Editor’s note: A correction has been made to this article. It previously stated that “UF/IFAS’ current highest recommendation for phosphorus on citrus is 16 pounds per 100 pounds of fruit per acre annually if soil tests and tissue samples indicate insufficient phosphorus content.” The information has been corrected to 16 pounds per 100 boxes.
For years, participation in Florida’s Best Management Practices (BMPs) program gave citrus growers a degree of regulatory peace of mind. By implementing the Florida Department of Agriculture and Consumer Services (FDACS) BMPs, growers were assumed to be in compliance with state water-quality standards for pollutants.
Much of that peace of mind has eroded. So much so that the directors of the Highlands County Citrus Growers Association (HCCGA) recently invited the University of Florida Institute of Food and Agricultural Sciences’ (UF/IFAS) Kelly Morgan to discuss the BMP situation. Morgan, a researcher long involved in citrus BMPs, is also director of the Southwest Florida Research and Education Center in Immokalee.
Morgan summarized the reasons for grower concerns. He said the FDACS Office of Agricultural Water Policy (OAWP) “has told us that many citrus growers are out of compliance (with BMP guidelines), meaning they are applying more phosphorus than IFAS recommendations would call for.” UF/IFAS’ current highest recommendation for phosphorus on citrus is 16 pounds per 100 boxes of fruit per acre annually if soil tests and tissue samples indicate insufficient phosphorus content.
UF/IFAS recommendations “were just that and never intended to be the number on which regulations would be implemented,” Morgan said. “As far as citrus is concerned, all our recommendations prior to 2008 were for healthy trees.” Since 2008, UF/IFAS has evaluated several micronutrient rates “and we now have better recommendations for those nutrients” when used on HLB-affected trees, Morgan said.
“We have now for the last five years been evaluating rates of nitrogen, and we’re gathering information from different areas of the state to determine if our recommendations need to be adjusted” for HLB-affected trees, he added.
Now that FDACS/OAWP has indicated that phosphorus is becoming a critical issue, “we will be evaluating those recommendations to see if additional phosphorus is needed by HLB trees,” Morgan said.
Indications are that HLB-affected trees need higher levels of all nutrients than UF/IFAS recommended in 2008. Morgan noted that HLB-affected trees, which have extensive root loss, take up less of the nutrients that are applied than healthy trees take up, causing the recommendations to be re-evaluated.
“This is a critical issue for growers,” Morgan said. He pointed out that growers don’t want to use more nutrients than necessary because doing so costs them more money.
“We’re (UF/IFAS) going to be re-evaluating all of our recommendations,” Morgan said. But he said the research behind the recommendations takes much time and money. “Most of our (nutrient funding) source actually is FDACS … but it’s not enough to address all the needs of all the crops in Florida. We need more help.” He said the Citrus Research and Development Foundation has also helped with nutrition funding. “We are also looking to the (Florida) Legislature to provide a lot of these funds,” he added. The Legislature provided much funding this year for some row crops “and we’re hoping that they’ll do that soon for citrus,” he said.
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