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Fresh-market tomatoes are produced on a raised-bed plasticulture system that relies heavily on soil-applied preplant fumigants for the management of soilborne pathogens, nematodes, and weeds. Since the transition from methyl bromide to alternative fumigants, growers have experienced a resurgence of several soilborne pests and pathogens, including root-knot nematode caused by Meloidogyne spp. and Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici race 3. This resurgence is attributed to the inability of the alternative fumigants to effectively disperse through the soil in the same manner as methyl bromide. Two supplemental fumigation strategies, the application of chloropicrin (PIC) below bed edges (herein “supplemental PIC”) and broadcast deep-shank applications of 1,3-dichloropropene (1,3-D), were evaluated in conjunction with standard raised-bed applications of Pic-Clor 60, Pic-Clor 80, and Pic 100 covered with a virtually impermeable film or a totally impermeable film. Large-plot replicated studies were conducted in two separate commercial tomato fields with a history of production losses caused by root-knot nematode and Fusarium wilt. Deep-shank 1,3-D applications significantly reduced the recovery of root-knot and total parasitic nematodes across field sites before the preparation of raised beds. Both supplemental PIC and deep-shank 1,3-D reduced root-knot galling and Fusarium wilt incidence, but the latter supplemental treatment statistically had the greatest impact. Fumigant applied within raised beds or plastic film had no significant effect on root-knot galling or Fusarium wilt. Although both supplemental fumigation strategies had a significant effect on pest and disease pressure, neither statistically improved tomato yields based on small subplot harvests. Controlled laboratory experiments confirmed the fungicidal activity of 1,3-D against F. oxysporum f. sp. lycopersici, with 75, 90, 95, and 99% lethal doses corresponding to estimated field application rates of 56.1, 93.5, 121.6, and 184.7 liters/ha, respectively. The results demonstrate how fumigant placement can improve pest and disease control activity with current fumigant alternatives to methyl bromide and further support the broader pesticidal activity of some chemical fumigants.

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.

Caladium is an ornamental aroid valued for its variably shaped bright foliage. Two new lance-leaved cultivars, ‘Pink Panther’ and ‘Crimson Skye’, were released in 2020 by the UF/IFAS caladium breeding program to meet the need for more lance-leaved cultivars. This new 9-page article is prepared for growers who are interested in growing caladium as a horticultural crop and for greenhouse or nursery growers who are interested in producing potted caladium plants.

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 15 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 9 of the Vegetable Production Handbook.

Chapter 19 of the Vegetable Production Handbook.

Chapter 12 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.

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 lettuce, endive, escarole, and spinach cultivation.

Aerated steam-based thermotherapy was developed and evaluated for its efficacy in managing three nematode species (Aphelenchoides besseyi, Meloidogyne hapla, and Pratylenchus penetrans) that are often transported as quiescent passengers on strawberry transplants shipped to Florida from out-of-state nurseries. Initial studies were focused on evaluating the intrinsic temperature sensitivity of each nematode species to hot water in laboratory conditions. Each nematode species was exposed to hot water at 40, 44, 48, and 52°C for 1, 5, 10, 30, 60, 120, and 240 min. Exposure for 60 min or higher at 40°C paralyzed all three nematode species when examined immediately after heat treatment. Examination of the nematodes 24 hr post-treatment suggested that 100% mortality of all three nematode species was achieved when nematodes were exposed to hot water at a minimum temperature of 44°C for 120 min. Further studies were conducted to evaluate the efficacy of aerated steam to kill all three nematode species by exposing nematode-infested strawberry transplants at 44°C for 60, 120, and 240 min. Exposure of nematode inoculated plants to steam for 60 or 120 min reduced the populations of all three nematode species, but this was not enough to completely eradicate any of the three nematode species. Exposure for 240 min, however, was the most effective in reducing the populations of the three nematode species. A 240 min of exposure to aerated steam completely eradicated A. besseyi and M. hapla while P. penetrans populations were reduced only by 85%. Furthermore, the aerated steam had minimal to no adverse effect on plant biomass. Results from both the laboratory and greenhouse studies indicated that M. hapla was more sensitive to heat treatment followed by A. besseyi and P. penetrans. Results from this study suggested that aerated steam-based thermotherapy has good potential as a non-chemical method of management of nematodes of strawberry transplants.

