The obligate root parasitic weeds commonly known as broomrape (Orobanche and Phelipanche spp.) cause severe damage to vegetable and field crops worldwide. Efficient control of these parasites is difficult due to their development and attachment to the host plant (via a specialized organ, the haustorium) under the soil surface and to their unique biological traits of massive seed production, facile seed dispersal, germination only under specific conditions, and seed longevity. The major damage inflicted by the parasites takes place underground, making control extremely challenging. Egyptian broomrape (Phelipanche aegyptiaca) is a devastating pest in the Mediterranean basin, parasitizing a wide host crop range, including tomato, sunflower, legumes, and carrot, resulting in severe crop losses. Twenty years of research have led to the development of integrated smart management strategies for combating this parasite in processing tomato fields. In particular, an explicit decision support system (DSS) designated PICKIT has been developed; this DSS is based on predicting parasitism dynamics and employing a range of selective targeted chemical applications (preplanting incorporation, foliar application, and herbigation). In this feature article, we describe the evolution of this research from the laboratory, through greenhouse and experimental field trials, to large scale commercial fields and the successful assimilation of PICKIT into agricultural practice. The use of PICKIT in fields of processing tomatoes in northern Israel has led to effective control of Egyptian broomrape, even in fields with high infestation levels, resulting in a tomato yield increase of an average of 40 tons ha⁻¹ compared with nontreated plots. In 2016, PICKIT was commercially implemented in 33 fields, totaling 400 ha, giving 95% Egyptian broomrape control and tomato yields of 115 to 145 tons ha⁻¹. The outcome of this research is now enabling farmers to grow tomatoes in Egyptian broomrape-infested fields with assured increased yields and hence high profits.

Weed infestations in agricultural systems constitute a serious challenge to agricultural sustainability and food security worldwide. Amaranthus palmeri S. Watson (Palmer amaranth) is one of the most noxious weeds causing significant yield reductions in various crops. The ability to estimate seed viability and herbicide susceptibility is a key factor in the development of a long-term management strategy, particularly since the misuse of herbicides is driving the evolution of herbicide response in various weed species. The limitations of most herbicide response studies are that they are conducted retrospectively and that they use in vitro destructive methods. Development of a non-destructive method for the prediction of herbicide response could vastly improve the efficacy of herbicide applications and potentially delay the evolution of herbicide resistance. Here, we propose a toolbox based on hyperspectral technologies and data analyses aimed to predict A. palmeri seed germination and response to the herbicide trifloxysulfuron-methyl. Complementary measurement of leaf physiological parameters, namely, photosynthetic rate, stomatal conductence and photosystem II (PSII) efficiency, was performed to support the spectral analysis. Plant response to the herbicide was compared to image analysis estimates using mean gray value (MGV) and area fraction (AF) variables. Hyperspectral reflectance profiles were used to determine seed germination and to classify herbicide response through examination of plant leaves. Using hyperspectral data, we have successfully distinguished between germinating and non-germinating seeds, hyperspectral classification of seeds showed accuracy of 81.9% and 76.4%, respectively. Sensitive and resistant plants were identified with high degrees of accuracy (88.5% and 90.9%, respectively) from leaf hyperspectral reflectance profiles acquired prior to herbicide application. A correlation between leaf physiological parameters and herbicide response (sensitivity/resistance) was also demonstrated. We demonstrated that hyperspectral reflectance analyses can provide reliable information about seed germination and levels of susceptibility in A. palmeri. The use of reflectance-based analyses can help to better understand the invasiveness of A. palmeri, and thus facilitate the development of targeted control methods. It also has enormous potential for impacting environmental management in that it can be used to prevent ineffective herbicide applications. It also has potential for use in mapping tempo-spatial population dynamics in agro-ecological landscapes.

Infestations with sunflower broomrape (Orobanche cumana Wallr.), an obligatory root parasite, constitute a major limitation to sunflower production in many regions around the world. Breeding for resistance is the most effective approach to reduce sunflower broomrape infestation, yet resistance mechanisms are often broken by new races of the pathogen. Elucidating the mechanisms controlling resistance to broomrape at the molecular level is, thus, a desirable way to obtain long-lasting resistance. In this study, we investigated broomrape resistance in a confectionery sunflower cultivar with a robust and long-lasting resistance to sunflower broomrape. Visual screening and histological examination of sunflower roots revealed that penetration of the broomrape haustorium into the sunflower roots was blocked at the cortex, indicating a pre-haustorial mechanism of resistance. A comparative RNA sequencing between broomrape-resistant and -susceptible accessions allowed the identification of genes that were significantly differentially expressed upon broomrape infestation. Among these genes were β-1,3-endoglucanase, β-glucanase, and ethylene-responsive transcription factor 4 (ERF4). These genes were previously reported to be pathogenesis-related in other plant species. This transcriptomic investigation, together with the histological examinations, led us to conclude that the resistance mechanism involves the identification of the broomrape and the consequent formation of a physical barrier that prevents the establishment of the broomrape into the sunflower roots.

Understanding the spectral characteristics of crops in response to stress caused by weeds is a basic step in improving the precision of agricultural technologies that manage weeds in the field. This research focused on the competition between corn (Zea mays) and redroot pigweed (Amaranthus retroflexus), a common weed that strongly reduces corn yield. The aim of this research was to characterize the physiological changes that occur in corn during early growth because of crop–weed competition and to examine the ability to detect the effect of competition through hyperspectral measurements. A greenhouse experiment was conducted, and corn plants were examined during early growth, with and without weed competition. Hyperspectral measurements were combined with physiological measurements to examine the reflectance and photosynthetic activity of corn. Changes were expected to appear mainly in the short-wave infrared region (SWIR) due to competition for water. Relative water content (RWC), chlorophyll content, photosynthetic rate, and stomatal conductance were reduced in the presence of weeds, and intercellular CO₂ levels increased. Deeper SWIR light absorption occurred in the weed treatment as expected, accompanied by spectral changes in the visible (VIS) and near infrared (NIR) ranges. The results highlight the potential of using spectral measurements as an indicator of competition for water.

• Aims To develop an in-situ, non-destructive method for observation and monitoring of the underground developmental stages of the root parasite Orobanche cumana. • Scope The parasitic weed Orobanche causes severe damage to vegetables and field crops. Most of the damage caused to the crops occurs during the underground, unobservable parasitism stage. Sunflower (Helianthus annuus ‘Adi’) plants were planted in soil that was artificially inoculated with O. cumana seeds. Clear Plexiglas mini-rhizotron plastic observation tubes were inserted into the soil. Seed germination, early stage of penetration, and formation of tubercles and spikes were observed non-destructively and were monitored throughout the growing season by mean of a mini-rhizotron camera. Use of this technology enabled the complete individual parasite life cycle from the very early development (including germination) to Orobanche shoot to be monitored. In addition, the effect of the systemic herbicide Cadre (imazapic) on the development of O. cumana was inspected and quantified. • Conclusions This novel methodology facilitates the in-situ study of major aspects of the host–parasite interaction and of parasite suppression, such as parasitism dynamics, parasite growth rate, and the effect of chemical treatments on the parasite.