Effects of Flame Weeding on Organic Garlic Production

A lack of efficient machines and strategies for cropping practices are still problems on small farms and in difficult landscapes, especially in organic crop production. The aim of this study was to develop a new weed control strategy for a typical organic garlic (Allium sativum) grown in Liguria, Italy. Flaming was proposed as an additional tool for the physical weed control program. A field experiment was conducted to test the effects of different flaming doses and timing on weed control and garlic production. The treatments consisted of a broadcast flaming at 16, 22, 37, and 112 kg·ha−1 of liquefied petroleum gas (LPG) at three different crop growth stages—emergence (BBCH 9), three to four leaves (BBCH 13) and six to seven leaves (BBCH 16)—once (at each growth stage separately), twice (at BBCH 9 and BBCH 13, BBCH 9 and BBCH 16, and BBCH 13 and BBCH 16 stages) or three times (all stages combined). Treatments were compared with a weedy control and hand weeding. One flaming treatment was effective in controlling weeds during the growing season. Frequent flaming treatments did not further reduce the weed biomass measured at harvest. A higher production than the weedy control, in terms of the number of marketable bulbs and yield, was obtained for all the flaming interventions carried out at more than 16-kg·ha−1 LPG dose. Garlic flamed once at BBCH 13 at any LPG dose or three times at more than 16 kg·ha−1 led to a comparable number of bulbs as hand weeding. Three flamings at an LPG dose of 22 kg·ha−1 also gave a statistically similar yield to hand weeding. In general, garlic was shown to tolerate up to three flaming treatments without a decline in the production. The decline in yield compared with hand weeding could be offset by the economical savings of the mechanization process and by integrating flaming with other mechanical tools used for weed management.

Weed Management in Autumn Fresh Market Spinach: A Nonchemical Alternative

Physical rather than chemical treatments are preferred for integrated production and are required for organic production to ensure a sustainable production. Weed management in many horticultural crops is heavily constrained by the limited number of herbicides available. Physical weed control strategies, on the other hand, are essential to organic vegetable production and greatly assist conventional vegetable farmers. A physical weed control strategy was developed and compared with a standard chemical strategy within an integrated farming system in fresh market spinach (Spinacia oleracea). The experiment was conducted on a farm in the Serchio Valley (Tuscany, central Italy) in 2004 and 2005, where spinach is one of the most important crops. The physical weed control strategy consisted of a stale seedbed technique and postemergence treatments using various mechanical and thermal machines. The chemical weed control strategy consisted of a single postemergence herbicide treatment using phenmedipham at 15.8% in compliance with integrated production norms in Italy. Strategy performance was assessed in terms of weed density and biomass, total labor requirement, and crop yield. Compared with the chemical system, the physical system required a substantially larger labor input (19 vs. 6 h·ha−1), but like the chemical system, did not require hand weeding. In addition, the physical system reduced weed dry biomass at harvest by 50% and increased spinach fresh yield by 35%. Physical strategies therefore are a valid alternative to the use of herbicides in fresh market spinach and may be especially desirable given the increasing importance of nonchemical weed control in integrated, organic, and conventional farming systems in Europe and the United States.

Effective mechanical weed control in processing tomato: Seven years of results

Open-air crops are important in Spanish horticulture. The limited number of herbicide active ingredients in minor crops, the waste problem of polyethylene (PE) plastic mulch and the high prices of biodegradable plastics leave hand-weeding and mechanical weed control as the most viable weed control methods. Different tools have been tested in northern European countries but their performance remains unknown in the edaphoclimatic situation of southern Europe. The objective of this work was to test novel physical weed control methods on processing tomato in northeastern Spain compared with other effective control methods, i.e., plastic and paper mulches. A first sequence of field trials was established from 2005 to 2008 at Zaragoza (Spain) to select the best physical control methods out of flamer, torsion weeder, finger weeder, flex-tine harrow and brush hoe used alone or in combination. The best method was the brush hoe which was then compared from 2009 to 2011 with PE mulch, biodegradable plastic mulch and paper mulch. Flamer, flex-tine harrow, torsion weeder and finger weeder performed quite irregularly due to crusty soil conditions and needed additional tools or repeated treatments to increase weed control efficacy. The brush hoe performed best in this soil situation working at about 5 cm depth. Weed biomass reduction was higher than 80% in 6 out of 7 years and similar yield was obtained in the brushed plots compared to the yield obtained with PE, biodegradable plastic and paper mulch. The brush hoe is thus a suitable option for weed control in processing tomato while the other tools were too weak to control aggressive summer weeds in the tested conditions.

