Aim Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group.Location Global.Methods Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions.Results Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long-lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success.Main conclusions A greater emphasis on pro-active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on-going monitoring and management, and ensuring resources are in place for long-term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track-record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans-boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best-practice procedures can be developed.

Goosegrass (Eleusine indica), regarded as one of the world's worst weeds, is highly pernicious to cash crop-growers in Malaysia. Following reports in 2009 that glufosinate-ammonium failed to adequately control goosegrass populations in Kesang, Malacca, and Jerantut, Pahang, Malaysia, on-site field trials were conducted to assess the efficacy of glufosinate-ammonium towards goosegrass in both places. Preliminary screenings with glufosinate-ammonium at the recommended rate of 495 g ai ha -1 provided 82% control of the weed at a vegetable farm in Kesang, while the same rate failed to control goosegrass at an oil palm nursery in Jerantut.The ensuing greenhouse evaluations indicated that the "Kesang" biotype exhibited twofold resistance, while the "Jerantut" biotype exhibited eightfold resistance towards glufosinate-ammonium, compared to susceptible goosegrass populations. The occurrence of glufosinate resistance in goosegrass calls for more integrated management of the weed to prevent escalating resistance and further proliferation of the weed in Malaysia.

The management of weeds in Malaysian rice fields is very much herbicide-based. The heavy reliance on herbicide for weed control by many rice-growers arguably eventually has led to the development and evolution of herbicide-resistant biotypes in Malaysian rice fields over the years. The continuous use of synthetic auxin (phenoxy group) herbicides and acetohydroxyacid synthase-inhibiting herbicides to control rice weeds was consequential in leading to the emergence and prevalence of resistant weed biotypes. This review discusses the history and confirmed cases and incidence of herbicide-resistant weeds in Malaysian rice fields. It also reviews the Clearfield Production System and its impact on the evolution of herbicide resistance among rice weed species and biotypes. This review also emphasizes the strategies and management options for herbicide-resistant rice field weeds within the framework of herbicide-based integrated weed management. These include the use of optimum tillage practices, certified clean seeds, increased crop competition through high seeding rates, crop rotation, the application of multiple modes of action of herbicides in annual rotations, tank mixtures and sequential applications to enable a broad spectrum of weed control, increase the selective control of noxious weed species in a field and help to delay the resistance evolution by reducing the selection pressure that is forced on those weed populations by a specific herbicidal mode of action.

Several laboratory and glasshouse experiments were conducted to assess seed germination, seedling establishment and growth patterns of wrinklegrass ( Ischaemum rugosum Salisb.) influenced by temperature and light regimes, and chemical media. Wrinklegrass was a positively photoblastic species, and seed germination was temperature-dependent and light-mediated. Seeds soaked in distilled water for 24 h, or oven-dried at the respective temperature regimes of 15, 20, 25, 30, 35, or 40 ∞ C prior to treatment in distilled water and incubated in darkness, failed to germinate. Likewise, no germination prevailed when the seeds were exposed to similar temperature regimes and treated with 0.2 M KNO 3 , 5% H 2 O 2 or 0.01 M HNO 3 , and incubated under continuous darkness. Seeds treated with 5% H 2 O 2 at 30 ∞ C, or oven-dried and treated with 0.01% M HNO 3 at 35 ∞ C registered 10 and 20% germination. Approximately 75 and 90% of the light-exposed seeds for all treatments germinated in the first three and six days at 25 ∞ C. No germination occurred at 15 ∞ C in the first three days after treatment. Seeds subjected to 40 ∞ C for six days after treatment recorded 36% germination. The optimum temperatures for seed germination were 25-30 ∞ C. Seed drying and soaking treatments widened the windows of the optimal temperatures for wrinklegrass germination. The acidic media of KNO 3 , H 2 O 2 or HNO 3 favored seed germination. Less than 5% of seed germination occurred with burial or water inundation at depths exceeding 2 cm. Seed burial or inundation at ≥ 2 cm depths inhibited seed germination. Seeds sown onto moist paddy soils registered ca. 50% germination. Free-floating seeds on the water surface registered ca. 98% germination within the first six days after seeding. The mean number of seedlings that survived was inversely proportional to water depths, with close to 100% mortality at the 14 cm depths of inundation. Both plant height and seedling survival were linearly proportional to the amount of root mass of seedlings which penetrated the soil. The weed was a prolific seed producer ( ca. 6000 seeds/ genet or 18 000 seeds/genet per year). The vegetative and reproductive efforts of each wrinklegrass plant registered values of 0.68 and 0.32, respectively.

Pseudo-first-order rate constants (k obs ) for hydrolysis of a sulfonylurea herbicide, azimsulfuron, AZIM, {N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbony]-1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide} (AZS) follow an empirical relationship:] 2 within the [NaOH] range of 0.1-2.0 M at different temperatures ranging from 40 to 55ЊC. The contribution of ␣ 3 [ Ϫ OH] 2 term is small compared with ␣ 2 [ Ϫ OH] term and this turns out to be zero at 60ЊC. Pseudo-first-order rate constants (k obs ) for hydrolysis of AZS within the [H ϩ ] range from 2.5 ϫ 10 Ϫ6 to 1.4 M follow the relationship: k obswhere pK a ϭ 4.37 at 50ЊC. The value of ␤ 1 is nearly 25 times larger than that of ␣ 1 . The rate of alkaline hydrolysis of AZIM is weakly sensitive to ionic strength.

A study was carried out to optimize selected parameters for decolorization of a triarylmethane dye, such as crystal violet by white rot fungus, Pycnoporus sanguineus, pellets. The parameters studied were initial dye concentration (ppm), agitation speed (rpm), and process time (days) and were optimized using response surface methodology (RSM). It is shown that process time, agitation speed, and their interactions have significant effects on the decolorization process. Following the optimization, the decolorization study was extended to a stirred tank reactor (STR) process. Effects of different geometry of impellers on the decolorization process and power consumption were studied. Novel impeller geometries, such as 180 • curved blade and 60 • angled blade impellers, were used in the STR. The application of 180 • curved blade impeller resulted in higher percentage of decolorization at a relatively less power consumption as compared with 60 • angled blade impeller.

No abstract

No abstract