Search

Field experiments were conducted to evaluate the effects of soil solarization or cover crop on bell pepper (Capsicum annuum) and lima bean (Phaseolus lunatus) rhizosphere microorganisms. In Experiment I, flat surface solarization (FSS), raised bed solarization (RBS), cowpea (Vigna unguiculata) cover crop alone (CP), and the combination of cowpea cover crop followed by raised bed soil solarization (CP + RBS) were compared with methyl bromide fumigation (MB) and an untreated control (UTC) for effects on rhizosphere bacteria and fungi on bell pepper. In Experiment II, effects of cover crop on rhizosphere microorganisms were examined on lima bean in a 3 × 3 split-plot experiment with three summer cover crop treatments: sunn hemp (SH) (Crotalaria juncea), cowpea (CP), and fallow (F) as main plots, and three organic amendments: sunn hemp hay (SHH), cowpea hay (CPH), and no hay (NH) as subplots. Rhizosphere bacteria including siderophore producers, gram-positive spore-formers, and fluorescent pseudomonads were assessed, as well as two fungi, Fusarium oxysporum and Rhizoctonia solani. In year 1 of Experiment I, CP + RBS reduced F. oxysporum and R. solani in the rhizosphere, resulting in levels similar to those in MB fumigation. This was not observed in year 2. Heavy rainfall in year 2 resulted in a severe outbreak of Pythium on bell pepper, which was most destructive in MB fumigated plots. Effects of solarization and cover crop on rhizosphere bacteria also differed between years. Fluorescent pseudomonads were abundant across treatments in year 1, but were greatly reduced in year 2, when the Pythium outbreak occurred. In Experiment II, populations of rhizobacteria on lima bean were not affected by cover crop in either year. At the end of year 1, isolation of R. solani from lima bean roots increased in SHH plots. SH cover crop reduced gram-positive spore forming bacteria and fluorescent pseudomonads. In year 2, CP followed by CPH had higher levels of fungi and bacteria than CP followed by either NH or SHH. Overall, cover crop amendments did not result in consistent enhancement of rhizobacteria, and some treatments resulted in increased abundance of pathogenic fungi. The most consistent treatment for reducing rhizosphere fungal populations was MB.

McGovern, R. J., McSorley, R., and Urs, R. R. 2000. Reduction of Phytophthora blight of Madagascar periwinkle in Florida by soil solarization in autumn. Plant Dis. 84:185-191. Three field experiments were conducted in southwest and west-central Florida in 1993 through 1995 to evaluate the effectiveness of soil solarization during autumn in reducing Phytophthora blight of Madagascar periwinkle (Catharanthus roseus) caused by Phytophthora nicotianae. Plots (3.6 by 3.6 m) were infested by incorporating winter wheat seed containing P. nicotianae in the upper 15 cm of soil. Solarization was then c onducted for 21 to 41 days, primarily during October, using clear, 25- or 50-µm low-density polyethylene mulch. The progress of Phytophthora blight, monitored for 31 to 42 days following planting, was significantly reduced by solarization in all experiments, and final blight incidence was reduced in two of three experiments. Solarization also reduced population dens ities of P. nicotianae.

Water-displacement and WinRHIZO root-scanning methods were compared for efficacy of root damage assessment. Results from both methods were similar and a highly significant relationship was found between the two methods in trial one (r2 = 0.9968, P < 0.0001) and trial two (r2 = 0.9988, P < 0.0001). Both protocols provide consistent root volume measurements; however, water displacement is preferred as an economical method if a quick evaluation of a large amount of roots is essential. For a more detailed root morphological and architectural analysis, WinRHIZO root scanning provides additional information about several root parameters that cannot be measured by simple water displacement.

