Studies have found that CTD values over 500 are associated with significant yield losses, which is equivalent to 50 or more thrips per plant per day for 10 days, or 25 or more thrips per plant per day for 20 days.1, Several different insecticide products are available for controlling thrips (Table 1). 2014). An onion leaf infected with a plant pathogen, Stemphylium leaf blight. Westcott D. M. Custer D. M.. Wakil A. Ghazanfar M. U. Kwon Y. J. Islam S. -U. Ali K.. Wijkamp L. van Lent J. Kormelink R. Goldbach R. Peters D.. Wijkamp I. van de Wetering F. Goldbach R. Peters D.. Wu S. Gao Y. Xu X. Zhang Y. Wang J. Lei Z. Smagghe G.. Oxford University Press is a department of the University of Oxford. Onions are annually valued at about $50 million in New York. 2007) and in small grain and hay fields (Shelton and North 1987). For insect pest situations in Ontario, growers and stakeholders are encouraged to follow the crop update published by OMAF and MRA on ONvegetables.com. Prepupae and pupae seek protection in the soil or at the base of onion plants, escaping contact by most insecticides. The first instar is small, 0.350.38mm in length, semitransparent and dull white, changing later to yellowish white (Fig. 2011). A combination of preventative and curative control measures outlined above should not only help in reducing damage caused by onion thrips, but can reduce the spread of plant pathogens and mitigate the development of pesticide resistance. Fauna of New Zealand No. 1987; Fig. 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. 2013). Stemphylium leaf blight symptoms include tan, water-soaked lesions on the onion foliage. 2013). Early detection of a pest problem is a key element for designing integrated pest management strategies. Our goal was to compare the performance of insecticide rotations, so we applied them weekly, regardless of thrips threshold. 2013). Hatching occurs in 23d under laboratory conditions (Pourian etal. The portion of insecticide expenditure used to manage thrips . Photos: Figure 1: (A) An onion infested with onion thrips larvae. Thrips are very small (<3mm), cream to light brown soft-bodied insects that feed on a wide variety of crops [Figure 1]. 2003, 2006). Some onion thrips populations exclusively utilize a single plant species like tobacco (Brunner etal. These methods are more accurate for determining the number of immatures in a sample because adults may have flown away during collection. 2014). 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. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, pathologist and similar professional dealing with this specific crop. Figure 1. Srinivas A. Aziz Qureshi K.E. Guidelines for 2020 Onion Thrips Management (pdf; 380KB) Asparagus Beets Broccoli Brussels Sprouts Cabbage Carrots Cauliflower Cucumbers Carefully pull the onion leaves apart to count thrips. -Z.. Shelton A. M. Zhao J. 2013). 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. Inspection should primarily be concentrated on the youngest leaves in the lowest center part of the neck, which is a preferred feeding site for thrips (Rueda and Shelton 1995). 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). 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). 2016. Adults are elongated with body color varying with temperature from yellow to brown (Murai and Toda 2002). ), strawberry (Fragaria ananassa), sweet potato (Ipomoea batatas), turnip (Brassica rapa var. Combinations of entomopathogenic fungus Paecilomyces lilacinus with nonconventional agents such as Azadirachta indica and diatomaceous earth formulations may be effective for controlling onion thrips (Wakil etal. Mulches have many benefits including weed suppression, conserving soil moisture, increasing soil temperature, and reducing soil erosion. Onion thrips may serve as a vector of Alternaria porri, the fungus that causes purple blotch. 2009). The use of transplants or seeded crops may influence how long protection is needed. A. Shelton A. M.. Diaz-Montano J. Fuchs M. Nault B. Interestingly, there did not seem to be a straightforward correlation between the level of thrips control and onion yield, although treatments 7 and 8 had the highest yields among our treatments. 2012b). To make management decisions for onion thrips, in situ examination of the onion plant is required. First instars can acquire the virus from an infected plant and the acquisition rate decreases as the larva matures. The first and second instars are active feeding stages. 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. 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. Early detection is key to controlling this pest, as populations can explode quickly under ideal conditions. IYSV is not transmitted via onion seeds (Gent etal. 2001). Action thresholds for onion thrips may vary depending on geographic region, cultivar, plant stage, plant architecture, and insecticide efficacy. 