Vidalia Onion News, February 2026 | Vidalia Onion Extension News

Pictured here are some early November transplanted onions, showing typical symptoms and signs of some frost and freeze damage to the foliage. You can easily see the foliage has necrotic areas that appear “bleached” or off color from the rest of the foliage. Some of this injury appears as smaller specks or spots, and some appears to have injured the entire side of some leaves.

A Cold January

We had 3 hard freezes in January that have left many of our onions with injury to the foliage. The dates and low temperatures recorded at the VOVRC are as follows:
January 15th: 21 degrees F
January 26th: 20.5 degrees F
January 31st: 19.8 degrees F
Each of these freeze events gave us anywhere from 12 to 20 + hours of below freezing temperatures. As a result, most fields are suffering from injury to the foliage.
The injury you may see on your crop can vary greatly depending on the variety, planting date, size, and location in the field.
The worst injury we’ve seen? Dryland corners, areas where irrigation does not hit, seem to have the most injury. This could be for lack of soil moisture to insulate from cold injury and reduced nutrient uptake in these areas due to lack of water.

Here’s some freeze injury that has left this foliage “speckled up”. Some of this injury resembles botrytis leaf blight, a common disease that we will start to see in the coming weeks. We know this is not botrytis because it came on suddenly after the freezes, and did not start out with the characteristic “cloudy” or “halo” lesions.

The entire upper surface of the leaves on this plant appear “bleached out” from freeze injury. One thing we have noticed is that some of the plant injury appears to just affect random plants more than others. Many of the other plants around this one show little to no injury.

Accumulated Heat Units on the Crop

Back in mid-January, when we held our crop update at the VOVRC, I discussed the growing degree day calculator and how we use it to monitor the crop. On January 20, we were close to 200 Growing Degree Days (GDDs) ahead of last years crop, when you consider a November 15th planting date. The cold weather we have been experiencing for the last 25 days or so has “flatlined” the progression of GDDs, and as you can see from the chart below, we are now at about the same GDD accumulation as we were at this same time last year. This is certainly evident in the crop as well. Crop growth has slowed tremendously in the last few weeks due to the colder temperatures, and many plants are smaller than many folks are accustomed to seeing in mid February.

This Growing Degree Chart from AgroClimate.org shows the accumulated Growing Degree Days (GDDs) above 50 degrees F for the Toombs County GA weather station. Our current accumulation is right at the same level as it was for the same time period last season, and just slightly above the historic average.

Disease Related Concerns from Cold Injury

This photo was captured last week in a field in Tattnall County. You can see freeze damage tissue with some darker lesions, caused by Stemphyllium leaf blight. This fungal pathogen often gets its start on damaged or dead foliage. It will be important to stay on top of our spray programs to manage Stemphyllium and other fungal diseases, especially with all the damage foliage in the crop right now.

As our crop progresses, disease management will be paramount moving forward. There are several things we need to watch for, some of which could be made worse by the cold injury. Most folks who are on a suitable spray program should not have to worry, and the message I want to relay to everyone is not to be slack on your program as we progress in the season.

Stemphyllium Leaf Blight– Stemphyllium is not a very aggressive pathogen for onions, but it often takes advantage of dead or damaged tissue to get started. This will be a big concern moving forward, especially with all the damaged foliage. I would encourage you to monitor your crop closely and use appropriate fungicides.

Dr. Bhabesh Dutta’s slides from our most recent crop update show us our options for Stemphyllium control in onion.

Bacterial Diseases– There’s a couple things to watch out for. Yellowbud (Pseudomonas coronafaciens) is one, but traditionally it has been of minor importance to the crop overall in most years. You may see some in your fields now. You’ll notice bright yellow colored foliage from newer growth. Often times, as the weather warms up, the plants will often overcome this disease with little to no implications. Copper can help.

Toombs County Extension Agent Jason Edenfield shared this picture with me of Yellowbud disease, caused by the bacterium Pseudomonas
coronafaciens. As name implies, it cause bright yellow foliage and can cause stunting. We often see this disease show up during colder periods in the season. However, plants often overcome and outgrow this disease as weather warms up, with little to no yield loss.

Another bacterial disease we may run into is Bacterial Streak (Pseudomonas viridiflava). For us, this disease is favored by excessive nitrogen fertilization and periods of rain during the cooler winter months. Cold injury to leaves could also serve as an infection point for this bacteria. Using copper fungicides in your spray program will help. Weeds are a source of inoculum for this disease, so you may see this more in weedy areas.

The image here shows Bacterial Streak starting on onion foliage. It often makes the leaves appear water soaked and dark or discolored.

Other Concerns from Cold Injury

One question from the freezes we’ve had is, “Did any internal damage to the bulb occur?” Some growers/consultants have reported seeing a low percentage of internal injury in some onions. I’ve been cutting some onions to inspect the bulbs as well. I still believe its too soon to fully guage the impact any freeze injury may have on bulbs. However, this is something each grower needs to monitor in their crop as it begins to grow.

Did any internal bulb injury occur? This is something we need to monitor, because it is still relatively soon after these freezes to know the full extent of any damage that did occur. I have cut open bulbs in several fields and yes, in some fields (especially older onions), I can see where some of the outer rings of the bulb appear discolored or pithy. What does this mean? I don’t know yet. Sometimes, outer layers of the onion bulb can “slough” off. We’ll continue to monitor the crop.

The most recent freeze injury occurrence that comes to mind was in 2022. This freeze happened much later in the season, on March 13, 2022. The onion crop was obviously much bigger, probably much more susceptible to a freeze at that time because some earlier varieties were close to harvest. The temperature during this freeze reached a low of around 24-26 degrees F. The injury from this freeze was not widespread, but several growers reported some damage. The outer 1-2 layers were damaged, and the most telling sign was very dark or discolored outer skins of these onions. We sampled these onions and found that different Burkholderia spp. had infected these bulbs. What likely happened was the freeze injured the outer onion layers and allowed this bacteria to be introduced into the bulbs.

These are photos from some freeze injury that occured in 2022. We still dont know if anything like this will happen to our 2026 crop, but growers should keep an eye out for this or other internal damage.

Be on the Lookout for Downy Mildew in the Coming Weeks

Downy Mildew from Tattnall County in 2024

We have not had any weather recently that would favor Downy Mildew development, but we likely will over the next few weeks as it gets warmer, and we have rain events. This is the time, if you haven’t started already, to begin protective sprays for Downy. Keep this in mind when thinking about Downy: It is favored by cool (not cold) temperatures such as 60-70 degrees F, with lots of moisture from rain or dew, and cloudy conditions. The earliest date we have confirmed Downy in the last 15 years was February 28 (in 2019). That means the infection likely started in mid-February that year.