The Florida Department of Agriculture and Consumer Services Division of Plant Industry’s (FDACS DPI) Bureau of Citrus Budwood Registration has several significant duties. Among them is to maintain disease-free source material for Florida citrus nurseries, test to ensure the cleanliness of private nursery budwood sources, and supplement private nursery budwood supplies with cuttings from the foundation block in Chiefland.
In other words, the Bureau serves to encourage and enable nurseries to establish and maintain private budwood sources (scion and increase blocks), and can supply budwood to nurseries when private sources are insufficient.
Typically, budwood can be harvested from private nursery increase trees for 36 months. As a means of helping nurseries increase budwood faster, DPI is permitting nurseries to harvest wood from increase trees for 60 months without having to convert them to scion trees.
However, any trees that wish to be used in this process will have composite testing done at the 36-month period to allow their eligibility for the additional 24 months. This will enable the nurseries to keep these trees in budwood production longer, without having to cycle in new trees. This seems like a simple step, but it is yet another incremental improvement in the process and a means of addressing the pressing needs of industry.
A Numbers Game
There were 21.6% fewer total citrus tree propagations in the 2016-2017 season than the prior year. DPI’s budwood cutting decreased 22%. Sixty-four percent of the budwood used for propagations is now coming from private sources. Essentially, the system is performing as designed. Once better HLB solutions are available, there may still be some lag time in ramping up budwood quantities, but steps are being taken to improve preparedness. Strategically, DPI has been comprehensively studying the entire process of citrus tree production and how they might proactively tackle the next impediment to rapid industry expansion. It would be tragic to have access to better tools to combat HLB, experience a sharp increase in the demand for trees, and not have the ability to produce and supply. These discussions rapidly focused the conversation on rootstock seed availability.
The number of new rootstocks available to nurseries and growers has be rapidly escalating. Many growers are experimenting with a range of scion/rootstock combinations, while larger trial plantings are hoped to produce data that will further inform future planting decisions. Growers are sometimes forced to alter their planting plans as seed for the most popular (and hopefully tolerant) rootstocks (US 942, UFR-5, etc.) is in short supply. Seed availability from UF/IFAS Southwest Florida Research and Education Center (SWFREC), A.H. Whitmore Foundation Farm, and private sources is not meeting demand.
What about rootstock liners from tissue culture (TC)? Doesn’t that solve the problem? Relative to overall demand for citrus trees, TC liners are certainly coming online at just the right time, but more seed is needed. Liners from seed are less expensive for nurseries to produce, and locally produced seed has a higher germination rate than imported seed. Any project to increase rootstock seed availability would be complementary to escalating TC liner production. Seed will continue to be in short supply. TC production will help fill the gap until seed production catches up. There will always be nurseries and growers who prefer one over the other.
Prime Property to Grow On
The Bureau’s Chiefland budwood facility is located on Florida Forest Service property. This location has been ideal for its current purpose, as it is far enough from the coast to provide limited protection from coastal storms and is outside of the main citrus production areas. It just so happens that a 10-acre block of Florida Forest Service land is available (and has been donated) just south/southwest of the existing Budwood facility.
This property has been deemed suitable for a new seed block planting. Since the trees will be outdoors and exposed, it would not be ideal to have the seed block adjacent to the budwood screenhouses. This new seed block site is approximately 1 mile away from the current structures (as the crow flies). The new block will accommodate 40 to 50 rootstock varieties, with greater volumes of those currently in high demand.
The trees for the project will start their life at the FDACS LaCrosse Phase II Budwood Facility. Here, seed has been planted (enough to produce 2,000 trees) to serve as a root system for the seed source trees. Once the base rootstock trees are of sufficient size (it is anticipated that this will be February 2018), they will be grafted with budwood of the target commercial rootstock varieties. All of this will be done inside a clean, protected facility. The plants will then be transferred to the Chiefland block in August 2018. It should take approximately three to four years before fruit is available for seed harvest from these trees. Larger volumes of seed will be available in 2020-2021.
Most of the trees in the new seed block will be planted on X-639, but DPI is considering planting some seed trees from rooted cuttings so that production could be restored more quickly after an extreme cold weather event.
The Florida Nursery, Growers and Landscape Association administered a grower survey in December to help determine the rootstock varieties that should be included in the new block. As more promising rootstocks are identified, they will be added to the DPI block, and eventually less successful selections will be replaced. All equipment to be used in the management of the new seed block will be dedicated to the farm to further minimize exposure to outside infection. Equipment is being sourced to enable DPI to perform the seed extraction on premises.
Funding for this project is being provided through the Citrus Health Response Program. This is a one-time funding source intended to address Florida’s declining rootstock seed production over the past seven years. HLB has reduced the volume of fruit on rootstock source trees and in some cases, the volume of seed per fruit. The seed block will be maintained using other funding sources moving forward. One additional staff position will be required for the project, but the seed block will be managed through the FDACS Chiefland office.
Though there are no guarantees, the industry continues to demonstrate its belief that better days are ahead and solutions will be found. Any actions that will enhance Florida’s capacity to recover are welcomed and appreciated; as is the forward thinking responsible for their implementation.