Intra-row Weed Research Articles

Technology for Automation of Weed Control in Specialty Crops

Specialty crops, like flowers, herbs, and vegetables, generally do not have an adequate spectrum of herbicide chemistries to control weeds and have been dependent on hand weeding to achieve commercially acceptable weed control. However, labor shortages have led to higher costs for hand weeding. There is a need to develop labor-saving technologies for weed control in specialty crops if production costs are to be contained. Machine vision technology, together with data processors, have been developed to enable commercial machines to recognize crop row patterns and control automated devices that perform tasks such as removal of intrarow weeds, as well as to thin crops to desired stands. The commercial machine vision systems depend upon a size difference between the crops and weeds and/or the regular crop row pattern to enable the system to recognize crop plants and control surrounding weeds. However, where weeds are large or the weed population is very dense, then current machine vision systems cannot effectively differentiate weeds from crops. Commercially available automated weeders and thinners today depend upon cultivators or directed sprayers to control weeds. Weed control actuators on future models may use abrasion with sand blown in an air stream or heating with flaming devices to kill weeds. Future weed control strategies will likely require adaptation of the crops to automated weed removal equipment. One example would be changes in crop row patterns and spacing to facilitate cultivation in two directions. Chemical company consolidation continues to reduce the number of companies searching for new herbicides; increasing costs to develop new herbicides and price competition from existing products suggest that the downward trend in new herbicide development will continue. In contrast, automated weed removal equipment continues to improve and become more effective.

Plant Growth Responses of Apple and Pear Trees to Doses of Glyphosate

ABSTRACT Glyphosate is commonly used for intra-row weed management in perennial plantations, where unintended crop exposure to this herbicide can cause growth reduction. The objective of this research was to analyze the initial plant growth behavior of young apple and pear plants exposed to glyphosate. Glyphosate was sprayed on 2-year-old 'Gala' apple and 'Abbè Fetel' pear plants at doses from 18 to 720 g per hectare of acid equivalent (a.e.). The plant height of neither species was not significantly reduced (less than 1%) by any glyphosate dose at 240 days after spraying, whereas the stem diameter and the dry mass of stem and leaves were reduced by 720 g a.e. ha-1. The glyphosate dose required to reduce the aboveground dry mass by 50% was 162 and 148 g a.e. ha-1 for apple and pear, respectively. Aboveground dry mass was reduced 2% and 6% for apple and pear plants, respectively, at 720 g a.e. ha-1. Hormesis was not observed in either species at doses down to 18 g a.e. ha-1. Both species showed low susceptibility to glyphosate; however apple was less susceptible than pear.

Cross-Flaming Application for Intra-Row Weed Control in Maize

Abstract. Flame weeding is the most common thermal intra-row weed control method used in agriculture as an alternative to herbicides in heat-tolerant crops. Within the seventh framework program project “Robot fleets for Highly Effective Agriculture and Forestry Management” (RHEA), the University of Pisa was responsible for the development of an automatic machine for intra-row cross-flaming in maize ( L.). This study focused on the selection of a range of liquid petroleum gas (LPG) doses able to control weeds without affecting crop yields, for the basic calibration of the machine. Tests were conducted in 2012 and 2013 during the growing cycle of maize both in weed-free and real-field weedy conditions. Five biological LPG doses (0, 52, 65, 104, and 130 kg ha-1) were applied at different maize growth stages once (2- and 5-leaf) and twice (2-leaf the first time and 16 days after the first time). The response of maize and weeds to cross-flaming was evaluated in terms of grain yield, weed density after flame weeding, and weed dry biomass at harvest. Log-logistic models were used to describe the responses of different growth stages of maize and weeds to single and repeated applications of LPG doses. Overall response of maize yield to flame weeding was influenced by LPG dose, number of flame weedings, maize growth stage, and presence of weeds. The results of this study indicate that two cross-flaming treatments applied separately with an LPG dose ranging from 36 to 42 kg ha-1 can provide an acceptable level of weed control in maize, enough to ensure economically acceptable yields.