Southern root-knot nematodes (Meloidogyne incognita; RKN) significantly reduce lima bean (Phaseolus lunatus) yields. Chemical control options for RKN are limited. We evaluated the efficacy of new nematicidal products on RKN in lima bean experiments conducted in greenhouse (GH) and microplot (MP) settings. Treatments included fluensulfone at low and high labeled rates, fluopyram, spirotetramat, fluopyram + spirotetramat, oxamyl, ethoprophos, and an untreated, RKN-infested control. GH treatments were arranged in a factorial design, with application of nematode eggs (0, 6,000, or 30,000 eggs pot−1) crossed with nematicide treatment. MP treatments were arranged in a randomized complete block design and all plots were infested with RKN-infested tomato root tissue and soil grown in the greenhouse. Root galling, RKN egg and juvenile densities, and aboveground plant dry masses were determined and analyzed using Mixed Model ANOVA. In the GH trials, fluensulfone at both rates provided the greatest reduction in RKN galling compared to the untreated control, whereas spirotetramat treatments were not significantly different from the untreated control. In the MP 2 trial, all treatments except spirotetramat significantly reduced RKN populations and had significantly greater yields relative to the untreated control. Oxamyl, ethoprophos, and fluensulfone (1.64 L ai/ha and 2.34 L ai/ha) treatments had the highest yields in the microplot study. Based on these results, the two new nematicides, fluensulfone and fluopyram, show good potential for managing RKN in lima beans.

Northern root-knot nematodes (Meloidogyne hapla) are rather uncommon nematode parasites of strawberries and vegetables in Florida, but when present they are capable of causing significant crop loss. Root-knot nematodes are largely unknown to strawberry growers in Florida and very little is known about their biology and behavior in the state. This 5-page fact sheet written by J. Desaeger and published by the UF/IFAS Department of Entomology and Nematology is intended to educate and provide information on this nematode to researchers, Extension agents, growers, industry representatives, and other stakeholders in the strawberry and vegetable community. http://edis.ifas.ufl.edu/in1224

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 D. phaseolorum AR4203 for ITS (KJ590738.1, 527 bp out of 547 bp), 100% for TUB (KJ610893.1, 459 bp out of 459 bp), and 100% for CAL (KJ612135.1, 522 bp out of 522 bp) (Udayanga et al. 2015). Their identity was confirmed by phylogenetic analyses using maximum likelihood and Bayesian inference methods. To complete Koch's postulates, pycnidia of the same three isolates were harvested and crushed in 2 mL Eppendorf tubes containing 0.01% Tween 20. Conidia suspensions were adjusted to 106 spores/mL. Three 5-week-old potted plants of 'Eletta Campana' and 'Carmagnola Selezionata' per isolate were inoculated using a 1 mL syringe with a needle by injecting 200 µL of the suspension into the stem. Plants were placed inside clear plastic bags for 48 h and maintained in the greenhouse. Control plants were injected with sterile deionized water and kept under the same conditions. The pathogenicity test was repeated once. Four weeks after inoculation, inoculated plants developed stem cankers from which the same pathogen was isolated, whereas controls remained healthy. To our knowledge, this is the first report of D. phaseolorum causing stem canker on hemp. This pathogen has been reported causing canker on sunflower and Phaseolus spp. (Gomzhina and Gannibal 2018; Udayanga et al. 2015; Vrandecic et al. 2009). This discovery may help shape future research into disease epidemiology and management for a crop in which very limited disease information is available at the moment.