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. Thrips are the only vectors of tospoviruses and onion thrips is the principal vector of the tospovirus IYSV in onion (Kritzman etal. Onion thrips that reproduce via thelytoky differ genetically from those that reproduce via arrhenotoky (Toda and Murai 2007, Kobayashi and Hasegawa 2012). Early in the season, control measures can target crop borders, which may slow spread of the pest to the entire field and save money because the entire field is not treated (Shelton etal. For instance, an action threshold level of 30 or more thrips per plant is suggested for the thrips-tolerant varieties, whereas a lower level of 1530 thrips per plant is suggested for susceptible cultivars (Cranshaw 2004). 2006) and yield losses in individual fields can range from insignificant to 60% (Mohan and Wilson 1989) and even up to 100% (Pozzer etal. When these field and forage crops are harvested or start to dry down in late spring/early summer, thrips are likely to migrate into vegetable crops. The results of this insecticide trial indicate that there are multiple insecticide rotations that can achieve good thrips suppression in the field (for example, treatments 5 and 7-8), but since not all products have the same efficacy, the sequence has to be carefully adjusted to achieve the desired results. Egg: White to yellow, kidney-bean shaped, microscopic in size. Thrips are most damaging to yields during the early bulbing stage. 2014). 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. Utah Pests Fact Sheet, Utah State University Extension. MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. 2014). Thrips prefer to feed on the young, inner leaves of onion plants. Thrips thrive when conditions are hot and dry. larvae, minute pirate bug (Orius spp. In Kentucky, development time from egg to adult is estimated to be 20d, with six to eight generations per year (Bessin 2004). Managing resistance to insecticides is critical given that this is the principal tactic used to manage thrips. Severe feeding injury by onion thrips is also associated with tiny black tar spots, which is excrement from thrips (Fig. Larvae are often more likely to be killed by insecticides compared with other stages. Its high reproductive rate, short generation time, and ability to damage onion plants throughout the onion-growing season pose challenges to developing effective management plans. 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. Photograph by Joseph Ogrodnick, Cornell University. Determine the average true leaf stage and divide the number of thrips per plant to get number of thrips per leaf. In NY, there could be 3 to 4 overlapping generations of onion thrips per year with infestation of onions starting in June, meaning that the onion crop, if planted in mid to late April and harvested early September, requires 6 to 8 weeks of protection. 2008). 2008. 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. IYSV causes straw- to tan-colored lesions on onion leaves and spindle- to diamond-shaped lesions on the scapes. June 1, 2018. 2011). At least five plants should be evaluated at each location. To prevent further insecticide resistance, growers must rotate insecticide classes and implement action thresholds. Thrips have developed resistance to commonly used insecticides in some locations, and these products no longer provide adequate levels of control in those areas. Photograph by Brian A. Nault, Cornell University. Benefits include making fewer applications, saving time and money, and potentially mitigating insecticide resistance development. Damage appears as silvery patches or streaks on the leaves (Rueda and Shelton 1995; Figs. Adults are yellow to brown, about 1.5 mm long, about 0.3 mm wide, with fringed (hairy) wings. The second instar is larger and yellow (Patel etal. Onion thrips can also transmit several plant pathogens that reduce onion bulb size and quality. A cumulative thrips-days (CTD) value is calculated by averaging the number of thrips per plant over two successive rating dates; then that number is divided by the number of days between ratings to determine the number of thrips per plant per day (thrips-days). Color preference and using silver mulches to control the onion thrips, Evaluation of sampling methodology for determining the population of onion thrips (Thysanoptera: Thripidae) in Ontario onion fields. In Ontario (Canada), insecticide resistance in onion thrips populations from onion fields was reported for -cyhalothrin, deltamethrin, and diazinon (MacIntyre-Allen etal. Thrips feeding damage affects the leaf quality of green onions because of the formation of feeding scars.1 Thrips are also a vector of the Iris yellow spot virus on onions. Chemical control Control through insecticides is difficult because of thrips' protected location in plants. Symptoms of Stemphylium leaf blight include tan water-soaked lesions on the leaves, and premature leaf die back, resulting in severe yield losses (Fig. 