question: If Weed B Gone kills weeds why doesn’t it kill grass when they’re both technically plants?
comment: It targets a type of plant called a dicot. So your grass is gonna be a monocot, which grow differently. Your weed B gone is targeting plants that are dicots, which are not grasses. Your grass can still die if you use too much, but dicots absorb the herbicide in weed b gone better which spares the grass at the correct dose.
passages: BULLET::::- Preemergence: Preemergence herbicides are applied before the weed seedlings emerge through the soil surface. Herbicides do not prevent weeds from germinating but they kill weeds as they grow through the herbicide treated zone by affecting the cell division in the emerging seedling. Dithopyr and pendimethalin are preemergence herbicides. Weeds that have already emerged before application or activation are not affected by pre-herbicides as their primary growing point escapes the treatment.
   Hot foam (foamstream) causes the cell walls to rupture, killing the plant. Weed burners heat up soil quickly and destroy superficial parts of the plants. Weed seeds are often heat resistant and even react with an increase of growth on dry heat.
  
  Since the 19th century soil steam sterilization has been used to clean weeds completely from soil. Several research results confirm the high effectiveness of humid heat against weeds and its seeds.
  
  Soil solarization in some circumstances is very effective at eliminating weeds while maintaining grass. Planted grass tends to have a higher heat/humidity tolerance than unwanted weeds.
   Invasive species introduced by humans can also affect biological soil crusts. Invasive annual grasses can occupy areas once occupied by crusts and allow fire to travel between large plants, whereas previously it would have just jumped from plant to plant and not directly affected the crusts.
   When herbivores trigger an inducible chemical defense pathway, the resulting HIPVs may be emitted from the site of feeding damage (local induction), or from undamaged tissues belonging to a damaged plant (systemic induction). For example, when an herbivore feeds on a single corn seedling leaf, the plant will emit volatiles from all its leaves, whether or not they too have been damaged. Locally induced defenses aid parasitoids in targeting their foraging behaviors to the exact location of the herbivore on the plant. Systemic defenses are less spatially specific and may serve to confuse the enemy once the source plant is located. A plant might employ both local and systemic responses simultaneously.
   This disease only infects cannabis or hemp plants. Symptomatic responses associated with this disease will be in the form of white lesions with concentric rings on the surface of the plants vegetative leaves, as well as browning and chlorosis on infected leaves. The first symptoms of this disease will occur on the older, lower leaves of the plant. "Septoria" has been known to spread rapidly within a growing season and will eventually attack all of the cannabis’ vegetative growth rendering it unable to perform any biological processes and ultimately die. If the disease is extreme most vegetative tissue will be destroyed, taking away the cannabis plant’s source of sugars and ultimately turning the entire host into a sink and reducing yields come harvest. Nitrogen deficient cannabis plants are more susceptible to being infected. Though "Septoria" destroys vegetative growth it has little to no impact on the formation of buds. This disease was discovered in New York dating back to 1884, and was recently found and studied in North Carolina.
   BULLET::::- Postemergence: These herbicides are applied after weed seedlings have emerged through the soil surface. They can be foliar or root absorbed, selective or nonselective, contact or systemic. Application of these herbicides is avoided during rain because the problem of being washed off to the soil makes it ineffective. 2,4-D is a selective, systemic, foliar absorbed postemergence herbicide.
  
  Section::::Terminology.:Method of application.
   Problems with herbicide resistant weeds may be addressed by applying herbicides with different modes of action, along with cultural methods such as crop rotation, in integrated weed management (IWM) systems. Paraquat, with its distinctive mode of action, is one of few chemical options that can be used to prevent and mitigate problems with weeds that have become resistant to the very widely used non-selective herbicide glyphosate.
   In another study, introduction of budworm to Douglas fir trees led to increased production of defensive enzymes in uninfested ponderosa pines connected to the damaged tree by an ECM network. This effect demonstrates that defensive infochemicals transferred through such a network can cause rapid increases in resistance and defense in uninfested plants of a different species.
   Section::::Metabolite production.
  
  Another instance is the analogous evolution of plant metabolite production as a response to herbivory. In this case, different plant species have evolved different mechanisms of chemical repellant to herbivores, yet each response provides the same function – resistance to herbivory. In some cases, plants living in completely different environments (geographic separation) and that are not taxonomically related can evolve different metabolites that provide the same function to the plant - protection against herbivory. This is another example of functional equivalency among taxonomically unrelated species.
  