Intrarow Weed Removal in Broccoli and Transplanted Lettuce with an Intelligent Cultivator

The performance of the Robovator (F. Poulsen Engineering ApS, Hvals⊘, Denmark), a commercial robotic intrarow cultivator, was evaluated in direct-seeded broccoli and transplanted lettuce during 2014 and 2015 in Salinas, CA, and Yuma, AZ. The main objective was to evaluate the crop stand after cultivation, crop yield, and weed control efficacy of the Robovator compared with a standard cultivator. A second objective was to compare hand weeding time after cultivation within a complete integrated weed management (IWM) system. Herbicides were included as a component of the IWM system. The Robovator did not reduce crop stand or marketable yield compared with the standard cultivator. The Robovator removed 18 to 41% more weeds at moderate to high weed densities and reduced hand-weeding times by 20 to 45% compared with the standard cultivator. At low weed densities there was little difference between the cultivators in terms of weed control and hand-weeding times. The lower-hand weeding time with the Robovator treatments suggest that robotic intrarow cultivators can reduce dependency on hand weeding compared with standard cultivators. Technological advancements and price reductions of these types of machines will likely improve their weed removal efficacy and the long-term viability of IWM programs that will use them.

Mechanical weed control on small-size dry bean and its response to cross-flaming

Dry bean (Phaseolus vulgaris L.) can be a profitable crop for farmers; however controlling weeds effectively without a decrease in yield remains a problem. An example where mechanical weed control is difficult to conduct is dry bean ‘Toscanello’, which is a small sized high-income niche product growing low to the ground. Concerning intra-row weed control, also flame weeding could be an opportunity but the dry bean heat tolerance needs to be studied. The aims of this research were to study the weed control efficacy of a spring-tine harrow and an inter-row cultivator in this bean variety, and to test the tolerance of dry bean cultivated under weed-free conditions to cross-flaming applied with different liquefied petroleum gas (LPG) doses. Flame weeding was applied at BBCH 13 and BBCH 14 bean growth stages by pairs of burners producing direct double flame acting into the intra-row space, with bean plants placed in the middle. The results suggest that the spring-tine harrow used two times at BBCH 13 and 14, respectively, lead to a yield similar to that of the weedy control. The inter-row cultivator could be an opportunity for small-sized dry bean crops producers, enabling them to obtain a similar yield compared to the hand-weeded control. Concerning the bean tolerance to cross-flaming the results showed that bean flamed at BBCH 13 stage had little tolerance to cross-flaming. Bean flamed at BBCH 14 stage was tolerant until an LPG dose of 39 kg/ha, giving yield responses similar to those observed in the non-flamed control.

GROWTH AND YIELD RESPONSE OF MAIZE (Zea mays) TO INTER AND INTRA-ROW WEED COMPETITION UNDER DIFFERENT FERTILIZER APPLICATION METHODS

A field experiment was conducted for two consecutive years to study the effect of fertilizer application methods and inter and intra-row weed-crop competition durations on density and biomass of different weeds and growth, grain yield and yield components of maize. The experimental treatments comprised of two fertilizer application methods (side placement and below seed placement) and inter and intra-row weed-crop competition durations each for 15, 30, 45, and 60 days after emergence, as well as through the crop growing period. Fertilizer application method didn't affect weed density, biomass, and grain yield of maize. Below seed fertilizer placement generally resulted in less mean weed dry weight and more crop leaf area index, growth rate, grain weight per cob and 1000 grain weight. Minimum number of weeds and dry weight were recorded in inter-row or intra-row weed-crop competition for 15 DAE. Number of cobs per plant, grain weight per cob, 1000 grain weight and grain yield decreased with an increase in both inter-row and intra-row weed-crop competition durations. Maximum mean grain yield of 6.35 and 6.33 tha-1 were recorded in inter-row and intra-row weed competition for 15 DAE, respectively.

