Hort 10/20Plant pests- organisms that compete with people for food or otherwise interfere with raising of horticulture cropsFive main groups of pests:- weeds- invertebrates- vertebrates- disease agents- manClassis pest control strategy- identify- understand life cycle- evaluate damage or effects- controlCultural practices- proper plant selectiono plant selectiono adaptabilityo host resistance- maintain good plant health- timingo diseases get worst at the end of season- sanitationPlant selection is important- hardiness zone (8a in Athens)o any plant you plant, hardiness zone is VERY important- shade vs. suno if a plant is exposed to 6-8 hours of sunlight, its perfect amount- soil moisture toleranceo wet-naturedo poor drainageo drought-proneMechanical controls- machines- devices- trapsChemical controls- traditional “chemical”- organico not persistento often plant-derivedo biological pesticidesPest-“icides”- Herbicides: weeds- Insecticides: insects- Fungicides: fungi- Bactericides: bacteria- Rodenticides: rodentsPesticide toxicity- Measured in LD50o The LD50 is the dose that kills half (50%) of the animals tested (LD= lethal dose”)o Measured in mg per kg body weight- Examples of LD50 of common pesticideso Acephate (orthene) 980o Aspartame 10,000o Insecticidal soap 16,900o Bacillus thuringiensis 15,000o Roundup (glyphosate) 3750o DDT (chlorinated hydrocarbon) 87o Aspirin 1750o Caffeine 292Do you have what it takes?- Weeds are efficient because…o Early germinationo Rapid seeding growtho Large leaf areao Massive root systemsWeeds- Most weeds produce large # of seedso Broadleaf plantain 36,000o Crabgrass 53,000o Annual bluegrass 2,000- Some weed seeds remain dormant for 20 years before germinatingo Hard seed coatHow weeds hurt- Competition (space, light)- Appearance factors- Harbor insects and plant diseases- Some are poisonous- Dulls mower blades- AllelopathyWeed biology- Weeds are classified as…o Annuals (summer and winter)o Biennialso Perennials (warm season/cool