witchweed การใช้

• Furthermore, witchweed is capable of wiping out an entire crop.
• An annual plant, witchweed overwinters in the seed stage.
• In the USA, this witchweed was discovered in the Carolinas in 1955.
• Witchweed seeds spread readily via wind and water, and in soil via animal vectors.
• Parasitizing important economic plants, witchweed is one of the most destructive pathogens in Africa.
• Management of witchweed is difficult because the majority of its life cycle takes place below ground.
• Still, witchweed has demonstrated a wide tolerance for soil types if soil temperatures are favorably high.
• In fact, it is so prolific that in 1957 Congress allocated money in an attempt to eradicate witchweed.
• Witchweed parasitizes maize, millet, sorghum, sugarcane, rice, legumes, and a range of weedy grasses.
• Maize, sorghum, and sugarcane crops affected by witchweed in the United States have an estimated value well over $ 20 billion.
• Soil temperature, air temperature, photoperiod, soil type, and soil nutrient and moisture levels do not greatly deter the development of witchweed.
• The majority of crops in Africa are grown by subsistence farmers who cannot afford expensive witchweed controls, who therefore suffer much as a result of this pathogen.
• To prevent witchweed from spreading it is necessary to plant uncontaminated seeds and to clean soil and plant debris off of machinery, shoes, clothing, and tools before entering fields.
• Through infestation mapping, quarantine, and control activities such as contaminated seed destruction, the acreage parasitized by witchweed has been reduced 99 % since its discovery in the United States.
• Increasing nitrogen levels in the soil, growing striga-tolerant varieties, trap-cropping, and planting susceptible crops harvested before witchweed seed is produced, are proven anti-striga tactics.
• Species of " Striga " ( witchweed ) are known to leave some of the highest seed densities in the soil compared to other plant genera; this is a major factor that aids their invasive potential.
• For example, the seeds of the parasitic plant witchweed ( " Striga asiatica " ) need to be within 3 to 4 millimeters ( mm ) of its host in order to pick up chemical signals in the soil to signal germination.