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Summary Cover crops can be a useful tool for managing plant-parasitic nematodes provided they are poor or non-hosts for the target nematode species. A glasshouse experiment was done to determine the host status of four common cover crops in Florida, sunn hemp, cowpea, sorghum sudangrass and sunflower, to pure populations of four common tropical root-knot nematode (RKN) species Meloidogyne javanica (Mj), M. incognita (Mi), M. enterolobii (Me) and M. arenaria (Ma). Tomato was included as a susceptible control. Eight weeks after nematode inoculation (WAI), tomato showed the highest root gall damage for all tested RKN species, with gall indices (GI) between 7 (Ma) and 8.5 (Me) and reproduction factor (RF) ranging from 20 (Ma) to 50 (Mj). No visible root galls were observed for any of the RKN species on sunn hemp and sorghum sudangrass at 8 WAI. However, Mj and Mi were able to reproduce slightly on sorghum sudangrass (RF = 0.02 and 0.79, respectively). Sunflower and cowpea were infected by all four tested RKN species, but host suitability varied. Sunflower root galling ranged from 1.1 (Me) to 4.5 (Mj) and RF = 3.2 (Me) to 28.7 (Mj), while cowpea root galling ranged from 0.6 (Mi) to 5.1 (Me) and RF = 0.8 (Mi) to 67.3 (Mj). Sunn hemp and, to a lesser extent, sorghum sudangrass were poor hosts to all four tested RKN species. Sunflower was a good host to all RKN species, but root gall damage and RF were lowest for Me. Cowpea was a good host to Mj, Me and Ma, but a poor host to Mi. Our results confirm and stress the importance of RKN species identification when selecting cover crops as an RKN management strategy.

Nicotinamide adenine dinucleotide (NAD) has been shown to induce plant defense responses to different plant pathogens, including reducing northern root-knot nematode, Meloidogyne hapla, penetration and increasing plant mass in tomato. We wanted to further evaluate NAD that are effective against the more economically important species, M. incognita and whether NAD treatments of tomato seedlings in transplant trays can protect plants in the field. Different NAD concentrations (1 mM, 0.1 mM and 0.01 mM) and three application timings (pre; post; pre and post inoculation) were evaluated in growth room and greenhouse trials. The highest tested NAD concentration (1 mM) suppressed second-stage juveniles (J2) infection for all three application methods. Root gall ratings at 30 days after inoculation (DAI) were also suppressed by 1 mM NAD compared to the other two concentrations, and egg mass number was significantly suppressed for all concentrations and application timings compared to the non-treated control. The rate of 1 mM NAD for all three application timings also improved plant growth at 30 DAI. Long-term effects of 1 mM NAD (pre, pre + post, or post applications) on nematode infection, growth and yield of tomato were evaluated in two additional experiments. All NAD applications suppressed root galls after 60 days, but only the pre + post 1 mM NAD application suppressed gall severity at 105 days, as well as suppressed egg counts by 50% at 60 DAT. No significant difference in plant biomass and fruit yield after 105 days was observed among the treatments. Two field trials were conducted in spring and fall 2020 using tomato seedlings (cv. HM 1823) treated with two different NAD concentrations (1 mM and 5 mM in spring; 5 mM and 10 mM in fall) and transplanting seedlings in fumigated (chloropicrin ± 1,3-dichloropropene) and non-fumigated plastic-mulch beds. No significant impact of NAD in terms of reducing RKN severity or overall tomato growth and production was seen in fumigated beds, but in non-fumigated beds 5 mM NAD slightly increased early fruit yield in spring, and 10 mM NAD reduced root-knot soil populations in fall.

Summary Populations reviously identified as Aphelenchoides besseyi were studied. Using an integrated approach, the A. besseyi species complex contains several cryptic species: A. besseyi sensu stricto, A. oryzae, A. pseudobesseyi sp. n. and other putative undescribed species. A population from Florida strawberry morphologically fits the A. besseyi of both Christie and Allen and is considered the only representative of this species. A Louisiana rice population fitted the descriptions of A. oryzae of both Yokoo and Fortuner; PUS length was consistently less than one-third of VA. Aphelenchoides oryzae, parasitising rice and other monocots, was re-established based on morphological and molecular datasets. Three populations from Florida ornamental plants (Dryopteris erythrosora, Echinacea sp. and Farfugium japonicum) differed from those of the two above-mentioned species and are described as A. pseudobesseyi sp. n. Populations previously identified as ‘A. besseyi’ from several countries were considered representatives of this new species, which usually had a large and conspicuous PUS, 8-14 μm wide and with a length greater than one-third of VA in 40-70% of studied specimens. Morphological variability made separation of A. pseudobesseyi sp. n. from A. oryzae and A. besseyi unreliable without the examination of numerous specimens and molecular analysis.

