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

Physical weed control in urban hard surfaces and turfgrasses.

Weed management is a major issue not only in agriculture but also in cities and in public and sport turfs. Weed development often generates negative aesthetic effects, a sense sloppiness, mechanical damages to hard surfaces, the reduction of visibility for drivers, the reduction of the quality of the quality of the turf, and can make difficult for pedestrians to walk. Specific trials were carried out in order to develop and set up machines and techniques for weed control in urban and sub-urban areas and on turfs

Development of machines for flaming weed control on hard surfaces

Weed control is a major issue not only in agriculture but also on hard surfaces in urban and suburban contexts. Weeds can cause serious damage to urban structures and are often considered as a sign of neglect. Moreover, citizens are becoming increasingly aware of environmental pollution and its potential risks for their health. Flaming represents a concrete alternative to herbicide applications on hard urban surfaces. Flaming can also be a good alternative to mechanical means (e.g., string trimmers) which can seriously damage surfaces because they are too intense and in any case are often not effective. The aim of this work is to describe LPG fed flaming machines designed and built at the University of Pisa, Italy. Liquefied Petroleum Gas (LPG) is a flammable mixture of hydrocarbon gases– propane and butane. Four different machines were developed and tested in four different urban and sub-urban contexts. A small backpack flamer equipped with a manual lance was tested on a stonewall, a trolley machine with a manual lance was used to clean the base of ornamental trees, a self-propelled machine was tested in a railway station, and a mounted machine was used in a suburban cycle way. Flaming was compared to the ordinary weed control systems such as using herbicides or mowing. The results showed that flaming can be both less expensive and more effective (on average less that 1 € m-2 year-1 maintaining weed cover below 5% to 6%) than the ordinary treatments in urban areas. Flaming was more effective than mowing in the suburban area but much more expensive, thus an integrated approach would be advisable in this context. Future research should be devoted to improving the efficiency of the treatment, using for example, new burners with secondary air and precision agriculture technologies

Application of precision flaming to maize and garlic in the RHEA Project.

Flame weeding is actually a well known and used physical treatment according to the increase in concerns about the effects of herbicides on human health and the environment and in the light of the new European laws. Flaming historically, was used at first as a pre-emergence treatment, both prior to planting and before crop emergence. Alternatively, flaming can be used also selectively after crop emergence or planting in tolerant species. Although inter-row weeds can be effectively controlled through mechanical cultivation, weeds that grow in the row are more difficult to control as, in some cases, cultivation is both ineffective and causes unacceptable levels of crop damage. This work aims to describe the specific machine for mechanical-thermal weed control which is being realized by the University of Pisa within the RHEA project. This machine is able to perform mechanical and thermal treatments at the same time in order to remove weeds mechanically from the inter-row space and perform in-row selective and precision flaming. The project is still on-going and the machine has not been fully realized and tested yet, thus no data is available at the moment

LPG burners for weed control

This article reports on the results of a study carried out on three prototypes of open flame burners for thermal weed control. Their performance is reported in terms of flame temperature and length, in order to ascertain the best ratio between primary and secondary air, and liquefied petroleum gas (LPG) consumption. To find the best ratio between primary and secondary air, the length and temperature of the flame were recorded for each of the three burners, examined by varying the inlet sections of the primary air and secondary air. The data on temperature and the flame length of each burner were processed using multiple regression analysis. The LPG consumption was determined with one of the burners using 10 different pressures in combination with three nozzles. The data obtained were subjected to non-linear regression using two gaseous outflow models. The various combinations of primary and secondary air inlet sections affected the values of the flame length and temperature. In general, the best combinations of primary and secondary air inlet for flame temperature did not correspond to those for flame length. However, this experiment showed that the inlet of secondary air is critical for the performance of this type of burner, in terms of flame temperature. The fuel consumption trial showed that the model proposed for the gaseous outflow is suitable for describing the values of LPG consumption collected during the trial. © 2015 American Society of Agricultural and Biological Engineers