  Section::::Symbiotic relationships.
   Corn varieties resistant to glyphosate herbicides were first commercialized in 1996 by Monsanto, and are known as "Roundup Ready Corn". They tolerate the use of Roundup. Bayer CropScience developed "Liberty Link Corn" that is resistant to glufosinate. Pioneer Hi-Bred has developed and markets corn hybrids with tolerance to imidazoline herbicides under the trademark "Clearfield" – though in these hybrids, the herbicide-tolerance trait was bred using tissue culture selection and the chemical mutagen ethyl methanesulfonate, not genetic engineering. Consequently, the regulatory framework governing the approval of transgenic crops does not apply for Clearfield.
   The results of these studies support the conclusion that both ECM and AM networks provide pathways for defensive infochemicals from infected or infested hosts to induce defensive changes in uninfected or uninfested conspecific and heterospecific plants, and that some recipient species generally receive less damage from infestation or infection.
  
  Section::::Nutrient communication.
  
  Section::::Nutrient communication.:Overview.
   Some plants become dominant when introduced into new environments because the animals in their original environment, that compete with them or feed on them are absent; in what is sometimes called the “natural enemies hypothesis”, plants freed from these specialist consumers may become dominant. An example is Klamath weed, that threatened millions of hectares of prime grain and grazing land in North America after it was accidentally introduced, but was reduced to a rare roadside weed within several years after some of its natural enemies were imported during World War II. In locations where predation and mutually competitive relationships are absent, weeds have increased resources available for growth and reproduction. The weediness of some species that are introduced into new environments may be caused by their production of allelopathic chemicals which indigenous plants are not yet adapted to, a scenario sometimes called the "novel weapons hypothesis". These chemicals may limit the growth of established plants or the germination and growth of seeds and seedlings.
   Plants produce many types of allelochemicals, such as thiopenes and juglone, which can be volatilized or exuded by the roots into the rhizosphere. Plants release allelochemicals due to biotic and abiotic stresses in their environment and often release them in conjunction with defensive compounds. In order for allelochemicals to have a detrimental effect on a target plant, they must exist in high enough concentrations to be toxic, but, much like animal pheromones, allelochemicals are released in very small amounts and rely on the reaction of the target plant to amplify their effects. Due to their lower concentrations and the ease in which they are degraded in the environment, the toxicity of allelochemicals is limited by soil moisture, soil structure, and organic matter types and microbes present in soils. The effectiveness of allelopathic interactions has been called into question in native habitats due to the effects of them passing through soils, but studies have shown that mycorrhizal networks make their transfer more efficient. These infochemicals are hypothesized be able to travel faster via mycorrhizal networks, because the networks protect them from some hazards of being transmitted through the soil, such as leaching and degradation. This increased transfer speed is hypothesized to occur if the allelochemicals move via water on hyphal surfaces or by cytoplasmic streaming. Studies have reported concentrations of allelochemicals two to four times higher in plants connected by mycorrhizal networks. Thus, mycorrhizal networks can facilitate the transfer of these infochemicals.
   The presence of weeds does not necessarily mean that they are damaging a crop, especially during the early growth stages when both weeds and crops can grow without interference. However, as growth proceeds they each
  