BACKGROUND Zucchini squash, Cucurbita pepo L., is an important vegetable crop in Florida. Physiological disorders and insect-transmitted diseases are major problems for squash growers in semi-tropical regions around the world. Bemisia tabaci (Gennadius) biotype B is a significant whitefly pest and is largely responsible for transmitting viruses and causing physiological disorders in squash. Several studies have shown that whitefly populations are reduced when crops are interplanted with non-host cover crops or mulches. The aim of the present study was to determine how the presence of buckwheat, Fagopyrum esculentum Moench, and a key predator, Delphastus catalinae (Horn), affect whitefly colonization on squash. RESULTS Whitefly densities were higher on squash than on buckwheat. The introduction of D. catalinae on squash significantly reduced whitefly populations. Overall, there were higher densities of D. catalinae on squash where the whitefly pest was more concentrated compared with buckwheat. CONCLUSION The study provided preliminary evidence that D. catalinae, when used in conjunction with buckwheat as a living mulch, may aid in reducing whiteflies in squash. This greenhouse experiment highlights the need to investigate a multitactic approach of intercropping buckwheat with squash and the incorporation of D. catalinae in the field to manage populations of whiteflies and whitefly-transmitted diseases. © 2015 Society of Chemical Industry

Survival of plant pathogens such as fungi, bacteria, nematodes, and, less commonly, viruses in association with soil particles or undecomposed plant matter in soil can provide an important source of inoculum for disease outbreaks. Sterilization, when strictly defined, refers to the nonselective inactivation of all organisms in a given substrate. Soil pasteurization is an example of partial sterilization which uses lower than maximum temperatures to destroy pathogens while preserving many beneficial microorganisms. The earliest attempts to eliminate soil-borne plant pests through heat were probably the indirect and unplanned result of primitive types of slash-and-burn farming in which litter is burned prior to cultivation. Roasting soil in flame-heated pans to control Thielaviopsis root rot and weeds was widely practiced in tobacco seed beds in the southern US starting in the late nineteenth and continuing through the early twentieth centuries. Hot water is often used effectively to rid plant propagative material such as seeds, bulbs, and nursery stock of pathogens.

Root-knot nematodes are important pests of cut foliage crops in Florida. Currently, effective nematicides for control of these nematodes on cut foliage crops are lacking. Hence, research was conducted at the University of Florida to identify pesticides or biopesticides that could be used to manage these nematodes. The research comprised on-farm, field, and greenhouse trials. Nematicide treatments evaluated include commercial formulations of spirotetramat, furfural, and Purpureocillium lilacinum (=Paecilomyces lilacinus) strain 251. Treatment applications were made during the spring and fall seasons according to manufacturer’s specifications. Efficacy was evaluated based on J2/100 cm3 of soil, J2/g of root, and crop yield (kg/plot). Unlike spirotetramat, which did not demonstrate any measurable effects on Meloidogyne incognita J2 in the soil, furfural and P. lilacinum were marginally effective in reducing the population density of M. incognita on Pittosporum tobira. However, nematode reduction did not affect yield significantly. Although furfural and P. lilacinum have some potential for management of M. incognita on cut foliage crops, their use as a lone management option would likely not provide the needed level of control. Early treatment application following infestation provided greater J2 suppression compared to late application, suggesting the need for growers to avoid infested fields.

Abundances of nematode genera were examined in several forest and field habitats located in close proximity in Florida, USA. Effects of selected habitat features were also evaluated, such as tree type, management and presence of litter, grasses or invasive species. Of 37 common taxa evaluated, ten were more abundant in forest and ten in field habitats. Several genera includingAcrobeloides,AphelenchoidesandMesocriconemawere common in all habitats. Light management, consisting of mowing of grasses, negatively affected 19 taxa. More genera appeared adapted to closed forest over open forest, and most of these were more common in plots with oak trees or oak litter than in plots with pine. Numbers ofParatylenchus,PlectusandXiphinemawere further increased by the presence of herbaceous plants on the forest floor. When invasive elephantgrass (Pennisetum purpureum) was included in plots with other grasses, numbers of eight genera that typically were common in grass plots were further increased.Alaimus,CervidellusandWilsonemawere negatively affected by the invasive elephantgrass. Most of the nine genera in guild Ba2 were more abundant in either forest (Acrobeles,Cervidellus,Plectus,Wilsonema) or grass (Eucephalobus,Zeldia) habitats, whileAcrobeloideswas common and two genera were rare in all habitats. The effects of habitats and habitat features on many different nematode taxa add to our growing knowledge of the ecological habits of free-living nematodes.