Robotic intra-row weed hoeing in maize and sugar beet

A prototype of robotic intra-row weed hoeing in maize and sugar beet is presented in this study. Weeds in the crop rows were identified using a bi-spectral image analysis system and shape analysis. Positions of weeds in the images were recorded. Selective weed control in the row was performed with a modified finger weeder driven by electrical motors. Speed of the finger weeder was increased at positions where only weeds were classified. The system was triggered by an encoder and controlled by a micro-controller. Roboter-gesteuerte Unkrauthacke in der Reihe von Mais und Zuckerruben Ein Prototyp einer roboter-gesteuerten Hacke zur Unkrautbekampfung in den Reihen von Mais und Zuckerrube wird in dieser Studie vorgestellt. Unkrauter und Kulturpflanzen wurden mit einer bi-spektralen Kamera und Formenanalyse erkannt. Die Positionen der Unkrauter im Bild wurden bestimmt. Die selektive Unkrautbekampfung in der Reihe geschah mit einer modifizierten Fingerhacke, die uber Elektromotoren angetrieben werden. Die Fingerhacke wurde beschleunigt, wenn nur Unkrauter in der Reihe klassifiziert wurden. Das System wurde mit einem Inkrementalgeber getriggert und uber einen Micro-Controller gesteuert.

Design and Evaluation of a Levelling System for a Weeding Robot

Abstract: Weed control is a critically important task in organic crop farming. Even though there are machines available for inter-row weeding, manual weeding is still the only choice for weed control in organic farms, especially in the narrow spaces between crop plants (intra-row weeds). Such an operation is highly labor intensive and costly in organic vegetable production. Automatic or robotic weeding could provide a potential solution for addressing labor related issues. In intra-row weed control, weeding end-effectors need to be positioned accurately to remove weeds growing very close to the plant while the robotic vehicle is continuously moving on a generally uneven and uncertain field surface. This study was aimed at assessing the performance of an end-effector auto-levelling system designed to accurately control the position of the end-effector during weeding operations in vegetable crops. The performance assessment was conducted via a set of laboratory experiments using a specifically designed and fabricated proof-of-concept prototype. To achieve the desired level of performance in actual field conditions, the prototype system required maintaining the end-effector base at horizontal position within a ± 0.25o angular error when the testbed (laboratory prototype) roll and pitch angles were varied from -8o to 8o. The test results verified that the developed end-effector base levelling system could maintain the drift of the end-effector tip position within 18 mm when input roll or pitch angle reached 8o. Meanwhile, the corresponding position error caused by angular error of the levelling plate was limited in 0.2 mm when the levelling plate at a height of 10 cm, which means the levelling system can efficiently reduce the effect of the rough field. The regularity of the end-effector tip position drift can also help us with end-effector control.

Innovative Strategies and Machines for Physical Weed Control in Organic and Integrated Vegetable Crops

Weed control is one of the most serious problems in vegetable crops, limiting cultivated plants correct development, yields, product quality and farmers income. Therefore, the aim of this work was to set up and improve innovative strategies and machines for physical (mechanical and thermal) weed control in organic or “integrated” vegetables production in many important areas of Northern, Central and Southern Italy. Therefore, on-farm experiments were carried out since 1999 on fresh marketable spinach, processing and fresh market tomato, cauliflower, savoy cabbage, greenhouse cultivated leaf beet, garlic, chicory, fennel and carrot. These research activities started are still ongoing. The traditional farm weed management system was always compared to one or more innovative strategies that were defined according to the characteristics of the environment (i.e. soil type and conditions, water availability, etc.), typology of cultivation, crop rotation, expected technical and economical results. The innovative strategies were the combination among preventive methods (false or stale seed-bed technique), cultural methods (i.e. crop spatial arrangement that was often adjusted in order to improve operative machines effectiveness) and direct control methods (flaming, precision hoeing, etc.). Different kinds of specific implement such as flex tine and rolling harrows (patented by the University of Pisa, patent n. PI/2004/A/000071), and flamers (designed and realized by the University of Pisa) were used to perform false or stale seed-bed technique. Precision hoes equipped with rigid tools and hoeconformed rolling harrows, equipped with elastic tines for selective intra-row weed control, were used to perform post emergence interventions. The use of the innovative weed management systems always resulted in significant weed abundance reductions (from 70 to 100 %), relevant yield increases, high contractions of manpower requirement (from 20 to 80 %) and consequent relevant reductions of costs and increases of farmers gross incomes (from 15 to 75 %) in comparison with those obtained performing the standard systems. The results of these on-farm experiments emphasise that physical weed control can be effectively performed using the innovative machines designed and built at the University of Pisa. These machines can also be easily adjusted in order to be used in other crops and agricultural contexts. Moreover, the present versions of the machines, realized as “low-tech” implement in order to be available on the market at low costs, were recently modified within the RHEA Project, a 7th Framework Programme EU funded research project, in which an automatic and robotized hoeing-flaming machine able to perform VRA cross flaming was designed, fully realized and tested obtaining very promising results.