Cross-flaming application for intra-row weed control in maize

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 (Zea mays 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

An automatic machine able to perform variable rate application of flame weeding: design and assembly

This paper describes the design and development of an automatic machine able to perform Variable Rate Application of cross flaming in maize fields. The VRA flaming machine was designed to remove weeds mechanically from the inter-row area and perform selective and targeted cross flaming along the crop rows. The mechanical treatment will be performed in a continuous way, even without weed presence. On the contrary, cross flaming on the maize rows is applied selective and automatically only if weeds are presence. Flame weeding is applied by means of prismatic burners fed by Liquefied Petroleum Gas, able to treat 25 cm wide strips of soil surface including crop rows. Flaming can be used selectively in maize, which can tolerate the heat released from the burners. Mechanism of morphological tolerance is the presence of many layers of the outer leaf tissue protecting the inner growing point. A low or a high LPG dose can be chosen automatically according to the weed cover percentage detected by a weed detection system. The ignition system of the VRA flaming machine is almost instantaneous and the complete flame in the burner is obtained in 0.4 s. The machine is provided with an automatic steering system in order to avoid damaging the maize plants with the rigid tools used for mechanical weed removal. The VRA flaming machine is a new technology for precision agriculture and was designed and built within the “Robot fleets for Highly Effective Agriculture and forestry management” (RHEA) Project, funded by EU, aimed to develop a fleet of heterogeneous autonomous robot units in order to perform site-specific treatments related to crop protection in different agricultural scenarios

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

Thermal weed control on horizontal and vertical surfaces in archaeological sites as an alternative to herbicides

Flaming could be an alternative weed management at archaeological sites because it controls a wide range of weed species without inducting future resistance. The aim of this study was to test the weed control efficiency of flaming on various horizontal and vertical surfaces of archaeological buildings. Working times and costs were recorded. Flaming performances were compared to the normal herbicide treatments and mowing. Results showed that repeated flaming reduced weed cover by 100%. Working times and total costs decreased by increasing the number of applications over time. This is because the repeated flaming applications deplete the weed root stocks, thus keeping the mortar between the stones or bricks and the building materials free from weeds and their seeds for a long time. The method involved zero toxicity for humans and animals, thus providing safe accessibility to the archaeological buildings and visitor pathways. The application of flaming did not cause any damage or change of colour to the treated materials, although specific, multidisciplinary studies on this subject will have to be conducted in the next future, in order to exclude any negative effect on the remains. The results of these studies showed that flaming is a viable alternative for controlling weeds growing on archaeological surfaces

Thermal weed control in Photinia x Fraseri “Red Robin” container nurseries

A near-zero tolerance policy on weeds by markets for nursery crops calls for weed-free container-grown plants, and forces growers to frequently remove weeds. Thermal weed control could represent a novel method to control weeds in shrubs from container nurseries, thus avoiding the use of herbicides and mulches. The aims of this study were to develop custom-built machinery for thermal weed control in container nurseries and to test the weed control efficiency of flame weeding and steaming in Photinia x fraseri "Red Robin" containers. A liquefied petroleum gas (LPG) fed flamer and a steamer with a dedicated diffuser were built. Four treatments were applied for a total period of 24 months: steaming once every four months, steaming once every two months, flame weeding once every two months or once a month. Temperature values measured at different depths in the substrate after thermal applications were recorded and analyzed. Photinia x fraseri features (height, diameter, and dry biomass) and aesthetic parameters as affected by thermal treatments were also evaluated. The trend in temperature values of the substrate over time followed a two-phase exponential decay. All the thermal treatments lead to a continuous near-100% weed control level, which is the level required by growers for aesthetic reasons. No damages caused by heat on Photinia x fraseri were observed. Container nursery producers could thus adopt thermal methods as a substitute for chemical solutions for weed control management