In Florida, Javanese root-knot nematode (Meloidogyne javanica) is widely distributed and causes extensive damage to a number of economically important crops. Soil fumigants are commonly used to manage this soilborne pest; however, increasing societal concerns regarding the negative effects of these products on environmental and human health are driving a shift towards more sustainable management options. Of particular interest are naturally occurring nematode suppressive soils. Identifying farming practices and ecological factors that enable suppressive organisms to function and persist in soil will support the implementation of natural biological control. In this study, we evaluated suppressiveness to M. javanica in 12 soils from Florida. Using next-generation sequencing technology, we characterized the bacterial and fungal communities in these soils to further understand how those communities may contribute to nematode suppressive soils. In spring 2018, soil was collected from multiple geographic regions, production systems, and management practices within the state of Florida. In a soil-based suppressiveness assay, soil collected from 7 out of 12 of the sites reduced the recovery of inoculated J2-stage M. javanica relative to that of soil that had been steam-pasteurized. In a plant-based suppressiveness assay, all soils reduced root galling on cucumber by M. javanica relative to that of their steam-pasteurized counterparts. Contrary to other studies on pathogen suppressive soils, enhanced soil bacterial and fungal diversity was not associated with suppressiveness to M. javanica. Differences in soil fungal community composition was a stronger driver of suppressiveness than bacterial community composition, with the fungal orders Xylariales, Mortierellales, and Agaricales showing positive correlation with nematode suppressiveness across 64 % of the sites surveyed. Overall, Florida soils hold considerable potential to naturally regulate M. javanica populations. The use of soil management practices that promote the abundance and activity of suppressive microorganisms may reduce horticultural reliance on soil fumigants.

The last decade has seen a sharp increase in nematicide research in the agricultural industry. As a result, several new synthetic nematicides have become available to growers, and several more are expected in the near future. This new interest in nematicides is directly related to the growing demand for safer and more selective products, and the increasing regulatory pressure on many of the traditional nematicides. This has led to a ban of several widely used fumigant (e.g. methyl bromide) and non-fumigant (e.g. aldicarb) nematicides. The loss of traditional nematicides, combined with a lack of replacement products and awareness of the damage that nematodes can cause, has not only raised concern among growers, but has also created new opportunities for the crop protection industry. Nematicides have become a priority, and many companies are now allocating significant research dollars to discover new nematicides. The new nematicides are very different from previous products: (i) they are more selective, often only targeting nematodes, and (ii) they are less toxic, and safer to use. This review article describes these new developments by discussing the challenges that are associated with finding new nematicides, reviewing the nature, characteristics, and efficacy of new nematicides, and discussing the impact they could have on future nematode management.

Host resistance governed by the Mi gene is available in many commercial tomato cultivars, and is effective against the most common tropical root-knot nematode species (Meloidogyne incognita, M. javanica and M. arenaria). The resistance has some drawbacks like the lack of activity against other common root-knot nematode species like M. hapla and M. enterolobii, the widespread emergence of resistance-breaking races of M. incognita, and the reported heat sensitivity of the Mi gene. In Florida, many tomato fields often also harbour soilborne pathogens and weeds, such as nutsedge, together with root-knot nematodes. Therefore, most tomato fields in Florida are fumigated, and nematode-resistant tomato cultivars are rarely planted. Two field trials were conducted during fall 2017 and spring 2018 to evaluate the potential of Mi-tomato cultivars in Florida, with or without additional use of a soil fumigant and/or nematicide. Root-knot severity in both seasons was significantly reduced in cultivars having Mi (Sanibel, Skyway, and Tasti Lee + Mi), as compared to the cultivar without Mi (FL 47). Fumigation with chloropicrin at 225 kg/ha and nematicides (fluensulfone in fall and fluazaindolizine in spring) also significantly reduced nematode damage. This was mostly noted for the cv. FL 47, and mostly during the fall growing season, when early nematode pressure was higher. End-of-season root-knot nematode soil populations were significantly lower with Mi cultivars. Chloropicrin on the other hand tended to increase end-of-season root-knot soil populations. No breakdown of resistance due to high soil temperature (>30 °C) was observed. Soil fumigation significantly increased fruit yield, especially in fall (95% increase) and to a lesser extent in spring (14.5% increase), and mostly so for cv. FL 47 and cv. Sanibel. Overall, cv. Sanibel produced the highest fruit yields.