Florida accounts for more than 75% of the national cut foliage production. Unfortunately, root-knot nematodes (RKN) (Meloidogyne spp.) are a serious problem on these crops, rendering many farms unproductive. Currently, information on the Meloidogyne spp. occurring on most commonly cultivated cut foliage crops in Florida, and tools for their rapid identification are lacking. The objectives of this study were to (i) identify specific RKN infecting common ornamental cut foliage crops in Florida and (ii) evaluate the feasibility of using the mtDNA haplotype as a molecular diagnostic tool for rapid identification of large samples of RKN. A total of 200 Meloidogyne females were collected from cut foliage plant roots. Meloidogyne spp. were identified by PCR and RFLP of mitochondrial DNA. PCR and RFLP of mitochondrial DNA were effective in discriminating the Meloidogyne spp. present. Meloidogyne incognita is the most dominant RKN on cut foliage crops in Florida and must be a high target for making management decisions. other Meloidogyne spp. identified include M. javanica, M. hapla, Meloidogyne sp. 1, and Meloidogyne sp. 2. The results for this study demonstrate the usefulness of the mtDNA haplotype-based designation as a valuable molecular tool for identification of Meloidogyne spp.

Understanding rooting dynamics using the minirhizotron technique is useful for cultivar selection and to quantify nematode damage to roots. A 2-yr microplot study including five bermudagrass (‘Tifway’, Belonolaimus longicaudatus susceptible; two commercial cultivars [TifSport and Celebration] and two genotypes [‘BA132’ and ‘PI 291590’], which have been reported to be tolerant to B. longicaudatus) and two St. Augustinegrass (‘FX 313’, susceptible, and ‘Floratam’ that was reported as tolerant to B. longicaudatus) genotypes in a 5 x 2 and 2 x 2 factorial design with four replications, respectively, was initiated in 2012. Two treatments included were uninoculated and B. longicaudatus inoculated. In situ root images were captured each month using a minirhizotron camera system from April to September of 2013 and 2014. Mixed models analysis and comparison of least squares means indicated significant differences in root parameters studied across the genotypes and soil depths of both grass species. ‘Celebration’, ‘TifSport’ and ‘PI 291590’ bermudagrass, and ‘Floratam’ St. Augustinegrass had significantly different root parameters compared to the corresponding susceptible genotypes (P ≤ 0.05). Only ‘TifSport’ had no significant root loss when infested with B. longicaudatus compared to non-infested. ‘Celebration’ and ‘PI 291590’ had significant root loss but retained significantly greater root densities than ‘Tifway’ in B. longicaudatus-infested conditions (P ≤ 0.05). Root lengths were greater at the 0 to 5 cm depth followed by 5 to 10 and 10 to 15 cm of vertical soil depth for both grass species (P ≤ 0.05). ‘Celebration’, ‘TifSport’, and ‘PI 291590’ had better root vigor against B. longicaudatus compared to Tifway.

Florida vegetable growers have relied on methyl bromide (MeBr) fumigation to manage soil pathogens, nematodes, and weeds. This system combined with raised beds, polyethylene mulch, and seepage and/or drip irrigation has been effective for producing high vegetable yields. Alternatives to MeBr such as solarization and organic amendments have given favorable results in small trials, but there are few large-scale studies. The objectives of this study were to evaluate the effects of long-term organic amendment applications and soil sanitation treatments on weed and nematode populations on pepper (Capsicum annuum L.) and watermelon (Citrullus lanatus [Thunb.] Manst.). During 1998 and 1999 fall vegetable seasons, main plots received a yearly organic amendment (biosolids) application or a non-amendment control, with sub-plots consisting of soil sanitation treatments with solarization, MeBr, Telone® (1,3-dichloropropene), or a non-fumigated control. Each sub-plot was further divided into two sub-sub-plots, one receiving additional weed and without control weed control. During the solarization period (60 d in 1998–1999; 90 d in 1999–2000), percent weed cover was higher in the non-biosolid plots than the biosolid plots for the first part of the solarization period, but there were no differences during the last 30 days in both seasons. Purple nutsedge was able to germinate on the north edge of the beds for a border effect; a point of vulnerability when beds run east–west. With the pepper crop, the number of weeds and percent weed cover were greater in the non-fumigated plots and Telone®-treated plots than in plots treated with MeBr or in solarized plots with and without biosolids. Nematode population densities from plot to plot within the site were highly variable, which likely accounted for the relatively few consistent effects from treatments observed during the experiment. The data do provide some indication of the importance of weeds in the recovery and buildup of nematode populations. During spring 1999, both root-knot and stubby-root nematodes were more abundant in the sub-sub-plots that had not received weed control. The results suggest that solarization and organic amendments can be viable alternatives to MeBr. However, MeBr produced the most consistent results.

