First Report of Meloidogyne javanica on Globe Artichoke in Florida, USA

Globe artichoke (Cynara cardunculus var. scolymus L.) is native to the Mediterranean region and cultivated worldwide for its edible flower buds and the medicinal value of its leaves (Pignone and Sonnante 2004). In 2019, artichokes were planted on 29 km2 predominantly in California, with a yield of over 100 million kg (USDA 2020). It has been grown as a specialty crop in Florida since 2017 (Agehara 2017a). Meloidogyne spp. (root-knot nematodes/RKNs) can lead to yield losses to artichoke (Greco et al. 2005). In June 2020, artichokes (cv. Imperial Star) with stunting, wilting, and galled-root symptoms were observed in a research field with sandy soil located at the University of Florida Gulf Coast Research and Education Center (UF/GCREC), Wimauma, Florida. The goal of this report was to identify the RKN species collected from two symptomatic artichoke roots. Morphological measurements (mean, standard deviation and range) of 15 second-stage juveniles (J2s) included body length = 409.1 ± 31.6 (360.3 - 471.3) µm, body width = 15.4 ± 1.6 (12.4 - 18.8) µm, and stylet length = 14.7 ± 0.7 (13.9 -16.1) µm. Perineal patterns of five matured females had a high dorsal arch and double lateral lines. Morphological characteristics of the RKN cultures were consistent with the description of M. javanica (Eisenback and Triantaphyllou 1991). DNA was extracted respectively from two RKN females isolated from the diseased artichoke roots. The nematode species was confirmed with primers Fjav/Rjav and resulted in ≈ 670 bp fragment (Zijlstra et al. 2000). The COXII region of mtDNA was amplified by C2F3/1108 (Powers and Harris 1993), and the sequencing results were submitted to the NCBI with GeneBank Accession No. MZ397905. The molecular sequences had 100% identity with M. javanica in COXII (MK033440 and MK033439). The pathogenicity test was conducted in the greenhouse at UF/GCREC from May to August 2021 (temperature = 26.7 ± 4.1°C, relative humidity = 83.9 ± 14.6 %). Each of the ten 6.5-in-diameter plastic pots containing 3.8-L pasteurized soil was seeded with one artichoke seed. Five pots were inoculated with 5000 eggs of the field RKN cultures 4-week after planting, and five pots served as the untreated control. Two months after inoculation, galled symptoms were only observed in inoculated plants with an average gall index (Bridge and Page 1980) of 6.2 ± 2.2; 99,240 ± 72,250 eggs were extracted from each root system, and the nematode reproduction factor was 19.9 ± 14.4. Meloidogyne spp. has been reported on artichoke in Europe, Asia, and South America (Greco et al. 2005). This is the first report of RKN on artichoke in the United States. Meloidogyne javanica caused severe root gall symptoms and visible aboveground damage in the form of chlorosis, stunting, and wilting of artichoke planted at the UF/GCREC research farm. Meloidogyne javanica is the predominant RKN species at the UF/GCREC research farm and one of the most common RKNs in Florida (Gu and Desaeger 2021). Artichoke is a new crop in Florida, and RKNs is likely to be one of the main soilborne problems for its production in the state. Its long growing season (October - May) (Agehara 2017b) allows for high nematode reproduction rates. Several new growers have already reported RKN as a problem in their fields. For artichoke to become a commodity in Florida, managing RKNs will be critical. This report provides new information on the risk that RKNs pose to artichoke, a newly established specialty crop in Florida.

The first report of Meloidogyne enterolobii on Thai basil in Florida, United States

