Theo van Hintum , Frank Menting , in Developments in Plant Genetics and Breeding , 2003
Because of the high similarity of tomato virus isolates, a common origin seems likely although where this origin is located is still unclear. The extent of PepMV distribution in Peru, together with the fact that many of the wild Peruvian Lycopersicon populations sampled were isolated and had not been manipulated by man, led to the conclusion that this virus has been present in the region for a long time and that other factors might be involved in its spread. Myzus persicae does not transmit PepMV. In southern Spain a faster spread of PepMV was observed in bumble-bee pollinated greenhouses than in those with no pollinator insects.
Transmission through seeds by either cultivated crops or wild species is an important parameter for the development of epidemics, as plants grown from infected seeds constitute a primary source, in the crops or at their proximity, from which the virus can be efficiently disseminated by aphids. Transmission of CMV through seeds has been described for several species, based on biological or serological techniques ( Palukaitis et al., 1992 ), and more recently by RT-PCR detection of the virus. Testing ungerminated seeds for the presence of the virus is pertinent from an agronomic point of view but can lead to overestimation of seed contamination , due to contamination of the seed coat, even if, in the case of CMV, it is generally admitted that the virus is too unstable to remain viable as an external contaminant of the seeds. True transmission of CMV through seeds, that is, by the embryo, has been clearly established for bean, spinach ( Yang et al., 1997 ), lentil ( Makkouk and Attar, 2003 ), lupin ( O'Keefe et al., 2007 ), and more recently, pepper ( Ali and Kobayashi, 2010 ). Detection of the virus in seed lots or in plants germinated from seeds has also been documented for common bean, Vigna unguiculata and V. radiata ( Abdullahi et al., 2001; Babovic et al., 1997; Bashir and Hampton, 1996; Bhattiprolu, 1991; Chalam et al., 2008; Lahoz et al., 1994 ); pea and faba bean ( Latham and Jones, 2001 ); chickpea, vetch, and several clovers ( Latham et al., 2001 ); tomato ( Park and Cha, 2002 ); alfalfa ( Jones, 2004a ); butterfly pea ( Odedara et al., 2007 ); and hull-less oil pumpkin ( Tóbiás et al., 2008 ). Transmission rates are generally quite low (below 2.5%), although sufficient to successfully initiate epidemics, but higher rates were reported for lentil (up to 9.5%), tomato (8%), spinach (15%), and cowpea (21%).
7.1 Seed Transmission
Adusumilli N. Rao , . David E. Johnson , in Advances in Agronomy , 2017
The category of research material has, in specific cases, its own regeneration problems. Material with male sterility will need maintainer lines; addition lines can lose the added chromosome; chlorophyll and other mutants can have problems in reaching the generative stage; lethal mutants can only be regenerated via heterozygotes, etc.
Store the plates in the dark at 4 °C for 48–72 h to stratify the seeds, which promotes even germination.
Yu Gao , Jenny C. Mortimer , in Methods in Cell Biology , 2020
Maps should be based on scouting or with drones outfitted with a video camera. If using drones, the suspected weedy patches should be ground-truthed. Your knowledge of individual fields is the most important tool you have to identifying weedy areas.
Yet this is the final time to do something about the weeds in the field.
If weeds and their seeds are not removed prior to harvesting, then preventing their spread within the field or from field to field is important. Limiting seed spread in the field requires knowing what portions of the fields are infested. One method is to map the field before harvest. This can be done in advance of harvest, by marking infested areas in the field on a map and then planning a strategy to avoid contamination of the weed-free areas.
Harvest the weed free portion of the fields first, leaving the weedy portions for last to prevent further spread of weed seeds. After harvesting the infested patches be sure to thoroughly clean the combine to remove as many weed seeds as possible (video:weed seed combine cleaning).
The Syngenta soybean herbicide portfolio also includes Boundary® 6.5 EC, BroadAxe® XC, and Prefix® herbicides, for effective weed control across a range of geographies,soil types and trait systems. Sequence® herbicide also delivers knockdown and residual control of weeds such as pigweed, crabgrass and annual grass in soybeans.
For dicamba-tolerant soybeans, we recommend Tavium® Plus VaporGrip® Technology herbicide, the market’s first premix residual dicamba herbicide. Through the contact control of dicamba, Tavium manages the emerged weeds you see, and through the residual control of S-metolachlor, it manages the weeds you don’t see yet. This powerful combination provides up to 3 weeks longer residual control than dicamba alone.
Plan For Next Year
Taking these preventive actions to minimize contamination from weed seed will help ensure the hard work you’ve put into this season pays off and can help prevent weeds from growing on your farm in the future.
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If you do see weeds in your fields at harvest, consider some of these tips outlined by the United States Department of Agriculture: