{"id":2271,"date":"2019-07-16T17:31:44","date_gmt":"2019-07-16T09:31:44","guid":{"rendered":"https:\/\/www.agrinoon.com\/agriculture\/?p=2271"},"modified":"2019-07-16T17:31:44","modified_gmt":"2019-07-16T09:31:44","slug":"corn-seed-blend-refuge-isnt-effective-option","status":"publish","type":"post","link":"https:\/\/www.agrinoon.com\/agriculture\/2019\/07\/16\/corn-seed-blend-refuge-isnt-effective-option\/","title":{"rendered":"Corn seed blend refuge isn\u2019t the most effective option"},"content":{"rendered":"<div><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/img.agropages.com\/UserFiles\/FCKFile\/zkc_2019-07-15_07-28-57_173.jpg\" alt=\"\" width=\"600\" height=\"450\" \/><\/div>\n<div><em>Using a seed blend refuge is not as good as a structured refuge, but it can slow the development of resistance. ( Farm Journal )<br \/>\n<\/em><\/div>\n<div>Since 1996, corn and cotton farmers have rapidly adopted the use of Bt crops. They could plant and rest, knowing the Bacillus thuringiensis (Bt) protein would protect their crop from hungry insects. However, Bt is losing its power.<\/p>\n<div>\u201cWe never expected these Bt crops to last forever \u2014 we knew insects would gain resistance,\u201d says Pat Porter, Texas A&amp;M Extension entomologist. \u201cWe use refuge to slow it, and we made it to our 20-year goal for most pests. Now we\u2019re seeing more and more resistance.\u201d<\/div>\n<div><\/div>\n<div><strong>Mother Nature Always Finds A Way<\/strong><\/div>\n<div><\/div>\n<div>When it comes to insect resistance it\u2019s not \u201cif\u201d it happens but when. Matthew Carrol, Bayer head of corn insect resistance management, recommends these practices to help slow insects\u2018 evolution:<\/div>\n<div><\/div>\n<ul>\n<li>Use pyramided traits for a multi-pronged defense.<\/li>\n<li>Make refuge a priority so susceptible pests breed with resistant pests.<\/li>\n<li>Consider options specific to the pest. For example, rotate crops if dealing with corn rootworm.<\/li>\n<\/ul>\n<div>\nIt\u2019s important to be careful when using insecticides to treat pests as they can develop resistance, too. Carroll says your best bet is to apply an over-the-top insecticide evenly across the field and to monitor it for escapes.<\/div>\n<div><\/div>\n<div><strong>Something is Better Than Nothing<\/strong><\/div>\n<div><\/div>\n<div>\u201cThere have been multiple studies based on computer models that show seed blend refuge can slow the development of resistance when compared to no refuge at all,\u201d Porter explains. \u201cHowever, the same studies also show that block refuges are superior to seed blend refuges in slowing the development of resistance.<\/div>\n<div><\/div>\n<div>\u201cBut, we know the compliance with structured block refuge is very low, so the argument is if growers aren\u2019t going to plant the best kind of refuge we\u2019re better off if they use the lesser refuge than nothing at all,\u201d he adds.<\/div>\n<div><\/div>\n<div>Who\u2019s on the hook for non-compliance? Seed companies. EPA has an agreement with seed companies, who are responsible for enforcing refuge requirements with their growers. There is no financial penalty.<\/div>\n<div><\/div>\n<div>Certain experts suggest seed blend refuge has more benefits than just grower compliance.<\/div>\n<div><\/div>\n<div>\u201dSeed blends distribute refuge plants randomly throughout the field, which improves the mixing of adult susceptible insects coming off non-Bt plants and those rare resistant insects coming off Bt plants,\u201c says Tim O&#8217;Brien, Syngenta commercial traits manager. \u201dSecondly, because refuge plants are interspersed randomly throughout the field, growers are forced to manage the field as a whole unit, and any insecticide application is equally applied to Bt and non-Bt plants.\u201c<\/div>\n<div><\/div>\n<div><strong>Resistance is Spreading<\/strong><\/div>\n<div><\/div>\n<div>For corn earworm\/cotton bollworm, there\u2018s only one remaining effective in-plant mode of action, Vip3A, to control the pest. However, the Vip3A trait has confirmed resistance in fall armyworm.<\/div>\n<div><\/div>\n<div>While there is no known resistance to Vip3A in field populations of corn earworm, individual insects collected from the field and tested in the lab have been found to have some level of resistance. So, the genes for resistance are in the wild populations. (Turn to page 16 to learn more about corn earworm\/cotton bollworm resistance.)