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Row Crop Disease Update

Corn:  Southern corn rust is now confirmed in 7 adjoining fields in Baker County.  I don’t think it is a coincidence that we are finding it now; development is following the rain periods of recent weeks.  I expect (stay tuned) to have more identified very soon.  Bottom line:  I think that the amount of southern rust is fairly low in the state right now, but that could change fairly quickly.  Wind and more wind yesterday and rains certainly were PERFECT for moving spores.

 Recommendation:  Any corn in the dough/dent stage as of now, i would likely not advise spraying for rust in SW Georgia, or anywhere else.  Corn in  late milk stage, I would likely not spray either, because, again, the amount of rust is low.  Any corn in SW Georgia that is at early milk, silking or tasseling stages in SW Georgia, I would certainly think about protecting with a fungicide.

 IF YOU THINK YOU FIND SOUTHERN RUST, PLEASE LET US KNOW

 Peanuts:  We are in a combat situation I believe now with white mold.  I am getting pictures of young plants that are affected.  Very warm soil temperatures followed by moisture followed now by hot temperatures creates PERFECT white mold conditions (southern stem rot, Nickie).  Typing this at 7:30 AM, it is already 79 degrees and 100% humidity.  I can almost hear the white mold…..

 Recommendations:  Now is not the time to be timid on white mold control.  The weather is here, teh crop is developing, protect the crop with fungicides from leaf spot and white mold.

 Cotton:  No target spot or areolate mildew, but conditions are favorable.  Please advise your growers to pay attention and scout.  FIRST BLOOM is an important time to check your crop for target spot.  Even if you don’t spray, be aware.  Also, keep your eyes open for reddened, stunted, distorted plants that COULD be our new viral disease.  If you find plants like that, please let me know so we can check them out.

 Soybeans:  Asian soybean rust is present in kudzu across the Coastal Plain.  Conditions (windy and passing storms) are PERFECT for moving it to soybeans.  IF THEY WERE MY BEANS, I WOULD DEFINITELY APPLY A FUNGICIDE BY R3, POD SET STAGE, especially if I was putting out dimilin and boron, and even if I wasn’t.  GOOD INSURANCE.

By  Bob Kemerait 

Slippery Algae in Turfgrass

Published on 06/13/19

Rain, overwatering can cause slippery algae to pop up in turfgrass lawns

By Clint Waltz for CAES News

Recent dry weather encouraged the use, and possible overuse, of irrigation systems. Followed by tropical conditions characterized by heavy rainfall and humidity, there have been reports of a jelly-like substance growing in turf.

The jelly-like matter is Nostoc, a genus of cyanobacterium formerly classified as blue-green algae. The algae — commonly known as star jelly and witch’s butter, among other names — may appear suddenly in lawns and other turf areas in warm temperatures following a period of rain, and the algae can also be an indication of overwatering.

In turf, Nostoc generally emerges on a site where the grass is growing poorly due to severe compaction, overwatering or both. It does not cause the turf to decline or die, but it does colonize areas where it has favorable growing conditions and the grass was already thin.

Poor drainage and compacted soils create a favorable environment for Nostoc. It dries out when moisture or rainfall diminishes, but it has only gone into dormancy. With enough moisture, it will come back to “life.”

In its hydrated, gelatinous, green state, it can be a safety hazard because it’s slippery — so be careful walking on it.

However, when it dries out, it can restrict turfgrass growth. Nostoc dries into a black crust that can prevent stolons from rooting, or “tacking,” into the soil. This delays the growth and spread of turfgrass.

Nostoc can be difficult to control. To discourage its growth, encourage the growth of the grass. Algae is less of an issue with an actively growing turfgrass canopy.

The first step is to check the irrigation system to make sure it is watering properly (i.e., not too often or too much). The turfgrass species grown in Georgia perform better when grown on the slightly dry side, so scaling back irrigation and adjusting the irrigation schedule will benefit the grass and can discourage algae.

The second step is to improve the internal soil and surface drainage. Core aeration opens the soil, allows oxygen into the root system and reduces compaction.

Allow the soil surface to dry out, then break up the Nostoc “crust” by cutting the upper ¼- to ½-inch. Breaking the algae into pieces will encourage it to spread. This also permits the turfgrass stolons to root into thin areas and outcompete the Nostoc.

With proper irrigation and core aerification, the grass can cover, and eventually predominate, the area where the Nostoc was present.

For more information about turfgrass in Georgia, go to www.GeorgiaTurf.com.

Clint Waltz is a Cooperative Extension turf specialist with the University of Georgia College of Agricultural and Environmental Sciences.