Thai basil (Ocimum basilicum var. thyrsiflora) is an important ethnic aromatic herb native to Southeast Asia. According to the Vegetable Production Handbook of Florida 2020-2021, Asian vegetables are currently grown on more than 4,000 ha in Florida, and Thai basil is one of the most commonly grown among these. Meloidogyne spp. cause severe damage to different basil cultivars (Brito et al. 2007). During May-July 2020, plant stunting and galled root symptoms were observed on Thai basil plants sampled from a commercial Asian vegetable farm in Wimauma, Florida (27°44.951' N; 82°16.271’ E); 1,972 root-knot nematode second-stage juveniles (J2s) were extracted from 200 cm3 soil. A pathogenicity test was performed in September 2020 at the University of Florida Gulf Coast Research and Education Center, Wimauma, Florida. Ten of 20, three-week-old nematode-free Thai basil plants were inoculated with 5,000 eggs of field nematode cultures. Two months after inoculation (temperature = 22.8 ± 3.8 °C, relative humidity = 85.6 ± 14.0 %), average gall index (Bridge and Page 1980) = 5.4 ± 1.1 were only observed in inoculated plants, and 69,276 ± 18,904 eggs were extracted from roots using the NaClO method (Hussey and Barker 1973); 5 ± 7 J2s / 200 cc soil were recovered by the modified Baermann funnel technique (Forge and Kimpinski 2007). Nematode reproduction factor (RF) = 13.86 ± 3.78 (Nicol et al. 2010). Morphological measurements (mean, standard deviation and range) of J2s (n=20) included body length = 394.0 ± 22.3 (362.8 - 437.9) µm, body width = 15.7 ± 1.2 (13.6 - 18.3) µm, and stylet length = 12.8 ± 1.1 (10.4-14.5) µm. The perineal pattern of matured female (n=5) was oval-shaped with coarse and smooth striate; the dorsal arch was high and round; no lateral line presented. Morphological characteristics of females and J2s were consistent with those described for M. enterolobii (Yang and Eisenback 1983). DNA was extracted from a single female picked from infected Thai basil root using NaOH digestion method (Hübschen et al. 2004). The D2-D3 expansion segment of 28S rDNA and the COXII region on mitochondrial DNA were amplified by PCR using the primers 28S391a/28S501 and C2F3/1108 (Ye et al. 2020); the species was also confirmed with species-specific primers Me-F/Me-R (Ye et al. 2020). PCR products were sequenced by the Genomic Sciences Laboratory (North Carolina State University, Raleigh, NC, USA) and the results were recorded in the NCBI with GeneBank Accession Nos. MW488150 and MW507374. The sequences showed 100% identity with M. enterolobii in D2/D3 (KP901079, KP411230) and COXII (MN809527, KX214350). M. enterolobii (M. mayaguensis) has been reported on sweet basil in Florida (Brito et al. 2008). To our knowledge, this is the first detection of M. enterolobii on Thai basil in Hillsborough County, Florida. It is not clear to what extent M. enterolobii reduces the yield of Thai basil, but the RF value obtained in the pathogenicity test indicates the crop is certainly a very good host. Limited information is available on the distribution of M. enterolobii in Florida and the US. M. enterolobii is known to break down the root-knot resistance of crops including soybean, sweet potatoes, and tomatoes (Philbrick et al. 2020). This nematode is considered one of the major emerging threats to agriculture in the southeastern US. A multistate research and outreach program (FINDMe program) was initiated in 2019 to study the distribution and management of this nematode in the southeastern US.

Use of Ultraviolet Light to Suppress Powdery Mildew in Strawberry Fruit Production Fields

We designed and deployed an apparatus to apply UV light for suppression of powdery mildew in open field production of strawberry. The unit was evaluated in a commercial production field for one season, and for two additional seasons in open field research plots at the University of Florida Gulf Coast Research and Education Center. The apparatus contained two 180 cm long hemicylindrical arrays of twenty 55 W low-pressure discharge UV-C lamps (operated at 30 W; peak wavelength 254 nm) backed by polished aluminum reflectors covering two adjacent beds of the strawberry planting. The lamp arrays were suspended within a steel carriage that was tractor-drawn through the planting at 2.3, 4.6 and 5.6 km/h. Night-time applications of UV-C at doses ranging from 65 to 170 J.m-2 either once or twice weekly provided suppression of foliar and fruit disease that was consistently equal to or better than that provided by a commercial calendar-based fungicide spray program.

Odum’s dark bottle and an ecosystem approach

Eugene Odum was an ecological pioneer, writing the discipline’s first textbook, Fundamentals of Ecology, in 1953. Although his work is almost 70 years old, it laid the groundwork for contemporary landscape systems thinking. Since Odum’s time, a lineage of ecological research and theory has helped to define concepts pertaining to ecology, ecosystems, and nature. With these terms in peril of becoming ambiguous, especially in the design arts, this chapter revisits the origins and development of ecologic thinking in order to construct a more critical understanding of nature, and the role of the designer for Building with Nature. One particular experiment by Odum is used as the foundation of concept development. A pond is his reference site and he ‘dissects’ it, using dark and light bottes to illustrate its nuances and the overall ecosystem idea. Three important principles can be derived. First, the ecologist, or the designer, should understand the ‘nature’ of the system, or site, where they are working. Second, nature is formed through functional interactions over extended periods of time. Lastly, through an ecosystem approach, it is shown that systems involve indirect effects. In ecological networks, sites are impacted by forces beyond their immediate boundaries, as well as through other social and cultural systems. Case studies located along the Florida Gulf Coast are used to explain Odum’s and others’ concepts. Florida has developed in parallel with human’s capacity to manipulate their environment. For this reason, it is a useful reference site, illustrating trajectories in ecological thinking.

Genetic classification of two Vibrio species isolated from Florida Gulf Coast using multi-locus sequence analysis

Prokaryotic species classification has lagged dramatically behind eukaryotic species due to the dependence on the difficult DNA-DNA hybridization technique required for species designation. This is disadvantageous for the general understanding of the diversity of microbial life and unique microorganisms, along with their metabolic abilities, like bioremediation of hazardous waste. This applies to the secondary metabolites microorganisms produce that can be beneficial for humans and other living organisms, such as antibiotics or other industrially important compounds. In an effort to isolate and identify new microbial species, environmental samples were collected from marine sediment environments as marine habitats are under-sampled compared to non-marine habitats. Two marine isolates designated MI-1 and MI-2 were isolated from marine sediment environments off the Gulf Coast of Florida and chosen for further study because of their antibacterial production and unique colony pigmentation. They were genetically analyzed through sequencing of the 16s rRNA gene, shotgun cloning, and an eight-gene multi-locus sequence analysis comparison to 66 other species of the same genus. From these, MI-1 and MI-2 can be classified as members of the Vibrio genus most closely related to Vibrio ruber and a distinct strain from V. ruber type strain VR-1.