Evaluating methods and factors that affect dicamba volatility

Abstract

Background: Dicamba is a herbicide with a moderate volatility profile and low dose effects on broadleaf weeds. Dicamba volatility can be strongly reduced with formulation technology and volatilization reducers.Objective: This literature review on the dicamba herbicide aims to present new perspectives for its use, characteristics, volatilization risks, technologies to mitigate these risks and the main methods used to assess volatility in Brazil and worldwide.Conclusions: Dicamba volatility can be mitigated with appropriate formulations and/or the use of adjuvants to reduce volatility. There has been an evolution in adapting new salts and technologies to reduce dicamba volatility. There are different methods of evaluating herbicide volatility, in particular, for the quantification of volatilized dicamba either in laboratory or field studies. Available methods can be fast and consistent and can assess volatilization from different surfaces, weather conditions and technologies to reduce volatilization. Under some conditions it is desirable to combine this method with bioassays.

Chemical Weed Control and Crop Injuries Due to Spray Drift: The Case of Dicamba

“…Dicamba is a white crystalline solid and a strong acid with pKa = 1.87 [2,12]. As a herbicide, it is used in salts, and its structure is shown in Figure 1.…”

“…As a herbicide, it is used in salts, and its structure is shown in Figure 1. Its most common salts are dimethylamine salt (DMA), sodium salt, diglycoamine salt (DGA), and isopropylamine salts (IPAs) [1,2]. Salts have different forms and solubility in water [1] than pure dicamba.…”

“…Dicamba (3,6-dichloro-2-methoxy benzoic acid) [1] is a systemic herbicide that belongs to the group of synthetic auxins [2]. Dicamba is a selective herbicide that is mainly efficient against woody plants and a wide range of annual and perennial broadleaf weeds [3].…”

“…Dicamba applied alone or in mixtures can effectively control several weed species, including several glyphosate-resistant weeds like Amaranthus palmeri, Conyza canadensis, and Ambrosia artemisifolia [3,5]. Unfortunately, there is a plethora of cases where dicamba has injured very sensitive non-target plants [5], causing off-target problems in millions of hectares [7] due to particles and droplets or due to vapor drift from volatilization [2]. Indeed, the European Food Safety Authority (EFSA) raised a serious concern about the long-range transport of dicamba through the atmosphere.…”

“…Indeed, the European Food Safety Authority (EFSA) raised a serious concern about the long-range transport of dicamba through the atmosphere. The outcome of off-targeted injured vegetation is cupping deformation, leaf epinasty, and chlorosis [2,7,10,11].…”