Post-Hurricane Disease Management Advice

Josh McGillAll In For Citrus Podcast, Diseases

Megan Dewdney, associate professor of plant pathology with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), joined the October All In For Citrus podcast to discuss Hurricane Ian and tips on disease management after the storm. Hurricanes weaken citrus trees and spread disease. 

disease management

Citrus canker stem lesions on grapefruit (Photo by Beth Bolles, UF/IFAS)
Citrus canker stem lesions on grapefruit (Photo by Beth Bolles, UF/IFAS)

“If a tree has a full canopy, the wind will put a lot of stress on a tree,” Dewdney said. “It can also expose the root systems and topple the trees. You can see drowning of the roots if you have flooding and standing water for three to four days, so that can cause some real significant problems.”

Phytophthora, which was a growing problem before the storm, will be aggravated by Ian. Dewdney suggested growers get samples pulled in groves affected by the storm to get an idea what phytophthora counts are in the soil.

She said treatment recommendations would follow normal thresholds for the disease, meaning there is no need to lower thresholds due to the hurricane. 

“If you already are on a phytophthora program, we’d recommend you stay on that rotation,” she advised.

Dewdney also discussed how the storm will spread citrus canker. The disease is notoriously spread by wind.

“Unfortunately, hurricanes and canker have a long sordid history. Where we are going to have further problems in young trees and mature trees is canker lesions on the stems,” Dewdney said. “In your older trees, where you already have canker, you may need to step up your canker program a little bit more than average. I am more concerned about the young trees because you are going to get the stem canker on these young limbs that are forming scaffolding. That will enable them to produce early-season inoculum for about four years. That’s a long time that you will be battling against canker on those trees, just when you are wanting to establish healthy leaves and a good canopy.”

Dewdney recommended growers start a Blockade program in the spring on young trees affected by canker. She said that will hopefully tamp down the infections to some degree.

To hear more about post-hurricane disease management, check out the October All In For Citrus episode. The podcast is a joint project between AgNet Media and UF/IFAS.

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