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Kratom (Mitragyna speciosa) belongs to the coffee family of Rubiaceae. The tree is native to Southeast Asia and primarily grown in Malaysia, Thailand, and Indonesia. Recently, it has been introduced and cultivated in other countries including the United States. The leaves and extracts of the leaves are used for medicinal and recreational purposes. In February 2022, kratom root and soil samples were submitted to the University of Florida Nematode Assay Laboratory for diagnosis by a commercial grower in Florida. Root galls were observed on the roots. On examination of soil and root samples, it is revealed that high numbers of root-knot nematodes (Meloidogyne sp.) are present. Molecular species identification was performed by a combination of the mitochondria haplotyping and species-specific primer techniques using TRNAH/MHR106 and MORF/MTHIS primer sets and Meloidogyne incognita-specific primers (MIF/MIR). The root-knot nematode infecting kratom is identified as M. incognita by molecular analysis. To our knowledge, this paper is the first report of M. incognita infecting kratom in the United States.

The Mi gene in tomato confers resistance to Meloidogyne javanica, M. incognita, and M. arenaria, the most common tropical root-knot nematode (RKN) species found in Florida. Fusarium wilt (Fol) is another major problem in Florida tomatoes which may interact with RKN and cause more plant damage. To study the interactions between RKN, Fusarium, and Mi in tomato, two greenhouse experiments were conducted. Both experiments used different isolines (with and without I-3 and Mi genes) of the tomato cultivar Tasti Lee®. In the first experiment, all four isolines were subjected to two levels of RKN (~10,000 eggs/pot and no eggs) and two levels of Fol (1000 cc soil with 1,000 cfu/g at planting and no Fol), both applied at planting. In the second experiment, the two isolines without I-3 were exposed to the same two levels of RKN as described above and three levels of Fol (50 ml Fol with 1×106 cfu/m at planting, at 10 DAT, and no Fol). Fol reduced root-knot infection and reproduction when both Fol and RKN were inoculated at planting but not when Fol was inoculated 10 days later. Plant damage from Fol was exacerbated in the presence of RKN, especially when both pathogens were present at planting. Isolines with I-3 grew better in Fol-inoculated soil but had no effect when Fol and RKN were both present. Isolines with Mi gene reduced RKN infection and reproduction but did not affect plant damage caused by Fol. In summary, while RKN reproduction was reduced in the presence of Fol, the overall plant damage was more severe when both pathogens were present.

Florida leads the commercial production of caladiums, a popular ornamental. In Florida, root-knot, sting, and stubby root nematodes are found in caladium fields. Root-knot nematodes are considered the most important of all pests in caladiums that are grown in sand. This publication will help caladium growers understand what plant-parasitic nematodes are and current nematode management strategies for the caladium industry.

Chapter 13 of the Vegetable Production Handbook.

Chapter 16 of the Vegetable Production Handbook.

Chapter 15 of the Vegetable Production Handbook.

Chapter 6 of the Vegetable Production Handbook.

Chapter 17 of the Vegetable Production Handbook.

Chapter 10 of the Vegetable Production Handbook.

Chapter 18 of the Vegetable Production Handbook.

Chapter 19 of the Vegetable Production Handbook.

Chapter 12 of the Vegetable Production Handbook.

Chapter 4 of the Vegetable Production Handbook.

Chapter 7 of the Vegetable Production Handbook.

Chapter 8 of the Vegetable Production Handbook.

Two Florida populations of foliar nematodes were collected from strawberries originating from Cashiers, North Carolina (USA) located west from Willard, the type locality of Aphelenchoides besseyi. Both nematodes were cultured on Monilinia fructicola and identified using morphological characteristics and molecular assays as Aphelenchoides besseyi and Aphelenchoides pseudogoodeyi sp. n., a herein described new species related to Aphelenchoides goodeyi belonging to the Group of Aphelenchoides exhibiting stellate tails. The morphological and biological characters of Florida A. besseyi fit those of the original description of this species. A. pseudogoodeyi sp. n., which was initially misidentified as Aphelenchoides fujianensis, differed from the type population of the latter species from China because it was without males, and females lacked a functional spermatheca, whereas type A. fujianensis is an amphimictic species. Phylogenetic analyses using near full-length 18S ribosomal RNA (rRNA), the D2-D3 expansion fragments of 28S rRNA, and partial COI gene sequences indicated that A. besseyi is a species complex. A. pseudogoodeyi sp. n. grouped in different clades from those of the type A. fujianensis, instead merging with populations identified of ‘A. fujianensis’ from Brazil and other countries, suggesting that the latter are conspecific and incorrectly identified. The Florida A. besseyi infected strawberry and gerbera daisy, but not soybean and alfalfa. A. pseudogoodeyi sp. n. is mainly mycetophagous. Localized inoculation of 300 specimens applied with filter paper adhering to the blade of the soybean leaves resulted in nematode penetration into the mesophyll with subsequent development of lesions limited to the inoculated area of the blade.

