FORT PIERCE, Fla.—New citrus varieties are now in their fourth year of growth and show signs of hope for growers in the Indian River District.
University of Florida/IFAS officials and research scientists invite growers to tour the 20-acre Millennium Block on Nov. 7, 9 a.m. until 2 p.m.
“We are excited about collecting a second year of data for assessing fruit yield and fruit quality,” said Ronald D. Cave, Director of the UF/IFAS Indian River Research and Education Center (IRREC) in Fort Pierce, the center of the world’s premier grapefruit production region. “There certainly are notable visual differences among the numerous scion and rootstock combinations. I hope growers will come to see those differences and the data from last season’s harvest.”
The grove is a living experiment of more than 5,500 citrus trees representing 142 scion and rootstock combinations, some of which are tolerating citrus greening better than others. The grove is situated in the heart of the Indian River citrus production district that is internationally renowned for its peerless fresh grapefruit. This research is expected to reveal which citrus varieties and rootstocks will allow growers to stay in business, said Cave.
Research in the Millennium Block (MB) citrus grove began with the first plantings in 2019. Cave said The Indian River region has seen a steep decline over the last 20 years due initially to the introduction of citrus canker, followed by the world’s most serious citrus disease, citrus greening. Breeders have developed new trees, some of which appear more tolerant of the bacterium that causes citrus greening.
The scion is the above-ground foliage and fruit, while the rootstock is the below ground roots that are adapted to different soil types and impart resistance to soil-borne diseases but also influences tree growth and fruit quality.
“Hurricanes Ian and Nicole impacted fruit from the 2022 harvest, so we are eager to evaluate this season’s production,” said Cave.
Pummelo grapefruit-like hybrids perform well
Mark Ritenour, a professor of horticulture and postharvest technology, points out more than a few varieties that show full canopies and decent crop loads. Among the grapefruit and pummelo hybrids that performed best last year was UF 914, which is a seedless, red-fleshed grapefruit-like hybrid developed by UF/IFAS breeders at the Citrus Research and Education Center.
This year’s fruit harvest is now underway, Ritenour said.
“Fast-track” release options
The research must continue for at least seven years to be robust enough to recommend the best scions and rootstocks to growers. However, some of these varieties are already available for grower testing through a New Varieties Development & Management Corporation and UF/IFAS “Fast Track” release option (https://nvdmc.org/fast-track/).
“With over 142 new citrus scion-rootstock combinations, we expect that some will rise above the others and be viable options for the industry,” said Ritenour. “’Star Ruby’ grapefruit, for example, is one that is not performing well under these Florida conditions.”
Macselynia Hossain, an IRREC agricultural assistant, is involved with the harvest. He said new data will be available to growers who attend the MB tour.
2023 harvest data expected in a few weeks
“I am currently working with data that focuses on brix–or sugar content–acidity, ratio, and yield, and I hope to have it summarized before the tour,” said Hossain. “For this year’s data, we will have a new baseline to evaluate the grove trees. Data and findings will increase each year.”
Pete Spyke, a Heritage citrus grower and IRREC Advisory Committee member, said only four citrus rootstocks were used in the region. “We are looking at about 30 rootstocks in the MB grove,” Spyke said.“The assumption is that they will replace the three or four rootstocks the industry has focused on for so long.”
Flavia Zambon began her new position as assistant professor of horticultural production of citrus and other tree crops last week. Previously, Zambon was a postdoctoral researcher at IRREC leading the evaluation of grapefruit scion and rootstock combinations planted across 42 blocks among 16 private growers’ properties.
“The Millennium Block is the pinnacle of local variety trials with several combinations that can guide us for tailored choices for the future of the Indian River grapefruit region,” said Zambon. “We will select the most promising combinations before their commercialization. The growers can make informed decisions based on the data we analyze and provide to them.
Please use the following link to sign up for the event.