lecture 03

lecture 03 - 1/18/11 Weed Life Cycles Plant Life...

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Unformatted text preview: 1/18/11 Weed Life Cycles Plant Life Cycles BTNY 304 Annuals Winter Summer Biennials Perennials Simple Creeping Some photographs were taken off various websites and are intended for instrucDonal purposes only Perennial Structures Perennial structures  ­ herbaceous Rhizomes Tubers Bulbs Stolons Weed Life Cycles Annuals – complete life cycle in one growing season Seeds germinate, plants grows, flowers, produces seeds and dies in one growing season or less Individual established plants are relaGvely easy to control Season ­long pressure on crops is aHributed to mulGple flushes of new plants over the growing season Are weed problems in nearly all cropping systems Perennial structures – woody Shrubs Vines 1 1/18/11 Weed Life Cycles Biennials – live for two growing seasons – are associated with undisturbed sites and perennial cropping systems – disturbing the site greatly inhibits their establishment 2 1/18/11 Weed Life Cycles Perennials – live 3 or more years Flowering does not trigger senescence and death of the enGre plant Underground structures conGnue to live Types of perennials Simple perennials – start from seeds, grow vegetaGvely and produce a taproot Spread of the species is primarily by seeds Needs undisturbed areas to survive Types of perennials Creeping perennials – reproduce by both seeds and vegetaGve structures VegetaGve reproducGve structures are the major means of spread, compeGGon and survival Survives in most cropping systems because of their rapid recovery capability 3 1/18/11 Types of perennials Woody perennial shrubs and vines Produce woody stems that survive winters Many produce new plants from creeping roots and seeds Trumpet Creeper (Campsis radicans) 4 1/18/11 A perennial or biannual weed in the seedling or early vegetaGve stage of growth behaves as an annual can be treated as an annual in terms of herbicide applicaGons or mechanical control. Once perennials characterisGcs develop, special control measures are needed to successfully kill it. From a herbicide standpoint: Small weeds (grown from seedlings) can be controlled with contact herbicides provided good coverage in obtained Large annual and biannual weeds are harder to control with contact herbicides due to lack of coverage Established perennial weeds require a translocated herbicide for control 5 ...
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