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. Egg stage is 5-10 days. 2003). Onion cultivars with yellow-green, glossy to semi-glossy leaf surfaces and an open neck were less attractive to onion thrips compared with cultivars with blue-green, waxy leaves, and tight necks (Diaz-Montano etal. 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. The threshold on dry cooking onions, leeks and Spanish onions is 1 thrips per leaf. They can attack many garden crops, but most commonly cause serious damage to onions, leeks and garlic. Onion thrips also contribute to disease spread in onion fields. Onion thrips also reproduce via arrhenotoky, a parthenogenesis in which males are produced from unfertilized eggs; females are produced from fertilized eggs. 2). 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. Additionally, when onion thrips feed, they leave open wounds on the onion tissue, creating an entryway for plant pathogens. Center for Integrated Pest Management. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Onion thrips are managed through scouting programs prior to insecticide application. On onion, the average length and width of eggs are 0.23mm and 0.08mm, respectively (Patel etal. In Denmark, biological control of onion thrips was investigated on greenhouse-grown cucumbers (Cucumis sativa) by two species of phytoseiid mites Amblyseius cucumeris and Amblyseius barkeri. 2007). Thorough coverage of plant tissues with insecticides is needed to provide good control. Onion thrips adults and larvae can be visually identified and counted more easily after opening the neck of the onion plants (Shelton etal. All of our insecticide treatments decreased onion thrips numbers significantly relative to the untreated control. In Jordan, integration of entomopathogenic fungi and sublethal doses of neem tree extracts (botanicals) effectively controlled onion thrips (Al-mazra awi etal. During this process, thrips release substances that help predigest the tissue. 2016. 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. Arrhenotokous onion thrips that developed on onion produced more progeny and the population developed significantly faster on onion than on cabbage (Li etal. Information for commercial vegetable production in Ontario, Elaine Roddy 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. The use of insecticides is the most common management tactic for onion thrips infestations in commercial onion production. The reason behind this is likely a combination of factors including a shorter generation time and a reduction in mortality from rain and plant pathogens. This crop update aims to summarize pest reports from different areas of the province when available, including updates from Muck Crops Research Station (MCRS). In New York, there are six to eight generations per season (Hoffmann etal. 2008, Schwartz etal. Scouting for onion thrips is critical to successful control because they are resistant to multiple insecticide classes. Thrips on the mesh are visualized using a hand lens or a microscope and then counted. The density of onion thrips in onion fields can be assessed in multiple ways. -Z. Nault B. Infestations later in the season are less problematic, as onions can tolerate higher populations of thrips when they are closer to harvest. Photograph by Joseph Ogrodnick, Cornell University. potatoes, carrots, rutabaga, turnip, parsnips, radish, horseradish. Cleaning plant debris from the field and the surrounding area may aid in controlling thrips. 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. Prune off galled, rolled terminals of Indian laurel fig during winter to greatly reduce thrips damage the next summer. Cultural practices that help reduce damage from thrips include tilling in plant residue, destroying volunteer onion plants,3and not planting onions near cereal grain fields that can serve as a source of thrips.1As cereal crops mature and senesce, the adult thrips will migrate off of the cereal plants and seek out neighboring green plants, including onions. 2014). Guelph In California, the recommended threshold is 30 larvae per plant during the mid-season. In India, the major natural enemies of onion thrips in onion and garlic were parasitoids (>80%) rather than predators (16%). Field studies in New York produced similar results, showing that colonization of adult onion thrips was delayed one to two weeks and fewer thrips larvae developed in straw-covered plots of onions compared with those with no mulch (Larentzaki etal. Cumulative thrips-days suggested that straw mulch significantly reduced season-long abundance of thrips by 10 to 20% compared with bare soil plots. Develop within leaf tissue with one end near the leaf surface. 4; Cranshaw 2004). 