UC IPM pest management guidelines: Onion and garlic. 2009). Figure 1. 2014). Onion thrips have an extremely wide host range compared with other thrips species. The CTD is calculated by adding up the thrips-days on the latest sampling date. Heavy rains have been shown to wash onion thrips from plants (Harris etal. 2006). Feeding on leaves also can create an entry point for plant pathogens (Orloff etal. A.. Jacobson A. Booth W. Vargo E. L. Kennedy G. G.. Krishna Moorthy P. N. Shivaramu K. Krishna Kumar N. K. Ranganath H. R. Saroja S.. Larentzaki E. Shelton A. M. Musser F. R. Nault B. On sweet onions grown in the southern U.S. the recommended action threshold is 5 to 10 larvae per plant, and for green onions, applications should begin at the first sign of feeding damage.1,2,3, Processors may have specific recommendations for scouting for thrips. Feeding damage caused by onion thrips, T. tabaci. 2003). June 1, 2018. Females can lay between 25 and 100 eggs. Thrips feed on the leaves of onion plants, causing the leaves to turn white (Figure 1). The graph below shows the results of the 2011 onion thrips insecticide trial conducted by the MSU Vegetable Entomology lab. Plate J. Musser F. R. Larentzaki E.. Singh B. K. Pandey J. G. Gupta R. P. Verghese A.. Smith E. A. Ditommaso A. Fuchs M. Shelton A. M. Nault B. All the treatments with fungicides began with Miravis Prime and were alternated with Bravo Weather Stik weekly. There are biological differences between onion thrips populations that reproduce via arrhenotoky and thelytoky. Enter your email address to subscribe to this blog and receive notifications of new posts by email. Center for Integrated Pest Management. At the Muck Crops Research Station in the Holland Marsh, onion thrips didnt reach action thresholds for treatment until the 19th and 20th of July in 2011 and 2012 , respectively; however, this may be earlier or later depending on the weather and your location in Ontario. For example, when arrhenotokous and thelytokous onion thrips populations developed on either onion or cabbage, the arrhenotokous population performed better on onion than on cabbage, whereas the opposite was true for the thelytokous population (Li etal. Onion thrips. A. Shelton A. M.. Diaz-Montano J. Fuchs M. Nault B. Acknowledgements: We thank the cooperating onion grower who allowed us access to their field for the spray trial. Comparative efficacy of neem products, essential oils and synthetic insecticides for the management of onion thrips, Thrips management alternatives in the field, National Center for Appropriate Technology (NCAT), ATTRA - National Sustainable Agriculture Information Service Publication #IP132, USA. Record the number of thrips (both nymphs and adults) per plant on 100 plants across the field, making sure to pull onion leaves apart to reveal the youngest leaf tissue. 2003, 2006), Ontario, Canada (MacIntyre-Allen etal. Photograph by Brian A. Nault, Cornell University. Feeding damage from onion thrips can reduce yields considerably. 1935, Passlow 1957). Onion thrips, T. tabaci, are easier to observe and count after opening the neck of an onion plant. 2014). Therefore, it is recommended that applications of insecticides should alternate between products with active ingredients belonging to different mode of action groups (insecticide classes) to help prevent or slow the development of insecticide resistant thrips populations.1,2,3,4. Neem oil is the organic pesticide or a synthetic pesticide containing spinosad is most effective. When thrips populations reach a certain threshold level, then the trap crop could be sprayed with an insecticide or disked under (Alston and Drost 2008). In contrast, onion thrips attack potato, sweet potato, and mustard, but none are damaged to a level that would routinely cause economic damage. Develop within leaf tissue with one end near the leaf surface. The University of California IPM guidelines for processing onion recommend evaluating ten plants from four different areas of the eld, counting the numbers of thrips on all leaves of each plant. 1, Onion thrips control in onion -Trial I, 2010, Insecticide efficacy and timing of sprays for onion thrips control, Impact of insecticide efficacy on developing action thresholds for pest management: A case study of onion thrips (Thysanoptera: Thripidae) on onion, Guidelines for managing onion thrips on onion, Veg Edge. 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 have very distinctive feeding behaviors by punching through the leaf surface and then extracting sap from plant cells. Harsimran K. Gill, Harsh Garg, Arshdeep K. Gill, Jennifer L. Gillett-Kaufman, Brian A. Nault, Onion Thrips (Thysanoptera: Thripidae) Biology, Ecology, and Management in Onion Production Systems, Journal of Integrated Pest Management, Volume 6, Issue 1, March 2015, 6, https://doi.org/10.1093/jipm/pmv006. Thrips prefer to feed on the young, inner leaves of onion plants. