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13SUMMER 2015 SPUDSMART.COM tested and evaluated in Canada for many years in experimental plots with good results says Noronha. In addition field trials of insecticide efficacy carried out in 2014 also provided data supporting Captures suppression of wireworm damage. For example marketable yield was 26.9 metric tonnes per hectare from Capture-treated plots 28 metric tonnes per hectare from Thimet-treated plots and 23.25 metric tonnes per hectare from untreated check plots see Table 1. All tubers were evaluated based on processing industry standards. Of the seven insecticides evaluated in the field trials by Noronhas team only one other experimental product showed significant wireworm damage suppression in addition to Capture and Thimet. Marketable yield of plots treated with Ethoprop an organophosphate insecticide not currently registered for use in Canada was 26.6 metric tonnes per hectare. Bifenthrin is a pyrethroid insecticide that acts by creating a protective zone around the mother and developing daughter tubers. Bifenthrin remains active in the soil for an extended period of time protecting tubers for the growing season. The insecticide has been used for many years and on millions of acres in the United States and other countries. According to McMillan Captures use this season will expand dramatically from the approximately 5000 acres put down in Prince Edward Island in 2014 he says to include potato-growing areas in Western Canada Ontario and Quebec. DONT DRIBBLE Meanwhile whether or not bifenthrin will be the answer for wireworm damage control in 2016 and beyond is going to depend on producers says Bob Vernon who heads up AAFCs national wireworm research project and is one of Canadas leading wireworm experts. Bifenthrin may in fact work differently in its effectiveness to Thimet in that bifenthrin has a large repellent component to it which might be driving wireworms away from the planted rows of potatoes he says. That opens up a certain amount of variability with bifenthrin use farmers will be in control to a certain extent of the effectiveness of bifenthrin more so than with Thimet. Dribble application of Thimet is well established and consistent from farmer to farmer. Bifenthrin on the other hand should not be dribbled in. It must be sprayed on both sides of the furrow at planting and the variability in bifenthrins application width of furrow amount of water applied coverage area makes all the difference to its effectiveness. The wider the furrow at planting and the better coverage of that larger open furrow with bifenthrin the better chance farmers will have of repelling wireworms from the area where the daughter tubers will ultimately be formed says Vernon. The idea he says is to set up what is essentially a force field that is as wide as possible at the time of planting. Narrower furrows will result in smaller force fields which the daughter tubers can grow outside of and are then susceptible to wireworm damage. Give it a good shot this year. Apply the bifenthrin in a wide furrow with lots of water spray on both sides and use that as your comparison with Thimet. If youre not willing to apply it as prescribed then dont bother because youll lose potatoes says Vernon. STUNNING EVIDENCE Although Capture protects marketable yield with comparable results to Thimet one important question remains does it kill wireworms Laboratory results conducted by Noronha indicate Capture does not kill wireworms but stuns them while they are in contact with the insecticide. Capture paralyzes them and as soon as you take them out of the soil with Capture in it they come back to life and start moving again pretty quickly she says. It does reduce damage for processing it does increase marketable yield so there is suppression of the number of holes and scars per tuber. Its not necessarily controlling the population. TUBER YIELD WITH NO DAMAGE MTHA UNMARKETABLE YIELD MTHA MARKETABLE YIELD MTHA MEAN NUMBER OF BLEMISHES PER TUBER Check Untreated Plot 0 5.5 23.25 18 Capture 1.5 1.9 26.9 8 Thimet 1 1.8 28 7 Experimental Product Ethoprop 3 1 26.6 5.5 Table 1. Insecticide Trials 2014 SOURCE WIREWORM RESEARCH UPDATE BY CHRISTINE NORONHA. FOUR REPLICATES PER INSECTICIDE. ALL TUBERS EVALUATED USING PROCESSING INDUSTRY STANDARDS. RUSSET BURBANK POTATOES AFTER IN-FURROW APPLICATION OF INSECTICIDE. Processing Industry Standards Holes and scars are removed. If the tuber loses more than five per cent of its weight it is considered unmarketable for the processing industry. We evaluated tubers from farmers who used Capture on their farms. It seemed to work. Overall I think farmers were satisfied with it. CHRISTINE NORONHA Tuber exhibiting wireworm damage. PHOTO BOB VERNON AAFC.