Eudorylaimus, Aporcelaimellus and Mesodorylaimus are dominant members of the omnivorous nematode fauna in Florida, USA. Ecological studies that included numerical data on these genera were reviewed to determine key aspects of their ecology and behaviour. These three genera were also the dominant omnivores in many parts of Europe and often occurred together. Multiple species within genera may be present in samples as well. Although results varied with habitat, these omnivores were present in nearly all stages of succession but often reached their greatest numbers in later stages of succession such as old-growth forests. They also showed remarkable adaptation to extreme environments, including Antarctic habitats, dune sands and temperate sites without vegetation. They were found in a variety of soil types but limited by soil pH < 4.0. Compared with other nematode taxa, they were among the genera most sensitive to moisture levels in sandy soils and to pollution by heavy metals. Some reports also indicated adverse impacts from inorganic fertilisers and other agrichemicals. Much remains unknown about the ecology of these common nematodes, which are widely distributed in soil ecosystems.

Experiments were conducted to examine the diurnal responses and abundance of arthropods at the autumn equinox in 2010. Experiments were conducted in 3 different fields, each with a different plant species: sunn hemp (Crotalaria juncea L.), bahiagrass (Paspalum notatum Flugge), and sandbur grass (Cenchrus spp.) using a randomized complete block design. Data were collected on numbers of arthropods caught in pitfall traps and on sticky cards. The long-legged flies (Diptera: Dolichopodidae) and thrips (Thysanoptera) collected were consistently diurnal, while ants (Hymenoptera: Formicidae), springtails (Collembola: Entomobryidae), micro-Diptera and tumbling flower beetles (Coleoptera: Mordellidae) were diurnal in one experiment. Elateridae and Aphididae tended to be nocturnal taxa, but plant height had some effect as well because aphid numbers were significantly higher in tall (182.3 cm) sunn hemp than in short (88.1 cm) sunn hemp at night time only. Cicadellidae were active during both day and night time and showed different levels of activity in pitfall traps and on sticky cards. Pitfall traps were found to be very effective for sampling insect taxa including Formicidae, Elateridae, and Collembola, while micro-Diptera, thrips, aphids, and Mordellidae were commonly caught on sticky cards. Cicadellidae and Dolichopodidae were commonly recovered in pitfall traps and on sticky cards.

Organic heirloom tomatoes (Solanum lycopersicum L.) are difficult to grow in Florida as a result of root-knot nematodes (Meloidogyne spp.) (RKN) and hot, humid growing conditions. Although grafting with resistant rootstocks has been shown effective for RKN management in tomato production, little research has been conducted on grafted heirloom tomatoes under Florida conditions. In this 2-year study, two susceptible heirloom tomato scions, ‘Brandywine’ and ‘Flamme’, were grafted onto two hybrid rootstocks, i.e., interspecific tomato hybrid rootstock ‘Multifort’ (S. lycopersicum × S. habrochaites) and tomato hybrid rootstock ‘Survivor’ (S. lycopersicum). Non-grafted and self-grafted scions were used as controls. Three field trials were conducted including the 2010 and 2011 organic field trials as well as a transitional organic field trial in 2011. There was a lack of RKN pressure in the organic field in 2010. In 2011, the RKN population was higher in the transitional field than the organic field, whereas grafting with hybrid rootstocks significantly reduced root galling (P ≤ 0.0001) in both fields. In the organic field, the hybrid rootstocks performed similarly and significantly reduced root galling compared with the non-grafted and self-grafted scions by ≈80.8%. In the transitional field, compared with non-grafted scions, the root galling reduction by ‘Survivor’ (97.1%) was significantly greater than that by ‘Multifort’ (57.6%). In general, tomato plants grafted onto ‘Multifort’ tended to be more vigorous than all other treatments. There was no clear relationship between root galling and tomato yields. Grafting did not significantly affect the total marketable yield for the scion ‘Flamme’ in both years. Total marketable yield was similar among treatments in 2010 but varied in 2011 for the scion ‘Brandywine’. In 2011, the non-grafted ‘Brandywine’ and ‘Brandywine’ grafted to ‘Survivor’ produced significantly higher (P < 0.05) yields than other treatments in the organic field. However, in the transitional field, ‘Brandywine’ grafted to ‘Multifort’ resulted in significantly higher (P < 0.05) yields than the non- and self-grafted ‘Brandywine’ treatments. Grafting with appropriate rootstocks may play an effective role in RKN management during the transition to organic production when high populations of nematodes are present.