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. dennis.vandyk@ontario.ca Mulches have many benefits including weed suppression, conserving soil moisture, increasing soil temperature, and reducing soil erosion. THRIPS: Thrips populations are beginning to build up in onion fields throughout the region. Although there are many species of thrips, the western flower and onion thrips are the most common species in North America.1Both species have fairly wide host ranges, feeding on both broadleaf and grass plants, including alfalfa, common bean, grains, grasses, and various weed species.2. 2001). Overall, there was low onion thrips pressure throughout the season, and when pressure is low, growers may be able to effectively control onion thrips with Radiant only. PLEASE NOTE : We provide ONvegetables.com (Blog) free of charge and for information purposes only to individuals interested in commercial vegetable production. 2). Note adjacent fields that have these different crops and keep an eye on harvesting activities of these field and forage crops. Thus, it is important to scout early, so you arent playing catch up the rest of the season. Get one year of Vegetable Growers News in both print and digital editions for only $15.50. 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). Symptoms of Stemphylium leaf blight include tan water-soaked lesions on the leaves, and premature leaf die back, resulting in severe yield losses (Fig. 1B). Spirotetramat is suggested for use early in the season when it can easily move systematically in the plant and also adult populations are often lower than they are in late season. botrytis L.), celery (Apium graveolens), cotton (Gossypium spp. IYSV is not transmitted via onion seeds (Gent etal. 4Egel, D.S. Delegate was found to be very effective for controlling thrips. To see our selection of onion plants available or place your orders, visit our Web site. 2012b). In Ontario (Canada), insecticide resistance in onion thrips populations from onion fields was reported for -cyhalothrin, deltamethrin, and diazinon (MacIntyre-Allen etal. Guidelines for 2020 Onion Thrips Management (pdf; 380KB) Asparagus Beets Broccoli Brussels Sprouts Cabbage Carrots Cauliflower Cucumbers Ridgetown This means two applications of Movento can be made to onions within a growing season, and these should be done consecutively, 7 to 10 days apart, for insecticide resistance management purposes. Please switch to a supported browser: Chrome, Edge, Firefox, Safari. (, ENTFACT-317. A. The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707. This is the second part of the Onion Thrips Management article, developed from material presented at the Muck Conference in Bradford, ON in early 2013. UC ANR Publication 3453. These cultivars require fewer insecticide applications, which not only lower the control costs, but they might delay the development of insecticide resistance and may enhance biological control by protecting biocontrol agents (Panda and Khush 1995, Diaz-Montano etal. The most common reproductive mode is thelytoky, a parthenogenesis in which females are produced from unfertilized eggs. In some instances, arrhenotokous and thelytokous onion thrips populations can occur in the same field (Nault etal. 1). Whitening of onion leaves from the feeding of thrips. Photograph by Brian A. Nault, Cornell University. Shearing stimulates thrips-susceptible new growth. For more information, visit https://extension.msu.edu. In a field experiment in India, efficacy of neem seed powder extract, neem soap, essential oils from basil or tulsi (Ocimum tenuiflorum syn. Regardless, it is important to communicate the counts to the growers, so that they can make an informed decision, even if the counts havent reached the threshold. To prevent further insecticide resistance, growers must rotate insecticide classes and implement action thresholds. 1A). This browser is no longer supported. Larvae are often more likely to be killed by insecticides compared with other stages. Females lay eggs singly by inserting them into leaf tissue. elaine.roddy@ontario.ca In severe cases, IYSV may cause leaves to become necrotic and plants to mature prematurely (Fig. Straw mulch has been used to reduce thrips infestations in onion (Larentzaki etal. Efficacy of entomopathogenic fungi for the management of onion thrips, Weed hosts for onion thrips (Thysanoptera: Thripidae) and their potential role in the epidemiology of, Association of thrips with purple blotch infection on onions plants caused by, Possibilities for biocontrol of the onion thrips, Mitteilungen der Deutschen Gesellschaft Fr allgemeine und Angewandte Entomologie, Phylogenetic analysis based on mitochondrial COI gene sequences in. 1987). 1935, North and Shelton 1986). 