University of Fort Lauderdale

Biochar is a highly effective soil amendment that has been widely used for ecological remediation and has shown great potential in promoting plant nutrient acquisition and growth. However, it remains unclear whether biochar addition influences competition between invasive and native plants and thus is suitable for the restoration of communities invaded by exotic plants. We conducted a field experiment and a 15N labeling test to investigate the impact of biochar addition on N uptake of invasive Spartina alterniflora and native Phragmites australis under both intra- and interspecific competition. Biochar addition significantly promoted the NO3−-N uptake rate of both P. australis and S. alterniflora under interspecific competition, and promoted the NH4+-N uptake rate of both P. australis and S. alterniflora under both intra- and interspecific competition. However, biochar addition did not influence the competitive balance between S. alterniflora and P. australis. We conclude that biochar addition can enhance N uptake of both native and invasive plants, but cannot alter their competitive superiority in N acquisition or shift their N form preferences. The findings suggest that biochar application will not be useful if we target at restoring wetlands due to exotic plant invasions, as it cannot enhance the competitive advantages of natives over invasives. However, biochar may be applied if we target at restoring degraded wetlands caused by other disturbances such as such as salinization and nutrient impoverishment, as it will not enhance the competitive advantage of invasives over natives.

ABSTRACT Alluaud's little yellow ant, Plagiolepis alluaudi Emery 1894, (Hymenoptera: Formicidae), is an emerging nuisance species in floriculture and residential areas around the globe. Originally described from Madagascar, it ranks among the smallest widespread formicine pests. To date, no evaluations of management protocols for this species have been reported. In ants, feeding preference is related to ant body size and viscosity and nutritional content of the food source. Optimizing these factors could lead to improved bait performance. To assess population management implications of various bait parameters on a small pest ant species, four commercial ant baits of varying viscosities, active ingredient (AI) group and concentration, and nutritional content were evaluated in laboratory and field assays against P. alluaudi . All four products negatively affected P. alluaudi survival compared to the untreated control, and all products were associated with greater visitation compared to the control, suggesting all AIs tested are viable candidates for P. alluaudi management. However, their direct use for population management in the field may be limited, as feeding cessation was eventually observed on all four baits. When baits were diluted with water, viscosity was reduced and survival was initially higher compared to with undiluted baits. However, similarly low levels of survival were maintained over time. Most importantly, we found in a 2‐year observational field study involving sustained baiting within an infested structure that only the bait formulation with the lowest overall viscosity was able to alleviate P. alluaudi nuisance indoors. Our results suggest that diluting baits may be a viable strategy for targeting very small pest ant species, and the greater time to lethality of diluted baits, resulting from reduced toxicant concentration, may be a reasonable trade‐off allowing smaller ant species to continue feeding for a sufficient duration on a bait formulation.

Integrating cover crops and bionematicides presents a sustainable approach to managing plant-parasitic nematodes (PPN) in organic vegetable production systems. The integration of sunn hemp, Crotalaria juncea ('Crescent sun') and sorghum-sudangrass, Sorghum bicolor x S. sudanense ('Sweet Six BMR') with bionematicides was evaluated in two locations in central (Gulf Coast Research and Educational Centre-GCREC) and south (Fort Lauderdale Research and Educational Centre-FLREC) Florida for the effectiveness of PPN suppression. Field experiments were conducted with establishing cover crops in each location 3 months before planting organic zucchini on plastic beds equipped with a drip application system used to inject three commercial bionematicides (thyme oil, neem oil and azadirachtin) and the broth culture of Xenorhabdus bovienii bacteria associated with Steinernema feltiae. Cover cropping with sunn hemp and sorghum-sudangrass significantly reduced population densities of root-knot nematodes (Meloidogyne spp.) at GCREC, whereas only sunn hemp reduced the root-knot nematode population at FLREC. Galling severity on zucchini roots caused by Meloidogyne spp. was significantly lower in azadirachtin and neem oil applications integrated with sunn hemp. The impact of integrating cover crops with bionematicides on other PPN, such as Mesocriconema spp., Nanidorus minor and Hoplolaimus spp., varied among the treatments at both locations. Integrating cover crops with bionematicide applications provided additional control options for zucchini, but the efficacy of different bionematicides depended on the nematode species present in the soil and the cover crop species used. These findings underscore the importance of adaptive nematode management, where control strategies are customised to target the specific nematode populations causing economic damage in each field.