Non-fumigant nematicides were evaluated on cucurbits in two commercial farms in 2017 (Cucumis sativus and Cucumis melo) and three commercial farms in 2019 (Cucumis sativus, Cucurbita pepo and Citrullus lanatus). In 2017, non-fumigant nematicides (fluopyram, oxamyl, fluensulphone, and Majestene) were applied as stand-alone rescue treatments in a cucumber and cantaloupe field heavily infested respectively with Meloidogyne javanica and M. hapla. In 2019, non-fumigant nematicides (fluopyram, oxamyl, and Majestene) were applied both as stand-alone treatments, and as mixtures, in (i) a cucumber field (same as 2017) having a high population of M. javanica, (ii) a squash field previously planted with strawberry and having a high population of M. hapla, and (iii) a watermelon field, previously known to have a high population of sting nematode (Belonolaimus longicaudatus). In 2017, an additional tomato greenhouse study was conducted using the soil from both fields. Both fields in 2017 were re-planted following the rescue nematicide applications, and in the cantaloupe field the new crop established well enough to allow for commercial harvesting. All nematicide treatments in the 2017 cantaloupe field, except for oxamyl, were able to significantly reduce M. hapla root infection after 70 days. Oxamyl did reduce M. javanica root infection in the 2017 cucumber field after 30 days, but the re-planted crop did very poorly, and the field was abandoned after less than one month. In the greenhouse tomato trial, similar trends were observed with better efficacy of the nematicides against M. hapla as compared to M. javanica. In 2019, stand-alone applications of oxamyl and Majestene, and especially the fluopyram + Majestene cocktail significantly reduced the end-season soil population of M. javanica in the cucumber field. No significant effect of any of the products or cocktails was noted on B. longicaudatus in the watermelon field. In the squash field, oxamyl by itself tended to increase soil population of M. hapla, but the mixed application of fluopyram + oxamyl showed some suppression of M. hapla. In both 2017 and 2019 field trials, plant vigor and yield were not significantly affected by the application of any of the nematicides or cocktails. While the nematicides provided better suppression of M. hapla as compared to M. javanica in 2017, the opposite was noted in 2019. This was probably related to the more severe nematode pressure in 2017, especially in the M. javanica field. M. hapla populations tended to decrease during the spring season as soil temperatures increased, while the more tropical B. longicaudatus and especially M. javanica populations increased during the season. Results from this study indicate that although all three nematicides offer an opportunity for cucurbit growers in Florida to help manage nematodes during the cropping season, their efficacy in terms of reducing soil population density or root gall severity, will be dependent on the time of the year, the type of cucurbit that is grown, and the species of nematode present. Some evidence was shown of improved efficacy when nematicide cocktails were applied, but more research is needed to investigate this.

The sting nematode (Belonolaimus longicaudatus) is one of the most economically damaging pests of strawberry in Florida. In this study we evaluated in-season application of fluopyram for management of B. longicaudatus populations at nine commercial strawberry farms. In-crop application of fluopyram reduced B. longicaudatus population densities in soil by the end of the growing season in four out of six of the commercial strawberry farms where B. longicaudatus was detected during the growing season. At the four sites, relative suppression of B. longicaudatus by fluopyram ranged from 54 to 96%. Despite significant suppression of B. longicaudatus population densities in soil, in-crop application of fluopyram did not result in greater strawberry plant vigour by the end of the growing season. Overall, in-crop application of fluopyram shows considerable potential to reduce B. longicaudatus populations on strawberry in Florida.

