North Florida have been characterized by hot summers and mild winters for the last three decades. This factor has increased interest in cold-hardy citrus production for the fresh market. ‘Satsuma’ are the most commonly grown citrus cultivars for fresh markets in north Florida. The citrus acreage in north Florida increases each year with major cultivation in Gadsden, Jackson, Jefferson, Taylor, Madison, and Suwannee counties. According to the north Florida Cold Hardy Citrus Association, there are 2,000 acres approximately under CHC for the fresh market in north Florida, and these acreages are continuously increasing. Since CHC is a newly emerging industry, most of the citrus groves are young (5-8 years), and growers coming to citrus production have limited citrus growing background. Currently, growers are depending on the information on nutrient and water management, disease, and pest control, weed management, pre- and postharvest plant care etc., developed for the citrus growing regions in, central and south Florida. Growers cannot benefit from that information because of the different nature of soil and climatic conditions. In addition, that information is developed for citrus production for processing while we are dealing with cold hardy citrus for fresh markets in North Florida. Therefore, an integrated research-driven extension program focusing on rootstock/scion evaluation for early fruiting, best management practices for citrus in cold-hardy regions, marketing, fruit storing, freeze and cold protection techniques etc., is needed to develop the recommendation for sustainable citrus production in north Florida. The project objective is to evaluate scion/rootstock combinations for high cold tolerance and disease resistance, ii) develop research-based recommendations for nutrient and irrigation management for citrus production in north Florida, iii) develop best management practices (pruning, heading, canopy size) to improve tree health, fruit size, and fruit quality.

UF950 is a seedless and easy to peel mandarin cultivar developed by UF/IFAS Citrus Research and Education Center, Lake Alfred. Its fruit size is similar to clementine with dark orange in color both internally and externally. It is very sweet in taste and matures in December. Here at NFREC we have evaluating this cultivar for more than six years. We have evaluated its yield and other fruit quality characteristics. It has shown great cold tolerance in north Florida. In our previous research trials, UF950 was evaluated just on two rootstocks i.e., swingle and US897. In our new research project, we are evaluating UF950 on eight different HLB and cold tolerant rootstocks from citrus breeding programs at UF and USDA. The main objective is to identify the best rootstock for 950 which can produce good quality and high yield while limiting the chances of alternate bearing.

Currently, winter cold and freeze events are the main threats to the citrus industry in north Florida compared to HLB. We have successfully grown many citrus varieties despite exposure to cold winter temperatures (down to 15 to 20 F). Many new citrus cultivars, including mandarins, sweet orange-like hybrids, and grapefruit-like hybrids with genetics for improved disease resistance and cold-hardiness are being developed by the University of Florida Citrus Breeding programs in Lake Alfred (Fred Gmitter, Jude Grosser) and Gainesville (Jose Chaparro).  For example, Marathon, UF950, UF914, Sugar Belle etc. are new cultivars named from the Lake Alfred program and UFDawn, UFGlow, and UFSunrise have been released by Gainesville program. Likewise, various new rootstocks are being released by citrus breeding programs at Lake Alfred and USDA Fort Pierce FL. There is a need for the testing and evaluation of these new scion and rootstock cultivars to identify cold tolerant, disease resistant and early maturing scion/rootstock combinations to diversify the fresh market citrus industry in north Florida. Our main objective is to establish a new replicated scion/rootstock trial at the North Florida Research and Education Center (NFREC) and continue to monitor the Asian Citrus psyllid and HLB in north Florida.

Passionfruit (Passiflora edulis) is an ideal candidate for Florida specialty crop production. Passionfruit is a tropical/subtropical perennial vine that has a great potential to be grown under Florida’s humid subtropical climate. Internationally, the farm gate value of passionfruit varies from $2 to $4 per fruit. Thus, we believe a farm gate value of $3 per pound is easily achievable. In the last few years, passionfruit imported from New Zealand is being sold at approximately $11/lb at leading U.S. supermarket chains, an indication of the high demand in the domestic market. There is initial evidence indicating passionfruit can be a viable horticultural crop for Florida growers. However, information is lacking on cultural practices necessary to produce high-quality fruit using either open field or high tunnel production systems (training, pruning, irrigation, nutrition, pest control, etc.), as well as cultivar performance, and fruit harvest maturity and handling. These are the most critical, initial barriers for growers. Relevant information developed from this project will be made available to interested growers, with the goal of passionfruit becoming a profitable specialty crop in south, central and north-central Florida growing areas to permit an extended production window and reliable supply chain. Water, nutrient and pest management are key components of sustainable agriculture. This project will comprehensively address the nutrient and water management practices, IMP of key pests, and the economic viability of outdoor and high-tunnel culture of passionfruit production in Florida.

Blackberry breeding program at UF has discovered a novel type of fruiting habit, everbearing (EB), in several blackberry lines. These lines have very low or no chilling requirement for floral initiation, budbreak, and fruiting, and are distinctly different from existing FF or PF cultivars. These EB lines can produce two major crops a year in central Florida, first on the floricanes in spring and then on primocanes in hot summer and fall month. This EB trait offers an unprecedented opportunity to develop low-chill blackberry cultivars and has the potential to confer growers’ major advantages, including high spring crop yield, fall/winter crops in tunnels for season extension, possibility for double cropping, expansion of production to south Florida and other tropical areas. So far, these EB lines have been tested only at one site in central Florida. The EB trait appears to be a recessive trait, with the EB phenotype masked in breeding crosses involving FF or PF parents. Consequently, it is difficult to select EB lines in such crosses based on phenotype. Current EB lines also have small berries, and they must be crossed with FF and PF cultivars/selections that have large berries to develop commercially accepted low-chill cultivars. The project objective is to characterize the phenotypic and physiological expression of the EB trait in multiple environments across Florida with different chill hours.

Commercial production of pomegranate has been an important specialty crop industry in California and has emerged as an alternative specialty crop in Florida in recent years. California farmers have been switching to drought tolerant crops like pomegranate because of water restrictions and costs. Florida growers’ interest in pomegranates increased as citrus growers face unprecedented challenges from citrus greening and berry growers face fierce competition from other countries. Florida growers have urged testing of pomegranate varieties to evaluate their plant growth and fruiting characteristics in Florida. The overall goal of the project is to develop strategies to increase marketable yield of pomegranate in California and Florida.

The purpose of this project is to assess the effect of shade cloths of different intensities, colors and shading duration on plant growth, fruit yield and quality for sustainable blackberry production. High summer temperatures are a big limiting factor for quality fresh market blackberry production in Florida because high temperature (above 85℉) limits flower formation, fruit setting, and fruit quality, resulting in low yield due to poor fruit quality and malformed fruits. We are investigating the shade cloth of different fabric, color, and intensities along with duration of shading to lower the summer temperatures and UV-radiation thereby improving the fruit yield and quality for fresh market blackberry production.