The presence of the North American Marmorkrebs (Procambarus fallax f. virginalis) in European inland waters is entirely driven by ongoing propagule pressure from the ornamental trade. Since 2003 at least 25 independent introduction events have been confirmed, of which some have eventually resulted in established populations. This study links a maximum-entropy model that forecasts the probability of Marmorkrebs introduction based on socioeconomic predictors to an updated species distribution model based on environmental predictors in order to explore the risk of further Marmorkrebs establishment in Europe. In line with related research, the probability of Marmorkrebs release was largely affected by gross domestic product and human population density, i.e. predictors very likely related to the density of Marmorkrebs owners, whereas environmental suitability was mostly influenced by minimum temperature and the availability of lentic habitats, which was indirectly assessed by terrain slope. While considerable parts of Europe were predicted as potentially suitable for establishment, high probabilities of introduction were forecasted in much smaller geographic areas. The consensus map of the model predictions suggests that introduction and subsequent establishment of Marmorkrebs is likely to occur in much of Germany, the Benelux countries, England, Italy, and areas of high human population density throughout France and Spain, as well as parts of southernmost Scandinavia and Southeastern Europe. Monitoring trades of Marmorkrebs in these high-risk regions is recommended and implications for proactive measures are discussed, including the need for consistent trade regulations at the EU level.

Fallow management is a major strategy for weed control and soil fertility restoration in tropical farming systems. From 1995 to 1998, weed infestation was evaluated in plots managed under 0, 1, 2 and 3 year fallow durations of (1) a natural bush fallow dominated by Chromolaena odorata;(2) a planted Mucuna pruriens fallow; and (3) a modified bush fallow without C. odorata. The study was conducted at the Nigerian Institute for Oil Palm Research (NIFOR), Benin City, Nigeria. The 3 · 4 factorial experiment was set up in a split plot arrangement. The three fallow types were the main plots and the four fallow durations were the subplots. Each year, the subplots were planted to maize (Zea mays, cv. TZSR-W) as appropriate and harvested 14 weeks after planting for yield comparison. Continuous cropping and the modified natural bush fallow increased weed diversity and biomass. Irrespective of fallow type, weed infestation was more gradual in the first year of cropping after fallow than in subsequent cropping years. Regardless of cropping intensity, C. odorata and M. pruriens fallows promoted broad-leaved weeds, chiefly Ageratum conyzoides, Tridax procumbens and Phyllanthus amarus, whereas the modified bush fallow promoted grasses. Maize grain yield was higher in the C. odorata and M. pruriens fallows than in the modified bush fallow, but the yield difference diminished with cropping intensity.

Mimosa diplotricha is an invasive perennial, scrambling, thorny, leguminous shrub of neotropical origin widely acknowledged as a major economic, agricultural and ecological burden in its introduced ranges. Although the plant is thought to have been present in Nigeria for well over two decades, its mode and time of introduction is uncertain. In spite of the continuing spread of, and the menace caused by M. diplotricha in Nigeria, no attempt has been made to map the distribution of the plant countrywide. Therefore, we conducted a countrywide survey between 2007 and 2009, sponsored by the Weed Science Society of Nigeria (WSSN) to determine the spread and status of Mimosa diplotricha in Nigeria. A further objective of this paper was to review literatures on Mimosa diplotricha in Nigeria and elsewhere to enable comparison. In this paper, we report on the spread, distribution and problems of Mimosa diplotricha in Nigeria based on the field monitoring surveys conducted. The distribution of this invasive plant in Nigeria has been mapped and is presented together with its ecology and problems being caused. Since the early 1990s, the weed has started to spread and invade many parts of the country causing significant damage to many natural and semi natural ecosystems. The different control options used by farmers to control Mimosa diplotricha in Nigeria are discussed. Based on the successful control of this invasive plant using the biocontrol agent, Heteropsylla spinulosa in countries such as Australia and Papua New Guinea (PNG), we discussed the biological control prospects for the management of Mimosa diplotricha in Nigeria. Such control attempts stands to benefit from international collaborations between Nigerian institutions and a host of others in Australia, PNG and/or Brazil. Finally three major causes for the massive and continuing spread of this weed in Nigeria are presented with recommendations for the Nigerian government and institutions to: 1) formulate policies and legislations regarding the control and management of invasive alien plant species which is currently nonexistent; 2) enlighten the general public on the dangers of invasive alien plant species such as Mimosa diplotricha; and 3) initiate actions such as early detection and rapid response (EDRR) and biological control in order to prevent further spread of, and invasion by invasive plant species including Mimosa diplotricha.

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A range of herbicides was evaluated for the control of Chromolaena odorata (L.) K & R in oil palm at the Nigerian Institute for Oil Palm Research. Glufosinate‐ammonium quickly dessicated treated foliage but weed plants soon recovered. Glyphosate‐isopropylamine and glyphosate‐trimesium produced similar results, both formulations controlling treated vegetation and suppressing regrowth for up to 12 weeks after treatment. Triclopyr and hexazinone + diuron were effective for up to 20 WAT, whereas imazapyr controlled regrowth for up to 36 WAT. Regrowth of the weed from its roots was better suppressed when the foliage was left undisturbed for 4–7 days after herbicide treatment. Repeated annual applications of triclopyr, hexazinone + diuron, the two formulations of glyphosate or imazapyr progressively reduced the biomass of C. odorata in the plots. In particular, imazapyr effectively eliminated the weed after the second application. Taking crop tolerance into consideration, the most promising herbicide treatments were glyphosate at 2.4 kg a.i. ha−1 and low rates (0.5 kg a.i. ha−1 or less) of imazapyr.