Plant Health

In the agricultural and horticultural sectors, weeds must be controlled to prevent them from competing with crops for light, water and nutrients. In addition, weeds can have a detrimental effect on crop quality and may function as host plants for diseases and pests. Failure to control weeds can result in significant financial losses of up to 34%. The majority of weeds are controlled through herbicides, which have the advantage of being cost effective. The disadvantages of herbicides, however, are their potential side effects on the environment and the development of resistance to herbicides.

Variation in weed populations

The foremost characteristic of weed populations is their variability in space and time, which is influenced by the cultivation system. Surviving seeds and other survival structures in the soil ensure the long-term impact of the cultivation measures on weeds, and this remains the primary reason for growers to use herbicides.

Contrary to diseases and pests, the importance of weeds is often underestimated due to their chronic nature. Despite the use of control measures, the current total loss of revenue in the European Union due to weeds is estimated to be 10%.

Integrated weed control systems

The growing herbicide resistance of weeds in conjunction with societal concern about the adverse effects of herbicides on the environment compel us to seek out sustainable cultivation systems that are less dependent on chemical crop protection agents. To decrease the use of herbicides while simultaneously preventing the growth of weed populations, we are working on integrated weed control systems. These systems are based on knowledge about weed biology and the ecology of crop-weed interactions.

Smart techniques

The variability of weeds in space and time can be tackled through the use of new advances such as vision technology. Intelligent combinations of crop rotation, physical and mechanical control methods and dispensing herbicides through smart application techniques are all part of our ongoing research.

Publications:

• Transdisciplinary weed research: new leverage on challenging weed problems?- 2016
• Ecologically sustainable weed management: How do we get from proof-of-concept to adoption?- 2016
• Combining a weed traits database with a population dynamics model predicts shifts in weed communities. - 2015
• Effect of possible climate change on arable weed species emergence in the Netherlands : an exploratory study with 3 case studies: Cirsium arvense, Sonchus arvensis and Galinsoga parviflora. - 2012
• Satellite-based herbicide rate recommendation for potato haulm killing. - 2012
• A robot to detect and control broad-leaved dock (Rumex obtusifolius L.) in grassland. (2011)
• Predicting herbicidal plant mortality with mobile photosynthesis meters. - 2011
• Linking Farmer Weed Management Behavior with Weed Pressure: More than Just Technology. - 2010

Our experts are working on controlling diseases and pests. We are drawing upon our in-depth knowledge of the pathogen and the crop to develop an effective management strategy for diseases. We have built up considerable expertise thanks to years of research on pathogens such as Phytophthora and Alternaria.

Phytophthora infestans

Globally, the potato blight caused by Phytophthora infestans is the most destructive disease for potatoes. Losses are estimated to total €10 billion per year. The pathogen continually adapts and has become increasingly aggressive over the years, making it much harder to control. We are working on an integrated control approach that employs several 'Best Practices'. The most important examples include:

• Preventing early sources of
  inoculum by analysing the cultivation area to clarify which sources are
  contributing to the early incidence of disease. This can be latent
  infected propagating material, waste heaps or oospores. Targeted
  measures can diminish the importance of these early sources.
• Cultivating
  resistant varieties: varieties with one or more resistance genes are
  affected less quickly and are less likely to be affected. Using
  fungicides on these varieties can be reduced, depending on the degree of
  resistance already present.
• Using targeted fungicides:
  fungicides have stronger and weaker properties. These properties should
  be exploited for the optimal deployment of the fungicides. Adapting to
  the incidence of disease, crop growth, the environmental degradation
  present and protecting against foliage and tuber damage are all
  important factors.
• Use decision-making support systems: these
  systems draw upon the combined knowledge of the pathogen(s), weather
  conditions, the incidence of disease, fungicides and crop growth. These
  systems are used to generate a recommendation that is geared, firstly,
  toward controlling the disease as quickly as possible and, whenever
  possible, cutting back on the use of fungicides.

By continuously responding to the latest developments and using the most advanced technologies, our experts are working on the sustainable control of Phytophthora infestans.

Alternaria solani

In recent years, Alternaria solani, which causes Alternaria disease (Early Blight), has been widespread in potato cultivation in the Netherlands. In some potato varieties, Alternaria can cause significant damages to the crop yield and quality. Losses due to the premature death of the crops are now estimated to be 5 to 10% of the total yield. Several factors should be examined when looking to the cause of the rise in Alternaria.

• Climate change, with more periods of extreme weather (wet, dry and warm).
• Lower levels of fertilisation used in potato cultivation.
• The use of more specific Phytophthora resources that do not have side effects on Alternaria.
• Possible genetic changes in the Alternaria population, such as fungicide resistance and aggressiveness.

Our experts carry out research to combat these and other crop diseases. A great deal is known about how to combat Phytophthora, but the situation is quite different for Alternaria. We do know, however, that many of the same control measures can be applied to combat Alternaria.

• Cultivate potato varieties that are less susceptible to Alternaria
• Avoid
  stressors during potato cultivation through proper fertilisation and
  prevent drought stress by sprinkling the plants with water, when
  necessary.
• Bear in mind resistance management when using fungicides.
• The right time to conduct the first spraying is a topic of discussion.
• Use
  decision-making support systems: these systems combine all the
  knowledge of pathogens, weather conditions, the incidence of disease,
  fungicides and crop growth. Further development is required for
  Alternaria because the plant stress factor is not sufficiently
  established.

By continuing to respond to the latest developments and research on the epidemiology of Alternaria, we can use a more sustainable approach to gain better control of the disease.

Integrated pest management (IPM) is the term used to describe an optimum combination of farm management measures designed to produce healthy crops. When growing agricultural and horticultural products, farmers are obliged to deal with harmful insects, mites, gastropods and other pests. Damage from insects reduces both the quality and quantity of the yield.

Infestation depends on many factors

IPM forms the backbone of our approach at Wageningen Plant Research: which measures must be introduced when, and how do you do this efficiently? Infestation depends on the population density and the favourability of the conditions in which they are able to develop. Weather, climate, farm management measures, crop choice and natural enemies are all factors that affect the ability of pests to develop. The character and resilience of the affected plants are factors that determine the economic damage the pests cause. All species of plants have their own defence mechanisms. Expertise about crops and pests, and knowledge of practical conditions, enable us to deploy targeted research methods.

Wageningen has in-house expertise for all relevant pests in agricultural and horticultural crops, and maintains both national and international networks. Three of the most important groups of pests are: soil pests, flies and sucking insects.

We are developing effective and sustainable techniques for the purpose of infestation-free horticultural products in international trade chains. The use of methyl bromide fumigation on horticultural products is prohibited in the EU and in many countries outside the EU. For this reason, import and export companies have a real need for alternative and sustainable disinfestation techniques that can quickly and effectively kill quarantine organisms and other pests.