The accidental introduction of the economically destructive zebra mussel into US waters when a ship's ballast water was released led Congress to create the Nonindigenous Aquatic Nuisance Prevention and Control Act in 1990. This act covers any plant, animal, or other “viable biological material,” such as a virus, that disperses to an aquatic ecosystem in which it is not historically found. In contrast to the Lacey Act provisions, a nonindigenous species does not have to be from a foreign country. To be termed a nuisance, a nonindigenous species must threaten the abundance or diversity of native species or the ecological stability or commercial productivity of the infested waters. The act mandates creation of a task force to implement a program to prevent the introduction and dispersal of aquatic nuisance species, but it does not specify who determines which species are a nuisance ( Bean and Rowland, 1997 ).
Crop rotation is an effective tool against herbicide resistance development as it reduces the selection pressure. Resistance to isoproturon in A. fatua was significantly reduced while shifting from rice–wheat (67%) to rice–berseem–sunflower–wheat (8%), sugarcane–vegetables–wheat (9%), and cotton–pigeon pea–wheat (16%) ( Malik and Singh, 1995 ).
Interference is defined here as the detrimental effects of a plant species on another as a result of their interaction, including both competition and allelopathy. In the same light competition is the relationship between two or more organisms in which the supply of a growth limiting factor falls below their combined demands. This is often the case for crops and weeds in soils with low soil fertility (due to mainly degraded sandy soils) and semiarid areas (resulting from soil moisture deficiencies). Three major factors that influence competition are (1) weed factors (weed species, density, onset, and duration of crop–weed interaction), (2) crop factors (crop type, seeding rate, spatial arrangement, and architecture and availability growth factors), and (3) environmental factors [water and light (climate), tillage, soil fertility, and ground cover]. Competition detrimental to crop is enhanced when there is poor timing of application of weed management in the critical period of weed competition and at reduced frequency of weeding. Poor timing of operations coupled with irregular rainfall patterns disrupt weed management practices planned at the farm level. In rice systems, critical times for weeding have been identified generally as a period before tillering, booting, and flowering as it varies with planting system (direct seeding/transplanted) ecology (flooded/irrigated/rainfed). The situation is invariably the same for cassava, maize, and sorghum ( Table 6.1 ).
Government Legislation and Regulations in the United States
Robert L. Zimdahl , Cynthia S. Brown , in Fundamentals of Weed Science (Fifth Edition) , 2018
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There are numerous reports in the veterinary medical literature of H. perforatum causing photosensitization in domestic animals and in some locations it is considered a noxious weed . Wet and/or desiccated plant tops can also cause photosensitization in humans, ruminants, horses, and other mammals. Onoue et al. (2011) , using in vitro methods, showed that hypericin, pseudohypericin, and hyperforin had photoreactivity when exposed to 250 W/m 2 of sunlight. In sunlight, quercetin attenuated the generation of singlet oxygen by hyperforin and quercetin had no effect on hypericin. The photosensitizing chemical is hypericin, a phenanthroperylenequinone that has complex physical chemical behavior ( Ernst, 2000; Theodossiou et al., 2009 ). In most bioassays hypericin is present as a monosodium salt. The maximum absorbance of hypericin salts is 548 and 591 nm in ethanol solution and it has red fluorescence at 594 and 642 nm. Hypericin associates with proteins (albumen, low-density lipoprotein, etc.) and has red fluorescence. In light, it has a high triplet quantum yield. It is an efficient singlet oxygen producer and superoxide anion generator, and these radicals can trigger apoptosis and cellular necrosis. Hypericin can also cause phototoxicity in the lens and retina, thereby damaging the eye ( Ehrenshaft et al., 2013 ). Damage to proteins in the lens of the eye is not repairable and temporal summation results in cataracts due to damage to cx-crystallin protein in the lens. Using self-reporting information, a study showed that there is an association between cataracts and the use of H. perforatum extract ( Booth and McGwin, 2009 ). Photosensitization is a dose-limiting side effect of H. perforatum extracts. There are reports of photosensitization occurring after oral use of phytopharmaceutics containing H. perforatum—both were uses of extract prepared for topical use ( Ulbricht et al., 2010 ).
