Effects of Pre- and Postanthesis Applications of Demethylation Inhibitor Fungicides on Fusarium Head Blight and Deoxynivalenol in Spring and Winter Wheat

Abstract

Anthesis is generally recommended as the optimum growth stage for applying a foliar fungicide to manage Fusarium head blight (FHB) and the Fusarium-associated toxin deoxynivalenol (DON) in wheat. However, because it is not always possible to treat fields at anthesis, studies were conducted to evaluate pre- and postanthesis treatment options for managing FHB and DON in spring and winter wheat. Network meta-analytical models were fitted to data from 19 years of fungicide trials, and log response ratio ([Formula: see text]) and approximate percent control ([Formula: see text]) relative to a nontreated check were estimated as measures of the effects of six treatments on FHB index (IND: mean percentage of diseased spikelets per spike) and DON. The evaluated treatments consisted of either Caramba (metconazole) applied early (at heading [CE]), at anthesis (CA), or late (5 to 7 days after anthesis; CL), or Prosaro (prothioconazole + tebuconazole) applied at the same three times and referred to as PE, PA, and PL, respectively. All treatments reduced mean IND and DON relative to the nontreated check, but the magnitude of the effect varied with timing and wheat type. CA and PA resulted in the highest [Formula: see text] values for IND, 52.2 and 51.5%, respectively, compared with 45.9% for CL, 41.3% for PL, and less than 33% for CE and PE. Anthesis and postanthesis treatments reduced mean IND by 14.9 to 29.7% relative to preanthesis treatments. The estimated effect size was also statistically significant for comparisons between CA and CL and PA and PL; CA reduced IND by 11.7% relative to CL, whereas PA reduced the disease by 17.4% relative to PL. Differences in efficacy against IND between pairs of prothioconazole + tebuconazole and metconazole treatments applied at the same timing (CE versus PE, CA versus PA, and CL versus PL) were not statistically significant. However, CA and CL outperformed PA and PL by 7 and 12.8%, respectively, in terms of efficacy against DON. All application programs had comparable efficacy against IND between spring and winter wheat types, but efficacy against DON was 10 to 16% greater for spring than winter wheat for applications made at or after anthesis. All programs led to an increase in mean grain yield and test weight relative to the nontreated check.

Integrating Management Practices to Decrease Deoxynivalenol Contamination in Soft Red Winter Wheat

“…Several tillers on a wheat plant can develop fertile spikes and shed pollen across a range of days as all of these tillers are not at the same development stage during heading and anthesis (Kiesselbach and Sprague, 1926;Noversoke, 2014;Tilley et al, 2019). More uniform spike development could lead to more uniform anthesis and better fungicide efficacy, as current fungicides (prothioconazole + tebuconazole and metconaxole) have been shown to reduce FHB incidence by only approximately 50% compared to a non-treated control (Paul et al, 2018). Phosphorus can be applied in a variety of placements in the soil during fall application; however in-furrow application at planting has been shown to result in greater grain yield compared to broadcast application (Peterson et al, 1981;Fiedler et al, 1989;Grant et al, 2001).…”

Predicting plant disease epidemics from functionally represented weather series

“…One of the more significant findings was that summaries over windows which crossed anthesis were better input predictors than summaries that were restricted to either side of anthesis; our earlier modelling efforts generally focused on pre-anthesis weather with the objective of providing FHB predictions before anthesis so that fungicides could be applied [27]. However, post-anthesis fungicide applications against FHB may also be effective [31]. Functional modelling, as we have shown, can be useful in the process of developing simple (lr) models that are at least as good as existing models, that make use of novel predictors, and which add to the pool of existing models to choose from.…”

Relationship Between Efficacy of Fusarium Head Blight Chemical Control and Deoxynivalenol Contamination on Wheat Kernels

“…Reports indicated that efficient fungicide spraying significantly reduces FHB intensity and DON levels and increased both yield and thousand kernel weight, when compared to untreated controls (Nicholson et al,199). As shown, DON contamination in grains is directly related to FHB intensity (Blandino et al, 2006;Haidukowsky et al, 2005;Paul et al, 2018).…”

“…Quantitative damages caused by FHB, after no-till has been widely used by growers can be as high as 39.8% (Casa et al, 2004(Casa et al, , 2011. In addition to the quantitative damage, the qualitative due to the grains contamination by mycotoxins is equally important (Paul et al, 2007(Paul et al, , 2018. There are reports showing that the reduction of mycotoxin content related to FHB chemical control, i.e., as control increases deoxynivalenol (DON) contamination decreases (Haidukowsky et al, 2016).…”