Sunscalding on Fruits and Vegetables

Published on 06/14/19

High temperatures, few clouds lead to sunscalding concerns for Georgia producers

By Clint Thompson for CAES News

Even with the welcomed rain Georgia farmers experienced this week, sunscalding on certain fruits and vegetables remains a concern as producers continue with this year’s harvest, according to University of Georgia Cooperative Extension vegetable specialist Andre da Silva.

When temperatures are high and the sun is able to shine for weeks at a time with very little cloud cover, which had been the case in mid-to-late May, certain crops are vulnerable to developing sunburnt conditions — notably watermelons, tomatoes and bell peppers.

“The sun has definitely been too aggressive for some of our vegetable crops, especially with bell pepper, tomato, and watermelon. Growers have been asking for products to protect their crop from the sun,” da Silva said. “Unfortunately, there is not much research on this topic for us to make a recommendation. However, the first UGA research trial is being conducted this season.”

Watermelons are most susceptible to sun damage if they endure a prolonged dry period. Without moisture, the vines will begin to wilt and the fruit will be more exposed to the sun. When watermelons burn, the rind will appear yellow, rendering the crop unmarketable.

“Growers that need to exercise the most precaution are the watermelon growers who are using plastic mulch with overhead water application. If they haven’t been applying enough water, they will see their plants shrink. It’s hard for the root systems of those plants to get the water that the growers are applying,” da Silva said.

If watermelon producers can protect their crop from the sun, they’ll extend their harvest window into late June and around July 4 when watermelons are at peak demand and prices for farmers are at their best.

“We don’t expect temperatures to get this hot, this early,” da Silva said. “We need a little bit of rain every day with a little bit more clouds to avoid future sunburning, and then we’ll have good soil moisture.”

Prior to the June 8 weekend, the last substantial rainfall in south Georgia was during the weekend of May 11. According to the United States Drought Monitor, (www.droughtmonitor.unl.edu) drought conditions are considered moderate, though da Silva believes they’re still likely much worse. Along with fellow UGA vegetable scientists Bhabesh Dutta and Stormy Sparks, da Silva has traveled across south Georgia to survey the damage inflicted by the weekslong drought.

“If growers hadn’t been pumping up their irrigation this spring, they could very easily lose their crop this year,” da Silva said.

Direct contact of fruit to sunlight can cause blossom end rot disorders. Previous research trials from da Silva and colleague Tim Coolong on the UGA Tifton campus showed that fertilizer strategy, mainly those consisting of calcium nitrate, is key to reducing blossom end rot, a calcium-related disorder that affects mostly peppers and tomatoes.

For up to date information about weather events in Georgia, see the UGA Weather Network website at www.georgiaweather.net.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

App Helps Fruit Growers

Published on 06/18/19

App helps fruit growers in Eastern U.S. diagnose disease and insect problems

By Denise M Hatcher for CAES News

Walking through his peach orchard, a farmer notices something he has not seen before on the leaves of a few trees. He quickly pulls out his cell phone and accesses the MyIPM smartphone app.

Through a series of descriptions, audio and images, the free mobile app and tool can help users diagnose crop diseases, insect pests and disorders of fruit crops grown in the Eastern U.S., including apple, blackberry, blueberry, bunch grape, cherry, cranberry, peach, pear and strawberry.

The app was first developed by plant pathologists at Clemson University to give growers a “one-stop shop” to access all of the resources they might need for disease management, says Brett Blaauw, an assistant professor and peach specialist with the University of Georgia Department of Entomology. A couple of years later, two more apps were created: one focused on insect pests and another geared specifically for the Northeastern region of the U.S.

“When I came to UGA, I worked on merging the three separate apps into one master app, which included new tools, crops and functionality,” Blaauw said. “The single MyIPM app currently has nine crops with disease diagnostic tools and six crops for insect diagnostic tools.”

To date, the app has been downloaded more than 2,100 times. Designed to promote integrated pest management in commercial fruit crop production, one of Blaauw’s favorite aspects of the app is that it’s full of useful information for users of both Apple iOS and Android mobile operating systems.

“Not only is there a large list of chemistries that are labeled for each disease or insect pest, but users also have the ability to view high-resolution pictures to identify symptoms and signs of disease and insect injury,” he said. “With that said, my real favorite aspect is that the app is free.”

The app is continually being updated by leading Extension specialists at seven land-grant universities and the Southern IPM Center.

Feedback from users has been overwhelmingly positive. Of the users surveyed, 65% say that the app has helped them manage pests and 70% say that it has increased their knowledge of pests and IPM, according to Blaauw.

“Nearly everyone I talk to about the app is pleased with its functionality and ease of use,” he said.