Background Two field experiments were conducted to determine the efficacy and field performance of three new non-fumigant chemical nematicides (fluensulfone, fluopyram, and fluazaindolizine) and two biological nematicides (Burkholderia rinojensis strain A396 and Purpureocillium lilacinus strain 251) for management of root-knot nematodes (Meloidogyne javanica) on tomato and associated double-crops in Florida. Results In experiment 1, soil fumigation with metam potassium increased plant growth and reduced root galling on tomato by 77% relative to that of the untreated soil. All non-fumigant chemical nematicides reduced root galling on tomato (47-85% reduction); however, only fluensulfone showed a trend towards yield enhancement. In experiment 2, soil fumigation with chloropicrin increased plant growth and reduced root galling on tomato by 35% relative to that of the untreated soil; however, end-of-season populations of M. javanica in soil were larger than that of the non-fumigated soil. Fluensulfone showed a trend towards reduced root galling and enhanced fruit yield, whereas other non-fumigant nematicides did not. Double-cropped cucumber was 69% more galled when planted into soil previously fumigated with chloropicrin relative to that of untreated soil, and also showed reduced plant vigor and fruit yield. Conclusion Fluensulfone shows significant potential to be a component of an integrated pest management strategy for tomato in Florida. © 2019 Society of Chemical Industry.

In Florida, strawberry is an economically important horticultural crop. Plant-parasitic nematodes present a significant obstacle for strawberry growers in the sandy soils found in this state. Historically, nematodes have been controlled through the application of soil fumigants; however, there is interest in exploring the use of non-fumigant nematicides that can provide similar levels of control and at the same time be more environmentally friendly than fumigants. Using two field experiments, the effects of non-fumigant chemical and biological nematicides on plant vigour and fruit yield, populations of plant-parasitic nematodes, and populations of free-living nematode feeding groups were evaluated. In experiment 1, soil fumigation with metam potassium, as well as all non-fumigant chemical nematicides (fluopyram, fluensulfone, fluazaindolizine) failed to increase plant vigour, fruit yield, or suppress populations of plant-parasitic nematodes. In experiment 2, fluopyram increased fruit yield and suppressed Belonolaimus longicaudatus populations by the end of the growing season. Biological nematicides (Dazitol®, Majestene®, and Nemakill®) did not enhance crop establishment or suppress plant-parasitic nematode populations. Soil fumigation with 1,3-dichloropropene + chloropicrin provided consistent enhancement of plant vigour and fruit yield, as well as suppressed populations of B. longicaudatus; however, populations of free-living nematodes were also reduced. Overall, soil application of fluopyram shows potential to be a component of an integrated pest management strategy for the control of B. longicaudatus populations on strawberry in Florida.

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 (Hubschen 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.

BACKGROUND Biotic and abiotic factors such as microbes and soil temperature can affect nematicide efficacy. Two experiments were conducted to test the effect of three soil temperatures on the efficacy of nonfumigant nematicides (fluopyram, fluensulfone, oxamyl and fluazaindolizine) against Meloidogyne javanica in pasteurized and natural soil in planta. RESULTS The results showed that all tested nematicides were more efficacious in pasteurized than in natural soil. Temperature affected the nematicides differently with no effect of soil temperature on oxamyl and fluazaindolizine, whereas fluopyram and fluensulfone had greater efficacy at higher soil temperatures. CONCLUSION Temperature effects were noted for some but not all nonfumigant nematicides. Fluopyram and fluensulfone were less effective when applied in cold soil, whereas oxamyl and fluazaindolizine were not affected by soil temperature. Although all nematicides resulted in almost complete control of M. javanica in pasteurized soil, this was not the case in natural soil, and much more root damage and nematode reproduction was noted in the latter. © 2021 Society of Chemical Industry.

