While onion thrips are primarily known to spread tospovirus, such as Tomato spotted wilt virus, they also contribute to the spread of bacterial pathogens such as center rot, and fungal pathogens such as Stemphylium leaf blight. Abamectin and cyantraniliprole have provided moderate to excellent control of onion thrips larvae and adults, and had a residual activity of 57d. Spirotetramat is systemic with a residual activity of >10d, but it does not work well against adult onion thrips or late in the season when plants are maturing. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about growing onions. Please switch to a supported browser: Chrome, Edge, Firefox, Safari. In India, the major natural enemies of onion thrips in onion and garlic were parasitoids (>80%) rather than predators (16%). In our 2-yr study, the incidence . Extensive feeding by onion thrips not only results in plant stunting and reduced bulb weight, but it also predisposes onion plants to various fungal and bacterial pathogens that further decrease yield. Also, do not co-apply insecticides that need to move into the plant including Movento, Agri-Mek, Minecto Pro, Radiant or Exirel with chorothalonil (= Bravo) as it reduces the efficacy of the insecticides. In many cases, infestation of onion thrips begins along field edges rather than other parts of the field (Nault and Shelton 2012). UC ANR Publication 3453. Whitney Cranshaw, Colorado State University, Bugwood.org. Onion thrips adults emerge from overwintering sites in the spring and may fly to colonize weed hosts and volunteer onion plants before subsequent generations infest onion crops (Larentzaki etal. Adults often fly to and land on clothes or exposed skin because of the thrips attraction to white and yellow colors (Rueda and Shelton 1995). Arrhenotokous onion thrips that developed on onion produced more progeny and the population developed significantly faster on onion than on cabbage (Li etal. UC ANR Publication 3453. Knowledge of action thresholds for onion thrips can help onion growers optimize insecticide applications and other management tactics. Guelph Reductions in nitrogen levels in plants have reduced populations of insects (Mattson 1980), and this has been shown to be true for onion thrips in onion. 1996), tomato yellow fruit ring virus (TYFRV; Golnaraghi etal. Managing resistance to insecticides is critical given that this is the principal tactic used to manage thrips. Information for commercial vegetable production in Ontario, Elaine Roddy In Greece, only arrhenotokous onion thrips populations successfully transmitted TSWV (Chatzivassiliou etal. (, Onion thrips management- Part I: Identification and monitoring, Effect of neem based botanicals, chemicals and bio-insecticides for the management of thrips in onion, Integrated pest management (IPM) in field crops, Characterization of a tospovirus isolate of, Cornell International Institute for Food, Agriculture and Development, Cornell University, Developing economic thresholds for onion thrips in Honduras, Observations on some predators and parasites of, Straw mulch and reduced-risk pesticides impacts on thrips and, Injury and control of onion thrips (Thysanoptera: Thripidae) on edible podded peas. Onion thrips are one of the biggest pest problems in onion production. According to preliminary research from Cornell University in New York State, IYSV infected bulbs were 8 to 33% lighter when compared to uninfected bulbs. Onion thrips ( Thrips tabaci) are an important annual pest of onion. 35). Inspection of onion transplants for presence of thrips and discarding the infested ones may also be useful (Larentzaki etal. 2Schwartz, H.F. and Mohan, S.K. Stemphylium leaf blight symptoms include tan, water-soaked lesions on the onion foliage. 2007). 2009), while it may take 510d under cooler field conditions as reported in Utah (Alston and Drost 2008). Whitening of onion leaves from the feeding of thrips. Published by Oxford University Press on behalf of the Entomological Society of America. 2008), and males are 0.7mm in length. The graph below shows the results of the 2011 onion thrips insecticide trial conducted by the MSU Vegetable Entomology lab. The action threshold indicates the pest population level a grower should start treatment to prevent significant crop loss and is necessary for reducing insecticide resistance. For each application, the pesticides were tank mixed with Syl-Tac 1 % v/v and applied with a CO2 pressurized backpack sprayer equipped with a fan nozzle. 2008). Some onion thrips populations exclusively utilize a single plant species like tobacco (Brunner etal. Photograph by Brian A. Nault, Cornell University. 519-766-5337 Use trap crops. Funding for this research was provided by the USDAs Specialty Crop Block Grant Program. Host plant resistance is another tactic that has received attention, but no onion cultivars that have a high level of thrips resistance are commercially available. In some instances, arrhenotokous and thelytokous onion thrips populations can occur in the same field (Nault etal. [email protected] Movento has to be tank-mixed with a non-ionic (penetrating) surfactant to maximize leaf uptake since this product moves systemically in the plants. In the United States, Jacobson and Kennedy (2013) demonstrated that thelytokous populations of onion thrips also could transmit TSWV; however, populations varied in their ability to do so (range 0 to 45%). Larvae are often more likely to be killed by insecticides compared with other stages. Due to loss of cell contents, feeding by thrips reduces the ability of plant to photosynthesize and can thus reduce yield, especially when extensive feeding occurs during bulb formation of onions. Thrips. (Fok etal. Thrips on the mesh are visualized using a hand lens or a microscope and then counted. Onion cultivars with glossy and semi-glossy leaves have lower levels of epicuticular waxes, especially the wax ketone hentriacontanone-16, compared with standard nonglossy cultivars (Damon etal. In New York, 25 weed species supported reproductive populations of onion thrips, especially Brassica weed species such as Barbarea vulgaris Ait. Reports of their host range vary from more than 140 plant species in over 40 families (Ananthakrishnan 1973) to more than 355 species of flowering plants (Morison 1957). In contrast, plant pathogens are controlled on a calendar schedule and are advised to apply fungicides early in the season. A study in New York identified a number of cultivars considered partially thrips-resistant (OLYS05N5, Tioga, Peso, Calibra, Vaquero, Cometa, Medeo, NMSU 03-52-1, Delgado, T-433, Colorado 6, Arcero, Mesquite, White Wing, and Granero; Diaz-Montano etal. Thus, they tend to be more problematic in the western growing regions of the U.S. and are considered to be the most damaging insect pest of onions in California.1Cool weather slows their development, and heavy rain or overhead irrigation can significantly lower populations in an onion planting. Onion thrips also transmits Iris yellow spot virus (IYSV) (Bunyaviridae: Tospovirus), which further exacerbates the damage they cause and can ultimately result in complete crop failure. In contrast, onion thrips attack potato, sweet potato, and mustard, but none are damaged to a level that would routinely cause economic damage. Adults are yellow to brown, about 1.5 mm long, about 0.3 mm wide, with fringed (hairy) wings. We thank John Capinera (Professor Emeritus, University of Florida), Joe Funderburk (Professor, University of Florida), Gaurav Goyal (Agronomist, Dekalb), and Morgan Conn (Doctor of Plant Medicine Program, University of Florida) for their valuable suggestions and comments on early versions of this manuscript. The first and second instars are active feeding stages. Cal Poly strawberry research: Can robots kill pests? A. Shelton A. M. Gangloff-Kaufmann J. L. Clark M. E. Werren J. L. Cabrera-La Rosa J. C. Kennedy G. G.. Paibomesai M. McDonald M. R. Tesfaendrias M.. Patel N. V. Pathak D. M. Joshi N. S. Siddhapara M. R.. Pourian H. R. Mirab-balou M. Alizadeh M. Orosz S.. Pozzer L. Bezerra I. C. Kormelink R. Prins M. Peters D. Resende R de O. de Avila A. 519-350-7134 Thrips feeding damage affects the leaf quality of green onions because of the formation of feeding scars.1Thrips are also a vector of the Iris yellow spot virus on onions. Guelph ), strawberry (Fragaria ananassa), sweet potato (Ipomoea batatas), turnip (Brassica rapa var. Utah State University extension and Utah Plant Pest Diagnostic Laboratory, Logan, UT. Spirotetramat (Movento) is a good example of an insecticide that is effective against larvae, but much less so against adults (Guillen etal. Females lay eggs singly by inserting them into leaf tissue. Because thrips hide under folded leaves and near the base of the leaves, it can be difficult to get insecticides into those protected spaces where thrips are feeding.3, Insecticide applications should be scheduled based on scouting observations. At the end of the season, there was a significant decrease in green tissue across all treatments. A number of synthetic insecticides are registered for control of onion thrips in the United States (Table 2). Onion thrips can also transmit several plant pathogens that reduce onion bulb size and quality. However, because of the differences in spray recommendations for onion thrips and plant pathogens, it can be difficult for growers to implement a spray program that effectively combines both management approaches. A. For large onion fields (>2ha), 10 sampling sites with five plants per site (total of 50 plants per field) has been recommended (Rueda and Shelton 1995). The second instar is larger and yellow (Patel etal. Start early! 2011). The pest status of onion thrips can be attributed to its polyphagous nature, high reproductive rate, short generation time, high survival of cryptic (nonfeeding prepupa and pupa) instars, ability to reproduce without mating (parthenogenesis), ability to transmit plant pathogens, and development of resistance to insecticides (Morse and Hoddle 2006, Diaz-Montano etal. June 1, 2018. Therefore, measures against onion thrips should also be considered while planning control of A. porri (Thind and Jhooty 1982). Thrips thrive when conditions are hot and dry. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. [email protected] 2006) and yield losses in individual fields can range from insignificant to 60% (Mohan and Wilson 1989) and even up to 100% (Pozzer etal. Viruliferous adult thrips are capable of transmitting IYSV for life. There were eight different treatment combinations with the following insecticides: Agri-Mek, Lannate, Movento, Radiant, Tolfenpyrad (an experimental product), and Vydate. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Cornell integrated crop and pest management guidelines for commercial vegetable production. Thrips may also be found on the older leaves that are folded over. The spray trial was conducted in a commercial onion field in Michigan and consisted of 8 different spray programs, with varying action thresholds. While onion thrips prepupal and pupal mortality was high (>90%) in the high nematode concentration treatments in the laboratory, there was no effect of nematodes on thrips mortality on plants grown in the controlled environment (Kashkouli etal. Prune off galled, rolled terminals of Indian laurel fig during winter to greatly reduce thrips damage the next summer. Onion thrips is one of the most economically important pests of onion. Additionally, thrips infestations tend to be higher near the field borders early to mid-season, and then they eventually disperse within the field. 2). 1B). 2014). The portion of insecticide expenditure used to manage thrips . 2013). Prune during specific times of the year to help control certain thrips. A.. Srinivasan R. Sundaraj S. Pappu H. R. Diffie S. Riley D. G. Gitaitis R. D.. Trdan S. Valic N. Zezlina I. Bergant K. Znidarcic D.. Ullman D. E. Cho J. J. Mau R.F.L. In New York, there are six to eight generations per season (Hoffmann etal. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. However, onion fields transplanted with early-maturing cultivars are harvested much earlier than direct-seeded fields and often require few to no insecticide applications (B.A.N., unpublished). Onion thrips adults and larvae can be visually identified and counted more easily after opening the neck of the onion plants (Shelton etal. 2012). In Jordan, integration of entomopathogenic fungi and sublethal doses of neem tree extracts (botanicals) effectively controlled onion thrips (Al-mazra awi etal.