The app has been downloaded to more than 70 different countries, including India, Mexico and Canada.

Blaauw is currently working on adding a section on beneficial insects to help growers identify “good bugs” using the app. He hopes to see the app expanded to include more crops.

For more information on the MyIPM app, visit https://apps.bugwood.org/apps/myipmseries/.

Michele Hatcher is the editor of the Hexapod Herald, the newsletter of the University of Georgia Department of Entomology.

Bermudagrass Stem Maggot in Hayfields

By Will Hudson, Lisa Baxter and Dennis Hancock

We’ve had a number of calls from growers and agents in the last week or so concerned that they should be spraying for BSM.  Even in south GA, the flies are just now starting to show up.  You may be able to find some damaged stems, but most of the widespread browning of the grass is probably due to the extreme heat and dry weather following an unusually cool and wet spring.  BSM damage kills just the last 2 leaves, and does not turn the tips of the leaves brown.  They generally do not affect leaves lower on the tiller than the top 2.  Even in our well-watered research plots in Tifton, we are only seeing 10-20% damage in the most susceptible varieties.  The current drought situation has many producers delaying their hay harvest.  This means we have more mature bermudagrass than usual (and so there appears to be more damage).  There is likely no need to spray yet, but growers should be alert and be ready to spray after the next cutting if there is a noticeable amount of damage.

Downy Mildew Disease

Published on 06/04/19

Georgia vegetable growers need to apply fungicides to stay ahead of downy mildew disease.

By Clint Thompson for CAES News

Georgia vegetable farmers should be on alert as downy mildew disease has been spotted in at least three southern Georgia counties this spring. Additional counties could follow as weather conditions remain favorable for the disease into early June, according to University of Georgia Cooperative Extension plant pathologist Bhabesh Dutta.

Cucurbit crops — like cucumbers, melons, squashes and pumpkins — are susceptible to the disease. Dutta ranks downy mildew among the top diseases in cucurbit crops, along with Fusarium wilt and Phytophthora fruit rot.

Downy mildew disease can destroy plant foliage and cause the leaves to curl and die. Without healthy leaves and vines, a plant is vulnerable to blisters and sunscald during hot days, conditions most of Georgia has experienced since early May.

Much of the state has not experienced a substantial rainfall event since the weekend of May 11, and many growers have had no relief from temperatures that reached or eclipsed 100 degrees Fahrenheit.

“We really need some balanced days, not full-blown sunshine with 100 degrees Fahrenheit every day like we’ve experienced here recently, and also not heavy dew nights,” Dutta said. “We need some cloudy days, but most importantly, we need some rain.”

High temperatures during the day, followed by dew at night and in the early morning hours for the past three weeks, have led to the disease developing in cucurbit fields in Crisp, Decatur and Lowndes counties.

“Most of our growers are doing preventative sprays for downy mildew. We do have fairly effective fungicides that can manage downy mildew. I think growers are diligently following UGA recommendations and they should continue to do so,” Dutta said.

Growers need to be aware of what downy mildew symptoms look like and the damage it can inflict on vegetable crops. The pathogen thrives in wet, humid conditions and needs moisture on the surface of the plant for successful spore germination and further infection.

The pathogen that causes downy mildew can’t survive a hard frost, so it overwinters in frost-free regions like southern Florida. During May and early June, wind currents blow the spores into Georgia.

For up-to-date information about potential diseases impacting Georgia’s vegetable production, see https://site.caes.uga.edu/vegpath.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Turf Grass News

Turfgrass Blog: 2019 Edition

Clint Waltz, Ph.D.

University of Georgia Turfgrass Specialist

June 10, 2019

 

With the recent dry weather encouraging the use, and possible overuse, of irrigation systems then the recent tropical conditions – rainfall and humidity – I have had several pictures and questions about a jelly-like substance growing in the turf.  The jelly-like “stuff” is a Nostoc algae, a genus of cyanobacterium formerly classified as blue-green algae.  It has multiple common names like star jelly, witch’s butter, and others.  Under warm temperatures Nostoc may appear suddenly in lawns, and other turf areas, following a period of rain and can be an indication of overwatering.  In turf, it is generally on a site where the grass is growing poorly due to severe compaction, overwatering, or both.  It does not cause turf decline or death; it colonizes areas where it has favorable growing conditions and the grass was already thin.  Poor drainage and compacted soils create a favorable environment for Nostoc.  It will dry-out if the water or rainfall diminishes but it has only gone into dormancy.  With enough moisture, it will come back to “life”.

