A regional-scale study of the contribution of local, management and climate factors to the infestation of processing tomato fields with Amaranthus species

Abstract

Determining the various factors affecting weed infestation in arable fields is complicated by the considerable spatiotemporal variability of agricultural systems. A possible solution lies in regional-scale studies of weeds in commercial fields to provide insights into the influence of field properties, climate, and weed management practices on the efficacy of weed management. The current study focused on Amaranthus species – noxious weeds infesting many crops worldwide – in processing tomato fields in Northern Israel, a geographical region characterized by a significant climate gradient. This gradient provides an ideal opportunity to study the effect of climate on weed infestation and management. The objective of this study was to investigate the associations between Amaranthus infestations and local (field properties), climate, and management factors in processing tomato fields. A survey of 103 commercial tomato fields was carried out in 2018 and 2019 throughout the four major tomato-growing areas in Northern Israel. The spatiotemporal change in infestation for fields surveyed both pre- and post-weed control was evaluated relative to management and climate variables. A bootstrapped model selection for beta regression models with varying dispersion was performed to determine factors associated with weed infestation before and after weed management. The analysis showed that the application of sulfosulfuron pre-planting, could potentially reduce Amaranthus infestation depending on environmental and local conditions of the field; management comprising of more intense control measures reduced infestation; and precipitation led to an increase in mean infestation when occurring before planting, but a decrease when occurring after weed management. In addition, the onset timing of weed control was found to be negatively correlated with precipitation occurring post-treatment. Our findings show that management actions are key factors in controlling Amaranthus infestation but that these actions are affected by the local climate conditions. Therefore, this work indicates the need for a regional-scale perspective when making weed management decisions.