Genetics and Nutrition Are the ‘Way Forward’

Ernie NeffNutrition

Jude Grosser

“The combination of improved scion/rootstock genetics and optimized nutrition is clearly the way forward” for Florida’s HLB-stricken citrus industry, Jude Grosser declared in a Florida Citrus Growers’ Institute virtual presentation. Grosser is a University of Florida Institute of Food and Agricultural Sciences plant breeder. The Growers’ Institute is normally held in April but was cancelled this year due to COVID-19.

In his presentation, Grosser stated: “Supplemental applications of slow-release fertilizer containing an enhanced micronutrient package can help maintain tree health, good yields and high fruit quality. Supplemental applications of slow-release fertilizer containing an enhanced micronutrient package can also suppress CLas populations, which probably contributes to the improved tree performance.” CLas stands for Candidatus Liberibacter asiaticus, the causal agent of HLB.

“Data shows that good and repeatable results can be obtained in groves without psyllid control, and even with Diaprepes,” Grosser added. Asian citrus psyllids are the insects that spread HLB from tree to tree. Most citrus growers and researchers in the early days of HLB in Florida believed that maintaining psyllid control was essential to maintaining production in the face of HLB; many still do. In recent years, however, many growers have reduced psyllid control efforts, in part to reduce production costs. Diaprepes root weevil, though not as widespread as HLB, was considered the worst problem many growers dealt with before HLB was discovered in the state in 2005.

“New rootstocks in the citrus breeding pipeline are showing potential to mitigate HLB in grafted commercial scions, which could bring susceptible scions such as Honey Murcott and grapefruit back into play in Florida,” said Grosser.  

Speaking about genetics and nutrition, Grosser said, “We’ve learned from infected greenhouse trees that the deficiencies of nutrients in HLB trees are mostly a problem with the roots. And it’s the micronutrients and secondary nutrients that are impacted.” He added that nutrient deficiencies were about twice as great in roots as in leaves. “HLB is causing a micronutrient/secondary nutrient problem, primarily in the roots,” he said. “To get a tree back online, you have to correct these deficiencies.”

See Grosser’s full presentation here.

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About the Author

Ernie Neff

Senior Correspondent at Large