 

In its hydrated, gelatinous, green state it can be a safety hazard.  It is slippery.  Be careful walking on it.  However, when it dries-out it can become restrictive to turfgrass growth.  Nostoc dries into a black crust that can prevent stolons from rooting, or “tacking”, into the soil, delaying turfgrass growth and spread.

 

Nostoc can be difficult to control.  To discourage its growth, encourage the growth of the grass.  Algae is less of an issue with an actively growing turfgrass canopy.  The first step is to check the irrigation system to make sure it is watering properly (i.e. not too regular or too much).  The turfgrass species we grow in Georgia perform better when grown on the slightly dry side, so scaling back the irrigation and adjusting the irrigation schedule will benefit the grass and can discourage the algae.

 

Improve internal soil and surface drainage.  Core aeration opens the soil, allows oxygen into the root system, and reduces compaction.  While allowing the soil surface to dry-out then breaking up the Nostoc “crust” by scarifying the upper ¼- to ½-inch can break the algae into pieces and encourage its spread, it also permits the turfgrass stolons to root into thin areas and outcompete the Nostoc.  With proper irrigation and core aerification the grass can cover and eventually predominate the area where the Nostoc was present.

Clint

 

Summer Heat

Published on 05/23/19

Spring season brings summer heat to Georgia

By Clint Thompson for CAES News

Georgia temperatures are rising, and the weather is only going to get hotter with little rain in the forecast. That’s not good news for Georgia’s cotton producers who are in the middle of planting this year’s crop, says Jared Whitaker, University of Georgia Cooperative Extension cotton agronomist.

According to the UGA Weather Network at www.georgiaweather.net, temperatures eclipsed 90 degrees Fahrenheit in most of south Georgia this past weekend and are expected to reach 100 F by the middle of next week.

“Cotton is going to be the most sensitive crop to these types of conditions just because of the relatively poor vigor of cotton seedlings compared to other crops Georgia producers plant,” Whitaker said. “Cotton seed is very small and conditions need to be near perfect for several days after planting to ensure we get a suitable stand. When soils dry and temperatures rise, it becomes increasingly difficult for producers, especially in nonirrigated fields.”

Whitaker says that an informal survey he conducted last week revealed that around 50% of the state’s farmable fields had been planted. Progress was a little further along than usual because of good planting conditions in late April. Also, producers are trying to minimize their risk from losses that could occur at harvest by planting some cotton earlier than usual.

He is concerned that poor conditions could delay planting to the point that yields are affected.

“We really need to have a good stand established before the end of the first week of June to ensure that we have enough time to make an entire crop,” Whitaker said. Growers need rainfall within the next couple of weeks to get this crop started in the right direction.

“We’re always a week away from a drought,” Whitaker said. “And that’s certainly the case this year.”

The last substantial rainfall was recorded during the weekend of May 10 through May 12. Three days of rain yielded 1.5 inches in Tifton, Georgia; 0.81 inches in Alma, Georgia; 1.2 inches in Griffin, Georgia; and 1.52 inches in Vienna, Georgia.

But since much of the state’s crops are grown in south Georgia’s sandy soils, any moisture that region receives is soaked up quickly.

UGA Extension peanut agronomist Scott Monfort says that approximately 65% of Georgia’s peanut crop has been planted. But like the state’s cotton farmers, Georgia’s peanut producers will need to monitor their crop’swater needs during this extremely hot and dry period.

“To have high temperatures this early is pretty tough. It means these plants are going to go through heat stress earlier than normal this year and farmers are going to have stay on top of it as far as irrigating,” Monfort said. “While we normally wouldn’t irrigate this early, we might have to start if we lose too much moisture.”

Growers also need to be careful planting in fields with marginal moisture.

Summer doesn’t officially begin until June 21. Pam Knox, UGA Extension agricultural climatologist, believes that temperatures in June, July and August will depend largely on how much rainfall Georgia gets.

“There is not much correlation between early season heat waves and the rest of the summer. However, if it stays dry, then hotter-than-normal conditions are likelier just because all of the sun’s heat goes to warming the air instead of evaporating water from the soil and plants,” she said.

For more information about what weather to expect this summer, read Knox’s climate outlook on her blog at https://t.uga.edu/4YB.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Root-Knot Nematodes

Published on 05/27/19

UGA survey finds root-knot nematodes in 60% of vegetable fields

By Bryce Ethridge for CAES News

A recent University of Georgia Cooperative Extension survey of 431 Georgia vegetable fields found that more than 60% contained root-knot nematodes, tiny parasitic worms that feed on roots and destroy plants.

The survey was conducted May through December of 2018 by UGA Extension nematologist Abolfazl Hajihassani. His research group surveyed fields in 30 Georgia counties for plant-parasitic nematodes and found 10 genera of nematodes. Root-knot nematodes are the most important nematodes that vegetables producers should be concerned with, he said.

