seletividade de herbicidas aplicados em pré-emergência na cultura ...

ABSTRACT
ARANTES, J.G.Z., M.S., Universidade Estadual de Maringá, october, 2008. Seletivity of
pre-emergence herbicides applied to cotton (Gossypium hirsutum L.). Adviser:
Prof. Dr. Rubem Silvério de Oliveira Junior. Co-adviser: Prof. Dr. Jamil Constantin.
The few herbicide options for selective broadleaf weed control in cotton usually
lead to the application of treatments which may injure crop and eventually to yield
decreases. This work was aimed at evaluating the selectivity of herbicides applied at preemergence,
isolated or in tank-mixtures, for two cotton varieties (Delta-Opal and FMT-
701). Treatments applied were (rates in kg a.i. ha -1 ): Alachlor (1.2), S-metolachlor
(0.672), Diuron (0.900 and 1.200), Prometryn (0.900 and 1.200), Oxyfluorfen (0.192),
Alachlor + Diuron (1.2 + 1.2), Alachlor + Prometryn (1.2 + 1.9 and 1.2 + 1.2), S-
metolachlor + Diuron (0.672 + 1.2), S-metolachlor + Prometryn (0.672 + 0.9 and 0.672 +
1.2), Oxyfluorfen + Diuron (0.192 + 1.2), Oxyfluorfen + Prometryn (0.192 + 0.9). The
experiment was undertaken by using two fold checks. Evaluations performed were
related to the visual plant intoxication, stand, development and yield of both varieties, in
distinct experiments. Herbicide treatments did not influence cotton stand. Plants of both
varieties which presented reduced growth at the beginning of the crop cycle recovered
along the cycle, independent of herbicide treatment. When rates of diuron and prometryn
were increased, symptoms of crop injury were also stronger in relation to lower rates of
the same products. Oxyfluorfen, isolated or in tank mixture with diuron or prometryn,
propitiated intense symptoms of crop injury at 14 days after application. The only
treatment which was considered as non selective to both cotton varieties, taking into
account only crop yield, was the mixture of oxyfluorfen + prometryn (0.192 + 0.9 kg a.i.
ha -1 ).
Keywords: chemical control, pre-emergence, tank mixture.
ix