Effects of Grower Tools on Citrus Diseases and Roots

Ashley RobinsonDiseases, Root health

Individual protective covers are one of the tools being studied in the research project.

Citrus researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) are taking a more comprehensive look at how tools to manage HLB affect young trees. The goal is to develop integrated approaches and update management practices for growers.

After one year of the research project, some interesting results are already emerging.

The research project, “Establishing Healthy Citrus Plantings in the Face of Persistent HLB Pressure,” was developed to create HLB guidelines using some of the tools that growers are already implementing, including reflective mulch, individual protective covers (IPCs) and kaolin clay.

Megan Dewdney and Evan Johnson, plant pathologists at the UF/IFAS Citrus Research and Education Center, are playing an integral role in the project.

Dewdney says she has been monitoring greasy spot, sooty mold, melanose, citrus canker and HLB symptoms over the last year for the project. So far, none of trees being treated, as well as the control, have displayed any HLB or mealnose symptoms.

“We also haven’t seen much sooty mold. We saw a little bit starting late last year here and there, but only in the bagged treatments,” Dewdney says. The bagged treatments refer to trees covered with IPCs.

Greasy spot and citrus canker were discovered in just about every treatment, however. Dewdney says canker was seen in late summer and it progressively got worse. The control trees and trees receiving the reflective mulch treatment displayed the highest amount of canker, with up to 50% of leaves infected. Trees with kaolin clay had approximately 20-25% of leaves with canker infection, and trees under IPCs had nearly no canker at all.

Johnson is monitoring the tree roots. Since this project is using young trees, he says they can’t do a lot of destructive sampling. Instead, they bury clear, tiny tubes and insert a scanner into the tube. The scanner is able to take images at different depths to look at the monthly dynamics of the root system and how it is affected by the treatments and pathogens.

Since the project is still in its early stages, no major differences have been observed as the roots are just now starting to grow around the tube.

Based off historical data, Johnson expects trees receiving shade from the kaolin clay and IPCs to perform better.

“The trees with the bags on them are one of the first sets of trees where we have actually seen root growth growing around the tree. Whether that continues, we’ll have to wait and see,” Johnson says.

He predicts that by the third year of the project they should have enough root establishment to really compare the treatments and how the trees are performing.

Hear more from the research team in the April 2021 episode of the All In For Citrus podcast, a joint project of UF/IFAS and AgNet Media. 

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Ashley Robinson

Ashley Robinson

Multimedia journalist