Hemp is an annual herbaceous plant that is used for its fiber and oil in a variety of commercial and industrial products. In Florida, it is currently being explored as a new specialty crop. During a field trial from October to January 2019 in Wimauma, FL, a stem canker was observed on up to 60% of three-month-old plants of 'Eletta Campana', 'Carmagnola Selezionata', and 'Tygra'. Symptoms started on the main stems with light-to-dark brown lesions of different sizes and shapes. Over time, the lesions coalesced into large necrotic areas and bore pycnidia. Isolations were made from diseased stem tissues on General Isolation medium (Amiri et al. 2018) after surface disinfestation (Marin et al. 2020). The plates were placed in a growth chamber at 25°C under a 12/12 photoperiod. A fungus with white, floccose, aerial mycelium and pycnidia producing alpha and beta conidia was consistently isolated. Three single spore isolates were chosen for identification and pathogenicity tests. Pycnidia on PDA were globose to irregular and ranged from 170 to 250 μm long (210 ± 2.5, n = 50) and 140 to 220 μm wide (180 ± 2.7, n = 50). The alpha conidia were unicellular, hyaline, ellipsoidal to fusiform and ranged from 5.3 to 7.7 μm long (6.5 ± 1.6, n = 50) and 1.5 to 4.6 μm wide (2.8 ± 1.8, n = 50). The beta conidia were hyaline, elongated, filiform, straight or curved and ranged from 10.2 to 17.7 μm long (16.1 ± 2.2, n = 50) and 0.5 to 1.8 μm wide (0.8 ± 0.2, n = 50). Perithecia were not observed. Based on morphological features, the fungus was similar to anamorphs of Diaporthe spp. (Santos et al. 2011; Udayanga et al. 2015). DNA from the same three isolates was extracted using the FastDNA kit, and the ribosomal internal transcribed spacer (ITS), β-tubulin (TUB), and calmodulin (CAL) regions were amplified following Udayanga et al. (2014), and Sanger sequenced by Genewiz. Sequences were deposited in GenBank (accession no. MT497039 to MT497047 for ITS, TUB, and CAL). BLASTn searches revealed isolates 20-58, 20-59, and 20-60 were 96.34% identical to the epitype isolate

Soil fumigation remains the standard practice to manage soilborne pathogens such as plant-parasitic nematodes, bacteria, and fungi, especially in high-value crops. However, increasing regulatory pressure due to the inherent and broad-spectrum toxicity and negative environmental impact of chemical soil fumigants, its negative effect on overall soil health, and increasing demand for organic produce, has created a growing interest in biological fumigants. Many plants and microorganisms emit volatile compounds, which can potentially be used as bio-fumigants. In this mini-review, we summarize the current status of nematology studies focused on the development of volatile compounds emitted from plants and microorganisms as fumigants to control plant-parasitic nematodes. The gap of knowledge and challenges of studying volatile compounds are also addressed.

Integrated nematode management (INM) employs a diversity of management practices and focuses on key concepts such as targeted rotations, intercropping, advanced genetics for resistance breeding, remote sensing to monitor nematode distribution and densities, precision agriculture to target control treatments and molecular tools to measure soil suppressiveness. This chapter further discusses new building blocks of INM that could improve the future of nematode management. Outlooks on chemical control in the future; the growth of biological control; the need for resistance breeding; suppressive soil and its antagonistic potential for nematode management; climate change adaption; regional and site-specific approach in nematode management; loss of applied nematology positions at universities and plant protection agencies; and recommended INM programmes are described. For INM to become a reality, applied nematology needs to be at the forefront of the science of nematology again, and funded accordingly.

This chapter focuses on the 5 pillars and management tools available for integrated nematode management (INM), i.e. rotation, cultivar choice, soil management, targeted control and monitoring and evaluation. The management tools making up the pillar are also presented, i.e. prevention of nematode introduction, reduction of nematode population densities, improvement of crop tolerance and supportive tools and tactics. Some future challenges and opportunities for INM are also presented.

This chapter covers beet, radish, carrot, sweetpotato, cassava, taro, and malanga production.

This chapter covers production of legumes, such as peas and beans.

This chapter covers production of celery, okra, and parsley.

This chapter covers production of cole crops and Asian crucifers, including broccoli, cabbage, cauliflower, Chinese broccoli, Chinese cabbage, Chinese mustard (bok choy), kohlrabi, lobok/daikon, collards, kale, mustard, and turnip.

This chapter covers production of cucurbits, such as cantaloupe, cucumber, squash, watermelon, and pumpkin.

This chapter covers lettuce, endive, escarole, and spinach cultivation.