Cultural control practices, including the use of cover crops and mulches, are convenient non-chemical methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for their effects on soil surface arthropods, weeds, and mortality of snapdragon plants in the autumn of both 2007 and 2008 near Citra, Florida, USA. In both seasons, five treatments were compared: cowpea mulch, sunn hemp mulch, sorghum-sudangrass mulch, pine bark nuggets, and an unmulched control. Mulches were applied around snapdragon plants in small plots, and treatments arranged in a randomized complete block design with five replications. Arthropod groups sampled using pitfall and board traps varied in their responses to treatments. The numbers of Formicidae, Cicadellidae, Orthoptera, and small-bodied plant-feeders (aphids, whiteflies, and thrips) were higher in control or cowpea plots than several of the other mulch treatment plots, possibly because weed levels were higher in control and cowpe...

Breeding and improvement of new bermudagrass (Cynodon spp.) cultivars with superior nematode tolerance are essential because sting nematode (Belonolaimus longicaudatus Rau) is a major limitation for use of bermudagrass in the sandy coastal soils of the southeastern United States. The screening of both African (Cynodon transvaalensis) and common (C. dactylon) bermudagrass is necessary to develop triploid hybrid cultivars. Five commercial cultivars and 46 germplasm accessions of bermudagrass were tested for nematode responses in two greenhouse trials in 2009. Turfgrass was grown in sand-filled plastic conetainers and inoculated with 50 sting nematodes per conetainer. Nematode and root samples were collected 90 d after nematode inoculation. Fifteen bermudagrass accessions did not have measurable root loss from inoculation with sting nematode. Seven bermudagrass accessions, including ‘Celebration’, produced longer roots in sting nematode-infested soil than the standard ‘Tifway’. Differences in final nematode numbers were identified among the genotypes, and different relative responses were identified in variable ploidy levels and origins. This could aid a turfgrass breeding program by elucidating the genetic diversity available for breeding future bermudagrass cultivars for golf course cultivation.

Sting (Belonolaimus longicaudatus Rau) and spi- ral (Helicotylenchus spp.) nematodes are among the most common and damaging nematode species found on seashore paspalum (Paspalum vaginatum Swartz) in Florida. Restriction and cancellation of nematicides on turfgrass have accelerated the development of more environ- mentally friendly nematode management strat- egies. Use of nematode-tolerant or -resistant cultivars is the practice with the least ecological impact on nontargeted species. The objective of this study was to identify the nematode tolerance or resistance of commercial seashore paspalum cultivars. Seven cultivars were tested under greenhouse conditions in two sequential trials. The cultivars were grown in sand-fi lled plastic conetainers and inoculated with 50 sting nem- atodes or 500 spiral nematodes conetainer -1 . Nematode and root samples were collected 90 d after nematode inoculation. All seashore paspalum cultivars supported the reproduction of sting nematode, with a reproduction rate of 2.7- to 9.5-fold in the two trials. Population den- sities of the spiral nematode H. pseudorobus- tus (Steiner, 1914) Golden, 1956 declined on all cultivars. Seashore paspalum cultivars showed differences in root length reductions caused by nematodes. 'Salam', 'SeaDwarf', and 'SeaIsle Supreme' were most tolerant to sting nematode, and 'SeaSpray' and 'SeaIsle 2000' were most tolerant to spiral nematode. No cultivar was tol- erant to both nematode species.