Hajihassani conducted the survey to better understand the incidence, abundance and spread of plant-parasitic nematodes within vegetable fields in southern Georgia. The counties surveyed represent about 85-90% of the state’s vegetable production.

During the survey, soil samples were collected from vegetable fields and nematodes were extracted and identified to the genus level.

“Right now, the root-knot nematode is the main problem in most vegetable crops grown here, based on distribution, soil population density and incidence,” he said. “Therefore, root-knot nematodes will be the target of our future research, which will include the evaluation of old and newly introduced fumigant and nonfumigant nematicides.”

Root-knot nematodes can enter the plant’s roots and move through the cells where they grow, produce more eggs in only three to four weeks and cause the roots to swell. This reduces the plant’s growth and yield potential.

South Georgia’s sandy soils allow nematodes to reproduce frequently because they can move easily through the soil’s loose texture.

UGA Extension’s observations in the field indicated that fumigating the soil before applying plastic will stop the nematodes for the season, but only for that season.

Hajihassani said that there are a few nematode-resistant vegetable varieties available, but Georgia producers don’t want to use them because of quality issues. Growers prefer to plant high-yielding varieties and use chemical nematicides, although they’re not always 100% effective.

Currently, Hajihassani is researching the nine other types of nematodes the survey identified in case they could become threats to vegetable production in Georgia. This includes stubby root, ring, spiral, root lesion, reniform, lance, cyst, stunt, and dagger nematodes.

“Hopefully, in one to two years, we’ll have a good source of information as to what species of nematode we have,” he said. “Through Extension agents, we have already communicated the survey data with those growers who participated in our survey. Our aim is to continue sharing the data with growers, find out what problems they have and design the appropriate management techniques.”

Nematodes need three components to thrive: water, high temperatures and a suitable host. Georgia has water, hot summers and a variety of host plants, which has Georgia farmers concerned. Along with vegetables, nematodes can cause problems in cotton, peanut and tobacco plants.

For more information on Hajihassani’s work and plant-parasitic nematodes, visit https://t.uga.edu/4YK.

Cabbage Crops Signs of Disease

Published on 05/08/19

Farmers must watch cabbage crops closely for signs of disease

By Bryce Ethridge for CAES News

As temperatures increase this spring, Georgia cabbage farmers should scout their crops regularly to ensure that disease pressure is not too high, says University of Georgia Cooperative Extension vegetable specialist Andre da Silva.

If farmers are proactive and maintain proper pest management programs during the growing season, diseases like black rot and Alternaria leaf blight can be controlled, da Silva added.

Symptoms of these disease are easy to identify in the field, but once identified, yield may have already been compromised. The increase in temperatures and rainfall can create perfect conditions for disease, and da Silva and Bhabesh Dutta, UGA Extension vegetable disease specialist, are currently tracking the emergence of the two diseases throughout south Georgia.

“As we get to the summer — or later in the spring — the warmer temperatures increase the chance of these diseases,” he said. “If growers don’t pay attention and keep a proper pest management program, we might suffer a high loss.”

According to the UGA Center for Agribusiness and Economic Development, the farm gate value for cabbage in Georgia in 2017 was $53.6 million.

Alternaria leaf blight can cause spots on some brassica crops and render them unmarketable. Symptoms first appear on older leaves as small, dark spots that gradually enlarge with concentric rings. As the disease gets worse, younger leaves become infected. Infection becomes more problematic in humid and wet conditions.

Black rot causes v-shaped lesions on leaf edges which can lead to the plant’s death.

Lack of proper irrigation scheduling could also lead to the appearance of these diseases, particularly due to the application of high volumes of water.

“Since we’re starting to have warmer conditions with frequent rain showers, soil might have plenty of moisture to supply crop demand,” da Silva said. “There is no need to overirrigate, and if growers are irrigating their cabbage in those conditions, it’d create the perfect conditions for disease. That’s what we don’t want.”

As part of his research on the UGA Tifton campus, da Silva is looking for cabbage varieties that are more disease tolerant or disease resistant.

Until disease-resistant varieties are discovered, growers should keep these tips in mind when managing diseases in cabbage:

  • Maintain a proper pest management program.
  • Rotate chemical products to avoid disease resistance to a particular product.
  • Change up irrigation schedules to apply water only when necessary.
  • Frequently survey crops for symptoms.

To learn how to identify rot, contact da Silva at 229386-3806 or adasilva@uga.edu. For more information on the Department of Horticulture at UGA-Tifton, visit http://tifton.caes.uga.edu/departments/horticulture.htm