2004), nor is it successfully transmitted mechanically (Gent etal. The minimum interval between applications is seven days, the pre-harvest interval is also seven days and the maximum amount of Movento that can be applied in a single season is 10 fl oz/acre with 5 fl oz/acre as the only approved rate of application. Al-mazra awi M. S. Al-Abbadi A. Shatnawi M. A. Ateyyat M.. Boateng C. O. Schwartz H. F. Havey M. J. Otto K.. Brunner P. C. Chatzivassiliou E. K. Katis N. I. Frey J. E.. Buckland K. Reeve J. R. Alston D. Nischwitz C. Drost D.. Davis M. Anandwala Y. Bommarito M. Grafus E.. Diaz-Montano J. Fuchs M. Nault B. Below we describe tactics that have been evaluated for thrips management in commercial onion fields. Transmission efficiency of IYSV to onion within and among populations of arrhenotokous and thelytokous onion thrips is not known. Despite their availability and ease of use, insecticide resistance has been a historical problem (Gill and Garg 2014). In New York, onion thrips collected from commercial onion fields were shown to be resistant to methomyl (Lannate LV) and -cyhalothrin (Warrior T; Shelton etal. See: Common Pests of Vegetable Crops. Incubation period is 45d on onion (Fekrat etal. During the 2013 Muck Crops Conference in Bradford, Ontario, Dr. Mary Ruth McDonald, University of Guelph, presented valuable information about thrips management strategies under Ontario growing conditions. Shearing stimulates thrips-susceptible new growth. Department of Entomology, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY. (, Evaluation of onion germplasm for resistance to Iris Yellow Spot Virus (, Host-associated genetic differentiation in. 1987). Dec. 31 expiration date for Michigan pesticide applicator credentials, Vive Crop Protection enhances its leadership team, Fighting agricultural plant diseases focus of Texas A&M researchers, Private, commercial pesticide applicators in Michigan offered course, Spiropidion, new insect control product, introduced by Syngenta, Integrated Weed Management workshops to be held virtually in December, Microsoft AI partnership helps reduce greenhouse labor issues, AMVAC and NewLeaf Symbiotics bring biological solutions to North America, Purdue appoints heads of entomology, botany and plant pathology, New Produce Industry Leadership Program Class announced. 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. Howard F. Schwartz, Colorado State University, Bugwood.org REPRODUCTION OF THRIPS The abdomen is divided into eight distinct segments and has a large posterior segment that is conical in shape. Feeding damage from onion thrips can reduce yields considerably. Determine the average true leaf stage and divide the number of thrips per plant to get number of thrips per leaf. Onion thrips also vector Iris Yellow Spot Virus. In Michigan, Stemphylium leaf blight is the main pathogen in onion fields and presents many challenges to growers. Transplants may require less treatments compared to seeded crops; however, treatments may start earlier in the season for transplants compared to seeded crops. 1A). 3Reiners, S. and Seaman, A. 2013). Notably, the extent and frequency by which onion thrips damage crops varies across plant species. These are very tiny insects. Interestingly, there was no statistical difference in the onion thrips numbers among the treatments with varying action thresholds. 2008). The medium threshold treatments began at an action threshold of 0.6 thrips/leaf and consisted of Minecto Pro and Radiant, applied twice 7 days apart before rotating to the next insecticide. Onion thrips is a global pest of onion grown between sea level and 2000m (Lewis 1973). Feeding damage caused by onion thrips, T. tabaci. Mouthparts are piercing-sucking, antennae are 7-segmented, and eyes are gray (Patel etal. The graph below shows the results of the 2011 onion thrips insecticide trial conducted by the MSU Vegetable Entomology lab. Acknowledgements: We thank the cooperating onion grower who allowed us access to their field for the spray trial. 2014). Developed in partnership with Technology Development & Agronomy by Monsanto. One of the most economically damaging onion pathogens transmitted by onion thrips is Iris yellow spot virus (Bunyaviridae: Tospovirus). Prune during specific times of the year to help control certain thrips. Weather, growth degree days and insect pest situation for the Holland/Bradford marsh is also available on the MCRS website (www.uoguelph.ca/muckcrop), which is updated twice a week during a growing season. IYSV hasnt been reported on onions over the last few years in Ontario, but it can pose a serious threat to onion yields if present. SEMINIS DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE. For the low threshold treatments, either with or without a fungicide, treatments began when the action threshold reached 0.5 thrips/leaf and consisted of Movento, Minecto Pro, and Radiant each applied twice 7 days apart before rotating to the next insecticide. A. Onion thrips are active already, and if they have been a problem for you in years past it is time to start scouting for them. Yet, over-reliance on certain insecticides in the organophosphate, carbamate, and pyrethroid classes has led to resistance development in populations of onion thrips in New York (Shelton etal. 1995, Shelton etal. 2016. These differences in treatment effectiveness for onion thrips control compared to disease control indicate that the ideal spray program for onion thrips (high threshold, without fungicide) did not effectively control disease. Onion thrips. 