Issue link: http://read.dmtmag.com/i/643470
8 MARCH 1, 2016 Good Fruit Grower www.goodfruit.com Yee conducted several tests under varying tempera- tures and number of days and with piles uncovered or covered with tarps. Early results were promising on pupae deep in the pile, but he found that killing pupae near the surface of the pile was more challenging. So, he applied reflective insulation to keep the heat in the pile and came up with his best results: After nine days, 100 percent of the pupae died in a pile covered with reflective insulation, with temperatures reaching 102°F at the surface, 111°F at 5 centimeters deep and 137°F at 46 centimeters deep, despite the test being done in December when mean ambient tempera- ture was 36.5°F. Yee also tracked oxygen levels in the pile. Ambient air is 21 percent oxygen by volume; as expected, he found that oxygen levels declined deeper in the pile. "Oxygen levels may have had something to do with it too, but it's mostly heat, I suspect, so pupae in and on the surface of waste piles can be killed by biogenic heat," he said. "Insulating ground yard waste piles with a tarp or a tarp and additional insulation may be a simple, inex- pensive way of killing apple maggot pupae during cold months at waste transfer stations." Next steps Washington officials hired three experts to gather information — including the results of Yee's research — and study the threats composting facilities could pose to the state's commercial apple industry. Those results of that overall study are due this spring. These preliminary research results are promising, said Jon DeVaney, president of the Washington State Tree Fruit Association, but there remain many unanswered questions about risks to the industry: Will this be tested on a commercial composting scale? Will the composting industry and regulators accept and follow scientific guidance? Will yard waste be treated before being transferred to pest-free zones? Who will reg- ulate and ensure intensive monitoring for apple maggot in pest-free zones, and who will pay for it? Dr. Mike Willett, manager of the Washington Tree Fruit Research Commission, also stressed that Yee's research results are preliminary. "More work and thought will have to be given as to how best to replicate conditions encountered in feed stock piles," he said. "Also, in my experience, the number of insects tested may have to be substantially higher." In previous work to validate quarantine treatments, such as for the fumigation of spotted wing drosophila in cherries to Australia, USDA researchers treated 30,000 fruit infested with pests that were at their most resistant phase in the life cycle. "As Wee noted, his work used fewer than 100 pupae per treatment," Willett said. "The promising news was that 100 percent mortality appears to be possible." • Apple maggot, worries spread in Michigan A pple maggot infestations seem to be on the increase in Michigan, so growers should have a summertime control program ready this year, reported Michigan State University entomologist Dr. Larry Gut at the December Great Lakes Fruit, Vegetable and Farm Market EXPO. Numbers do appear to be on the rise, agreed Mike Haas, Michigan State University research assistant at the Trevor Nichols Research Center in southwestern Lower Michigan. "We have some evidence that they are becoming more prevalent, and that is primarily from adult catches on baited spheres," he said. He has not yet completed a comparative analysis to provide a percentage population upturn, but indicated that the numbers have been "increasing moderately" over the past few years. The upward trend in adult apple maggots probably relates to changes in control measures, Haas said. "When Guthion dropped out of the list of chemicals you could use for apple maggot, I think that had an impact. A lot of the newer materials aren't adulticides." Specifically, he mentioned that some of the neonicotinoids can kill the larvae and eggs of apple maggots, but aren't as successful against adults. Likewise, many diamides are listed for apple-maggot suppression only. He added, "The big picture is we're losing materials that have been very good against apple maggot, and while the injury in apples has not become a problem, it looks like it's a possibility that populations are building among adults, and it could potentially become a bigger problem for growers." For the coming season, Haas said several materials can do a good job against apple maggots, and Gut sug- gested the use of such pesticides as Assail (acetamiprid) and Imidan (phosmet) against the insects when they arrive in orchards during the summer. "The most important thing is to base the start of your apple-maggot program on monitoring," Haas remarked. He added, "Use either yellow, ammonium-baited sticky cards (early) or red sticky spheres baited with a fruit essence blend (anytime). Check regularly starting at the end of June or when 900 degree-days have accumu- lated." He noted that several applications will probably be necessary. —Leslie Mertz Results prove that applications of Stimplex increase tree fruit production and support the ability for young fruit to grow and better hold on to the tree. In fact, well-timed, regular applications of Stimplex are vital to maximizing the genetic potential of your crop. Get Stimplex in your mix today. Contact your local crop advisor or Stimplex representative. 1 800 575 9100 | INFO@ACADIAN.CA | ACADIANSEAPLANTS.COM ©2016 Acadian Seaplants Ltd. Stimplex Crop Biostimulant is a registered trademark of Acadian Seaplants Ltd. Here comes the Bloom. Get set with Stimplex. ®