Sting nematodes (Belonolaimus longicaudatus Rau) are the most damaging nematode species on bermudagrass (Cynodon spp.) in Florida. The recent cancellation of the nematicide fenamiphos has resulted in the need for alternative nematode management tactics. Utilization of resistant or tolerant cultivars could be one of the most environmentally friendly and least costly practices for nematode management on turf. However, information about the responses of newer bermudagrass cultivars to sting nematodes is not available. Eight dwarf and nine non-dwarf bermudagrass cultivars were tested in two sequential experimental trials under greenhouse conditions for their responses to sting nematodes. Tifdwarf' and 'Emerald Dwarf' were damaged the least among dwarf cultivars, as were 'TifSport' and 'Riviera' among the non-dwarf cultivars. 'Princess 77' and 'Celebration' produced greater amounts of roots than 'Tifway' under the stress of sting nematode root defoliation despite being good hosts for this nematode.

Four different types of organic mulches were evaluated for their effects on soil surface insects and related arthropods. Field experiments were conducted in fall 2007 and 2008 near Citra, Florida. In both the years, five treatments were compared: cowpea (Vigna unguiculata (L.) Walp.) mulch, sunn hemp (Crotalaria juncea L.) mulch, sorghum-sudangrass (Sorghum bicolor Moench × S. sudanense ((Piper)] Stapf) mulch, pine bark nuggets, and unmulched control. Data were collected on insects and other arthropods using pitfall traps. Results indicate that organic mulches can affect a wide range of different insects. Diptera, dominated by Asyndetus spp. (Dolichopodidae), were most dense in pine bark plots in both years. Populations of small plant-feeding insects such as Aphididae, Thripidae, and Aleyrodidae were most dense in cowpea and unmulched control plots in one season. It is possible that these insects were affected by weed growth in cowpea and control plots. Ants, which tend or feed on small plant fee...

Free-living nematodes in soil ecosystems are vital in the decomposition of organic matter and recycling of nutrients. The effects of various types of disturbances on nematode assemblages were examined in several experiments on a single soil: a short-term detrimental disturbance from solarisation, a short-term beneficial disturbance from amendment addition, and a long-term detrimental disturbance from bare ground without plant cover. Comparison of solarised and non-solarised field plots revealed lower numbers of fungivores in solarised plots. As a result, indices involving ratios of fungivores to bacterivores and fungivores to total free-living nematodes were decreased as well. Addition of an amendment increased numbers of bacterivores. This change was also reflected in calculated indices that expressed trophic groups as percentages of the total free-living nematodes. A severely disturbed site with bare ground that was without plant cover for more than 5 years was compared with an adjacent site maintained in grass. No plant-parasitic nematodes were recovered from the bare ground site, which contained lower numbers of nematodes in all trophic groups than the grass site. However, the structure of the free-living nematode assemblages in both sites was similar, as indicated by the proportions of various trophic groups and by ratios of fungivores and bacterivores. The free-living nematode assemblage in a site with a perceived severe long-term disturbance maintained a trophic structure similar to a site with perennial plant cover.

The influence of intercropping strips of non-crop vegetation on the above-ground arthropod community was assessed, including natural enemy populations and interference with pest colonization in an adjacent yellow squash crop (Cucurbita pepo L.). Four non-crop border treatments were evaluated including: sorghum × sudangrass hybrid (Sorghum bicolor (L.) Moench × S. sudanense (Piper) Stapf); pigeon pea, (Cajanus cajan (L.) (Millsp.); the native weed complex; and a bare ground control. Border treatments were established on both sides of experimental plots containing ‘Early Crookneck’ squash. Sticky cards, pitfall traps, pan traps, and in situ counts were used to assess differences in the arthropod community within each of the border treatments and the adjacent squash crop. Natural enemies were most abundant in the native weed complex and pigeon pea borders; however, the spill-over of natural enemies into the neighboring crop was only observed in 2008, when predatory Coleoptera were most abundant in b...