Intelligent versus non-intelligent mechanical intra-row weed control in transplanted onion and cabbage

Non-chemical weed control methods are increasingly in demand for conventional field vegetables, mainly accentuated by regulatory restrictions on the use of herbicides. Intelligent camera-based systems capable of guiding mechanical weeding devices so as to avoid injuring crop plants are now available for practise. The aim of the present study was to compare the weeding performance of an intelligent mechanical weeding machine with non-intelligent tools such as a weed harrow, finger and torsion weeders. Two experiments were conducted in transplanted onion and two in transplanted white cabbage, focussing on weed and crop effects. In broad terms, intelligent weeding was not superior to the simpler tools in onion, and only minor differences were found that could be attributed to the settings of the non-intelligent implements. It was only possible to estimate the effects on weeds in the one cabbage experiment with intelligent weeding, which showed no noteworthy differences between the intelligent tool and the simpler ones. Finally, a competition study was conducted on the importance of untreated weeds in close proximity to the transplant as a result of intelligent weeding. It showed that intelligent weeding capable of cultivating the soil close to cabbage plants can provide satisfactory weed control without any need for subsequent manual weeding.

The Research Progress of Intra-Row Mechanical Weeding Technology of Dry-Land

The farmland weeds directly affect the crops yields, and the intra-row weeds are more difficult to eliminate than inter-row weeds. With the harm of chemical weeding technology cognition by people, the growth of awareness of environmental protection consciousness and food safety, the non-chemical weeding technology get more and more attention. Mechanical weeding as a good alternative method get more attention, and the intra-row intelligent mechanical weeding technology becomes a hot spot of research. The research on intra-row intelligent mechanical weeding technology of China have a large gap compared with developed countries. In this work, the current research of intra-row mechanical weeding technology of developed countries and China was reviewed, and the development trend of intra-row intelligent mechanical weeding technology of China were prospected. The universities and research institutes should be encouraged to learn from foreign advanced technology and the design concept of intelligent weeding equipment, increase the investment in intelligent mechanical weeding technology research and promotion.

Co-robotic intra-row weed control system

The automation of intra-row weed control in row crop production systems is very challenging. This work describes the development and in-field assessment of an automatic intra-row, hoe-based weeding co-robot system with real-time pneumatic hoe actuation based on an accurate odometry sensing technique. The US National Science Foundation has identified a need for robots (called co-robots) that serve as co-workers and work beside, or cooperatively with, people. These co-robots have a symbiotic relationship with a human partner, where, as a team, they combine their relative strengths to jointly perform a task. Such co-robots should be relatively inexpensive and easy to use. In this work, mechanical weed control was achieved by a co-robot actuator that automatically positioned a pair of miniature hoes into the intra-row zone between crop plants. The design was tested in a precision transplanted row crop and may also be suitable for direct seeded row crops. Co-robot cost was minimised by limiting the system to a single, simple odometry sensor. Co-robot hoe actuation was controlled using pre-programmed knowledge of the crop planting pattern and real-time odometry data as the control input for hoe positioning. Low-frequency drift in the odometry control points relative to the actual plant locations was corrected occasionally as needed in real-time by a human partner monitoring system performance. The co-robot was evaluated in an experimental trial conducted on the UC Davis campus farm. Assessment was based upon the follow-up hand hoeing required after automated intra-row weeding in comparison to the labour required to manually hoe a control plot. The mean person hours required for hand hoeing weeds in the control were 0.241 h for the 100 m2 plot, while only 0.102 h 100 m−2 were required in follow-up labour to complete the weed removal in the plots weeded by the co-robot. This represents a 57.5% reduction in hand labour requirements for intra-row weed control and indicates that the co-robot could help reduce traditional hand hoeing labour requirements with mechanised weed control in intra-row areas between the crop plants.

