My research field comprises the ecology and biology of weeds (annual, perennial, parasitic) and focuses on how knowledge of this domain connects to the design of sustainable weed management systems. Diversity is key for creating durability in weed management and the use of cultural control measures, to replace and supplement curative control, is an important means for realizing this diversity.
Current weed management mainly relies on curative means, predominantly chemical control, but the intensive use of a relatively small number of herbicidal compounds creates a strong selection pressure towards herbicide resistance. After the introduction of the first herbicides it was believed that the weed problem would soon come to an end. Nowadays we have come to realize that each new strategy will result in adaptations of the weed community. It is the realization of this evolutionary facet that holds the key for the design of more sustainable weed management systems and that makes weed biology and management such a fascinating field of research.
It is my conviction that diversity in weed management can be obtained by making better use of cultural control measures. These measures, directed at a range of life cycle stages, aim to manage the size of a weed population in a longer term perspective. Many interesting research questions arise, as little is known on the effectiveness of individual measures, on possible trade-offs with yielding ability, on synergy among individual measures and on their combing ability with curative control measures.
Research includes the identification of crop traits related to weed suppressiveness, the optimization of the weed suppressive function of intercrops and cover crops and the exploration of crop rotation as a weed management tool. In most of this research a quantitative approach is used, in which experimentation is combined with modelling of crop-weed interactions and weed population dynamics.
Parasitic weeds form a special category of weeds, that often thrive in low-input agriculture. Research in this area is conducted in collaboration with partner institutions in Africa. Initially, our research mainly focussed on the interaction between the obligate root parasite Striga hermonthica and sorghum as a host crop. More recently, the research has broadened and includes Rhamphicarpa fistulosa, a facultative hemi-parasitic weed that forms an increasing production constraint in rice production systems in sub-Saharan Africa. Apart from fundamental aspects related to the host-parasite association, management options are evaluated in a farmer participatory manner, and the role and functioning of the broader crop protection system is considered.