A plethora of research has been conducted on the use of marigolds (Tagetes spp.) for nematode suppression, yet limited cover cropping with marigold is being practiced in commercial operations. Marigold is well known among nematologists for its ability to produce compounds such as α-terthienyl that are allelopathic to many species of plant-parasitic nematodes. However, there are contradictory reports on how this compound is released. The uncertainty centers on whether allelopathic compounds are released from root or shoot tissues, by growing live plants or soil-amended tissues, as a response to nematode penetration, or as a non-specific repellent. Other mechanisms by which marigold suppresses plant-parasitic nematodes include acting as a poor host, enhancing nematode-antagonistic microorganisms, or acting as a “dead-end” trap crop. Interpretation is complicated because multiple mechanisms may operate simultaneously. Understanding the exact mechanisms responsible for the nematode-suppressive effects of marigold could lead to further/broader incorporation into nematode management programs. This literature review revealed variable findings from marigold use. For example, in some instances using marigold was reported to be more effective than nematicides or soil fumigants and in other instances it had a negative impact on cash crop growth and yield. This variation has been attributed to differences in the way marigolds were used (e.g. intercrop/cover crop/soil amendment, seeding rate, time between marigold and cash crop), marigold cultivar, species or races of target nematodes, temperature, or age of marigold plant. Thus, future research should focus on determining the exact causes of this variability and on developing field IPM programs that take advantage of the nematode-suppressive potential of marigold.

The effectiveness of summer cover crops (CC) in suppressing weeds in a recently planted organic orange grove at a Certified Organic Research Site in Citra, Florida was evaluated between 2002 and 2005. In order to quantify the effectiveness of summer CC to suppress weeds, a cover crop/weed index (CC/WI) was also developed, which expresses the ratio of CC biomass production relative to that of weeds. Average biomass accumulation (Mg ha -1 ) was 10.1, 8.0, 5.8, 3.5, 2.6 and 1.7 for sunnhemp, hairy indigo, pigeon pea, cowpea, alyce clover and velvet bean, respectively. Corresponding N accumulation (kg N ha -1 ) was 173, 140, 120, 58, 44 and 52, while CC/WI values were 37.1, 10.1, 2.7, 27.0, 13.6 and 1.2. Sunnhemp, cowpea and alyce clover were more effective in suppressing weeds compared to tillage fallow. Sunnhemp was superior in terms of accumulating biomass and N but due to its height (>2 m), its use in young groves may be less desirable compared with more compact CC (e.g., alyce clover or cowpea).

Lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), is a serious pest of bean (Phaseolus vulgaris L.) and many other crops. The effect of mulching as a management method for LCB was examined in 2 field experiments conducted in small plots (1 m2) at 2 different locations (experiments A and B) in Alachua Co., FL. Both experiments were conducted in the summer and repeated in the fall, 2007. The treatments were arranged in a randomized complete block design with 5 replications at both locations. In experiment A, treatments were bare ground, plots with mulch, and plots with weeds (original weed cover); while in experiment B, treatments were bare ground and mulched plots. The mulch was obtained from a crop of sunn hemp (Crotalaria juncea L.) planted at another location. Data were collected on bean plant mortality, plant growth parameters (fresh weight, height, and length including roots of surviving plants), and population levels of potential predators. LCB attack was less (P ≤ 0.10) in mu...

Monoculture and mixed pastures in Florida provide habitat for a variety of resident and migratory bird species. The objectives of this study were to investigate the effects of grazing on vegetation structure and bird species richness and abundance in grazed monoculture and mixed pastures. Study pasture units were subject to four cattle grazing intensities: 0 = nongrazed (control), 15 = low, 20 = medium, or 35 = high animal units (AU) per pasture unit (no cattle, 1.3, 1.0, and 0.6 ha · AU −1 , on monoculture pastures and no cattle, 2.1, 1.6, and 0.9 ha · AU −1 , on mixed pastures). Monoculture pastures displayed a greater decrease in spatial heterogeneity of the vegetative community in the presence of grazing than mixed pastures. An increase in grazing intensity led to declines in total avian species richness and abundance and species richness within short-distance migrant, neotropical migrant, and permanent resident guilds on monoculture pastures. Declines in total species richness and abundance and neotropical migrant guild species richness and abundance were observed on mixed pastures subject to increasing grazing intensity. However, species richness within short-distance migrant and urban guilds and abundance within the grassland guild increased on this pasture type in the presence of grazing. Loss of spatial heterogeneity typically results in a lack of suitable habitat for birds that occupy the extremes of the vegetation structure gradient. This can lead to a loss of species richness and abundance. For the majority of avian guilds, a low grazing intensity of 1.3 ha · AU −1 and 2.1 ha · AU −1 on monoculture and mixed pasture, respectively, is recommended to maintain abundance. However, these grazing intensities may result in declines in species richness. Ultimately, if a range of avian species are to be supported on monoculture and mixed pastures, spatial heterogeneity of plant structure and composition must be maintained.