DEVELOPMENT AND EVALUATION OF SMALL-SCALE POWER WEEDER

Small-scale power weeders are an important and challenging task in many countries, where the farm size in hectare per capita is very low and is declining over time. Therefore, the development of suitable mechanized weeding methods is an imperative to meet the demand for farmers. An economical mechanical power weeder that can be used as inter and intra-row weeding method was developed and evaluated in triple hybrid 314 variety of maize. Developed power weeder consisted of engine, blades assembly and transmission system. Modified vertical blades were used with the weeder and mounted on a circular rotating element on its horizontal side; the motion was transferred to blades units by amended transmission system. The effect of weeder forward speeds, depth of operation, number of blades and soil moisture content on fuel consumption, plant damage, weeding index, effective field capacity, field efficiency, energy required per unit area and total cost were studied. Three levels of soil moisture content (7.73, 12.28 and 16.18 %), two blades arrangements (two and four vertical blades for each unit), three weeder forward speeds (1.8, 2.1 and 2.4 km/h) and two depths of operation (from 0 to 20 and from 20 to 40 mm) have been chosen. The results showed that, the minimum value of fuel consumption was 0.546 l/h and recorded by using two blades with 1.8 km/h weeder forward speed at depth of operation ranged from 0-20 mm and soil moisture content 16.18 %. The highest field efficiency was 89.88% by using two blades with 1.8 km /h weeder forward speed at depth of operation ranged from 0 to 20 mm and soil moisture content 16.18%. The minimum value of effective field capacity was 0.198 fed/h by using four blades, weeder forward speed 1.8 km/h, soil moisture content 7.73% and under depth of operation ranged from 20-40 mm. The lower value of total cost was 55.09 L.E /fed and was obtained by using two blades with 2.4 km/h weeder forward speed at depth of operation ranged from 0-20 mm and soil moisture content 16.18 %.

Evaluation and Economics of a Rotating Cultivator in Bok Choy, Celery, Lettuce, and Radicchio

A commercial intrarow rotating cultivator was tested for weed removal and impact on hand-weeding times in bok choy, celery, lettuce, and radicchio. The rotating cultivator was tested as an automated crop thinner and weeder in direct-seeded bok choy and lettuce as an alternative to hand-thinning and -weeding. The rotating cultivator utilized machine-vision guidance to align a rotating disk with the crop plant to be saved and to remove weeds and undesired crop plants. The rotating cultivator was compared to a standard interrow cultivator, which could not remove weeds from the plant line. Main plots were cultivator type, rotating, or standard, and subplots were herbicides: pronamide for lettuce or prometryn for celery. Weed densities, hand-weeding times, crop stand, and yields were monitored. Economic analysis was performed on a subset of the data. The intrarow rotating cultivator was generally more effective than the standard interrow cultivator for reducing weed densities and hand-weeding times. However, the rotating cultivator reduced seeded lettuce stands by 22 to 28% when compared to hand-thinning and standard cultivation, resulting in lower yields and net returns. In transplanted celery, lettuce, and radicchio, the rotating cultivator removed more weeds than the standard cultivator, and reduced stands by just 6 to 9% when compared to the standard cultivator. In transplanted lettuce, the rotating cultivator was more precise and did less damage to the crop. Because transplanted crops were larger than the weeds, they were more easily differentiated using this technology. Net returns were therefore similar between the two cultivators. What is needed for celery and leafy vegetables is an effective intrarow weed removal system that reduces or eliminates the need for hand-weeding yet does not reduce yields. The rotating cultivator was developed for transplanted crops, where it performs adequately, but it cannot be recommended in the seeded crops evaluated.

