Biennial weeds

Burning—Fire may be used to control limited infestations of annual or biennial weeds. Fire destroys only the above-ground parts of plants and is nsnally not effective against many herbaceous perennial weeds. 

Mowing—Mowing may be used to reduce competition between weeds and crops and to prevent flowering and seeding of annual or biennial weeds. Mowing is often used in orchards to control weeds and prevent soil erosion. To be most effective, mowing height must be adequate to ensure control of... 

A weed can be an annual, a biennial, an herbaceous or shrubby perennial, or even a tree species. This chapter introduces you to the way weeds work—how and why they are so efficient—and the range of organic methods you can employ to clear weeds and keep them under control. It is useful to be able to identify common garden weeds, especially perennials (see pp.80-81). Knowing how they reproduce, spread, and survive adverse conditions can help you to develop an effective control strategy. 

The scope of weed pests that affect growth and productivity of deciduous ornamentals and conifers is vast and includes herbaceous annuals, biennials, and perennials as well as woody vines and many species of trees. More than... 

Kathiresan R.M., Gurusamy. Allelopathic potential of paddy seeds and some plant products on Barnyardgrass. Biennial Conference of Indian Society of Weed Science. Annamalai University, Annamalainagar 1995 Abstract, pp.110. 

Evening primrose (Oenothera biennis L.), a biennial plant belonging to the Ona-graceae family, is considered a weed native to North America. It is cultivated in a number of countries on account of the nutritional and pharmaceutical properties of the oil which is in constant demand (Carter, 1988). The oil extracted, referred to as evening primrose oil (EPO), is a good source of GLA. Unlike commercial oilseeds, evening primrose does not produce a high yield of seeds, but is a preferred source of GLA as it does not contain any ALA. 

Chemicals used to control weeds are called herbicides. They kill plants by contact or systemic action. Contact herbicides kill only the plant parts which the chemical touches. Systemic herbicides are absorbed by roots or foliage and carried throughout the plant. Systemic herbicides are particularly effective against perennial weeds because the chemical reaches aU parts of the plant—even deep roots and woody stems, which are relatively inaccessible. Contact herbicides are usually used to control annuals and biennials and are characterized by the quick die-back they cause. Systemics may take a longer time to provide the desired results—up to 2 or 3 weeks, or even longer for woody perennials. 

Henbane Hyoscyamus niger) is a poisonous annual or biennial herb of the nightshade family, introduced into this country from Europe and occasionally found as a weed in a number of the Northern States. The leaves, flowering tops, and sometimes the seeds are used medicinally. 

Caraway is a crop with very small competitive ability against the majority of weed species and has slow development at the beginning. The timing of herbicides application is very important, especially at biennial caraway. There is a recommendation for regulating the perennial species (couch grass) and hardly regulated weeds (common thistle, sorrel) in a fore crop. The spectrum of the herbicides registered into caraway is narrow. The different sensitivity of cover crop and caraway to the herbicides plays the important role, as well as the coordination of the application term from the point of view of the efficiency and the sensitivity (Vaculik, 2006 2007 2008 Vaculik et al., 2008). 

Spartan (Sulfentrazone) Annual small seeded broadleaf weeds, including kochia, pigweed, lambsquarters, night shade and biennial wormwood Early pre-plant PPI or pre-emergence... 

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