  begin to require greater amounts of water and nutrients. Estimates suggest that weed and crop can co-exist harmoniously for around three weeks before competition becomes significant. One study found that after competition had started, the final yield of onion bulbs was reduced at almost 4% per day.
   Highway maintenance is an ongoing threat to the species, as the plant grows directly next to a highway. Dying plants have been observed at the highway's edge, a possible sign of herbicide application. The installation of a gas pipeline likely destroyed some plants and its maintenance is a threat to others in the area. Grazing is not a direct threat because cattle do not eat the foul-smelling plant, but their trampling may compact the soil. The introduction of buffelgrass for better grazing has led to drastic changes in the plant community, because it spreads and competes easily with other species.
   Perennial weeds with bulbils, such as lesser celandine and oxalis, or with persistent underground stems such as couch grass ("Agropyron repens") or creeping buttercup ("Ranunculus repens") store reserves of food, and are thus able to grow faster and with more vigour than their annual counterparts. Some perennials such as couch grass exude allelopathic chemicals that inhibit the growth of other nearby plants.
   A further method of herbicide application developed around 2010, involves ridding the soil of its active weed seed bank rather than just killing the weed. This can successfully treat annual plants but not perennials. Researchers at the Agricultural Research Service found that the application of herbicides to fields late in the weeds' growing season greatly reduces their seed production, and therefore fewer weeds will return the following season. Because most weeds are annuals, their seeds will only survive in soil for a year or two, so this method will be able to destroy such weeds after a few years of herbicide application.
   Examples of such ruderal or pioneer species include plants that are adapted to naturally occurring disturbed environments such as dunes and other windswept areas with shifting soils, alluvial flood plains, river banks and deltas, and areas that are burned repeatedly. Since human agricultural practices often mimic these natural environments where weedy species have evolved, some weeds are effectively preadapted to grow and proliferate in human-disturbed areas such as agricultural fields, lawns, roadsides, and construction sites. The weedy nature of these species often gives them an advantage over more desirable crop species because they often grow quickly and reproduce quickly, they commonly have seeds that persist in the soil seed bank for many years, or they may have short lifespans with multiple generations in the same growing season. In contrast, perennial weeds often have underground stems that spread under the soil surface or, like ground ivy ("Glechoma hederacea"), have creeping stems that root and spread out over the ground.
   Herbicides are designed to kill plants, and are used to control unwanted plants such as agricultural weeds. However herbicides can also cause phytotoxic effects in plants that are not within the area over which the herbicide is applied, for example as a result of wind-blown spray drift or from the use of herbicide-contaminated material (such as straw or manure) being applied to the soil. The phytotoxic effects of herbicides are an important subject of study in the field of ecotoxicology.
   Some cover crops suppress weeds both during growth and after death. During growth these cover crops compete vigorously with weeds for available space, light, and nutrients, and after death they smother the next flush of weeds by forming a mulch layer on the soil surface. For example, researchers found that when using "Melilotus officinalis" (yellow sweetclover) as a cover crop in an improved fallow system (where a fallow period is intentionally improved by any number of different management practices, including the planting of cover crops), weed biomass only constituted between 1-12% of total standing biomass at the end of the cover crop growing season. Furthermore, after cover crop termination, the yellow sweetclover residues suppressed weeds to levels 75–97% lower than in fallow (no yellow sweetclover) systems.
   In a study of tomato plants connected via an AM mycorrhizal network, a plant not infected by a fungal pathogen showed evidence of defensive priming when another plant in the network was infected, causing the uninfected plant to up-regulate genes for the SA and JA pathways. Similarly, aphid-free plants were shown to only be able to express the SA pathways when a mycorrhizal network connected them to infested plants. Furthermore, only then did they display resistance to the herbivore, showing that the plants were able to transfer defensive infochemicals via the mycorrhizal network.
   Weeds can also host pests and diseases that can spread to cultivated crops. Charlock and Shepherd's purse may carry clubroot, eelworm can be harboured by chickweed, fat hen and shepherd's purse, while the cucumber mosaic virus, which can devastate the cucurbit family, is carried by a range of different weeds including chickweed and groundsel.
  
  Insect pests often do not attack weeds. However pests such as cutworms may first attack weeds then move on to cultivated crops.
   When mixed with a weedkiller (normally as an aqua solution) the penetrant chemical causes a plant to absorb the poison in a more effective manner and so succumb more readily. Penetrants are most often used against plants that would otherwise be able to resist the weedkiller. Often such plants have tough leaves or shiny leaves that shed water easily.
   Weeds compete with crops for space, nutrients, water and light. Smaller, slower growing seedlings are more susceptible than those that are larger and more vigorous. Onions are one of the most vulnerable, because they are slow to germinate and produce slender, upright stems. By contrast broad beans produce large seedlings and suffer far fewer effects other than during periods of water shortage at the crucial time when the pods are filling out. Transplanted crops raised in sterile soil or potting compost gain a head start over germinating weeds.
   Section::::Examples.:Acquired pathogenic capabilities.
  
  In "Stagonospora" and "Pyrenophora", as well as in "Fusarium" and "Alternaria", horizontal gene transfer provides a powerful mechanism for fungi to acquire pathogenic capabilities to infect a new host plant. Horizontal gene transfer and interspecific hybridization between pathogenic species allow for hybrid offspring with an expanded host range. This can cause disease outbreaks on new crops when an encoded protein is able to cause pathogenicity.
  
  The interspecific transfer of virulence factors in fungal pathogens has been shown between "Stagonospora modorum" and "Pyrenophora tritici-repentis", where a host-selective toxin from "S. nodorum" conferred virulence to "P. tritici-repentis" on wheat.
  
presuppositions: Weed be gone should kill grass as well and not just weeds but does not.  Weed B Gone kills all plants.
corrections: Weed be gone can kill grass if used in a large amount.  Weed B Gone only targets dicot plants.
raw_presuppositions: Weed be gone should kill grass as well and not just weeds but does not.  Weed B Gone kills all plants.
raw_corrections: Weed be gone can kill grass if used in a large amount.  Weed B Gone only targets dicot plants.