Development of a mechatronic intra-row weeding system with rotational hoeing tools: Theoretical approach and simulation

Effective non-chemical weed control in the row planted crops and vegetables requires accurate cultivation of the inter-row, intra-row and close to crop area. This study presents a concept for cultivation of the intra-row and close to crop area. The weeding tool consists of an arm holder and three or more integrated arms, which are carriers of the end effectors. The hoeing tool rotates around a horizontal axis, which is positioned directly above the crop row and moves along it. The system is similar to the rotational crop thinning systems used in the past. Main differences compared with the thinning systems is the adjustment of the angular position of the arms in relation to the plane, perpendicular to the rotation axis and on-line tuning of the rotational speed depending on the travelling speed, detected distance between two adjacent plants and angular position of the weeding tool. Systems modularity allows application of various weeding strategies regarding the number of consecutive cultivation trajectories of the end effectors between adjacent plants. Trajectories number is affected by the in-row distance between the plants, used type of end effector and plants development stage.A virtual prototype of the weeding tool was used for testing the behaviour of the system for various weeding strategies, considering inter alia the problem of irregular distances between the adjacent plants. Weeding strategies with one, two and three consecutive trajectories between adjacent plants, with and without adjustment of the angular position were simulated and analysed. The size of the unaffected spaces around the crop plant was calculated. The results proved that an optimised adjustment of the arms angular position affects the size of the cultivated area between two adjacent plants and the unaffected space around the crop plant. Furthermore, advantages of the presented concept in terms of more flexible cultivation of the close to crop area were demonstrated. Based on the results of simulation, lower rate of plant injuring during the weeding can be expected, in comparison to the similar weeding tool concepts, without the possibility to adjust the angular position of the arms. In additional simulation set the behaviour of the system was observed while proportional (P-) control of the rotational speed and irregular in-row distances between plants were simulated. The results showed adequate adaptation and accurate positioning of the cultivated area between the adjacent plants, in spite of the irregularity of in-row distances.

Field sprayer for inter and intra-row weed control: performance and labor savings

Studies of new tools and methods for weed control have been motivated by increased consumer demand for organic produce, consumer and regulatory demands for a reduction in environmentally harmful herbicide use, and the decreased availability of farm workers willing to perform manual tasks, such as hand weeding. This study describes the performance of a new sprayer system for commercial production that integrates two herbicide applications in a single pass, selective herbicide (SH) application in narrow bands over the crop row, and a non-selective herbicide (NSH) application between crop rows. A real-time kinematic (RTK) global positioning system (GPS) was used for auto-guidance in seeding and spraying operations. Conventional broadcast SHs and experimental treatments were applied at a constant nominal speed of 5.5 km h-1 for comparison. Trials in commercial sugar beet fields demonstrated the following: (i) average hand-weeding time can be reduced by 53% (ii) the new sprayer system reduced SH use by 76%, and (iii) sugar beet density did not change significantly during treatment. These results demonstrate the feasibility of using the new RTK-GPS controller sprayer system for differential and efficient herbicide application in inter- and intra-row zones in row crop production.

Intra-row Weed Detection Method in Field Based on Texture and Color Feature

Intra-row Weed Detection Method in Field Based on Texture and Color Feature

Automated weed control in organic row crops using hyperspectral species identification and thermal micro-dosing

