C. Kempenaar

A robot to detect and control broad-leaved dock ( Rumex obtusifolius L.) in grassland

Broad-leaved dock is a common and troublesome grassland weed with a wide geographic distribution. In conventional farming the weed is normally controlled by using a selective herbicide, but in organic farming manual removal is the best option to control this weed. The objective of our work was to develop a robot that can navigate a pasture, detect broad-leaved dock, and remove any weeds found. A prototype robot was constructed that navigates by following a predefined path using centimeter-precision global positioning system (GPS). Broad-leaved dock is detected using a camera and image processing. Once detected, weeds are destroyed by a cutting device. Tests of aspects of the system showed that path following accuracy is adequate but could be improved through tuning of the controller or adoption of a dynamic vehicle model, that the success rate of weed detection is highest when the grass is short and when the broad-leaved dock plants are in rosette form, and that 75% of weeds removed did not grow back. An on-farm field test of the complete system resulted in detection of 124 weeds of 134 encountered (93%), while a weed removal action was performed eight times without a weed being present. Effective weed control is considered to be achieved when the center of the weeder is positioned within 0.1 m of the taproot of the weed—this occurred in 73% of the cases. We conclude that the robot is an effective instrument to detect and control broad-leaved dock under the conditions encountered on a commercial farm.

Sublethal effects of herbicides on the biomass and seed production of terrestrial non-crop plant species, influenced by environment, development stage and assessment date.

Guidelines provided by the OECD and EPPO allow the use of single-species tests performed in greenhouses to assess the risk of herbicides to non-target terrestrial plant communities in the field. The present study was undertaken to investigate the use of greenhouse data to determine effects of herbicides with a different mode of action on the biomass, seed production and emergence of field-grown plants. In addition, a single species approach was compared with a mixed species approach. Effects on the biomass of greenhouse and field-grown plants were found to be related at different effect levels, indicating that it might be possible to translate results from greenhouse studies to field situations. However, the use of single-species tests may not be valid. The response of a single plant species to sublethal herbicide dosages differed to the response of the same species grown in a mixture with other species.

Can photosynthesis-related parameters be used to establish the activity of acetolactate synthase-inhibiting herbicides on weeds?

Abstract The application of the acetolactate synthase (ALS)–inhibiting herbicide metsulfuron on greenhouse- and field-grown black nightshade and greenhouse-grown ladysthumb resulted in progressive inhibition of the level of carbon dioxide (CO2) fixation, the relative quantum efficiency of electron transport through photosystem I (ΦPSI) and II (ΦPSII), and the leaf chlorophyll content. Photosynthetic-related measurements, measured 2 to 4 d after treatment (DAT) at photon flux densities of 400 to 500 μmol m−2 s−1, provided valuable information before the visual symptoms that first appeared at 7 to 10 DAT with the herbicide. Measurements of the quantum efficiency for electron transport by photosystem II and the loss in leaf chlorophyll content appeared to be two of the most practical parameters to use when designing an early detection method to assess the toxicity of metsulfuron. The use of chlorophyll fluorescence would require a comparison of steady-state ΦPSII measurements for control and treated plants, which could be realized by either measuring in time (before/after application) or space (treated/untreated patch). Nomenclature: Metsulfuron; black nightshade, Solanum nigrum L. SOLNI; ladysthumb, Polygonum persicaria L. POLPE.

The Canon of Potato Science: 33. Haulm Killing

Harvesting can only be done successfully when the tubers have reached a certain level of maturity. Maturation of tubers improves skin set thus improving the resistance to scuffing and skinning, increases resistance to bruising and other types of damage during harvesting and handling, and prolongs storage life by decreasing storage decay and reducing water loss during storage. More mature tubers also have a higher starch content and lower reducing sugar content than less mature tubers. In many potato growing areas the potato crop does not senesce naturally and tubers do not mature naturally, but growers destroy the crop when it is still partly green and tubers are still growing. So, tuber maturation is artificially induced by killing the haulm. Killing potato vine (haulm) is usually done 10−25 days prior to harvesting the potato tubers, although in some cases it is done only a few days before harvesting. Green-crop harvesting also does occur under very specific conditions or in a two-step approach where vine removal and lifting is followed by a short phase of storage in the field under a thin layer of soil after which the tubers are collected. Crops approaching maturity require less time for skin set than crops which are still in full production. This means that the time between haulm killing and harvesting can be shorter when the haulm killing is done in a more mature crop.

Advances in Variable Rate Technology Application in Potato in The Netherlands

Precision agriculture is a farming management concept based on observing, measuring and responding to inter- and intra-field variability in crops. In this paper, we focus on responding to intra-field variability in potato crops and analyse variable rate applications (VRAs). We made an overview of potential VRAs in potato crop management in The Netherlands. We identified 13 potential VRAs in potato, ranging from soil tillage to planting to crop care to selective harvest. We ranked them on availability of ‘proof of concept’ and on-farm test results. For five VRAs, we found test results allowing to make a cost-benefit assessment. These five VRAs were as follows: planting, soil herbicide weed control, N side dress, late blight control and haulm killing. They use one of two types of spatial data: soil maps or biomass index maps. Data on costs and savings of the VRAs showed that the investments in VRAs will pay off under practical conditions in The Netherlands. Savings on pesticide use and N-fertilizer use with the VRAs were on average about 25%, which benefits the environment too. We foresee a slow but gradual adoption of VRAs in potato production. More VRAs will become available given ongoing R&D. The perspectives of VRAs in potatoes are discussed.

Netherlands public private partnerships aimed at Co-innovation in the potato value chain in emerging markets

Abstract Since 2013 the Netherlands Ministries of Economic and Foreign Affairs has been involved in private companies in research and development (R&D) in developing countries. This in a policy going “from aid to trade”. Especially in upcoming markets, R&D is carried out through Public Private Partnerships. Such partnerships not only include R&D organizations in the two countries but specifically also include businesses in both countries. This was to assure a logical flow of material and knowledge by all parties involved. Half of an R&D project is funded by the ministry and the rest is covered by a consortium of companies that contribute in kind and in cash. The policy is aimed at stimulating business development in developing countries and the Netherlands through cooperation and joint R&D. The paper explains how eleven consortia around potato business opportunities were formed, their R&D need was elicited and R&D projects formulated in the Asian countries China, India, Indonesia, Vietnam, Bangladesh and Myanmar, and Ethiopia and Kenya in Africa. In common are fact finding and descriptions of cropping systems, yield gap analysis and value chains in each country. Emphases differ with China looking for an integrated system of field operations, India for optimization of storage and processing, Indonesia to reduce pesticide and nutrient inputs, Vietnam for widening the varietal base, Bangladesh for combating late blight, Myanmar for cultural practices that lead to increased yield, Ethiopia where a potato processing unit is being established and Kenya importing seed potato from the Netherlands. Some content information is given as examples to illustrate the approach and some preliminary conclusion are discussed.