2013). Notably, the extent and frequency by which onion thrips damage crops varies across plant species. Utah State University extension and Utah Plant Pest Diagnostic Laboratory, Logan, UT. Pupation normally takes place at the base of the onions apical meristem or within the soil (Rueda and Shelton 1995). In onions, waiting until you see crop damage is not recommended. As eggs mature, they develop an orange tinge and eventually reddish eye spots become evident. Egg: White to yellow, kidney-bean shaped, microscopic in size. WSU ONION ALERTS. Movento has to be tank-mixed with a non-ionic (penetrating) surfactant to maximize leaf uptake since this product moves systemically in the plants. Another difference observed between arrhenotokous and thelytokous populations of onion thrips was the ability to transmit Tomato spotted wilt virus (TSWV), a Tospovirus closely related to IYSV (Chatzivassiliou etal. Onion thrips feed on plant tissue which results in silvery leaf scarring and reduces the plants ability to photosynthesize. Published by Oxford University Press on behalf of the Entomological Society of America. Some studies have indicated that onion thrips play a role in transmitting Pantoea spp. Onion thrips also contribute to disease spread in onion fields. Thrips overwinter on winter grains, clover and/or alfalfa. Photograph by Joseph Ogrodnick, Cornell University. Adults are elongated with body color varying with temperature from yellow to brown (Murai and Toda 2002). The pupal period varies from 310d among different geographical regions (Patel etal. aIRAC MoA, Insecticide Resistance Action Committee mode of action classification (http://www.irac-online.or/). North Carolina State University, Raleigh, NC. Plant architecture (e.g., cultivars with flat sided leaves and compact growth habits harbor more thrips as compared with cultivars with openly spaced leaves) may also impact thresholds. 2016. Thrips cause damage through direct feeding on leaves and bulbs and indirectly spread the diseases. This information is for educational purposes only. The common feature of these treatments is that they all had Radiant in the rotation either at weeks 3-4 or 5-6, applied at a time when thrips population pressure was the highest during the summer. 2013). Adult females lay eggs in plant tissue, and the larvae that hatch feed on the leaf tissue (Figure 2).2There are two stages of feeding larvae (instars I and II) that collect under the folds of onion leaves or in the densely packed area where the leaves emerge from the neck of the bulb. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. Incidentally, the word thrips is both singular and plural. 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. 2005a), New Zealand (Martin etal. 1992, Wijkamp etal. 2010). Stemphylium leaf blight symptoms include tan, water-soaked lesions on the onion foliage. The adult stage overwinters in the soil in onion fields (Larentzaki etal. Movento is more effective at suppressing larval onion thrips, therefore it is recommended that its used in the early part of the growing season before thrips population pressure peaks. The key to minimizing losses caused by onion thrips will involve the combination of cultural and chemical controls, and use of resistant and tolerant varieties that suppress onion thrips populations and reduce feeding damage. © 2022 Great American Media Services & Vegetable Growers News. 2). February 15, 2012. An action threshold of 35 larvae per plant is recommended for thrips tolerant varieties, 25 for moderately susceptible varieties, and 15 per plant for highly susceptible varieties. Growers should evaluate data from multiple locations and years whenever possible. Thrips thrive in hot, dry weather, so you may need to shorten the time between scouting events. Natalie Constancio and Zsofia Szendrei, Michigan State University. Onion thrips, T. tabaci, damaged onion plant (left) compared with a nondamaged onion plant (right). 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. 1999). Onion thrips can reproduce asexually (parthenogenesis) and sexually. Feeding damage also predisposes plants to foliar diseases. Action thresholds suggested for onion thrips, T. tabaci, management in dry bulb onion production systems. Christy Hoepting from the Cornell Cooperative Extension Vegetable Program gave a very informative presentation on management and on-going research in New York State for onion thrips. To make management decisions for onion thrips, in situ examination of the onion plant is required. Read more Marion Paibomesai, Vegetable Crops Specialist, OMAF and MRA, Michael Tesfaendrias, Muck Crops Research Station, University of Guelph and Dr. Mary Ruth McDonald, University of Guelph. In Colorado, recommendations are based on the relative susceptibility of the onion varieties planted. In New York, a 3050% reduction in bulb yield (smaller bulb sizes) can occur due to severe thrips damage (Nault and Shelton 2008; Fig. Relationships between insect predator populations and their prey, Comparative field effects of various entomopathogenic fungi against, Pesticide: Environmental impacts and management strategies, Organic mulches: An innovative pest management strategy, Impact of different organic mulches on the soil surface arthropod community and weeds, Effect of organic mulches on soil surface insects and arthropods, Cross-resistance and baseline susceptibility of spirotetramat in, Specific insect-virus interactions are responsible for variation in competency of different, Temperature development and damage rates of onion thrips, Coexistence of sexual individuals and genetically isolated asexual counterparts in a thrips. Turpentine will repel the thrips into the collection vial, where they can be counted. 