A hyperspectral imaging system was coupled to a precision, pulsed-jet, micro-dosing system to selectively deliver high-temperature, organic, food-grade oil for intra-row weed control in early growth tomatoes. The imaging system, based upon a multispectral Bayesian classifier, successfully discriminated the species of 95.9%, on average, of plant canopy for tomato, Solanum nigrum L. and Amaranthus retroflexus L. using canopy reflectance in the 384–810 nm range. Food-grade oil, heated to approximately 160 °C, was applied to weeds using a pressurized micro-dosing pulsed-jet. The target application rate was approximately 0.85 mg/cm2 in 10-ms-pulsed doses while traveling at a ground speed of 0.04 m/s. In an outdoor test, approximately 95.8% of S. nigrum and 93.8% of A. retroflexus were controlled 15 days post thermal treatment, while only 2.4% of the tomato plants received significant damage. Application coverage assessments of leaf surfaces immediately after the heated oil application found that tomato viability was retained if 50% or less of the leaf surface was inadvertently dosed, while 100% mortality was achieved for S. nigrum and A. retroflexus if more than 90% of their respective leaf surfaces were covered with heated oil.

Automated intelligent rotor tine cultivation and punch planting to improve the selectivity of mechanical intra‐row weed control

Rasmussen J, Griepentrog HW, Nielsen J & Henriksen CB (2012). Automated intelligent rotor tine cultivation and punch planting to improve the selectivity of mechanical intra‐row weed control. Weed Research52, 327–337.SummaryThere is much research on technical aspects related to sensor and mapping techniques, which enable so‐called intelligent cultivators to target the intra‐row spaces within crop rows. This study investigates (i) an expected advantage of an intelligent rotor tine cultivator (the cycloid hoe) in terms of crop‐weed selectivity and (ii) an expected synergistic effect between punch planting and post‐emergence weed harrowing, in terms of improved crop‐weed selectivity. Selectivity is defined as the relationship between weed density decline and associated crop density decline 1 week after cultivation. Punch planting is a sowing technique where holes are created in the ground with a minimum of soil disturbance, and seeds are inserted into them, without soil disturbance outside the holes. Two experiments were carried out with the cycloid hoe in organic sugar beet. The rotation tines were guided by RTK‐GPS relative to geo‐referenced sugar beets. Tines were moved into the row when there was enough space between crop plants to cultivate and kept outside when they were predicted to strike a crop plant. The selectivity of the cycloid hoe was tested against two machine variants without intelligent guidance: the rotor tine cultivator in a locked mode, where tines rotate within the crop row without taking crop plants into consideration, and an ordinary flex tine weed harrow. The experiments showed no differences between the three machine variants in terms of selectivity. Five experiments with punch planting in sugar beet and carrot crops showed no synergistic effects between plant establishment procedures and selectivity of post‐emergence weed harrowing. Even if punch planting and automated intelligent rotor tine cultivation were not combined, the results indicated that there was no reason to believe that a combination contributes significantly in mechanical intra‐row weed control in direct sown crops to the solution of the main problem of low selectivity, which still remains a major challenge. Future studies on precision intra‐row cultivation should focus on cutting implements, instead of tine implements that mainly work through soil burial.

Design and testing of an intra-row mechanical weeding machine for corn

As an alternative to chemical weed control, mechanical weed control between crop rows can be achieved using standard tools such as field cultivators. This paper addresses the related problem of achieving mechanical intra-row weed control in maize. The object was to non-specifically remove weed plants within the row by enabling dual tine carriers to engage the soil whilst circumventing the maize stalks. The maize stalks were distinguished from the weeds and maize leaves by utilising 1) the typical vertical quasi-cylindrical stalk of the maize plant, 2) the limited range of maize stalk diameters, and 3) by assuming constant plant spacing. To assess the performance of the machine, a video was taken during field plot experiments. This allowed determination of the number of plants that were “fatally damaged” after inadvertently being pushed over by the implement. This was assumed to cause the plant to die, or “minimally damaged” where the implement merely touched the plant, when the plant was assumed to survive. Experiments were carried out using three arrangements being 1) three rows without weeds, 2) three rows with broadleaf weeds (simulated by planting soybean) and 3) three rows with grassy weeds. The percentage of plants that were fatally damaged was 8.8%, 23.7%, and 23.7% in cases 1, 2, 3 respectively. In addition, the percentage of plants that were minimally damaged was 17.6%, 20%, and 25.9% in cases 1, 2,3 respectively.