rhizoctonia recovered from diseased seedlings.  I believe that Rhizoctonia “soreshin” could be especially problematic now because A) the seedlings were stressed significantly by the hot and dry conditions two weeks ago and then B) suddenly exposed to cooler and much wetter conditions.  There is not treatment for Rhizoctonia seedling disease on cotton once the seed is planted and furrow covered.

There is a high probability of wet weather continuing across the state for the rest of the week and into Memorial Day.  The most important consideration now is for our corn.  To spray, or not to spray…..

Reasons why we are at increased risk to disease (e.g., southern corn rust):

  1.  The low pressure system is bringing moisture out of the Gulf, moisture and winds that could be carrying spores of southern corn rust (and soybean rust).
  2. The rainfall and wet weather has created conditions for development and spread of rust.  These same conditions also make it difficult to apply fungicides.
  3. Some of the earliest-planted corn is approaching “tassel” stage, a growth stage when growers often consider an application of fungicide.

Reasons why the risk to corn diseases is not as high as it might be:

  1.  Southern rust has not yet been found in the state.
  2. Earliest planted corn (that approaching tassel) often “escapes” southern rust that greatly affects later plantings.

Bottom line:  The risk to southern corn rust, even with the wet conditions, is not high enough to make a general recommendation to apply a fungicide now, even if tassel stage is not far off.  However, growers who are very risk-averse may decide to spray anyway, just to make sure.  That is not a “wrong” decision, just one to be made depending on how cautious the grower is.

MORE ON RHIZOCTONIA IN COTTON

  1.  In my experience, in 4 out of 5 years the “base” fungicide treatment on cotton seed is sufficient to protect against Rhizoctonia seeding blight in most fields, except where grower plants into cooler and wetter soils or where there is reason to expect greater problems; e.g. poor rotation.  However, many growers still invest in additional elective seed treatments or in-furrow fungicide applications as “insurance” against seedling disease.  The 2018 field season (hot and dry and then extended wet and cool) is a perfect situation for cotton seedling disease and where, if we had known, investing in additional seed treatments or in-furrow fungicides would have been prudent.
  2. How long will growers continue to see plants die from Rhizoctonia soreshin?  Seedlings are VERY susceptible to injury from Rhizoctonia; as they continue to grow, the upper taproot becomes “hardened off” and “woody” and is more resistant to the pathogen.  With current conditions, we can expect cotton to continue to die from Rhizoc until it is approximately 8 to 10 inches tall.
  3. What to do now?  There is nothing that can be done, other than make re-plant decisions.  Replanting into a field where losses to Rhizoc have been severe increases risk for further losses.  If a grower replants because of seedling disease, I STRONGLY encourage the grower to invest in additional fungicide protection, either seed treatment or in-furrow.

Perennial Peanut Field Day

Thursday May 31 in Quincy FLA

If you have any questions, please feel free to call Kelly Paulk at (229) 256-3195 or e-mail at kpaulk@uga.edu

Downy Mildew on Cucumber

Bhabesh Dutta, UGA Vegetable Disease Specialist

Downy mildew of cucumber has been detected from the Brooks County, GA. These observations indicate that inoculum of downy mildew is currently in southern GA counties and under favorable conditions  potential disease outbreak in other cucurbits  can occur. I would suggest our cucurbit growers to look for the downy mildew symptoms in their fields and start applying protective spray of below stated fungicides.

Watermelon: Rotation (foliar application)  with  Orondis ultra (provide protection against both Downy and P. capsici);

Elumin+Bravo/Manzate;
Ranman+Bravo/Manzate;
Previcur flex+Bravo/Manzate

Please do not use Bravo after fruit set.

Other cucurbits: Orondis opti;

Elumin+Bravo;
Ranman+Bravo
Previcur flex+Bravo

If Orondis was used as a soil application, please do not use it as foliar (use restriction according to label).

 

 

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