A greenhouse experiment was conducted using a Soil-N Uptake Monitoring (SUM) system to determine nitrogen (N) and water uptake dynamics of citrus (CIT), perennial peanut (PP) (Arachis glabrata Benth), and common bermudagrass (BG) (Cynodon dactylon L.) over time. We also assessed the competition for water and N uptake between citrus and groundcover species and compared citrus N uptake measured using the SUM system with the 15N method. Nitrogen uptake followed cyclic patterns and was greatest for bermudagrass-based systems, while values were similar for PP and citrus systems. Competition for N uptake did occur during the summer months between citrus and BG, while no obvious competition for N uptake occurred between citrus and PP. Water uptake was greatest for the mixed systems and BG monoculture. Citrus, PP, and BG competed for water during the spring and summer seasons. None of the groundcovers significantly affected overall citrus tree growth. Nitrogen use efficiency was greatest for mixed systems and ber...

Two field experiments were conducted in north Florida to examine effects of solarization and reduced-risk pesticides on weeds, nematodes, soil-borne diseases, and yield of snapdragon (Antirrhinum majus). Five treatments were replicated five times in a randomized complete block design: fumigation with 80:20 methyl bromide:chloropicrin, solarization, solarization + Kodiak® (product with Bacillus subtilis), solarization + Biophos™ (product with dipotassium phosphonate and dipotassium phosphate), and non-treated control. Methyl bromide was generally superior to treatments involving solarization, which in turn were superior to the control, for improving flower yield and managing weeds, nematodes, and mortality due to plant disease. In the second year, solarization was more effective than methyl bromide in reducing plant mortality; however, surviving plants were larger and more productive following methyl bromide. In the second year, Biophos™ + solarization was as effective as methyl bromide in improving plant ...

Larra bicolor F. (Hymenoptera: Crabronidae) is a specialist parasitoid of Scapteriscus (Orthoptera: Gryllotalpidae) mole crickets, attacking adults and medium to large nymphs. Reproductive systems were dissected from 10 female wasps collected in northern Florida. Each had 2 ovaries, each with 3 ovarioles. The maximal number of mature eggs (10) plus developing oocytes (83) was 93. Female wasps deposit an egg on the venter of the host's thorax, and the wasp larva develops as an ectoparasitoid. Twenty newly-emerged female wasps housed in small cages with at least 1 male and with 7 potential hosts replaced daily deposited a mean 2.44 eggs (range 0–10) per day for a total lifetime production averaging 56 eggs (range 17–91) during a lifespan averaging 23.5 d (range 8–40). Assuming 3 wasp generations with fecundity as shown to 1 host generation, per year, the wasp should easily be able to outreproduce its host mole crickets. A few of the hosts became superparasitized with 2 or even 3 eggs, but at most 1...

Soil solarization is an important practice for small-acreage farmers and home gardeners and is used commercially in areas with high solar radiation and air temperature during the summer. In this technique, clear plastic films are used to increase soil temperature to manage soil-borne plant pests such as insects, diseases, nematodes, fungi, and weeds. Several different kinds of plastic films were evaluated in 2007 and 2008 for durability, weather tolerance, and weed suppression. Treatments were arranged in a randomized complete block design with five replications. In 2007, treatments were four clear plastic films including: ISO, VeriPack, Poly Pak, Bromostop®, and a white plastic control. In 2008, treatments were Polydak®, Poly Pak, Bromostop®, and white plastic. Films were evaluated for weed suppression based on the population density of weeds that emerged through breaks in the plastic, for durability in terms of number and size of breaks in the films, and for the total exposed soil area resulting from breaks. Purple nutsedge (Cyperus rotundus) was the major weed problem throughout both years. In both years, total exposed area was greater with white plastic and Bromostop® (81.5 ft2/bed) compared with other plastic films (2/bed). Due to their durability, Poly Pak, ISO, and VeriPack suppressed nutsedge more than Bromostop and white plastic. Although a number of very small (