Trinexapac-Ethyl and Sulfometuron-Methyl Selectivity to Young Eucalyptus Plants

Abstract

Trinexapac-ethyl and sulfometuron-methyl are the most widely used ripeners in sugarcane. The application is performed by airborne spraying. Thus, if weather conditions are unfavorable, spray drift to neighboring areas may occur. The objective of this study was to assess the selectivity of the plant growth regulators trinexapac-ethyl and sulfometuron-methyl, used as sugarcane ripeners, to eucalyptus (Eucalyptus urograndis) young plants. The experiment was installed in an eucalyptus commercial yield area, in the municipality of Tambaú, state of São Paulo, Brazil, and arranged in a 2 x 8 factorial design in randomized blocks with four replications. The treatments studied were trinexapac-ethyl and sulfometuron-methyl, sprayed in eight doses, 0; 1.0; 2.5; 5.0; 10; 25; 50 and 100% of the dose used in sugarcane as ripeners (200 g ha-1 of trinexapac-ethyl and 15 g ha-1 of sulfometuron-methyl). Chemical ripeners were applied on eucalyptus plants with 48 cm in height on average; 10.1 branches; 4.5 mm of stem diameter and 44.3 cm of crown diameter, at 46 days after seeding. Trinexapac-ethyl was selective to eucalyptus and stimulated crown diameter growth. At higher doses, sulfometuron-methyl promoted severe noticeable injuries in eucalyptus plants, such as apical bud death. However, during the assessment period the plants recovered and the visual symptoms of phytotoxicity and growth alterations were not observed at 60 days after application. The plant growth regulators trinexapac-ethyl and sulfometuron-methyl were selective to eucalyptus young plants.

Trinexapac-Ethyl Causes Stimulatory Effect on the Initial Growth of Eucalyptus urograndis Clones

“…This effect has already been observed for forest species in previous works, including studies that used the plant growth regulator trinexapac-ethyl (Velini et al, 2008;Pires et al, 2013;Correia & Villela, 2015).…”

“…This phenomenon has already been observed for several plant species and products, including trinexapac-ethyl in eucalyptus plants (Velini et al, 2008;Pereira, Nepomuceno, Pires, Parreira, & Alves, 2013;Correia & Villela, 2015).…”

“…The authors also emphasized that this response is related to the competition between the trinexapac-ethyl molecule and 2-oxogluterate by the cosubstrate Fe +2 /ascorbate-dependent dioxygenase. However, low doses of this compound do not negatively affect the initial growth of eucalyptus Correia & Villela, 2015).…”

Maize Crop Phytotoxicity in Response to Sub-Doses of Sulfometuron-Methyl

“…Starting from day 28 DAA, damages became more perceptible (grade 2), remaining until day 42 DAA, that is, small alterations were visible on some plants. In a study conducted by Correia and Villela (2015), it was possible to observe that eucalyptus seedlings exposed to the application of sulfometuron-methyl also recovered from the damages and stopped presenting visual phytotoxicity symptoms of abnormal growth on day 60 DAA.…”

“…In literature, there are works about plant phytointoxication caused by the application of sugarcane ripeners, such as ethephon and sulfometuron-methyl (Correia and Leite, 2012;Correia and Villela, 2015;Felisberto et al, 2015), as well as studies about the selectivity of herbicides derived from sulfonylurea (Burney and Jacobs, 2009;Pfleeger et al, 2010;Osiecka and Minogue, 2015). However, studies about the effect and the characterization of possible phytotoxicity symptoms, caused by sub-doses of sulfometuron-methyl on maize culture have not been conducted yet.…”