Crop signal markers facilitate crop detection and weed removal from lettuce and tomato by an intelligent cultivator

Hannahjoy Kennedy,Richard F Smith,Vivian L Vuong,Thuy T Nguyen,Steven A Fennimore,Rekha Raja,David C Slaughter

doi:10.1017/wet.2019.120

Abstract

AbstractIncreasing weed control costs and limited herbicide options threaten vegetable crop profitability. Traditional interrow mechanical cultivation is very effective at removing weeds between crop rows. However, weed control within the crop rows is necessary to establish the crop and prevent yield loss. Currently, many vegetable crops require hand weeding to remove weeds within the row that remain after traditional cultivation and herbicide use. Intelligent cultivators have come into commercial use to remove intrarow weeds and reduce cost of hand weeding. Intelligent cultivators currently on the market such as the Robovator, use pattern recognition to detect the crop row. These cultivators do not differentiate crops and weeds and do not work well among high weed populations. One approach to differentiate weeds is to place a machine-detectable mark or signal on the crop (i.e., the crop has the mark and the weed does not), thereby facilitating weed/crop differentiation. Lettuce and tomato plants were marked with labels and topical markers, then cultivated with an intelligent cultivator programmed to identify the markers. Results from field trials in marked tomato and lettuce found that the intelligent cultivator removed 90% more weeds from tomato and 66% more weeds from lettuce than standard cultivators without reducing yields. Accurate crop and weed differentiation described here resulted in a 45% to 48% reduction in hand-weeding time per hectare.

Highlights

IntroductionSpecialty crops represent 61% of California’s $46 billion agricultural industry (CDFA 2017)
High-value specialty crops are a majority of agricultural production in California
In the past 30 yr very few herbicides have been developed for vegetable crops, and the available herbicides generally control only a fraction of weed species that are present (Fennimore et al 2010; Fennimore and Doohan 2008; Lati et al 2016; Van der Weide et al 2008)

Summary

Introduction

Specialty crops represent 61% of California’s $46 billion agricultural industry (CDFA 2017). Weeds are difficult to control in lettuce and tomato due to labor shortages, increasing costs of hand weeding, and limited herbicide options (Fennimore and Cutulle 2019). There is no tolerance for contamination of bagged lettuce salad mixes with weed plant parts; and weeds must be controlled if lettuce is to be harvested (Fennimore et al 2010; Lati et al 2016; Slaughter et al 2008a). Weeds can be hosts to insects and pathogens that can infest crops (Fennimore et al 2014; Lati et al 2016; Lechenet et al 2017; Slaughter et al 2008a)

Objectives

Methods

Results