Parasitic weeds or parasitic flowering plants are destructive species that negatively impact agroand
ecosystems since parasitize cultivated and wild grown annual, biennial and perennial plant
species of different growth habits and habitats. Parasitic weeds attack most vegetables, forage
plants, shrubs, and fruit and forest trees, reflecting a high physiological/chemical and
environmental tolerance and/or these parasites adapt to separate plant cells, dissolve tissues,
enhance haustorium penetration and thus secure food and water availability for their own use.
Parasitic weeds are unusual and peculiar species in growth habits and habitats, hence not in direct
contact (except certain hemi-parasites) with soil and soil factors necessary for growth,
development and existence and for almost the entire life cycle. Instead, they are usually attaching
themselves to other plant species of different genera (except self-parasitism) and families through
an absorptive organ called haustorium (pl. haustoria) that develops upon attachment to host
tissues. Essentially all haustoria are modified roots (Nickrent, 2002), sucker like structures varied
in size, shape and morphology for different parasitic species and through which the parasite can
derive its food and /or water from host plant. Parasitic weeds are of widespread significance in
different parts of the world and a great concern to farmers and researchers. Certain species are a
serious threat to food security since parasitize many food crops of economic importance. However,
parasitic weeds are different in requirements for germination, attachment to host plants and host
parts attacked, degree of dependence upon hosts, and presence or absence of chlorophyll. Most
recent management methods are presented including (i) biological using natural enemies such as
fungi, bacteria and insects including Trichoderma, Phytomyza for Orobanche; Smicronyx sp and
fungal species for Cuscuta and Orobanche; (ii) Chemical by the use of herbicides such as
glyphosate for Orobanche control in fababean and different sulfonylurea herbicides for other
species (e.g. O. aegyptiaca and O. ramosa in tomato) and selective application of MCPA and 2,4-
D for mistletoes control; (iii) physical including soil solarization and plastic mulch for Orobanche
and Cuscuta species; (iv) organic methods using plant residues and natural products or allelopathy
(e.g. for Orobanche), root extracts (sunflower), plant oils of ginger, groundnuts, palm, sunflower,
safflower, castorbean, linseed, neem, coconut or tobacco seed oils, niger (Guizotia abyssiniaca),
and mustard oils, orobanchol and alectrol germination stimulants, different strains of
Streptomyces, certain fungal metabolites including cotylenins and fusicoccins; (v) trap and catch
species in crop rotation or intercropping systems ; (vi) genetically engineered crops (herbicide
resistant); (vii) plastic mulch with fertilizers (chicken manure, urea, ammonium sulphate); (viii)
resistant cultivars for different crop species and screening studies on tolerant/resistant crop lines;
(ix) mowing and general contact herbicides such as paraquat and dinoseb for Osyris and Cuscuta
(early infestation on perennial field crops) species control; (x) pruning and shading for mistletoes
control; and (xi) integrated control methods. This book reviews parasitic weed genera that occur in
Jordan and are of great importance to many other Middle East countries. It includes recent
research achievements in combating these parasitic weeds and presents a brief description of
species phonology, ecology, and economic importance as parasites of cultivated land, forestry and
wild species in the country. Recent literature on species biology, physiology, and ecology and on
developments on their control and management were reviewed for each parasitic genus separately
as deemed necessary.
Keywords: Parasitic weeds, Biology, Physiology, Ecology, Control methods.