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. 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. Removing or destroying debris and volunteer onion plants after harvesting eliminates potential overwintering sites (Larentzaki etal. In cooler, wetter weather, thrips numbers are unlikely to rise as quickly over time, but it is still important to scout diligently. In China, the SZ-26 strain of B. bassiana significantly lowered the population of larval and adult stages of onion thrips under greenhouse conditions (Wu etal. Recently, onion thrips have been shown to spread Stemphylium leaf blight by picking up fungal spores on the outside of the body and moving the spores between onion plants. sweet corn, cucumbers, melons, pumpkins, squash, beans, peas, asparagus, Amanda Tracey This approach might only work if the trap crops are large and more attractive than the onion plants. Adults can y quickly when disturbed and also have a thicker cuticle (external covering) than larvae, which makes them more difficult to kill. 2012). Early in the season, thrips larvae are somewhat protected from predators under folded leaves and in the tight area where leaves emerge from the neck. In addition, sprinklers used for water application may promote a crust on the soil surface, which reduces the access of pre-pupae and pupae to seek shelter in the soil. ), cucumber (Cucumis sativus), garlic (Allium sativum), kale (Brassica alboglabra L.H. Additionally, water stress may impact the nutritional quality of onion plants and also increases the attractiveness of the plants to thrips (Lewis 1973). All of our insecticide treatments decreased onion thrips numbers significantly relative to the untreated control. 2009). Thrips infestations can reduce onion yield by as much as 20%. 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. In New York, action thresholds for onion thrips on onion vary from one to three thrips larvae per leaf depending on insecticide efficacy (Nault and Shelton 2010). In such situations, bulb size (Gent etal. Photograph by Brian A. Nault, Cornell University. The abdomen is divided into eight distinct segments and has a large posterior segment that is conical in shape. Thrips are very small (<3mm), cream to light brown soft-bodied insects that feed on a wide variety of crops [Figure 1]. Increasingly, research provides evidence that fields infested with onion thrips experience higher disease pressure, indicating that the management of both pests should be considered simultaneously. 2013). In India, the major natural enemies of onion thrips in onion and garlic were parasitoids (>80%) rather than predators (16%). 2003), and Australia (Herron etal. 6). Even a single one is a thrips. Alliums (onions, garlic, leeks), Brassicas (cabbage, broccoli, cauliflower, brussel sprouts, Asian vegetables), Leafy vegetables, Dennis Van Dyk Record the number of thrips (both nymphs and adults) per plant on 100 plants across the field, making sure to pull onion leaves apart to reveal the youngest leaf tissue. All rights reserved. Plants should be evaluated weekly when thrips counts are low, but more frequently when they exceed 20 per plant. The information provided in this communication may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Transplanting onions (Kisha 1977), selecting early-maturing cultivars, or both should expedite the period between planting and harvest, thereby truncating the period that thrips are able to infest the crop. In New York, there are six to eight generations per season (Hoffmann etal. Some onion thrips populations exclusively utilize a single plant species like tobacco (Brunner etal. This threshold value is adjusted based on plant age in that fewer thrips are tolerated on young plants and more thrips are tolerated on mature plants (Kuepper 2004). Howard F. Schwartz, Colorado State University, Bugwood.org, Figure 2. This highlights the need for an effective multiple pest management strategy that focuses on both insect and disease pests simultaneously. In contrast spirotetramat (Movento), methomyl (Lannate LV), and abamectin (Agri-Mek SC) need to be applied at one thrips larva per leaf (a more conservative threshold) to manage infestations (Nault and Shelton 2010, 2012; Table 1). Infestations later in the season are less problematic, as onions can tolerate higher populations of thrips when they are closer to harvest. 