In early 2016, hop plants were introduced into Florida. By late 2016, the hop plants were showing stunted growth and were heavily parasitized by Meloidogyne javanica. In this study, we determined host susceptibility of 14 hop cultivars to M. javanica in a greenhouse experiment and monitored population development of plant-parasitic nematode species in the root zone of 17 hop cultivars planted in three newly established hop yards in Florida. Plant-parasitic nematodes in the rooting zone soil of field grown hop plants included M. javanica, Pratylenchus brachyurus, Paratrichodorus minor, Belonolaimus longicaudatus, Xiphinema setariae/vulgare complex, Mesocriconema xenoplax, and Helicotylenchus dihystera; however, soil population densities of P. minor, B. longicaudatus, X. setariae/vulgare complex, M. xenoplax, and H. dihystera remained low through the study. Root galling, M. javanica egg production, and soil population densities of M. javanica were consistently large on the 'Canadian Red Vine', 'Centennial', 'Chinook', and 'Comet' cultivars, and small on the 'Galena' and 'Triple Perle' cultivars. No differences were observed in soil population densities of P. brachyurus among hop cultivars. Overall, our study provides the first report of plant-parasitic nematode population development in the root zone on hop cultivars planted in Florida. In early 2016, hop plants were introduced into Florida. By late 2016, the hop plants were showing stunted growth and were heavily parasitized by Meloidogyne javanica. In this study, we determined host susceptibility of 14 hop cultivars to M. javanica in a greenhouse experiment and monitored population development of plant-parasitic nematode species in the root zone of 17 hop cultivars planted in three newly established hop yards in Florida. Plant-parasitic nematodes in the rooting zone soil of field grown hop plants included M. javanica, Pratylenchus brachyurus, Paratrichodorus minor, Belonolaimus longicaudatus, Xiphinema setariae/vulgare complex, Mesocriconema xenoplax, and Helicotylenchus dihystera; however, soil population densities of P. minor, B. longicaudatus, X. setariae/vulgare complex, M. xenoplax, and H. dihystera remained low through the study. Root galling, M. javanica egg production, and soil population densities of M. javanica were consistently large on the ‘Canadian Red Vine’, ‘Centennial’, ‘Chinook’, and ‘Comet’ cultivars, and small on the ‘Galena’ and ‘Triple Perle’ cultivars. No differences were observed in soil population densities of P. brachyurus among hop cultivars. Overall, our study provides the first report of plant-parasitic nematode population development in the root zone on hop cultivars planted in Florida.

Foliar or bud nematodes are liitle-known nematodes of the genus Aphelenchoides that were common in the early 1900's causing "crimp disease" of strawberries in Florida. Recently, these foliar nematodes have been observed again in the state, and seem to have come in with transplants from outside Florida. Foliar/bud nematodes can have a devastating effect on strawberries, as plants become stunted with curled up leaves, and little or no flowers and fruits are produced. No information is available on the biology and management of these nematodes in Florida. This publication aims to provide much needed information on these unknown pests. The following summarizes the different types of foliar nematodes, their biology, life cyclce, damage symptoms, survival strategies, dissemination, and management options.

The following work was initiated to determine the scope of application methodology and fumigant combinations for increasing efficacy of 1,3-dichloropropene (1,3-D) and metam sodium for management of root-knot nematodes (Meloidogyne spp.) in Florida. A series of five experiments were set up during spring and fall seasons to evaluate the potential of different fumigants, alone or in combination, in polyethylene film tomato production. The most promising chemical alternatives to methyl bromide, in terms of root-knot nematode management, were the combinations 1,3-D-chloropicrin, chloropicrin-proprietary solvent, and 1,3-D-metam sodium. Sprayed or injected metam sodium generally provided only short-term nematode management and by harvest nematode infection was not different from the nontreated control. Drip-applied metam sodium gave good nematode management under high nematode pressure, but needs further verification to establish (i) the importance of soil moisture and temperature on treatment efficacy and (ii) whether similar management can be obtained with fewer than three drip tubes. Broadcast applications of 1,3-D showed better efficacy as compared to applications on a preformed raised bed. Fumigation did not increase tomato yields in spring when root-knot nematode pressure was low, but during fall all chemical treatments increased yields three to five-fold, as root-knot nematode was a major yield-limiting factor.

