Research and Development in Tropical Agriculture, SA
Herbicide bioassays, development and mixture optimisation
Herbicide resistance diagnosis, resistance management and cross-resistance studies
Evaluation of pest management technologies
Technical assistance in integrated pest management
Weed identification & surveys
Weed seed production
Weedy rice characterization
Representation for companies with agricultural products
Distribution of EcoWeeder herbicide applicators
In service training and student internship
Scientific paper editing and technical writing
Content development and design of technical brochures
Pesticide residue analysis in plants, soil and water
Statistical analysis of complex datasets
Articles & Publications
Cytoplasmic-genetic male sterility gene provides direct evidence for some hybrid rice recently evolving into weedy rice
Zhang JX, Lu Z, Dai WM, Song XL, Peng Y, Valverde BE, Qiang S
ABSTRACT: Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of its progeny, but this notion remains unsupported by direct evidence. We screened weedy rice accessions by both genetic and molecular marker tests for the cytoplasmic male sterility (CMS) ...
Scientific Reports 5:10591. doi:10.1038/srep10591
ICE1 demethylation drives the range expansion of a plant invader through cold tolerance divergence
Xie HJ, Li H, Liu D, Dai WM, He JY, Lin S, Duan H, Liu LL, Chen SG, Song XL, Valverde BE, and Qiang S.
ABSTRACT: Cold tolerance adaption is a crucial determinant for the establishment and expansion of invasive alien plants into new cold environments; however, its evolutionary mechanism is poorly understood. Crofton weed (Ageratina adenophora), a highly invasive alien plant, is continuously spreading across subtropical areas in China, north-eastward from the first colonized south-western tropical regions, through cold tolerance evolution...
Molecular Ecology 24:835-850. 2015.
Glyphosate spray drift in Coffea arabica – Sensitivity of coffee plants and possible use of shikimic acid as a biomarker for glyphosate exposure
Lars C. Schrübbers, Bernal E. Valverde, Jens C. Sørensen and Nina Cedergreen
ABSTRACT: Glyphosate is widely used in coffee plantations to control weeds. Lacking selectivity, glyphosate spray drift is suspected to cause adverse effects in coffee plants. Symptoms caused by glyphosate can be similar to those produced by other stress factors. However, shikimic acid accumulation should be a useful biomarker for glyphosate exposure as shown for other crops...
Pesticide Biochemistry and Physiology 115:15–22. 2014.
Cyperus difformis evolves resistance to propanil
Bernal E. Valverde, Louis G. Boddy, Rafael M. Pedroso, James W. Eckert, Albert J. Fischer
ABSTRACT: Cyperus difformis L. is one of the worst weeds of rice world-wide and has evolved resistance to acetolactate synthase (ALS)-inhibiting herbicides in rice fields of California. Propanil use was intensified to control the widespread resistant biotypes. Rice growers have recently experienced poor control, suggesting resistance to this photosystem II-inhibiting herbicide may have evolved in C. difformis populations ...
Crop Protection 62:16–22. 2014.
News & Developments
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