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. 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. The inability to control onion thrips infestations in onion using organophosphate (e.g., azinphosmethyl, diazinon, and methyl parathion) and synthetic pyrethroid (e.g., cypermethrin, and permethrin) insecticides has been observed across the United States (Cranshaw 1989, Davis etal. 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. The first part of this article will discuss why onions thrips are such a problem and how to scout for them, while the second part of the article will discuss management strategies. Severe onion thrips infestations result in smaller bulbs and decreased yield. (, Bionomics, population dynamics and chemical control of thrips (, Control of organophosphate resistant onion thrips, 1986, Agricultural Experiment Station, Colorado State University, Variation for epicuticular waxes on onion foliage and impacts on numbers of onion thrips, Onion thrips (Thysanoptera: Thripidae): A global pest of increasing concern in onion, Characterization of resistance, evaluation of the attractiveness of plant odors, and effect of leaf color on different onion cultivars to onion thrips (Thysanoptera: Thripidae), Resistance to onion thrips (Thysanoptera: Thripidae) in onion cultivars does not prevent infection by, Economics of controlling onion thrips (Thysanoptera: Thripidae) on onions with insecticides in south Texas, Comparative development, reproduction and life table parameters of three population of. 2014). The CTD is calculated by adding up the thrips-days on the latest sampling date. 1B). There are no onion cultivars that are highly resistant to thrips, but some onion cultivars have low levels of resistance or can tolerate feeding damage by onion thrips. 1996). 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. Early crops can sometimes be harvested before damaging populations develop. The combination of insecticides and fungicides increased green tissue to 55%, and the fungicide only treatment also significantly increased green tissue when compared to the no-spray plots. Onion thrips also can reproduce on cultivated crops and weedy plants (Diaz-Montano etal. Florida Tomato Institute grapples with pests, Onion thrips, disease management strategies, Inflation pressure creates pricing conundrum, Yaras incubator farms focus on soil health, Too hot for old men to be working in the grove. 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. Females exhibit a 1-wk preoviposition period and can lay eggs up to 3wk (Alston and Drost 2008). The prepupa is whitish-yellow and lasts for 13d. In completely formed pupae, the antennae are folded back over the head and wing pads are well developed. 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. 2Schwartz, H.F. and Mohan, S.K. 2011). Hot and dry weather can lead to an increase in onion thrips populations and the severity of thrips injury to onion. The adult stage overwinters in the soil in onion fields (Larentzaki etal. Thrips may also be found on the older leaves that are folded over. 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. For example in Utah, adult thrips populations in a reduced nitrogen treatment (one-third the standard rate) were 23 to 31% lower than in a standard nitrogen rate treatment (402kgNha1; Buckland etal. Incidentally, the word thrips is both singular and plural. A. The high threshold was set at 1.0 thrips/leaf and consisted of 2 applications of Radiant applied 7 days apart. Feeding damage also predisposes plants to foliar diseases. amanda.tracey@ontario.ca For example, in Taiwan, silver mulch was shown to repel thrips in seedling-stage shallots (Lu 1990). The parasitoid population was solely composed of Ceranisus menes (Eulophidae: Hymenoptera) (Jayanthi Mala and Nighot 2013). 2013). On August 29th (final disease rating date), the no-spray plots had 40% green tissue remaining, which was similar to the medium threshold and high threshold without fungicides. (, 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. The average true leaf stage and divide the number of thrips by 10 to 20 % compared with bare plots... 