Phacelia tanacetifolia, an excellent cover, green manure and honey crop is now widely cultivated throughout the world. One of its principal European seed production regions is north-western Hungary, where the recent withdrawal of a potent herbicide, linuron, created a new challenge for many growers. The goal of this study is to identify the main factors determining weed species composition in the phacelia fields of the region and to assess the efficiency of tine harrow and clopyralid herbicide in reducing weed abundance and biomass. We carried out a series of weed surveys across the study region following a two-level design: (i) we estimated the cover of all weed species in 205 fields (broad-scale survey, BS); and (ii) in 22 of these fields, we provided more precise biomass measurements (counting the individuals and measuring the dry weights of all weed species) in microplots samples (fine-scale survey; FS). To characterize the fields, 34 background variables were also collected for all of the studied fields. In both investigations, Chenopodium album was by far the most abundant weed. Within the BS, using a minimal adequate model containing 11 terms with significant net effects, 20.93% of the total variation in weed species data could be explained. The variation in species composition was determined by environmental factors (soil pH, clay and K; precipitation and temperature), non-chemical management variables (crop cover, preceding crop, irrigation and tillage system) and herbicides (linuron and clopyralid). Variation partitioning demonstrated the dominance of environmental and cultural components in shaping the weed species composition. Although the effect of mechanical treatments was most likely masked in the BS by the soil properties, our FS suggests that tine harrow could efficiently decrease the total number and biomass of weeds and can be a useful tool in the phacelia management of the future.

Stachys annua (L.) L., a melliferous archaeophyte plant became a dominant weed of the cereal stubbles of the Carpathian Basin in the medieval three-field system. By the middle of the nineteenth century, this plant provided more than two-thirds of the Hungarian honey production, and its high quality monofloral honey turned into a characteristic brand of the Hungarian apiculture. Recognizing its importance, S. annua also briefly became a minor crop cultivated in “bee gardens” and arable fields in the late nineteenth century, possibly also in response to the first signs of its upcoming decline. Starting with the advent of the steam plough, the twentieth century has brought a drastic decline for S. annua due to a combination of deeper and earlier tillage operations, agrochemicals, and new competing weed species (in particular the common ragweed, Ambrosia artemisiifolia). The last remnant stands of this previously dominant weed species are of considerable ecological and historical value as farmland biodiversity hotspots. These sites are important refuge for rare weeds, wild pollinators (including bumblebees), and declining farmland birds, which could be targeted by eco-schemes under the European Union’s (EU’s) greening Common Agricultural Policy. The rediscovery of the cropping potential of S. annua and the development of an appropriate technology would also allow its cultivation as a valuable bee forage, catch crop, green cover, or oilseed plant in the future.

Az Észak-Amerikában honos közönséges mézontófüvet vagy facéliát (Phacelia tanacetifolia Benth.) a XIX. század vége óta termesztik a Kárpát-medencében. Elsőként kerti dísznövényként vetették, de ezzel egyidejűleg a benne rejlő méhészeti potenciált is felismerték. A “magyar méhészet jövőjének megmentőjét” látták a növényben, de a 2. világháborút követő időszakban, a nagybirtokrendszer széthullásával méhlegelőként csak lokálisan, kisüzemi keretek között vetették. A XX. század eleje óta számos kísérletben tanulmányozták takarmányozási felhasználhatóságát, és bár kezdetben ellentmondásos következtetésekre jutottak, az 1970-es évektől értékes takarmányként tartják nyilván. Szintén, több mint száz év alatt, nagyszámú kísérletben igazolták, hogy kiváló zöldtrágyanövény és főként a fonálférgekkel szemben talajfertőtlenítő hatással is rendelkezik. Az 1970-es évek vége óta a Kisalföldön fellendült a növény exportorientált vetőmagtermesztése, nagy- és kisüzemi keretek között egyaránt. Ez a tevékenység szorosan összekapcsolódott a vándorméhészettel, miáltal a növény napjainkra a legfontosabb mézelő növényeink közé lépett elő. Hazai termőterülete az elmúlt két évtizedben 1600 és 11000 ha között ingadozott.