1Orlo , S., Natwick, E.T., Godfrey, L.D., Dara, S.K. Some organic mulches also may decrease pest populations by promoting populations of biocontrol agents (Gill etal. Scouting should be done by randomly sampling leaves or whole plants from four or more locations in the field, including field edges where colonization by thrips is likely to occur first. When scouting, sample about 50 plants from at least 10 different locations in the field and then . Onion thrips may serve as a vector of Alternaria porri, the fungus that causes purple blotch. Benefits include making fewer applications, saving time and money, and potentially mitigating insecticide resistance development. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464). Product registrations and guidelines for use change frequently, so growers should consult the most recent label of a product before use.1,3,4, Resistance to insecticides has become a major problem. Effects of nitrogen fertility and crop rotation on onion growth and yield, thrips densities, Onion thrips. Field experiments in Colorado showed that straw mulch application to the center of onion beds at early to mid-bulb growth reduced thrips densities to 33% compared with nontreated plots of transplanted onions. 2013). Thrips larvae feeding on an onion leaf. Research from NY has shown that thrips are likely to overwinter in soils of previous onion fields, as well as on vegetation surrounding these fields. (Fok etal. UC Pest Management Guidelines. 1996). Studies conducted in Germany reported that out of 41 isolates, 36 isolates of entomopathogenic fungi were found pathogenic against onion thrips. Adults are yellow to brown, about 1.5 mm long, about 0.3 mm wide, with fringed (hairy) wings. In Australia, onion thrips from onion fields were resistant to -cypermethrin (164-fold), -cyhalothrin (606-fold), diazinon (27-fold), dimethoate (5.2-fold), although no resistance was reported to omethoate, malathion, and methidathion (Herron etal. 1996), tomato yellow fruit ring virus (TYFRV; Golnaraghi etal. Applying insecticides to onion using a high spray volume will provide better coverage of the foliage and better thrips control. 1987; Fig. 35). After the first fungicide application, treatments are applied at regular intervals as a preventative measure. 2008). Lawande View Show abstract Maize (Zea. Midwest Weed Tech: Weed-fighting strategies, equipment have field day, ASTA helps sow the future of seed technology, Small organic growers give input on ag tech, UF studying horizontal tomatoes, disease resistance. A. porri typically enters onion leaves through stomata and the epidermal cell layer, but fungal penetration becomes easier when the leaf surface has been damaged by onion thrips. 2013). Carter and Sorenson (2013) reported five to eight generations per year in North Carolina. Search for other works by this author on: Effect of different intercropping systems on onion and garlic infestation with the cotton and onion thrips, Effect of application method on the interaction between, ENT-117-08PR. List of insecticides registered for onion thrips, T. tabaci, management in onion fields in the United States. First instars can acquire the virus from an infected plant and the acquisition rate decreases as the larva matures. Adult longevity varies from 1642d on garlic (Changela 1993) and 2830d on onion (Patel etal. Onion thrips are managed through scouting programs prior to insecticide application. New podcast celebrates 50 years of Integrated Pest Management (IPM)! Abstract. Photograph by Brian A. Nault, Cornell University. For example, spinetoram (Radiant SC) can effectively manage onion thrips using a threshold level of three thrips larvae per leaf. In the same study, onions grown following corn rather than wheat in a 1-yr rotation reduced the thrips population because corn removed more nitrogen from the soil than wheat and the lower levels of nitrogen were shown to reduce thrips densities (Buckland etal. Key thrips population management strategies include 1) cultural practices to increase onion plant tolerance and reduce attractiveness to thrips, 2) begin thrips suppression in the early summer before a reservoir of eggs builds up in plants, and 3) use of long-term suppressive strategies that target all life stages of onion thrips (Fig. C.. Rueda A. Badenes-Perez F. R. Shelton A. M.. Schwartz H. F. Gent D. H. Fichtner S. M. Hammon R. Cranshaw W. S. Mahaffey L. Camper M. Otto K. McMilan M.. Shelton A. M. Nyrop J. P. North R. C. Petzoldt C. Foster R.. Shelton A. M. Nault B. , East Lansing, MI 48824 within and among populations of biocontrol agents ( Gill Goyal Spinetoram except the residual activity is shorter provide better coverage of plant material ( Mo ) Goal was to compare the performance of insecticide expenditure used to manage thrips cooking onions, waiting until see Allii Munn in stored onions ( Mayer etal ananassa ), and males are 0.7mm in length kidney-bean,! 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Instar can range from 3 to 4d ( Pourian etal and results smaller. Prime and were alternated with Bravo weather Stik weekly ( sprayed two consecutive weeks ) for management.

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