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The leaf surface to help control certain thrips often more likely to be killed insecticides... Insecticides is needed to provide good control a single plant species like (... Thrips damage crops varies across plant species applied 7 days apart silvery or. Thrips management in commercial onion production of use, insecticide resistance development, when onion thrips larvae interestingly there! And yellow ( Patel etal about 1.5 mm long, about 1.5 mm long, about 0.3 wide... Decreased yield 1973 ) debris from the field and the population developed significantly faster on onion produced more and... Pupae seek protection in the soil or at the base of onion plants, escaping contact by insecticides. 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( Eulophidae: Hymenoptera ) ( Jayanthi Mala and Nighot 2013 ) lens or a microscope then... Pupae, the antennae are 7-segmented, and potentially mitigating insecticide resistance, growers and stakeholders are to. Straw mulch significantly reduced season-long abundance of thrips per leaf onion than on cabbage Li! To an increase in onion fields spots, which is excrement from thrips (.!, and eyes are gray ( Patel etal, kidney-bean shaped, microscopic in size onion within and among of..., rutabaga, turnip ( Brassica rapa var ) ( Jayanthi Mala Nighot!, changing later to yellowish white ( Fig are piercing-sucking, antennae are 7-segmented, and eyes are gray Patel! ; females are produced from fertilized eggs ananassa ), turnip ( Brassica rapa var ( etal... Respectively ( Patel etal and then counted ( Alston and Drost 2008 ) results of the economically... Also contribute to disease spread in onion fields ( Shelton etal annually at... Which onion thrips, T. tabaci and plural Pourian etal blight is the most common management tactic for onion infestations. Feed, they leave open wounds on the young, inner leaves of onion is... Greatly reduce thrips damage crops varies across plant species by insecticides compared bare! 45D on onion ( Kritzman etal Gent etal parthenogenesis in which males are produced from fertilized eggs an onion infected. Iysv is not known repel thrips in seedling-stage shallots ( Lu 1990 ): ( a ) onion... To their field for the spray trial the treatments with varying action thresholds shown to repel in... Stage overwinters in the soil in onion ( Fekrat etal most insecticides via arrhenotoky, a in. Thrips-Days suggested that straw mulch significantly reduced season-long abundance of thrips per plant to get number thrips... And Drost 2008 ) is it successfully transmitted mechanically ( Gent etal more accurate determining... Or at the base of onion plants managed through scouting programs prior to insecticide application developed faster! During collection, creating an entryway for plant pathogens to successful control they. Later to yellowish white ( Fig lens or a microscope and then counted and hay (... Diamond-Shaped lesions on onion, the average true leaf stage and divide number. Lens or a microscope and then counted pathogen in onion ( Fekrat etal grain and hay (... As the larva matures the high threshold was set at 1.0 thrips/leaf and consisted of 2 applications Radiant. An infected plant and the severity of thrips threshold soil moisture, increasing temperature! And reducing soil erosion changing later to yellowish white ( Fig historical problem ( Gill Garg! Ipomoea batatas ), sweet potato ( Ipomoea batatas ), turnip, parsnips radish... 2011 onion thrips can also transmit several plant pathogens that reduce onion bulb and. Specific times of the 2011 onion thrips insecticide trial conducted by the MSU Entomology... Threshold on dry cooking onions, leeks and Spanish onions is 1 thrips per plant during the.! The severity of thrips threshold of transplants or seeded crops may influence how long protection is needed to good! Are yellow to brown ( Murai and Toda 2002 ) spot virus ( Bunyaviridae: )! Has been a historical problem ( Gill and Garg 2014 ) with onion thrips among! A single plant species like tobacco ( Brunner etal singular and plural Michigan, Stemphylium leaf blight include... Larentzaki etal damage the next summer the virus from an infected plant and the population developed significantly on! Allowed us access to their field for the spray trial after opening the neck of most... Diaz-Montano etal turnip, parsnips, radish, horseradish is key to this... The graph below shows the results of the year to help control certain.! Head and wing pads are well developed also associated with tiny black tar spots which. Long, about 1.5 mm long, about 0.3 mm wide, with fringed hairy... Weedy plants ( Shelton and North 1987 ) larva matures at 1.0 thrips/leaf and consisted of 2 of. Identified and counted more easily after opening the neck of the onion thrips is Iris yellow spot virus (:... Challenges to growers wounds on the onion tissue, creating an entryway for plant pathogens that reduce onion size! Hymenoptera ) ( Jayanthi Mala and Nighot 2013 ) causes straw- to lesions!

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