Physical weed control in processing tomatoes in Central Italy

Tomato is a very important vegetable crop in Italy. Improving the means of production for processing organic tomatoes could help guarantee better profits for farmers and, at the same time, enhance environmental management and safeguard consumers’ health. Weed control, in particular within crop rows, is one of the main problems in organic farming, and thus also for the organic cultivation of tomato. The aim of this study was to develop innovative strategies and equipment for effective physical weed control in processing tomatoes. A conventional weed management system incorporating herbicides was compared with an alternative system relying exclusively on physical control during three growing seasons (2006–2008) on a farm located near Pisa, Italy. The crop was transplanted mechanically onto paired rows. The conventional strategy consisted of three different chemical treatments, two post-transplanting PTO-powered rotary hoe passes and several hand-weeding treatments on the paired rows. The alternative system included a stale seedbed technique (performed by a rolling harrow pass and one flaming treatment), two post-transplanting precision hoeing treatments and several hand-weeding treatments. All the machines for the alternative system were adjusted and set up for processing tomatoes transplanted in paired rows. Each physical treatment (mechanical and thermal) within the alternative system allowed an ‘instantaneous’ (just before/just after) weed control from 50 to 100%, while the alternative strategy as a whole achieved values of weed dry biomass at harvest ranging from 22 to 126 g m−2. However, the alternative system required a total labor input that averaged 50% higher than the conventional strategy. The conventional system had on average more effective weed control than the alternative system, but both strategies controlled weeds effectively. Weed biomass at harvest averaged 36 and 68 g m−2 for conventional and alternative strategies, respectively. On the other hand, the alternative system generally led to a significant increase in fresh crop yield (+13% average yield for the 3 years).

Physical weed control in protected leaf-beet in central Italy

Leaf-beet is a typical and very important protected cultivation crop in central Italy. In leaf-beet protected cultivation, weed control is one of the most important problems because of its fairly long crop cycle (approximately 4–5 months). The aim of this research was to set up an efficient non chemical weed control strategy performed with innovative machines built and set up by the University of Pisa. A two-year (2006–2007) ‘on-farm’ experimental trial was carried out in Crespina (PI). A conventional weed management technique (consisting of one pre-transplanting chemical treatment) was compared with an innovative physical weed control strategy in an organic production system (consisting of using a stale seedbed technique, in several post-emergence precision hoeing and in-row hand-weeding treatments). In the conventional technique, leaf-beet was manually transplanted, while it was sown with a precision pneumatic planter in the organic system. All innovative machines for physical weed control were adjusted and set up for the protected cultivation. Similar yields were recorded for the two systems in this two-year trial. Total labor time (for weed management and crop planting) was appreciably lower in the conventional system in the first year of the experiment (−67%), while in the second year, some improvement in the physical weed control techniques decreased labor needs with respect to the conventional technique (−40%). Weed dry biomass at harvest was significantly lower in the organic cropping system (on average −50%).

Innovative strategies for on-farm weed management in organic carrot

Weed management is often the most troublesome technical problem to be solved in organic farming, especially in poorly competitive crops like vegetables. A four-year (2000–2003) series of trials was established to assess the possibility of adopting an innovative non-chemical weed management system in organic carrot grown on the Fucino plateau, i.e., the most important carrot-growing area in Italy. The system utilized for physical weed control was based first on a false seedbed technique followed by pre-sowing weed removal, performed with a special 2 m wide 6-row spring-tine harrow. Prior to crop emergence, a pass with a flame weeder equipped with four 50 cm wide-open flame burners was also performed. Post-emergence weed control consisted of one or more hoeing passes with a purpose-designed 11-tine precision hoe equipped with spring implements (torsion weeders and vibrating tines), in addition to hand weeding. This innovative system was applied to a novel planting pattern (sowing in ten individual rows within 2 m wide beds) and compared to the standard management system of the area (sowing within 2 m wide beds but in five bands, use of spring-tine harrowing and flame weeding pre-emergence and of traditional hoeing post-emergence). The new system was tested in different commercial farms including both early and late-sown carrot. Assessments included machine operative characteristics, labor time, weed density and biomass, crop root yield and yield quality, and economic data (physical weed control costs and crop gross margin). Compared to the standard system, the innovative system usually resulted in reduced labor time (from 28 to 40%) and total costs for physical weed control (on average −416 € ha−1). Use of the precision hoe resulted in intra-row weed reduction ranging from 65 to 90%, which also led to a marked reduction in the labor required for hand weeding. In 2001 the two systems did not differ in terms of yield and yield quality, whereas in 2002 and 2003 the innovative system showed a higher mean density of carrot plants (from 28 to 55%), root yield (from 30 to 42%), and gross margin (from 40 to 100%). Carrot yield was higher in farms which adopted an early sowing whereas root commercial quality was somewhat variable between systems and years. In general, results obtained with the innovative management system look very promising.