Selectivity of Methiozolin for Annual Bluegrass (Poa annua) Control in Creeping Bentgrass as Influenced by Temperature and Application Timing

Abstract

Methiozolin controls annual bluegrass in creeping bentgrass but application timing and temperature could influence efficacy in turf. In field experiments, sequential methiozolin applications totaling 3.36 kg ai ha−1provided excellent (> 90%) annual bluegrass control at 8 wk after initial treatment when treatments were initiated in February/March or May but programs totaling 0.84 and 1.68 kg ha−1provided poor control (< 70%) at both timings. Methiozolin at all rates caused minimal turf injury (< 8%) but creeping bentgrass was only injured from February/March applications. In growth chamber experiments, creeping bentgrass injury from methiozolin at 10 C was 2 and 4 times greater than at 20 C and 30 C, respectively, while annual bluegrass injury was similar across temperatures. In laboratory experiments, annual bluegrass had more foliar absorption of14C-methiozolin than creeping bentgrass at 30/25 C (day/night), compared to 15/10 C, but translocation was similar at both temperatures as > 90% of absorbed14C remained in the treated leaf after 72 h. Annual bluegrass distributed and recovered more radioactivity to shoots from root-applied14C-methiozolin than creeping bentgrass while both species had about 2 times more distribution to shoots at 30/25 C than 15/10 C. Metabolites were not detected in annual bluegrass or creeping bentgrass at 1, 3, or 7 d after treatment when grown at 15/10 C or 30/25 C suggesting uptake and translocation contributes to methiozolin selectivity in turfgrass.

Methiozolin sorption and mobility in sand-based root zones

“…The K d values observed are consistent with other soil‐active herbicides (Table ). These data corroborate previous researchers who reported that methiozolin has soil activity for control of annual bluegrass …”

“…) is a herbicide of the isoxazoline class . Methiozolin selectively controls annual bluegrass ( Poa annua L.) in creeping bentgrass ( Agrostis stolonifera L.) and hybrid bermudagrass ( Cynodon dactylon × C. transvaalensis Burtt‐Davy) . Currently, there are few options for selective annual bluegrass control in these turfgrasses, especially in golf course putting greens.…”

“…Methiozolin is absorbed by the roots and foliage of annual bluegrass . Root exposure and subsequent absorption is required for POST control .…”

Physiological effects of temperature on turfgrass tolerance to amicarbazone

“…Grasses grown at 40/35 °C averaged 10% more 14 C distributed to shoots than at 25/20 °C. Similar increases in acropetal movement were noted following root absorption of 14 C‐methiozolin in annual bluegrass and creeping bentgrass grown at 15/10 and 30/25 °C . Greater herbicide absorption and translocation at higher temperature may be related to the altered stomatal conductance and increased transpiration rate …”

A eficácia do controle químico varia com o genótipo de azevém e a temperatura do ar no momento da aplicação

“…Efeitos equivalentes foram observados para seletividade de rimsulfuron em milho (KOEPPE et al 2000) e bispyribac-sodium em Poa annua (MCCULLOUGH et al 2009). Porém, maior absorção de herbicidas pode ser verificada em temperaturas mais altas (FLETCHER et al 2007, MCCULLOUGH et al 2010, 2013.…”