Air-propelled agricultural residues kill weeds

Picture copyright Perez-Ruiz et al.

Crop production often results in abundant agricultural residues, and organic crop production suffers from an overabundance of weeds. Scientists Perez-Ruiz et al. recently showed that several gritty-textured residues, particularly those derived from maize cobs and olive pits, could abrade weed seedlings when propelled by air. Their use can contribute to the non-chemical control of weeds requested by organic farming and offers a potential solution to address herbicide-resistant weeds.

95% less herbicides in maize using improved drone imagery to locate weeds

Picture copyright López-Granados et al.

Johnsongrass, one of the most competitive weeds in maize, is actually controlled by broadcast application of at least two herbicide treatment. Agronomists López-Granados et al. designed a high-resolution method to locate weeds using drones to take visible and near infrared pictures, then algorithms to map johnsongrass patches (light green) in maize rows (dark blue). They deduce that site-specific control would save up to 95% herbicides, which will be consistent with European and the Spanish legislations.

Weeds to reduce nitrogen pollution

Picture copyright WORTMAN

Cover crops reduce nitrogen pollution from croplands, but naturally occurring weeds may provide similar benefits during fallow periods. Agronomist Wortman shows that nitrogen loss is 60% lower in weedy fields than in bare fields. Cover crops are 26% more effective than weeds in reducing nitrogen loss, but given the issues of cover crop adoption, cultivation of fallow weeds looks promising.

Weeds are good for agriculture, yes they are!

Picture copyright Hanzlik and Gerowitt

In industrial agriculture weeds have been considered solely as undesired plant species that should be removed with pesticides. Now scientists have found that weeds could help farming by, e.g., pollination, preventing water and soil runoff, and attracting predators of crop pests. There is therefore a need of weed surveys across Europe. Agronomists Gerovitt and Hanzlik reviewed the methods of weed surveying in 43 surveys, mainly in Europe, covering up to 4423 fields.

 

The fragile weed-bee affair

rollin
Picture copyright ROLLIN et al.

A million-years old relationship has been established between bees and weed flowers. Weeds indeed provide food to bees in the form of tasty pollen, and bees carry pollen from plant to plant to ensure pollination, weed reproduction and diversity. This win-win relationship is endangered by industrial agriculture practices such as weed control and the use of insecticides. Scientists Rollin et al. review agricultural practices that modify weed-bee long-standing collaboration.

 

Weeds do not decrease yields in organic farming

Industrial agriculture is a major cause of global warming due to greenhouse emissions of CO2 and N2O. Reducing the tillage is a potential solution because emissions are lower. However, in organic farming, the lack of herbicide should favour weed infestation. But are weeds really a problem for productivity? Armengot et al. compared the effect of reduced and conventional tillage on crop yields and weeds in a 2002-2011 field experiment under organic farming. They found that despite higher weed infestation by perennial species under reduced tillage, yields of wheat, sunflower and spelt were similar for both tillage systems. Therefore findings show that reduced tillage is a viable cropping system for organic farming.

 

Weed migration under climate change in Central Europe

Crop weeds are a major cause of economic loss. Recent changes such as global warming and pesticide-free cropping are changing weed patterns in agriculture. For example, thermophile weeds –  weeds that like warm – such as  tumbleweeb (Amaranthus retroflexus) have become more abundant in some cropping systems due temperature and precipitation changes. The review article by Peters et al. analyses the ecological mechanisms ruling weed migration.

 

Oilseed rape weed infection: how parasitic plants choose their partners?

Fostered by climate change the parasitic weed Phelipanche ramosa infests host crops such as tomato, hemp, tobacco and oilseed rape at an increasing rate. This weed can cause more than 80% yield loss of  oilseed rape. To solve this issue knowledge on the way parasitic weeds infect oilseed rape is needed in order to design agroecological solutions. A report by Gibot-Leclerc et al. shows unexpectedly that the P. ramosa weed grows faster on slow-growing Brassicaceae – the oilseed rape family – than on fast-growing mouse-ear cress A. thaliana. This finding demonstrates for the first time that the growth of parasitic plants does not depend only of the growth speed of the host plant.