This Extension bulletin is the result of collaborative work across several departments, including horticulture, plant pathology, crop and soil sciences,
entomology, food science and technology, and agricultural economics. A cross-discipline group called the Vegetable Team led the development of this document and research faculty contributed.
This publication represents the latest information available on the production of short-day onions in south Georgia. The authors would like to extend their thanks to the many people involved in editing, proofing, and putting this document into its final form.
July 10, 2018
Sara Delheimer, Impact Writer for the USDA Multistate Projects, sent the final Impact Statement for the W-2008 multistate project which received the 2018 Western Region Multistate Project Award.
October 1, 2017
Oregon Department of Agriculture has released a new factsheet on Phytomyza gymnostoma. This pest goes by the common name of Allium leaf miner (ALM) or onion leafminer and is one of the most important Allium (garlic, leek, and onion) pests in Europe. In 2015, ALM was found in the United States in Pennsylvania.
June 1, 2015
Overwintering sites of Iris yellow spot virus and Thrips tabaci (Thysanoptera:Thripidae) in Colorado
Iris yellow spot virus (family Bunyaviridae, genus Tospovirus) and its insect vector, onion thrips, Thrips tabaci Lindeman, are of economic concern worldwide in regions where onions (Allium cepa L.) are grown. Several weed species have been described as additional hosts and likely green bridges for survival of Iris yellow spot virus, however, there is little work regarding the overwintering habits and potential of onion thrips as a source of inoculum during the following season. The results of this work confirm onion thrips and Iris yellow spot virus presence near three Colorado onion fields throughout the winter, onion thrips reproduction on six non-allium plant species, and larval acquisition of Iris yellow spot virus from two non-allium plant species. Thrips were monitored by sticky traps during the winter months from 2011 to 2013. Thrips activity seemed to cease when the average temperature was cooler than 0°C and resumed once the average temperature warmed above 0°C. Onion cull piles were constructed and were apparently conducive to survival of thrips, but no live thrips were collected from the piles after onion bulbs began to decay. Iris yellow spot virus was detected by RTPCR in live adult and larval thrips from onion; common mallow, Malva neglecta Wallr.; dandelion, Taraxacum officinale Weber in Wiggers; flixweed, Descurainia sophia (L.) Webb. Ex Prantl; prickly lettuce, Lactuca serriola L.; and salsify, Tragopogon dubius Scop. during the winters from 2010 to 2013. Iris yellow spot virus was detected in prickly lettuce and flixweed. The five weed species were grown from seed in a greenhouse and exposed to viruliferous thrips to elucidate their potential as green bridges. Of the five weeds, Iris yellow spot virus was detected in eight of 15 salsify leaf samples, and in three of six thrips, larval samples reared on the plant. Winter annuals play a role in overwintering survival of onion thrips and Iris yellow spot virus, providing inoculum the next growing season, and weed management during the winter might be warranted.
June 1, 2015
Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a well-known onion pest worldwide. Onion thrips cause both direct and indirect damage to onion by feeding and ovipositing on leaves that may cause green onions (scallions) to be unmarketable and dry bulb onion size to be reduced. Onion thrips can also transmit several plant pathogens that reduce onion bulb size and quality. One of the most economically damaging onion pathogens transmitted by onion thrips is Iris yellow spot virus (Bunyaviridae: Tospovirus). In this article, we discuss onion thrips geographical distribution, host range, biology, damage, monitoring, economic thresholds, and management in onion production.