Local de absorção de fomesafen como mecanismo de resistência em biótipo de Euphorbia heterophylla resistente aos inibidores da PROTOX

Abstract

Palavras-chave: resistência de plantas daninhas, amendoim-bravo, fomesafen.ABSTRACT -Three trials were carried out to verify if the site of formesafen, absorption leaves or soil, affects the efficacy of controling this herbicide in wild poinsettia biotypes resistant and susceptible to the product; and to determine which plant structures are more important for fomesafen absorption. In the first two trials, fomesafen dose-response was evaluated on biotypes susceptible and resistant to PROTOX inhibitors, in the pre (first trial) and post emergence (second trial) applications. In a third trial, different deposition sites of fomesafen were evaluated using the double pot system to verify the structures of wild poinsettia plants which were most important to fomesafen absorption. Overall, the results indicated that shoot absorption of fomesafen was more limited on wild poinsettia biotypes with PROTOX resistance than on susceptible ones and that these differences between biotypes were less important when applied in pre-emergence. When applied to soil, fomesafen efficacy increased when the herbicide was placed near wild poinsettia shoots than close to their roots. These results support the hypothesis that leaf differences between resistant and susceptible plants may limit fomesafen absorption on biotypes resistant to PROTOX inhibitors.

Eletrolite leakage as a technique to diagnose euphorbia heterophylla biotypes resistant to ppo-inhibitors herbicides

“…But, when this herbicide was applied to the soil, there was no significant difference between the biotypes. These results strongly suggest that the mechanism of R is related to absorption of PPO inhibitors by the shoots in EPHHL (Trezzi et al, 2009b).…”

“…But this result is in disagreement with the obtained FR results for these biotypes using whole plant assays and with herbicides applied to the shoots. In these experiments, the obtained RF using the herbicide efficacy data ranged between 39 and 62 (Trezzi et al, 2005) and between 1.4 and 2.1 (Trezzi et al, 2009b).…”

Déficit hídrico na eficiência de herbicidas e nas características bioquímicas de Euphorbia heterophylla

“…Dessa forma, o fomesafen e o lactofen proporcionaram controles maiores que os inibidores da ALS sem serem afetados pelo déficit hídrico. Trezzi et al (2009) observaram que fomesafen aplicado em pós-emergência em plantas de E. heterophylla na dose de 200 g ha -1 (valor próximo ao utilizado neste estudo), exerceu cerca de 80% de controle aos 14 DAA. A influência de fatores do ambiente na atividade de herbicidas relaciona-se, também, às mudanças morfológicas impostas às plantas, por isso, plantas em estresse hídrico podem apresentar cutículas desidratadas que podem reduzir a absorção de fomesafen, resultando, assim, em menor eficiência do produto ao controle das plantas daninhas (PEREGOY et al, 1990).…”

Manejo de plantas daninhas eudicotiledôneas na cultura da soja Roundup Ready

“…De difícil controle por herbicidas, foi considerada por Cardenas (1972) como mediamente nociva, já tendo alguns biótipos resistentes (resistência cruzada) a herbicidas inibidores da enzima acetolactato sintase (ALS) e da enzima protoporfirinogênio IX oxidase (PROTOX) (Vargas et al, 1999;Trezzi et al, 2009), além da suspeita de uma possível resistência aos inibidores de EPSPS (Vidal et al, 2007). Essa espécie é comumente citada como uma das mais importantes infestantes da cultura da soja no Rio Grande do Sul.…”