The occurrence of herbicide-resistant weeds worldwide

Abstract

:The 1995/6 International Survey of Herbicide-Resistant Weeds recorded 183 herbicide-resistant weed biotypes (124 di †erent species) in 42 countries. The increase in the number of new herbicide-resistant weeds has remained relatively constant since 1978, at an average of nine new cases per year worldwide. Whilst 61 weed species have evolved resistance to triazine herbicides, this Ðgure now only accounts for one-third of all documented herbicide-resistant biotypes. Triazine-resistant weeds have been controlled successfully in many countries by the use of alternative herbicides. Due to the economic importance of ALS and ACCase inhibitor herbicides worldwide, and the ease with which weeds have evolved resistance to them, it is likely that ALS and ACCase inhibitor-resistant weeds will present farmers with greater problems in the next Ðve years than triazine-resistant weeds have caused in the past 25 years. Thirty-three weed species have evolved resistance to ALS-inhibitor herbicides in 11 countries. ALSinhibitor-resistant weeds are most problematic in cereal, corn/soybean and rice production. Thirteen weed species have evolved resistance to ACCase inhibitors, also in 11 countries. ACCase inhibitor resistance in L olium and Avena spp. threatens cereal production in Australia, Canada, Chile, France, South Africa, Spain, the United Kingdom and the USA. Fourteen weed species have evolved resistance to urea herbicides. Isoproturon-resistant Phalaris minor infesting wheat Ðelds in North West India and chlorotoluron-resistant Alopecurus myosuroides in Europe are of signiÐcant economic importance. Although 27 weed species have evolved resistance to bipyridilium herbicides, and 14 weed species have evolved resistance to synthetic auxins, the area infested and the availability of alternative herbicides have kept their impact minimal. The lack of alternative herbicides to control weeds with multiple herbicide resistance, such as L olium rigidum and Alopecurus myosuroides, makes these the most challenging resistance problems. The recent discovery of glyphosate-resistant L olium rigidum in Australia is a timely reminder that sound herbicide-resistant management strategies will remain important after the widespread adoption of glyphosate-resistant crops.

Seletividade de formulações de glyphosate a Trichogramma pretiosum (Hymenoptera: Trichogrammatidae)

“…Apesar de existirem mais de 90 marcas comerciais de glifosato no mundo (Heap, 1997), todas elas apresentam o mesmo mecanismo de ação, independentemente dos sais utilizados (Hartzler, 2001). No Brasil, esse herbicida é formulado com diferentes sais, como o sal potássico, sal de isopropilamina e sal de amônio.…”

Atividade alelopática do filtrado de cultura produzido por Fusarium solani

“…Ent retanto, os atuais métodos de controle -especialmente os que envolvem o uso de produtos químicos sintéticos, como os herbicidas -têm apresentado exaustão, sobretudo porque tem havido redução na eficiência dos produtos disponíveis no mercado, principal men te pel o cre sce nte apa rec ime nto de biótipos de plantas daninhas resistentes a esses produtos (Christoffoleti et al, 1994;Jasieniuk et al, 1996). Heap (1999) menciona que no mundo ocorrem, a cada ano, nove novos casos de plantas daninhas resistentes a herbicidas e que existem mais de 230 biótipos resistentes a diferentes classes de herbicidas, em 42 países. No Brasil, a resistência de plantas daninhas aos herbicidas disponíveis no mercado já foi relatada para as espécies picão-preto (Bidens pilosa ), capim -co lchã o (Dig itaria ciliare s), capim-marmelada (Brachiaria plantaginea) e amendoi m-bravo ( Eup horbia heterophylla) (Lopes-Ovejero et al, 2005;Vidal et al, 2005;Christoffoleti, 2001;Vidal, 1997).…”

Análise comparativa dos efeitos alelopáticos das substâncias químicas titonina e titonina acetilada

“…Quando se consideram os problemas decorrentes do uso indiscriminado de herbicidas sintéticos (Anaya, 1999;Killham & Foster, 1996) e o aumento sistemático no número de espécies de plantas daninhas resistentes aos atuais produtos no mundo (Vidal & Meroto, 2001; Heap, 1997;Jasieniuk et al, 1996;Christoffoleti et al, 1994;LeBaron, 1991;Holt & LeBaron, 1990), a necessidade de colocar à disposição da agricultura produtos alternativos assume aspecto ainda mais relevante.…”