Tomatoes are a major commodity in Florida, with an estimated production value of $453 million. Among the many pests and diseases that affect tomatoes, nematodes are one of the major problems. Since the ban on methyl bromide, these ubiquitous soil pests have become much more difficult to manage. This 5-page fact sheet written by Homan Regmi and Johan Desaeger and published by the UF/IFAS Entomology and Nematology Department discusses the use of nematode-resistant tomato cultivars as a tool to help manage root-knot nematodes in Florida. http://edis.ifas.ufl.edu/in1250

Anthranilic diamides, which include the new commercial insecticide, chlorantraniliprole, are an exciting new class of chemistry that target insect ryanodine receptors. These receptors regulate release of stored intracellular calcium and play a critical role in muscle contraction. As with insects, nematodes express ryanodine receptors and are sensitive to the plant alkaloid, ryanodine. However the plant parasitic nematode, Meloidogyne incognita, is insensitive to anthranilic diamides. Expression of a full-length Drosophila melanogaster ryanodine receptor in an insect cell line confers sensitivity to the receptor agents, caffeine and ryanodine along with nanomolar sensitivity to anthranilic diamides. Replacement of a 46 amino acid segment in a highly divergent region of the Drosophila C-terminus with that from Meloidogyne results in a functional RyR which lack sensitivity to diamide insecticides. These findings indicate that this region is critical to diamide sensitivity in insect ryanodine receptors. Furthermore, this region may contribute to our understanding of the differential selectivity diamides exhibit for insect over mammalian ryanodine receptors.

Fluazaindolizine is a new highly effective and selective product for the control of plant parasitic nematodes. Specificity for nematodes coupled with absence of activity against the target sites of commercial nematicides suggests that fluazaindolizine has a novel mode of action. The discovery, structure-activity development and biological properties for this new class of nematicides are presented.

BACKGROUND: Methomyl is a widely used carbamate insecticide that has traditionally been applied as a foliar spray. More recently, methomyl has been labeled as a soil application via drip chemigation. Not much is known about the insecticidal and nematicidal potential of soil-applied methomyl. Methomyl soil applications were evaluated for their potential to control soil nematodes and foliar insect pests in a series of lab and greenhouse tests. RESULTS: Methomyl showed rapid knockdown of Meloidogyne incognita (Kof. & White) Chitwood in aqueous assays, with EC50 and EC90 values that were similar to oxamyl and averaged 4.9 and 15.2 mg L−1. In the greenhouse, soil applications of methomyl ranging from 0.56 to 4.0 kg ha−1 provided significant M. incognita control similar to oxamyl during early growth (up to 25 days after planting) of pea and bean. Higher application rates and split applications improved nematode control, but also increased the risk of phytotoxicity. Methomyl soil applications were highly effective on several insects including Myzus persicae (Sulzer), Aphis gossypii (Glover), Frankliniella occidentalis Perg. and Spodoptera exigua (Hubner). Methomyl was about 5–9-fold more potent on M. persicae and A. gossypii when applied via soil drench as opposed to foliar spray. Potency on Bemisia tabaci Genn., S. exigua and Trichoplusia ni Hubner was about the same with the two application methods. CONCLUSION: Methomyl soil applications showed good potential for early control of various insect and nematode pests. Further testing is required to verify activity under field conditions. Copyright © 2011 Society of Chemical Industry