Abstract

Parasitic weeds or parasitic flowering plants are destructive species that negatively impact both agro- and ecosystems. They attack cultivated and wild grown annual, biennial and perennial plant species of different growth habits and habitats. They parasitize most vegetables, forage plants, shrubs, and fruit and forest trees. They reflect a high physiological/chemical and environmental tolerance and/or these parasites adapt to separate plant cells, dissolve tissues and food materials, and facilitate penetration secure food and water for their own use. Parasitic weeds are unusual and peculiar species in growth habits and habitats, hence not in direct contact (except certain hemiparasites) with soil and soil factors necessary for growth, development, and existence and for almost the entire life cycle. Instead, they usually attach themselves to other plant species of different genera (except self-parasitism) and families through an absorptive organ called haustorium (pl. haustoria) develops upon attachment to host tissues. Essentially, all haustoria are modified roots (Nickrent, 2002), sucker-like structures, and varied in size, shape, and morphology for different parasitic species. The parasite can derive its food and /or water from the host plant. Parasitic weeds are of a widespread significance in different parts of the world and serious concern to farmers and researchers. Certain species are a real threat to food security since they parasitize many important food crops. However, parasitic weeds are different in requirements for germination, attachment to host plants and in the host parts they attack, 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, 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 residue and natural products or allelopathy (e.g. for Orobanche), root extracts (sunflower), plant oils (ginger, groundnuts, palm, sunflower, safflower, castorbean, linseed, neem, coconut or tobacco seed oils, niger, and mustard), 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 (at early infestation in perennial field crops) species control; (x) pruning and shading for mistletoes control; and (xi) integrated control methods. This book reviews the parasitic genera that occur in Jordan and are of great importance to many 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 developments on their control and management were reviewed for each parasitic genus separately as deemed necessary. 

Keywords: Parasitic weeds, Biology, Physiology, Ecology, Control methods