Weeds from the Orobanchaceae family are serious parasitic pests in crop production, e.g., Striga asiatica (L.) Kuntze, Striga hermonthica (Del.) Benth and S. aspera (Wild) Benth ( Rodenburg and Johnson, 2009 ). There is another group of weeds that produce chemicals that are detrimental to crops such as P. hysterophorus with its allelopathic effect but Desmodium spp. has allelopathic effect on other weeds, e.g., S. asiatica and S. hermonthica. Allelopathic effect of Desmodium spp. to Striga spp. has been utilized to develop a push–pull technology, which is a climate smart weed management technology ( Khan et al., 2011; Pickett et al., 2014 ). Under the push and pull technologies the weeds are used to interfere with germination of parasitic weeds to enhance crop growth and they provide competition useful for increasing growth.
7. Other Crop Seed: Any seed that comprises 5% or less of the product by weight can go unnamed. Smaller seed amounts, other than pure seed and weed seed, are combined in this percentage.
14. Sell By Date: Each state allows seed to be sold for a fixed number of months after the initial testing or retesting. Allowances vary, and some states require tags carry “sell by” dates. Seed tags include these dates alongside state-specific listings.
11. Guaranteed Analysis: Seed tags on all-in-one, fertilizer-inclusive products include a guaranteed analysis of the fertilizer and soil amending ingredients. To help consumers compare products easily, all fertilizer product labels carry three numbers denoting the fertilizer’s N-P-K ratio — the proportion of the nutrients nitrogen (N), phosphorus (P) and potassium (K). These numbers reflect each nutrient’s percentage by weight. Learn more about understanding fertilizer information from Pennington Fertilizer by reading Numbers to Grow By: Understanding Fertilizer Labels.
What a Seed Tag Tells About Grass Seed
Choosing the best grass seed for your lawn projects can seem overwhelming when you’re faced with so many choices in local stores. Differences in packaging, products and applications can complicate even the simplest comparisons. The bag itself provides important information about the product, the technology behind it and the types of projects it suits best, such as patching and repairing or seeding new lawns. But labels aren’t the only way to determine the best investment for your time and money. Products also carry seed tags to tell you more about what’s inside the package.
15. Name and Address of the Seed Company
10. Noxious Weeds: Noxious weeds are categorized by state and listed separately on the seed tag. Noxious weeds are regulated and may be restricted or prohibited from state to state. Seed tags note the name and the number of seeds found per pound during testing. This is different than the other items on the seed tag that are calculated by percentage of total package weight.
1. U.S. Department of Agriculture Agricultural Marketing Service, Federal Seed Act, issued March 1940, amended August 1988, revised April 1998.
The following label properties and their references are listed in the same order as they would appear on the bag of seed:
For this reason, if a rate of 2-4 lbs. of seed is recommended for 1,000 square feet of bare ground, then it is wise to go with the higher rate, as not all of the 2 lbs. of seed will germinate.
Typical layout of a grass seed label. Note that only one cultivar- Transition 2400 variety of ryegrass, is listed. The other seed varieties are not identified as to which cultivar they are.
Purity– This is the % by weight per bag of the particular species of grass seed. In the sample label, the purity of the creeping red fescue is 49.17%. If the whole bag weighed 100 lbs., then 49.17 lbs. would be creeping red fescue.
An informational resource for your gardens and home
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Being able to understand the information on a grass seed label will help in selecting a high-quality seed. All mixes and blends of grass seed are not of the same quality, but all seed labels must list certain information which will enable the buyer to decide whether that particular seed is of a quality suitable for their needs. It may not be necessary or practical to use a high-quality seed in all situations, but the information on the label will still be useful.
Label of ryegrass blend consisting of seed coated with a substance to enhance retention of moisture on the seed coat to help ensure optimum germination. The weight of the coating is 50 % of the bag contents.