<\/div>\n<div><\/div>\n<div><strong>Blended Refuge Increases Risk<\/strong><\/div>\n<div><\/div>\n<div>Porter fought against seed blend refuge in 1996, and today he still sees hazards.<\/div>\n<div><\/div>\n<div>Partially resistant insects \u201dcan move from plant to plant and live to reproduce, potentially spreading resistance,\u201d he says. \u201cThe risk we see with seed blend refuge is this big question: How dangerous are the single toxins expressed in non-Bt refuge ears that have been cross pollinated by Bt pollen? We know the toxins are now expressed at lower doses in these ears and might be accelerating resistance. That\u2019s what scares us all.\u201d<\/div>\n<div><\/div>\n<div>\u201d[Seed blend refuge] provides built-in refuge compliance,\u201d EPA explains. \u201dHowever, block refuge, when followed, is more effective for ear-feeding pests, such as corn earworm.\u201d<\/div>\n<div><\/div>\n<div><strong>Bt Traits Aren\u2019t All Equal<br \/>\n<\/strong><\/div>\n<div>For certain insects, Bt proteins are high dose, which means they kill almost all of the pests. The only survivors would be those with two resistance alleles, says Pat Porter, Texas A&amp;M Extension entomologist.<\/div>\n<div><\/div>\n<div>Scientists estimate there should only be one in 1,000 or even 10,000 insects with the resistance allele. However, their offspring would be unlikely to survive because they would likely be heterozygous, meaning they have one resistant and one susceptible allele and would be killed by the high dose.<\/div>\n<div><\/div>\n<div>\u201cMost older Bt toxins are high dose for European corn borer, and they have held up for 20 years,\u201d Porter says.<\/div>\n<div><\/div>\n<div>However, for many pests the Bt toxin isn\u2019t a high dose, which means even a single resistant allele might allow the insect to survive. For example, armyworm has resistance to multiple traits on the market that once controlled the caterpillar.<\/div>\n<div><\/div>\n<div>\u201cIf you grow Bt crops and see unacceptable pest populations you need to spray them with insecticide. What happened recently with western bean cutworm is a great example,\u201d Porter says. \u201cFarmers weren\u2019t checking their fields because they didn\u2019t think or know they needed to. It was disastrous, and now farmers are scouting in areas with resistance to the Cry1F and Vip3A traits.\u201d<\/div>\n<div>\n<div class=\"tl clearfix mt10\">\n<h4 class=\"p-source c-999 cb pt5\"><span style=\"color: #000000;\"><strong>Source<\/strong>:\u00a0<a class=\"c-orange fs16\" style=\"color: #000000;\" href=\"http:\/\/news.agropages.com\/Media\/MediaIndex-53.htm\" target=\"_blank\" rel=\"noopener noreferrer\">Ag Professional<\/a><\/span><\/h4>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Using a seed blend refuge is not as good as a structured refuge, but it can slow the development of resistance. ( Farm Journal ) Since 1996, corn and cotton farmers have rapidly adopted the use of Bt crops. They could plant and rest, knowing the Bacillus thuringiensis (Bt) protein would protect their crop from&hellip; <a class=\"more-link\" href=\"https:\/\/www.agrinoon.com\/agriculture\/2019\/07\/16\/corn-seed-blend-refuge-isnt-effective-option\/\">Continue reading <span class=\"screen-reader-text\">Corn seed blend refuge isn\u2019t the most effective option<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-2271","post","type-post","status-publish","format-standard","hentry","category-industry-news","entry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.6 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Corn seed blend refuge isn\u2019t the most effective option - agrinoon<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.agrinoon.com\/agriculture\/2019\/07\/16\/corn-seed-blend-refuge-isnt-effective-option\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Corn seed blend refuge isn\u2019t the most effective option - agrinoon\" \/>\n<meta property=\"og:description\" content=\"Using a seed blend refuge is not as good as a structured refuge, but it can slow the development of resistance. 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